33. Systemic Candidiasis and Leaky Gut Syndrome

Systemic candidiasis means that there is infection with candida, a type of fungus which effects the body generally rather than just locally and it has been present for a long time. The many claims about this condition are examined as well as those for leaky gut syndrome.
The following headings will apply:

I came across the term “systemic candidiasis” on several CAM websites. It is not a condition that I was acquainted with, except under the most severe of conditions. Candida albicans is a fungus or yeast, often called thrush. Systemic means affecting the whole body as opposed to localised as in candida of the mouth, for example.

Background to Candida Infection

Candida albicans is a small, single cell fungus and yeast. It is often found in the environment and usually does not cause any problem. However, it can at times. Infections are often called “thrush”. Babies may get it in their mouths as can older people, especially if they have dentures and poor oral hygiene. Lack of saliva may also contribute in the elderly. Vaginal thrush is well known and often occurs after antibiotics or in poorly controlled diabetes where glucose levels are high. The vagina normally contains many bacteria, especially a type called lactobacilli. They produce lactic acid which makes the vagina acidic and less favourable to candida. Antibiotics kill the “good” bacteria and allow the thrush to proliferate. It is important to see bacteria as good as well as bad and if antibiotics kill the normal bacteria in the bowel, this also upsets the gut. Candida infection can occur in skin, especially in sweaty skin folds in those who are obese and possibly have poor personal hygiene.

Candida or thrush on the mouth and tongue

Candida infection is real and well recognised.1Candidiasis. PatientUK It is usually just topical, meaning confined to a small area such as the mouth, vagina or part of the skin. A systemic disease is one that affects the entire body. Systemic candidiasis does occur but almost invariably in those whose immune system is seriously compromised. AIDS is an obvious cause but also malignancies such as leukaemia and lymphomas which impair the immune system. Some people have their immune system suppressed to prevent rejection of organ transplants or for treatment of serious diseases. High doses of steroids may have this effect. Systemic candidiasis is called an opportunistic infection as it does not occur in a person with a normal immune system. People with such infections are seriously ill but fortunately there are now drugs that can help to combat the infection.

Treatment of Candida Infection

There are drugs that have been around for many years that can treat topical candida infections. Nystatin was isolated in 1950. Like penicillin and many other antibiotics and antifungal drugs is comes from a bacterium. This one is called Streptomyces noursei. More potent creams and vaginal applications have been available for several decades. They include econazole, miconazole and triconazole. They are all effective as creams but are not available as tablets as they are not absorbed from the gut. Itraconazole is absorbed and so tablets of itraconazole may help to reach the parts that topical applications fail to reach. It can be very useful in vaginal thrush. However, for treating systemic disease something rather more potent, if more toxic, is usually required and this means intravenous amphotericin B. This drug has also been around for a long time having been extracted from the bacterium Streptomyces nodosus in 1955.

When treating vaginal thrush, it is important to ask about a sexual partner. The male may harbour the candida without symptoms and if only the female is treated, he will give it back to her. It is essential to treat them both simultaneously.

In summary:

  • Candida is a well-recognised cause of illness that can be easily recognised and isolated in the laboratory.
  • It is usually localised but if systemic candidiasis occurs in someone who is not known to be immunologically compromised, it is important to look for a cause such as AIDS or a malignancy of cells of the immune system.
  • Effective treatment for candida has been available for many years.

Claims About Systemic Candidiasis

Nevertheless, it is easy to find websites that claim to have an entirely different take on systemic candidiasis. I start with one called Health Highway as my first offering of what utter rubbish is available to the unsuspecting user online. Since I wrote this, it has been removed but similar sites are available and one is listed in the “further resources” section. According to the Health Highway:

“Some of the most common symptoms of a systemic fungal infection are sinus problems, digestive disorders, thrush, vaginal yeast infection, athletes foot, cracking sound in neck, stiffness in joints and muscles, failing eyesight and toenail fungus. Any one of these symptoms is most likely related to a fungal infection.”

Sinus problems are not caused by thrush although sometimes there is a bacterial infection. Athlete’s foot and fungal toenail are caused by fungi but not candida. A cracking sound in the neck is a symptom of arthritis that starts around 40 years of age and progresses from there. Stiffness in joints and failing eyesight are also a feature of advancing years and nothing to do with candida infection. They go on to say:

“Infections usually worsen with age, little by little, year after year. They eventually cause serious life-threatening diseases like cancer.”

Cancer is not a
deficiency disease

Candida as a cause of cancer is certainly a new and novel idea.

I was struck by the paragraph headed “Why medical doctor’s don’t know about Candidiasis.” The apostrophe in “doctor’s” was their error, not mine. They do not understand grammar either. They continue:

“This infection is very hard for the medical community to detect. It cannot be seen under a regular microscope. A candida germ is about 100 times smaller than a single blood cell. If diagnosed, it is very difficult to treat.”

Basic facts are wrong

This is a gross factual error. Candia albicans is roughly spherical in shape and between 2 and 4 microns in diameter.2Candida albicans A micron or µm is a thousandth of a millimetre or a millionth of a metre. A red blood cell has a diameter of about 7.5µm and is about 2.5 µm at its thickest part, so candida cells are about half the size of a red blood cell, not a hundredth of the size. Both candida and red blood cells can be seen quite easily under the normal light microscope.

“Medical doctors do not have the drugs to treat a systemic fungal infection. Drug manufacturers have not been able to develop any drugs which are effective against invasive candidiasis and other systemic fungal infections.”

As explained earlier, even amphotericin to treat systemic fungal infections has been around since the 1950s although it has been improved in recent years.3Introduction to antifungal drugs The absurdity continues:

“The athletes foot fungus is a common problem among many. This ‘moisture loving infection’, which lives in tissues or bones in the feet, is capable of travelling out through the moisture-rich skin between the toes. They then feed on the skin tissues and cause what is commonly known as ‘athletes foot’.”

This time, rather than being too liberal with their apostrophes they have neglected it in “athlete’s foot”. Athlete’s foot is caused by a fungus called Trychophyton, not candida. Athlete’s foot occurs from external infection, not from deep in the bone or soft tissues. It occurs when feet are sweaty, softening the skin and permitting infection. They continue:

“Neither the off-the-shelf drugs nor prescