There are so many herbal medicines that it is impossible to cover them all, but many basic principles can be discussed. This section contains the following headings:
- Background to Herbal Medicines
- Poppy Juice
- St John’s Wort
- Evening Primrose Oil
- Aloe Vera
- Chamomile or Camomile
- Herbal Remedies to Aid Weight Loss
- Professional Regulation
- Further Resources
- Site Index
This is a long list but by no means exhaustive. If you wish to go directly to any heading, click on the title in blue above. If you are unable to find the topic that you want, it may be in the next chapter Other Natural Products which includes a section on medicinal cannabis. Cannabis as a recreational drug is not discussed.
The question is not whether some herbal products have a pharmacological effect. It would be most surprising if they did not, considering the origin of many drugs. The question is whether they offer treatments that are better or safer than conventional medicines or if they should be consigned to history, along with blood-letting, mercury and arsenic. Evidence of efficacy will be discussed along with the claims that are made for them and problems of toxicity. This section will explore the history of herbal medicines. It will examine a number of herbal substances and look at herbal treatments for diabetes. It will conclude with an overview of the place of herbal remedies in the 21st century, including licencing, dosage and reliability of the substance sold. There will also be a number of examples of advertisements for medicines from years gone by. Today they may seem quite shocking.
Background to Herbal Medicines
Herbal remedies have been used for millennia. The Ancient Egyptians used them as did the Greeks, the Romans and the Druids. There was often a degree of secrecy about them, probably for commercial reasons. It may have been priests or the “wise women” who often also acted as midwives who used them. They also knew about poisons. In the Middle Ages, the wise women had to be careful not to be accused of witchcraft. Socrates was sentenced to death in 399BC and had to drink a cup of hemlock.1The Suicide of Socrates The precise effects of the hemlock were accurately described by his pupil Plato. Ellis Peters wrote a series of Cadfael novels about a 12th century monk who was an expert on herbal remedies.
Nicholas Culpeper (1616-1654) was an English botanist, herbalist, physician and astrologer. He wrote The English Physician (1652) and the Complete Herbal (1653). He should not be confused with Thomas Culpeper who was executed for adultery with Katherine Howard, the fifth wife of Henry VIII. The works of Nicholas Culpeper are extensive and are still regarded as a source of reference.2The Complete herbal by Nicholas Culpeper 1653 The Chelsea Physic Garden was founded in 1673 by the Worshipful Society of Apothecaries for the study of useful plants. It continues to have links with the Royal College of Physicians, and they have a Garden Fellow and advisor to the Chelsea Physic Garden.
There is sometimes an assertion that the pharmaceutical industry spends billions of pounds each year on research and development of drugs that are of dubious value and often toxic whilst herbal remedies offer a “natural” solution which, being natural, is 100% effective and 0% toxic. If this was true, the industry would simply revert to selling herbal products with far fewer expenses and much more profit. The suggestion that there is no profit to be made because natural products cannot be patented is untrue. The purification process may be patented, or the molecule can be improved, and this is patented. However, the use of herbs for treatment of disease is not as simple as it may seem.
Despite the “natural” tag, we must remember that there are very many highly toxic poisons in nature. Just because a substance has been used for a long time, does not mean that it is either effective or safe. Blood letting was used for a great many centuries as a supposedly effective and logical treatment. Herbal remedies require Randomised Controlled Trials just as much as any other pharmacological product. This may require putting the ingredient into a capsule of tablet to disguise the taste. As with medicines, both efficacy and toxicity must be tested.
Herbal products also tend to have a problem of batch to batch variation and this can be very difficult to control, especially as there may be more than one active ingredient. This makes it very difficult to know the correct dose. An inadequate dose is useless, whilst an excessive dose is toxic. There is an adage that the difference between a medicine and a poison is the dose.
Belladonna atropina or deadly nightshade was the origin or the drug atropine.
Bella donna is Italian for “beautiful lady”. Women used to put the juice in their eyes to dilate the pupils to enhance their allure.
The Traditional Herbal Medicine Registration Scheme came into effect in the UK on 1st May 2011. This means that the quality and safety of herbal medicines bearing a Product Licence (PL) or Traditional Herbal Registration (THR) number, has been assessed by the Medicines and Healthcare products Regulatory Agency (MHRA). In the UK, the first THRs were granted in 2006 and almost 200 had been granted by the end of 2012. This is an index of quality control in batch preparation and if anyone seeks to buy herbal remedies it is wise to look for this. However, it does not mean that they have been tested for efficacy and everything else that is required of a pharmaceutical product. It is no guarantee that it works. In the United States, herbal products may be marketed only as food supplements. No specific health claims may be made without approval of the Food and Drug Administration (FDA).
To believe that herbal remedies are “natural” and hence without toxicity is naïve. They have usually been much less investigated than conventional medicines. Therefore, there is much less evidence about both efficacy and toxicity. Liver damage from herbal remedies is well documented. They may also have interactions with one another and with prescribed drugs. Dosage is often a problem. Many people regard green tea as having health giving properties and, in moderation, they may be right. However, there is often a feeling that if something is good, even more is even better. Green tea in excess can be toxic with problems including liver damage.3Safety of green tea extracts
Perhaps the most feared adverse effects of any medicine is teratogenicity. This is the ability to cause abnormalities in babies if taken in pregnancy and the first three months when the organs are forming is the most vulnerable time. There is no reason to assume that herbal remedies are any safer than conventional drugs4Are herbal medicinal products less teratogenic than Western pharmaceutical products. and they should be avoided in pregnancy.
There are so many herbal remedies that it is impossible to discuss them all. Therefore, a limited number have been chosen for further discussion. The next sections examine drugs that have their origins as herbal remedies but since then, they have been improved on.
Digitalis was first used by William Withering in 1785 to treat the dropsy although its use may go back to the Romans. Dropsy is swelling of the body, especially the lower limbs, usually due to heart failure. Digitalis makes the heart pump more forcibly. It comes from the foxglove, Digitalis purpurea, although a better source is Digitalis lanata. In 1875 the German chemist Oswald Schmiedeberg first isolated pure digitoxin from digitalis.
Nowadays it is possible to get digoxin tablets which offer far greater reliability of dose than digitalis leaf and a longer shelf-life. However, the ratio of therapeutic dose to toxic dose is so low that if it had been produced in the last 60 years, it would have been refused a product licence. As it has been around much longer and there is no alternative, it remains.
Around 400BC in Ancient Greece, Hippocrates is said to have given a tea of willow leaf to women in labour to help pain. The active ingredient we now call aspirin. It sounds rather like giving an aspirin to help the pain of childbirth, which is unimpressive compared with the modern choice of pethidine. In 1763 the Reverend Edward Stone of Chipping Norton near Oxford gave dried willow bark to 50 parishioners suffering from rheumatic fever. This is probably the first documented use of aspirin. It is effective as a pain killer, it lowers temperature in a fever and it also has an anti-inflammatory effect, which is useful in rheumatic fever which is a disease we do not see in Britain these days. It was the first of a class known as non-steroidal anti-inflammatory drugs (NSAIDs).
At the end of the 19th century the German pharmaceutical firm Bayer led the way in producing acetyl salicylic acid or Aspirin. I use a capital letter as Aspirin was a trade name. It was derived from “A” for acetyl, “spir” as it originated from Spiraea ulmaria the Linnaean or Latin name for herb meadowsweet and “in” as a suffix of a drug name.5The history of aspirin Salicylic acid was found in the meadowsweet flower as well as the willow. It was called “salicylic acid” as the willow tree is Salix alba in Latin. It is very useful in mild pains and fever as with colds or influenza but should not be used below the age of 12 in case of a rare, but serious complication called Reye’s Disease. It is used much less for pain and fever but much more in the prevention of coronary heart disease or strokes. It impairs the action of platelets and has an anti-inflammatory effect.6Aspirin and other anti-platelet drugs The best known side effect is irritation of the stomach causing erosion and sometimes severe bleeding.
The German pharmaceutical company, Bayer extracted salicylic acid from coal tar. They found that it reduced fever but it was very irritating to the stomach. Therefore they tried adding the acetyl group and this improved matters although aspirin is still rather irritant. However, it seems that only when the acetyl group was added was its analgesic (pain-relieving) property noted. This makes me even more sceptical about Hippocrates using willow leaf tea for the pain of labour. In rheumatic fever, willow bark would have reduced fever. I do not know if it would have reduced inflammation but it would not have helped pain.
Another drug that reduces fever is quinine. It comes from the bark of the chinchona tree that is native to the Andes, from Costa Rica to Bolivia. During the 17th century Jesuit missionaries noted the anti-malarial properties of chinchona and brought the knowledge to Europe. The old term ague could just mean a fever, but it usually referred to malaria which was prevalent in the fens and even in Westminster. However, malaria was much more of a problem in the Empire. There was great demand for the drug but only South America produced it until the first British and Dutch plantations were established in the mid-1800s and it was cultivated in India.7History of Quinine and its use Against Malaria
Its bitter taste was a problem in making it acceptable to take daily to prevent malaria and so it was added to a carbonated drink. Hence the origin of Indian tonic water. It was then found to be a very suitable vehicle for gin. Quinine is now synthesised artificially and related products such as chloroquine have been developed.
If you go to a malaria area, take the recommended anti-malaria tablets. Advice will depend on local patterns of resistance. You would have to drink a very large amount of gin and tonic to get an adequate dose of quinine.
Poppy seed juice has long been known for its pain relieving properties. It has been cultivated by many ancient civilisations. It also gives a sense of euphoria which helps to overcome severe pain but in the absence of pain may lead to addiction. Opium contains about 12% morphine. Morphine was first isolated in 1804 by the German pharmacist Friedrich Sertürner, who named it morphium after Morpheus, the Greek god of dreams. Morpheus was the son of Somnus, the God of Sleep. It was not until the development of the hypodermic needle in 1853 that its use spread. Codeine is related to morphine and diacetyl morphine or diamorphine is a form that is more potent and more soluble.
The German firm Bayer sold diamorphine under the trade name Heroin. It was named after the Greek Hero as it produced euphoria and a sense of wellbeing. After the First World War, Bayer lost the rights to both Aspirin and Heroin as part of war reparations. What we now call heroin is an illegal concoction of morphine and diamorphine “cut” with all sorts of muck. Diamorphine is a fine white powder that is very soluble. Heroin is usually brown and forms a suspension rather than a clear solution.
At the end of the 19th century, drugs such as morphine, heroin and cocaine could be bought over the counter. Since then, with international cooperation, we have had the Dangerous Drugs Act and the Misuse of Drugs Act. This included the Opium Convention in The Hague in 1912 and the Defence of the Realm Act of 1916 to curb the use of cocaine by soldiers in London on leave from war service.8History Learning Site. Defence of the Realm Act
Cocaine also comes from South America. It was used in the Andes to combat pain and fatigue. Pure cocaine was first extracted in Europe in 1860. In the First World War it was given to soldiers to reduce fatigue on forced marches. The local anaesthetic properties of cocaine were recognised but it is rarely used now as related synthetic drugs such as lidocaine are preferred. Crack cocaine has a more rapid euphoric effect and so is even more addictive. Cocaine impairs the re-uptake of noradrenaline by sympathetic nerves and so has a marked effect in constricting blood vessels. People who sniff a lot of cocaine may find that this closing down of blood vessels in the septum of the nose (the part that separates the nostrils) leads to damage and death of tissue so that the septum may slough off and there is nothing left between the nostrils.
In 1902 Coca Cola changed its recipe to replace cocaine with caffeine. Back then it really did contain “coke”.
Curare is another drug from South America. Natives from the Amazon and Orinoco river basins found that they could concentrate the poison from the plants and then dip the tips of darts in it before shooting them with blowpipes. The plant Strychnos toxifera produces the strongest type of curare for the hunters of the rainforests. The poison from this and other plants causes temporary paralysis of muscles.
Tubocurarine is related and was introduced into medical practice in the early 1940s. For surgery on the abdomen, it is better to have a lighter anaesthetic and reversible muscle paralysis to give good relaxation of the abdominal muscles.
Penicillin was derived from the fungus Penicillium notatum. It is now synthesised and there are a number of synthetic or semi-synthetic variants that have such advantages as being resistant to stomach acid, being effective against a different range of bacteria and being resistant to the enzyme penicillinase that some bacteria produce which destroys penicillin.
The story of Sir Alexander Fleming finding Penicillium on an agar plate when he returned from holiday is well known. He recognised the significance but it took the efforts of Howard Florey and Ernest Chain to enable industrial production, to make the vision real.
Back in the 1970s, I met a doctor who had been the ship’s surgeon on a destroyer during the Second World War, and he had been in charge of the entire ship’s supply of penicillin which was kept locked away. It was 10,000 units. In the 1970s, a megaunit or 1,000,000 units, which is 100 times the whole ship’s supply, would have been a single penicillin injection.
Streptomycin is an antibiotic produced from Streptomyces griseus, a bacterium found in the soil. It was the first antibiotic to be effective against tuberculosis. There are now several other related synthetic antibiotics such as neomycin, gentamicin and kanamycin.
Nowadays we are facing an enormous problem of resistant and multiply resistant bacteria, due principally to the injudicious use of antibiotics. The search is on for new drugs or different approaches. One possibility is phages or bacteriophages which are viruses that kill bacteria. Another promising area is kelp, a common form of seaweed with the Latin name Laminaria ochroleuca. It harbours a range of actinobacteria, which have proved a rich source of antibiotic and antifungal drugs. I have not given a reference as it is a rapidly advancing field and your own search may produce something more up to date.
The bacterium Clostridium botulinum produces a very deadly toxin that paralyses muscles. It is one of the most potent poisons known. It used to be seen as a potential risk of home bottling of fruit. It was discovered in 1820. A very dilute form is used in Botox which is injected into the face to cause paralysis of the local muscles to take out wrinkles. As well as being used extensively in the “anti-aging industry”, injections can be used to treat nervous tics, strabismus (squint) and blepharospasm (incontrollable blinking). It can also be used for an overactive bladder. The effect lasts about three months but it can be repeated again and again.
Senna is a laxative. There are many other examples including cascara and rhubarb. All these drugs have been discovered in nature and improved on by man. Senna is still used at times to treat constipation, although a stool softener is usually preferred, rather than something to increase the peristalsis or propulsion of the muscles of the wall of the bowel. A soft motion is easily moved along. Excessive stimulation of the bowel muscles will cause spasm and pain.
Liquorice was found to benefit gastric ulcers and heartburn. However, it can cause a low blood potassium level, water retention with swollen ankles and possibly high blood pressure. Nowadays it has been replaced by more effective remedies. It has also been recommended for psoriasis, canker sores, irritable bowel syndrome, high cholesterol, muscle cramps, cancer pain, arthritis, bleeding, stomach ulcers, and many other conditions. However, the evidence is that in these conditions, it is ineffective.9Liquorice, drugs.com
St John’s Wort
St John’s wort is also called hypericum. Wort is pronounced as wert. It is named after John the Baptist, whose feast day is on 24th June when daylight is long and the plant is in full bloom. Its five yellow petals resemble a halo, and its red sap symbolises his blood. He was beheaded after criticising the morality of King Herod and his wife. The story of Salome dancing for Herod and his guests is well known. He offered her anything she named up to half of his kingdom but her mother made her ask for the head of John the Baptist on a plate.10(Gospel according to Mark. Chapter 6 verses 17-29) Wort comes from Old English from around AD900 along with old German and Norse and it means a plant. The name Hypericum comes from the Greek, meaning “greatest health”.
Many artists have been inspired by the story of Salome asking for the head of the Baptist. She does not look very pleased by her gift.
The picture by Caravaggio hangs in the National Gallery in London
It has been used for centuries, if not for a couple of millennia, for depression and anxiety. It is also said to have antibiotic properties and may be effective against the herpes virus. It is commonly used in Germany. The flowers and leaves of the plant Hypericum perforatum are used. They contain many different compounds including hypericin, which is thought to be one of the compounds with pharmacological properties. These compounds are extracted from the plant with alcohol.
Some of the proprietary preparations are standardised for hypericin, making them more consistent than products that are not. It is possible and even likely, that other ingredients in the preparation have some effect on depression but as they are not standardised this is likely to be variable between batches. Different brands will have different amounts of hypericin and other ingredients, so it is best to choose a standardised brand and to stay with the same brand.
St John’s wort looks promising as a treatment for mild to moderate depression but it is uncertain if it is effective at all in severe depression. There have been comparisons with other antidepressants but usually the older ones. These studies have been fairly positive, indicating that it helps depression and possibly has fewer side effects. Unfortunately the trials have been for short periods such as 4 or 8 weeks, and so it is uncertain how well St John’s wort will compare in terms of efficacy and adverse effects over a longer period of use. The numbers in such studies have tended to be small. Larger, more powerful trials are required.
A Cochrane review from 2008 found the evidence inconsistent.11St John’s wort for depression The variability of the potency of doses remains a problem. Studies from Germany where it is used more extensively were consistently more positive, suggesting bias. The Germans tend to be very uncritical in their acceptance of CAM. It was more effective than placebo and often as good as standard antidepressants but with less subjects dropping out because of side effects. However, nowadays “talking therapies” rather than drugs are often preferred for mild to moderate depression.
The mode of action of St John’s wort is unknown. It is thought that it may affect serotonin, noradrenaline and dopamine uptake. These are nerve transmitters in the brain. The usual recommended dose is about 900mg a day of hypericum extract.
If anyone were to apply for a product licence to register it as a pharmaceutical preparation, it would be refused as the present level of evidence is too sparse although this is one of the best researched herbal remedies. The dearth of good evidence for it shows how very poor is the evidence behind other herbal products. It is probably better in depression with an element of anxiety. The orthodox antidepressants have a number of indications other than the treatment of depression, such as enhancing the effect of morphine in severe pain but it would be unsafe to assume that St John’s wort would also be effective.
The NICE guidelines on the management of depression in adults and children used to warn about uncertainty regarding appropriate doses, persistence of effect, variation in the nature of preparations and potential serious interactions with other drugs. It advised that it should not be used. Interactions with other drugs are an important issue.12St John’s wort): drug interactions and clinical outcomes. These include oral contraceptives, anticoagulants and anticonvulsants. In Germany it is used quite often to treat depression in children and adolescents. In the UK the use of antidepressants in children and adolescents is discouraged in favour of cognitive and behavioural therapy. NICE states that for children and young people, St John’s wort should not be prescribed. “Although there is some evidence that St John’s wort may be of some benefit in adults with mild to moderate depression, this cannot be assumed for children or young people, for whom there are no trials upon which to make a clinical decision.”13NICE guidance, depression in children and young people
There are a number of contraindications to its use:
- It should not be used in pregnancy or lactation (breast feeding), due to lack of evidence of safety.
- It should not be taken at the same time as other antidepressants, especially the SSRIs as there is risk of a “serotinergic crisis”. I do not intend to expand on this but it is a very nasty state with symptoms that may include: confusion, agitation, headache, changes in blood pressure and temperature nausea and vomiting, rapid heart rate and loss of muscle coordination.
- For the same reason it should not be used with the tryptan group of drugs which are used for migraine.
- It should not be used in bipolar disease, formerly called manic depression, as it may cause mania.
- There are a number of drug interactions with St John’s wort.14Clinical risks of St John’s Wort co-administration. Oral contraceptives (the pill), warfarin, ciclosporin (after organ transplants), anticonvulsants for epilepsy, HIV treatments and digoxin are just some.
Before a patient is started on a licensed antidepressant, he or she needs to see a doctor for a diagnosis. A prescription is issued that is dispensed by a pharmacist and the doctor will arrange follow up. None of this is obligatory for St John’s wort as it can be bought in health food shops and off the shelves in supermarkets with no supervision with regard to diagnosis or advice. This is most unsatisfactory for the management of a serious and potentially fatal disease. People die from depression. Ideally patients should consult a doctor first, even if they wish to buy the medicine after. They must tell the doctor of their intention and be followed up as they would be if given a prescription. They should also be advised to find a brand that is standardised and to stay with the same brand.
If a conventional antidepressant is being used there should be a “washout” period before starting a new class, including St John’s wort. The patient should be warned about drug interactions, including with antidepressants and oral contraceptives if appropriate.
The most commonly reported side effects of St John’s wort include:
- Gastrointestinal symptoms such as nausea, vomiting or diarrhoea
- Allergic reactions
- Dry mouth
- Photosensitivity is uncommon and tends to be with high doses, but people taking it should increase their sun protection and avoid strong sunlight.
In conclusion, it seems that St John’s wort has benefit in the treatment of mild depression and may have fewer side effects than conventional antidepressants. However, nowadays the “talking therapies” are often considered better than medication in mild depression. It is rarely compared with the newer rather than the older antidepressants. It may still have adverse effects and should not be regarded as safe in pregnancy, breast feeding or in children. The low volume of evidence about it would not permit a product licence as a drug. It should not be started on the basis of self-diagnosis or because a person “feels a bit down”. Conventional medicines are classified as:
- Prescription only medicines (POM) that can only be obtained with a doctor’s prescription
- Pharmacy medicine (P) that may be sold by a pharmacist but not by anyone else
- Over the counter medicines (OTC) than can be sold in pharmacies or elsewhere including self-service in a supermarket
All other medicines for depression are POM. Self-diagnosis and self-medication is to be depreciated. Remember side effects and interactions. Do not use in young people.
Although most public interest in St John’s wort has been for mild to moderate depression, it has a number of other attributes. It has an antibiotic effect and can be active against MRSA although there are a number of other well researched antibiotics that are probably better. It has an antiviral effect, including against the HIV/AIDS virus and it may have anti-tumour activity.15Hypericin–the facts about a controversial agent. However, hypericum, the active ingredient of this preparation, reduces blood levels of antiretroviral drugs.16Lopinavir/ritonavir: a review of its use in the management of HIV infection Hence, adding this drug to treat the HIV virus will be counterproductive. The liver is induced to produce more enzymes that inactivate the prescribed drugs and so it reduces their effect. This is called enzyme induction. This is an excellent example of why patients should be careful about self-medication for serious diseases.
Do not assume that you can safely add these drugs to those already prescribed by your doctor. A systematic review of interactions between herbal remedies and prescribed medicines found that St John’s wort was the worst offender.17Interactions between herbal medicines and prescribed drugs
Evening Primrose Oil
Several years ago, evening primrose oil seemed to offer potential in a number of conditions, especially premenstrual symptoms. However, over the years it has not lived up to expectations. A systematic review of herbal treatments for premenstrual symptoms found that there was, as usual, a shortage of good quality trials and a tendency to mix in conditions so that they were not comparing like with like. The review found no evidence for the use of evening primrose oil or St John’s wort in premenstrual syndrome (PMS) but there was some evidence in favour of Vitex agnus castus. There were four trials involving about 500 women, and it was reported to be consistently better than placebo. Single trials also support the use of either Gingko biloba or Crocus sativus.18Herbal treatments for alleviating premenstrual symptoms Another systematic review found poor quality trials again. There were 62 herbs, vitamins and minerals for which claims of benefit for PMS were made, with randomised controlled trials for only ten. Meta-analysis was not feasible as trials were so variable. There was some support for the use of calcium for PMS, and possibly chasteberry. Vitamin B6 may be effective. No evidence of benefit with evening primrose oil or magnesium oxide was found.19Herbs, vitamins and minerals in the treatment of premenstrual syndrome
Evening primrose oil was claimed to be particularly effective for breast pain and it even had a product licence to be prescribed for this indication. However, this was withdrawn after it was found to be ineffective.20Breast pain It is no use for treatment of symptoms of the menopause.21Menopause: a review of botanical dietary supplements It was also claimed to be useful in atopic eczema and isolated papers do support it. Nevertheless, reviews show that overall it seems to confer no benefit.22What’s new in atopic eczema?
In summary, evening primrose oil was claimed to be beneficial in premenstrual syndrome, especially with breast pain, in helping symptoms of the menopause, especially hot flushes (the Americans call them hot flashes) and in skin disease, especially eczema. However, it has failed to live up to expectations and cannot be recommended. The gynaecological conditions mentioned above are those in which a very strong placebo effect may be expected. Atopic eczema may also show a strong placebo response or improve as part of the natural history of the disease, irrespective of treatment.
This is another product for which much has been claimed. As a general rule, the more varied the claims for a single substance, the more sceptical the reader should be. One of the problems with aloe vera that the producers acknowledge is that reliability and reproducibility of products is important as the effect is said to be so variable. This is a general problem with herbal remedies. A review of aloe vera as a functional ingredient in food found that there are different factors affecting the chemical composition of the gel, such as species and variety, climatic and soil conditions, cultivation methods, processing and preservation.23Aloe vera as a functional ingredient in foods. The main therapeutic applications have been revised and the possible damaging effects of the product are commented upon. The paper concludes that more research is needed to confirm the therapeutic and beneficial effects and to clarify the myth surrounding aloe vera. Quality and safety of the products in the food industry needs to be established.
A Cochrane review found weak evidence of aloe vera being useful in lichen planus in the mouth.24Interventions for treating oral lichen planus Psoriasis may be helped by aloe vera.25Alternative therapies for common dermatologic disorders A paper from Egypt suggests that aloe vera has some anti-tumour properties that may be beneficial if it can be developed into a useful drug.26Antitumor properties and modulation of antioxidant enzymes’ activity by Aloe vera However, caution should be exercised as just because something seems to be effective in vitro (in glass) does not mean that it is effective in vivo (in life). With the current level of evidence, it is not justified to suggest that aloe vera cures cancer.
A review of aloe vera in skin conditions suggested that there was much promise but that the evidence was not yet adequate.27Aloe vera in dermatology: a brief review It was based on 40 studies of in vitro and in vivo experiments, including those on animals. The results suggest that oral administration of aloe vera in mice is effective in wound healing. Topical application is not effective to prevent radiation-induced injuries as in radiotherapy and it offers no protection against sunburn. It can be effective for genital herpes, psoriasis, human papilloma virus (HPV), seborrheic dermatitis, aphthous stomatitis, xerosis, lichen planus, frostbite, burn, wound healing and inflammation. However, there may well be better treatments. The conclusion was that even though there are some promising results with the use of aloe vera for various skin conditions, clinical effectiveness of oral and topical aloe vera is not sufficiently and meticulously explored as yet.
Once again, we have a herbal substance which seems to show promise but the evidence is poor. A major problem is the variability of commercial products. It would be wrong to assume that promise should be seen as effectiveness waiting to be proved. It may be misguided. Aloe vera is an interesting plant but at present its potential use remains unknown.
Chamomile or Camomile
This is another herbal remedy that has been known for thousands of years. Chamomile or camomile has two common varieties. There is German Chamomile (Chamomilla recutita) and Roman Chamomile (Chamaemelum nobile). The dried flowers of chamomile contain a variety of chemicals. It is used for many ailments such as hay fever, inflammation, muscle spasms, menstrual disorders, insomnia, ulcers, wounds, gastrointestinal disorders, rheumatic pain, and haemorrhoids. Essential oils of chamomile are used extensively in cosmetics and aromatherapy. Many different preparations of chamomile have been developed, the most popular of which is in the form of herbal tea. More than one million cups are consumed each day. It is said to have a relaxing effect.
Chamomile tea is well known and used for its sedative properties. However, a search to find the evidence for this, including such important matters as whether it really could relax without causing drowsiness and sedation produced remarkably little. There are no studies of its sedative properties in humans,28A review of the bioactivity and potential health benefits of chamomile tea which is remarkable. As an agent to help sleep, it may possibly be of value in aromatherapy, but evidence is very limited.29Medicinal plants for insomnia There is no evidence of its use in other forms.
A review called “Chamomile: A herbal medicine of the past with bright future” was effusive almost to the point of embarrassment for an article in a journal about molecular medicine.30Chamomile: A herbal medicine of the past with bright future The references were not stunning enough to support the accolade. I was struck by the claim that chamomile enhances the immune system as this is a claim that always makes me sceptical. It said that drinking chamomile was associated with a significant increase in urinary levels of hippurate and glycine, which have been associated with increased antibacterial activity. That is not the same as enhanced immune activity. Glycine is the simplest of the amino acids. Hippurate or hippuric acid is found in the urine of horses especially if they have been fed on meadow hay which has herbs in it. Nowhere in PubMed or elsewhere have I been able to find any substantiation that elevated levels of these chemicals indicate enhanced immune competence.
There is nothing to substantiate its claim for benefit for the common cold. There was nothing about chamomile for dysmenorrhoea (painful periods). The article says that topical applications of chamomile have been shown to be moderately effective in the treatment of atopic eczema. It was found to be about 60% as effective as 0.25% hydrocortisone cream. Hydrocortisone cream is usually used as 0.5% in infants and 1% elsewhere, and it is the mildest of the steroid creams. Therefore, to be 60% as effective as 0.25% hydrocortisone cream, is exceptionally unimpressive. In short, they seem remarkably enthusiastic about a substance that is really quite mundane.
Chamomile or camomile is widely used, mostly for its properties with regard to relaxation, causing relief of anxiety without sedation and aiding sleep. However, there is little or no objective evidence to support this use. A substantial placebo effect may be expected. Perhaps relaxation without sedation is too good to be true and it is said that if something seems too good to be true it probably is not true. The product seems to do little harm and if people are getting benefit without adverse effects, even if it is just placebo, then let them continue.
Valerian has been used for centuries to alleviate anxiety whilst not causing sedation. Despite this great potential there is a severe lack of studies. A Cochrane review found only one study of Valerian for anxiety. There were 36 subjects and it found no significant differences between valerian and placebo or valerian and diazepam.31Valerian for anxiety disorders The authors wanted to see more and bigger trials.
Another Cochrane review examined the effectiveness of 32Kava extract for treating anxiety. There were 12 of 22 trials that met the inclusion criteria as double-blind, placebo-controlled RCTs. The meta-analysis of seven trials suggested a significant treatment effect for the total score on the Hamilton Anxiety Scale (a well recognised and validated tool to measure anxiety) in favour of kava extract. Few adverse events were reported in the reviewed trials, which were all mild, transient and infrequent. They suggested that kava extract might be an effective symptomatic treatment for anxiety although the size of the effect seems to be small. There was no mention of funnel plotting and so I wonder about selective publication too.
Chamomile, valerian and kava appear to offer relief of anxiety and possibly better sleep without causing sedation by day. If this is true, it represents a very significant advance on conventional pharmaceutical treatments. In the 1960s the barbiturates were superseded by the benzodiazepines such as diazepam and temazepam as barbiturates are very dangerous if taken in overdose, especially if taken with alcohol. The benzodiazepines were a distinct advance in safety in overdose but they still caused sedation and addiction. As with barbiturates, sudden withdrawal in a habituated person can lead to convulsions.
However, the evidence in favour of any of these herbs is scanty and poor. They have been grossly under-investigated. The blame must lie with those who sell the products who have not apparently bothered to find if their product lives up to the promise. The trouble is that they do not need evidence to sell their product. There may be few published papers because most trials are negative and not published, especially if underpowered. It would seem, on the limited evidence, that if they have any effect it is slight and may be no more than placebo.
Nevertheless a non-sedative anxiolytic is a great prize. Should it be marketed on the grounds that if its only benefit is placebo it would be wrong to deprive people of this or should it be withdrawn as useless? To recommend a pure placebo may be seen as either pragmatic or dishonest. This is an ethical problem with no easy answer.
Peppermint has been used since antiquity for its medicinal properties. As with so many other herbs, it is claimed to be of value in very many fields.
Peppermint oil is an extract of the Mentha piperita. It appears to have a relaxant effect on smooth muscle as in the gut and is advocated for spasms including irritable bowel syndrome. Unlike many herbal remedies, this one has been extensively studied, often with good methodology and with promising results. The use of CAM for irritable bowel syndrome (IBS) has been reviewed with positive findings for peppermint oil.33Complementary and alternative medicine modalities for the treatment of IBS In a randomized, double-blind, placebo-controlled study of 90 outpatients with IBS, the use of peppermint oil led to a significant reduction in symptoms and improvement in quality of life compared to placebo.34The effect of enteric-coated, delayed-release peppermint oil on IBS A systematic review reported significant and consistent improvement in symptoms of IBS compared to placebo.35Effect of fibre, antispasmodics, and peppermint oil in the treatment of IBS
A great advantage of peppermint oil is its safety. Common side effects include heartburn and a burning sensation around the anus, but they are generally mild. Enteric-coated or pH-dependent capsules that keep the capsule intact until it is out of the stomach reduce the problem. Peppermint oil is less effective than conventional smooth muscle relaxants in terms of reducing the symptoms of IBS but it may be better tolerated due to fewer side effects. It does not cause dry mouth or blurred vision. The safety of peppermint oil during pregnancy is not clear. It causes heartburn because it relaxes the cardiac sphincter which is the muscle at the top of the stomach which holds it closed when food or drink is not being swallowed. This allows acid to regurgitate into the oesophagus.
Peppermint oil may also be found in some liqueurs, especially crème de menthe. It relaxes the cardiac sphincter, which guards the opening from the oesophagus to the stomach, and may release some wind and improve comfort after a large meal.
Peppermint tea is very popular, but its effects have not been adequately researched.36A review of the bioactivity and potential health benefits of peppermint tea
The use of peppermint oil in the treatment of irritable bowel syndrome has a firm scientific basis. It is effective and safe. A formulation of peppermint oil in a capsule is commercially available and is often prescribed. There are three principal drugs used for IBS. They are hyoscine (trade name Buscopan), mebeverine (trade name Colofac) and peppermint oil capsules (trade name Colpermin). They are perceived as being in that order for potency, from highest to lowest, and the more potent they are, the more severe are side effects. The decision of which to prescribe is a trade-off between potency and adverse effects. In difficult cases two or even all three may be prescribed simultaneously.
Menthol is also derived from peppermint. It is often used for inhalation to help clear the airways with a cold.
According to one source, “In herbal medicine, garlic has been traditionally used for such ailments as asthma, deafness, leprosy, bronchial congestion, arteriosclerosis, fevers, worms and liver and gall bladder troubles. Garlic is good for heart, a food for the hair, a stimulant to appetite, a strengthening food, useful in leucoderma, leprosy, piles, worms, catarrhal disorders, asthma and cough.” This is a most impressive and diverse list and not to be taken seriously. It does imply that the website takes it all uncritically. The reference has been removed as the website no longer exists. Nevertheless, it is time to look for the evidence.
A paper from Italy was called 37Potential beneficial effects of garlic in oncohematology. This means malignancies of the blood such as leukaemia. It is the American spelling. It looked at the basic science in terms of the potential biochemical advantages conferred by garlic for both the prevention and possible treatment of malignancies. Note that it is discussing potential rather than proven benefits and the authors regard their paper as a forerunner to clinical trials.
The 38Health effects of garlic were reviewed in American Family Physician in 2005. This is a very reputable journal from their equivalent of the Royal College of General Practitioners. It is an excellent paper and is available in full online free of charge. The use of garlic dates back to antiquity and includes the Egyptians, Chinese, Greeks and Romans. It is quite a short paper that reviews a number of claims for garlic. Its conclusion is that there is insufficient good quality evidence.
As is so often the case with such substances, there is a great problem of variable quality of trials. Small numbers of subjects, short follow up and variable quality of test substances all occur. The digestive system can inactivate important chemicals and cooking tends to destroy them. Early trials and meta-analysis of garlic for lowering cholesterol were impressive but later trials of better quality show less impressive results and suggest that benefit is lost after 6 months. Early trials were also more promising in terms of the effect of garlic on hypertension (high blood pressure). Recent results are variable and generally unimpressive. In 2009 a systematic review of garlic for hypertension also blamed poor methodology for failure to reach a conclusion.39A systematic review on the influence of trial quality on the effect of garlic on blood pressure. A meta-analysis from 2009 found that there was no beneficial effect of garlic on cholesterol.40Garlic supplementation and serum cholesterol: a meta-analysis For both high blood pressure and high cholesterol there are safe alternatives of well proven effectiveness.
Garlic may have some anti-platelet effect, rather like low dose aspirin but perhaps with less risk. It is recommended that garlic should be reduced or stopped before surgery in case of bleeding. There is not enough evidence to replace aspirin with garlic to prevent heart attacks or strokes. Some trials find that garlic in normal doses does not affect platelets. It seems that it should not be relied upon for its anti-platelet effect.
Most trials do not show improved control of diabetes.
It does have some antimicrobial effects, but it is no substitute for conventional treatment. The main side effect appears to be body and breath odour. It is possible to buy odourless garlic, but it is unclear if this has the same effect.
A PubMed search of “garlic” produced 3,641 results, including 425 reviews. The beneficial effect on cancer seems still to be theoretical and based on biochemistry with human studies yet to appear. In cystic fibrosis there are recurrent chest infections which cause severe lung damage and usually death in the late 20s or 30s although improved management may let them see 40. A Cochrane review looked for an adjuvant for antibiotics to improve efficacy and fight the problem of bacterial resistance. It found that ß-carotene, garlic and zinc supplementation were of no value.41Antibiotic adjuvant therapy for pulmonary infection in cystic fibrosis
It is commonly claimed that garlic is beneficial in prevention or treatment of the common cold. A Cochrane review was again critical of the quality of the evidence.42Garlic for the common cold It could find no support for garlic for the common cold. Being a natural sceptic, I have always assumed that if a person takes large amounts of garlic, then no one comes close enough to pass on a cold.
In conclusion, much has been claimed for the beneficial effects of garlic but trials have been unimpressive. Generally, the quality of trials has been poor and, as usual, the better quality trials tend to have the less impressive results. Even in terms of cancer prevention, which did initially look promising, an American review was unimpressed. It was called “Garlic intake and cancer risk: an analysis using the Food and Drug Administration’s evidence-based review system for the scientific evaluation of health claims.”43Garlic intake and cancer risk The Food and Drug Administration is a very important regulatory body. Its conclusion was that there is no credible evidence to support a relation between garlic intake and a reduced risk of stomach, breast, lung, or endometrial (body of uterus) cancer. Very limited evidence supported a relation between garlic consumption and reduced risk of bowel, prostate, oesophageal, larynx, oral, ovary, or kidney cancers.
There are a number of formulations of “odour-free garlic” on the market, but the evidence for them is even lower than for conventional garlic.
Preparations of the plant Echinacea are variously used to treat or prevent the common cold and sometimes to enhance the immune system, whatever that means. A Cochrane review of 2009 found that the preparations used varied significantly which is a common problem in herbal remedies, especially for this product.44Echinacea for preventing and treating the common cold. The Cochrane review did at least find 19 placebo controlled trails that met its requirements. However, results were variable and inconclusive, and it was impossible to give a firm recommendation either way.
Cochrane reviews of vitamin C for the common cold have also consistently failed to find any benefit.45Vitamin C for preventing and treating the common cold
Another review looked at Echinacea, Rhodiola and Ginseng to ask if they improve the immune system in athletes. Athletes who undergo strenuous exercise, especially in endurance sports, frequently use herbal supplements to improve performance.46Effects of herbal supplements on the immune system in relation to exercise. They were unable to detect any improvement in immune function although I do not know what they were actually measuring. I always like to ask what was measured when claims are made about enhancing the immune system.
Ginseng is very popular in oriental traditional medicine. A systematic review of randomised controlled trials in the Korean literature was useful for those who are not fluent in Korean.47Ginseng for Health Care: A Systematic Review of Randomized Controlled Trials in Korean Literature. Whilst there seemed to be little problem of toxicity from the substance, the quality of methodology was so poor that it would be unsafe to draw conclusions.
It is also popular amongst sportsmen wishing to take performance enhancing substances which have not been banned. However, its effectiveness is rather dubious, and if it is effective it has to be taken for at least eight weeks.48Herbs in exercise and sport An American review from 2010 found that trials of ginseng to improve athletic performance were of poor quality and unimpressive but it said that the market for the product is worth $US300 million a year.49Evaluation of the ergogenic properties of ginseng That is a great deal of money for something of dubious worth. Even at the elite level, sports training and nutrition is seriously lacking in a scientific basis except when it comes to how to avoid detection after taking banned substances.
Ginseng is also recommended to enhance libido and sexual performance. The effect of this or any other aphrodisiac is disappointing.50Natural aphrodisiacs It may possibly be of benefit in erectile dysfunction but the quality of trials is poor.51Red ginseng for treating erectile dysfunction I found no results in a search for “ginseng versus sildenafil for erectile dysfunction”. Sildenafil is better known by the trade name Viagra. There are a number of products that are advertised as “herbal Viagra”. Why not take the real thing as it has been proved to be safe and effective? This is more than can be said for the herbal concoction. Viagra, or sildenafil to give it its correct name, can now be bought in pharmacies without a prescription.
Ginseng is also popular as a treatment for the fatigue that is often associated with cancer and its treatment. However, once more the evidence is very limited.
Phyto-oestrogens are plant substances that have oestrogenic properties. In other words they can simulate female sex hormones. They are often written as phytoestrogens, especially in the USA where they spell oestrogen without an O. These chemicals came to light about 50 years ago when it was observed that some plants could have an adverse effect on fertility in livestock. They are often promoted as “natural” and by spurious implication, safer alternatives to HRT. Hormone replacement therapy is usually used around the menopause when women are no longer able to produce adequate amounts of their own hormones. These plant hormones bind very weakly to the oestrogen receptors in the body and do so 100 to 1,000 times less avidly than normal oestrogens. Therefore, they are very weak oestrogens.
There are more than 20 compounds that can be found in more than 300 plants, such as herbs, grains, and fruits. The three main classes of dietary phyto-oestrogens are isoflavones, lignans, and coumestans:
- Isoflavones are primarily found in soy beans and soy products, chickpeas, and other legumes
- Lignans are found in oilseeds, cereal bran, legumes, and alcoholic drinks (beer and bourbon)
- Coumestans can be found in alfalfa and clover.
Most food sources of these compounds include more than one class of phyto-oestrogen. Black Cohosh is a substance that is recommended by herbalists for a variety of conditions and it is highly recommended for menopausal symptoms although some authorities say that it has anti-oestrogenic effects. There are many side-effects associated with it and the European Medicines Agency has given warning about the possibility of hepatitis resulting from its use.52European Medicines Agency. EMEA public statement on herbal medicinal products containing cimifugae racemosae rhizome (black cohosh root) Some users have required a liver transplant.
Observational studies have found a lower prevalence of breast cancer, heart disease and hip fracture rates among people living in places like Southeast Asia, where diets are typically high in phyto-oestrogens. These diseases have many factors in their causation. There is a lower incidence of obesity, greater physical activity and more frequent and more prolonged breast feeding in the studied population than our own societies. Therefore, it is unwarranted to hold the diet responsible.
Much of the evidence about phyto-oestrogens and osteoporosis is based on animal studies. In humans the evidence is conflicting. A 3-year study of more than 400 postmenopausal women concluded that ipriflavone did not prevent bone loss.53Ipriflavone in the treatment of postmenopausal osteoporosis The substance was also linked to lymphocytopenia which is a reduction in a certain type of white blood cell and a cause for concern. A systematic review of RCTs was unable to give unequivocal support for the benefit of phyto-oestrogens for the prevention of osteoporosis.54Natural health products in the prevention and treatment of osteoporosis
Phyto-oestrogens are also recommended as anti-androgens and hence are of possible protective benefit with regard to carcinoma of prostate and benign prostatic hyperplasia (enlarged prostate gland). However, a systematic review and meta-analysis was slightly positive but not enthusiastic.55Soy and soy isoflavones in prostate cancer Whether they also reduce sperm count and fertility has not been examined.
An American cohort study followed 3,734 Japanese men in Hawaii who had been tracked since 1965 for a longitudinal study of cardiovascular health.56Brain aging and midlife tofu consumption Cognitive (mental) function was assessed in the living participants and their wives. They were aged 71 to 93 years. MRI and later autopsies looked for changes in brain tissue. Those who had consumed the greatest quantity of tofu in midlife had lower cognitive test performance (lower mental function) and lower brain weight than those who had consumed the least tofu. The authors noted that the degree of impairment in the highest consumption versus the lowest consumption group was “roughly of the magnitude as would be caused by a four year difference in age or a three year difference in education.” They postulated that the effect might be due to isoflavones inhibiting key enzymes in an oestrogen synthesis pathway.
Oestrogen is known to be involved in repair of nerve structures that degenerate over time and it has been observed that higher levels of oestrogen are associated with a lower incidence of Alzheimer’s disease in women. Around the menopause some women become forgetful. Another study found a beneficial effect of phyto-oestrogens on mood and cognitive function in postmenopausal women.57Psychological assessment of the effects of treatment with phytoestrogens on postmenopausal women
Oestrogens and similar substances are highly complex and variable. This applies both to natural and synthetic oestrogens. Oestrogens may have a positive effect on bones, limiting osteoporosis or a negative one aggravating it. They may have a positive or negative effect on breast or uterus. In both cases a positive effect may increase the risk of cancer and a negative one gives protection. The ideal oestrogen for HRT has a positive effect on bone, a negative effect on breast and uterus and relieves the symptoms of the menopause. The synthetic hormone tamoxifen is often used in women who have had breast cancer. It has a negative effect on breast but positive on bone and uterus. Therefore, it reduces the risk of breast cancer and osteoporosis but increases the risk of cancer of the uterus. In addition to all this, there is the question of an oestrogen’s effect on the brain.
There is a great deal of evidence about phyto-oestrogens but there is also much confusion with contradictory results. In summary:
- Much of the evidence relates to animals and in vitro studies and there are questions as to how readily it should be extrapolated to humans.
- When a substance is not given as a drug in a predetermined dose but is part of the diet, the amount taken may be highly variable. This may cause problems such as a positive effect at low dose and a negative effect at higher doses. Positive is called agonist and negative is antagonist.
- Some of the results, such as those related to cognition, are contradictory. This may be due to agonists and antagonists working in different directions.
- Epidemiological studies about multifactorial diseases must be interpreted with care. When comparing different populations we cannot be sure that only one parameter is changed.
- There is very little good, long term evidence about the effects of phyto-oestrogens in human populations. Many questions remain to be answered. If a diet high in phyto-oestrogens does protect women against breast cancer, osteoporosis and heart disease, does it also impair fertility? If it protects men against prostatic cancer, does it also impair sperm production?
- The evidence to suggest that phyto-oestrogens are protective against osteoporosis is at best poor. Long term safety is not established.
- There have been many studies on the efficacy and safety of mammalian HRT including the enormous “million women study”. This was mentioned in the chapter on cohort or longitudinal studies. The million women study was basically very reassuring but it did outline some causes for concern. The assumption that plant oestrogens are as effective but safer is totally unwarranted. There is absolutely nothing comparable for phyto-oestrogens to show that they afford benefits or that they are less liable to cause harm.
HRT is derived from mares. It comes from mammals, our close relations. Why it should be more “natural” to take plant hormones or phyto-oestrogens rather than mammalian hormones is a mystery. Women are mammals, not plants. For people who still insist that “natural” is safe there is one piece of mischief to drop their way. The phyto-oestrogens are usually derived from soya. Most soya comes from the USA and South America such as Argentina. Much of the soya that we import is genetically modified. There is no evidence that GM food is dangerous to those who eat it, but their response will be interesting.
Turmeric is a well-known yellow spice that is often used in Indian cooking. It even stains a glazed plate yellow and it takes several washes to remove it. The main active component of turmeric that is thought to be curcumin. Turmeric has been studied for its antioxidant, anti-inflammatory, antibacterial and anticancer properties. It has also been claimed to have a beneficial effect on blood pressure and arthritis.
Simply putting “curcumin” in a PubMed search produces more than 14,000 results with options on a vast number of conditions. Even adding “reviews” produced more than 1,700 results. A result that was put forward was called 58Curcumin, Cardiometabolic Health and Dementia. Having extolled its virtues in animal and in vitro experiments, it then said that human studies are relatively unconvincing.
A systematic review and meta-analysis of randomized controlled trials of turmeric extracts and curcumin for arthritis claimed to be the first of its kind. 59 Efficacy of Turmeric Extracts and Curcumin for Alleviating the Symptoms of Joint Arthritis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. Initial searches yielded 29 articles, of which 8 met specific selection criteria. They found low risk of bias, but the number of trials is rather small. They concluded that turmeric extract (about 1000 mg/day of curcumin) is as effective as pain relief in arthritis. They concluded “However, the total number of RCTs included in the analysis, the total sample size, and the methodological quality of the primary studies were not sufficient to draw definitive conclusions. Thus, more rigorous and larger studies are needed to confirm the therapeutic efficacy of turmeric for arthritis.”
Bearing in mind the problems that some people have with the NSAID pain killers, this is quite promising but there is a long way to go before it can confidently be recommended as a medicine for this condition. It is said to have anti-inflammatory effects. Beware of dosage as liver damage with curcumin has been described.
A meta-analysis of turmeric and curcumin in lowering blood lipid levels in patients with cardiovascular risk factors came from China. 60 Efficacy and safety of turmeric and curcumin in lowering blood lipid levels They found six trials with 218 subjects, including the controls. This is rather a small number and there was significant variation between trials (heterogenicity). The results were favourable in reducing low-density cholesterol (bad cholesterol) and triglycerides (fats). There was no effect on high density (good) cholesterol. Side-effects were mostly abdominal pain, nausea and diarrhoea. Overall, the results seem quite favourable with a tolerable side-effect profile of complaints that are not too serious and presumably stop on stopping the substance. There was no discussion of varying doses and responses.
The final conclusion was, “Due to uncertainties related to dosage form, dose and medication frequency, it is premature to recommend the use of turmeric or curcumin in clinical settings. Nonetheless, the analysis does provide a synthesis of the currently available evidence and supports larger scale clinical trials of curcumin.” This seems a reasonable interpretation of the evidence.
A paper from Iran was a systematic review and meta-analysis of turmeric or curcumin for treating raised blood pressure. 61 The effect of Curcumin/Turmeric on blood pressure They found 11 studies comprising 734 participants that were eligible and included in the meta-analysis. No favourable effect of curcumin administration on systolic (the higher) blood pressure or diastolic (lower figure) blood pressure levels.
In summary, there is no evidence to support the use of turmeric for dementia or to treat raised blood pressure. It may be an adjunct to reducing cholesterol. It may possibly have a useful effect in arthritis, especially bearing in mind the problems of the non-steroidal anti-inflammatory drugs (NSAIDs). However, much more research is needed, examining reliable doses and side-effects. Turmeric is also mentioned below in the section about diabetes.
There are a number of substances that are claimed to improve the control of diabetes. We must examine the evidence.
A Cochrane review has examined the value of cinnamon in the control of diabetes, based on glycolysated haemoglobin or HbA1C results.62Cinnamon for diabetes mellitus This is a commonly used indicator of overall control of diabetes. The review found that it was no more effective than placebo.
A Cochrane review of sweet potatoes for diabetes found only three trials and of such poor quality that no conclusion could be reached.63Sweet potato for type 2 diabetes Other reviews have included Omega-3 polyunsaturated fatty acids and prevention of diabetes by zinc supplements. In both cases they were unimpressed.
Tumeric has been discussed above. Its scientific name is Curcuma longa and it is sometimes referred to as curcuma. It has been used by traditional Indian healers. It is said to relieve pain, heal wounds, reduce inflammation and possibly to reduce the risk of type 2 diabetes. Inflammation is part of the process that leads from obesity to diabetes.
There are few papers on the subject of turmeric and many are in the Journal of Alternative and Complementary Medicine which I regard as a suspect source. However, there is a suggestion that it may be of value in the prevention of diabetic retinopathy.64Therapeutic implications of curcumin in the prevention of diabetic retinopathy As blindness is one of the most feared complications of diabetes, this could be of importance. However, it is too soon to recommend it and more research of good quality is required.
A review of the health benefits of ginger in reducing the extent of cardiovascular disorders, diabetes mellitus, and digestive problems focussed on the molecular basis rather than clinical trials.65Ginger and its health claims However, clinical trials seem to be absent and until they show positive results it would be unwise to extrapolate from molecular biology to people. With ginger, turmeric and cinnamon the risk of adverse effects from taking them would seem to be low but it would be wise to keep the amounts consumed in moderation.
Herbal Remedies to Aid Weight Loss
Over the years, many herbs and supplements have been advocated to aid weight loss. They are usually claimed to increase the metabolic rate and hence to burn Calories faster.
The first systematic review and meta-analysis for nearly 20 years of herbal products to aid weight loss was published in early 2020.66Effectiveness of herbal medicines for weight loss: A systematic review and meta-analysis of randomized controlled trials It was a substantial piece of work which included:
- Green tea (12 studies)
- Malabar tamarind (11 studies)
- White kidney bean (seven studies)
- Ephedra (five studies)
- African mango (three studies)
- Yerba mate (three studies)
- Veld grape (two studies)
- Licorice (two studies)
- Mangosteen (two studies)
- Miscellaneous herbal medicines (17 studies)
Statistically and clinically significant weight loss was reported for some products that were studied in three or fewer trials, but the investigators advised cautious interpretation because of the small number of studies, poor methodology, and poor reporting of herbal medicine interventions. Once again, the problem is poor quality studies. Their conclusion was that they could not recommend any of the interventions.
For those who wish to try these substances, thinking that even if they do not work, there will be no harm, there is bad news. Many of these substances have been associated with adverse effects, especially damage to the liver. Furthermore, when patients see a doctor with symptoms of these problems, they may fail to tell that they have been using them. This may be because they cannot believe that something that is “natural” can also be deadly. Approximately 10% of cases associated with green tea extract have been fatal.67Liver injury from herbals and dietary supplements
This heading and the contents are reproduced in the chapter Exercise, Obesity and Diets for Weight Loss. You may wish to look at that chapter for further information.
The Traditional Herbal Medicine Registration Scheme came into effect in the UK on 1 May 2011, but there is still the question of the professional regulation of those who sell or prescribe them. The Health Professions Council has been asked to establish a statutory register for herbal practitioners and a formal consultation will take place on legislative proposals for establishing the register and for reforms of associated medicines legislation. By 2019, nothing new has been announced.68British Herbal Medicine Association
Herbal tablets are advertised as an alternative to thyroxine for treating thyroid deficiency. They are encouraging people to stop an important and effective treatment for a nonsense backed by pseudoscience and quackery.
It is also important to distinguish between the regulation of herbal products and the regulation of herbal practitioners. A search for a register of herbal practitioners turned up, amongst others, the Unified Register of Herbal Practitioners. It says, “The United Register of Herbal Practitioners (URHP) is a leading international register of professional herbal practitioners.”69Unified Register of Herbal Practitioners However, it has no statutory authority.
It also says about itself, “A URHP Herbal Practitioner may be practising in Ayurvedic, Western Traditional, Unani Tibb, Tibetan or Traditional Chinese Medicine: they each have their individual strengths and what binds them, and the URHP, together is the recognition of the energetics of herbal medicine. This understanding of energetics is based on recognition of the Vital Force within each living object, be it a person or a herb and using this knowledge to provide a completely individual herbal prescription. Once we get into “energetics” and “Vital Force” with capital letters, the bull-shit buzzer is on full alarm.
In 2015 a report by a committee chaired by Professor David Walker, called 70Report on the regulation of herbal medicines and practitioners was published. It seems a diligent piece of work but, at the time of writing, it still does not seem to have brought legislation. It notes that it is estimated that up to 20% of the population use herbal products at some time in their lives. It noted “Much has changed since the previous reviews of herbal medicine by the House of Lords Science and Technology Committee in 2000 and the Department of Health Review chaired by Professor Michael Pittilo (2008). The largest change has been the Introduction of the European Traditional Herbal Medicinal Products Directive in 2004 which took full effect in the UK in 2011. This legislation effectively banned the importation and sale of large-scale manufactured herbal medicine products. This step severely limited the scope of some herbal practitioners to continue practising, particularly those from the Traditional Chinese Medicine (TCM) and Ayurvedic traditions. The possibility of enabling continued access to unlicensed manufactured herbal medicine products by authorised practitioners was explored but was not feasible under European regulations.”
These substances can be quite potent and toxic. Therefore, it is imperative to have adequate legislation to control both the products and the practitioners.
Herbal products certainly have pharmaceutical effects. This is unsurprising considering the origin of so many drugs. They should be seen as like drugs and treated with similar respect. They have a number of features in common:
- They may have a beneficial effect over and above any placebo effect but this cannot be assumed and they must be subjected to properly controlled trails, preferably with double blind placebo control.
- If there is already a product that has been shown to be effective it should be compared with that. It may be no better than current therapies but have fewer adverse effects but this must be demonstrated.
- There should be post-marketing surveillance for adverse effects. Freedom from teratogenesis (ability to cause abnormalities in babies if taken in pregnancy) should not be assumed and it should not be used in early pregnancy until there is abundant evidence of its safety. Being around for years is no guarantee of safety. German measles has been around for centuries but it was only in 1948 that the rubella syndrome was recognised.71Perinatal lessons from the past Both this and the problems of thalidomide were recognised in Australia.
- There should also be post-marketing surveillance for drug interactions. If a doctor is prescribing medication it is inappropriate to assume that herbal remedies may also be taken and they will be safe and effective. Most people do not tell their doctors if they are taking herbal medicines and interactions may be unsuspected.
There are also a few general differences between herbs and registered drugs:
- Herbal remedies may well contain more than one active ingredient. This is unusual with drugs but there are some exceptions.
- Licensed drugs tend to have a single active ingredient and the dose is specified in milligrams and it is accurately replicated from batch to batch. For herbal drugs, the dose of each portion and the ratio of active ingredients may vary. This makes quality control very difficult.
- The quality of research and evidence for herbal drugs is often very poor or non-existent as scientifically valid evidence. Anecdotal evidence, meaning stories that someone says that it works, are not good enough.
If you buy a bottle that says, “paracetamol 500mg tablets”, that is what it contains. They will not contain 200mg, 700mg or no detectable paracetamol. Hence, you can be assured of the dose. Not only is the potency of herbal medicines often very variable but the appropriate dose is usually not well defined. If an adult takes two tablets of paracetamol four times a day, that should be fine. If you take 12 tablets six times a day you will get liver failure and die. This can be extrapolated to herbal remedies too.
When it comes to herbal remedies and supplements, people often think that if a little of something is good, a lot will be even better. As we have seen before, the difference between a medicine and a poison is the dose. I suspect that many cases of liver damage from herbal remedies or supplements result from people taking far too much. As noted above, eight tablets of paracetamol a day is safe but 72 tablets a day is not.
With regard to teratogenesis from plants, a PubMed search produced 20 reviews, but two journals not included in PubMed, were very interesting. One was from the Brazilian Journal of Pharmaceutical Sciences.72Medicinal plants with teratogenic potential The other is from a journal called “Spatula DD – Peer Reviewed Journal on Complementary Medicine and Drug Discovery”73World wide potential of plants causing teratogenicity-an overview
An American report in 2014 from the Drug-induced Liver Injury Network noted that unregulated herbal or dietary supplements used by bodybuilders and by middle-aged women trying to lose weight had become increasingly important as causes of liver injury over the course of the last 10 years.74Liver injury from herbals and dietary supplements in the U.S. The body building supplements seemed to be less dangerous than the others. Supplements associated with death or need for a liver transplant included energy boosters, “herbal Viagra,” Chinese herbal mixtures and various colon and other “cleanse” products. No doubt the users all thought that these were safe and “natural” at the time. The authors concluded that numerous herbal dietary supplements have been associated with liver injury and this is more likely to require liver transplantation than toxicity from conventional medications. They would like to see greater regulation of the market.
The THR logo does not mean that it works, but there is some assurance of quality in that it contains what it says on the packet
In summary, make sure that there is evidence of efficacy and safety. Beware of variable doses. Treat herbal remedies like any other drug. Do not assume safety. Remember that they can cause drug interactions.75Clinical evidence of herb-drug interactions Remember that you are not using “the wisdom of centuries” in most cases but a drug that is untested. Do not be fooled by pseudoscientific claims. Demand evidence.
If you do buy herbal products try to get a brand with the Traditional Herbal Registration (THR) logo on it. A BBC programme called “Trust me I’m a doctor”, broadcast in July 2015 investigated a number of herbal products on sale and found that between about 25 and 33% of those without the THR logo did not have detectable amounts of what was supposed to be the main ingredient. Those with the THR logo were much more reliable.
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A review of the risks of herbal medicines. Unfortunately the abstract only is allowed free of charge. Payment is required for the full text
- Herbal medicines granted a traditional herbal registration (THR)
List from the gov.uk website
- List of banned or restricted herbal ingredients for medicinal use
List from the gov.uk website
- Medicines and Healthcare Regulatory Authority. Herbal safety updates.
The organisation that controls the safety of medicines in the UK gives regular updates about safety issues with regard to herbal medicines. For anyone who still thinks that “natural” is synonymous with “safe” this will be sobering reading.
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This website is now completed, although I shall continue to do updates. The following list shows the sections or chapters. Just click on the topic in blue to go to that part of the site.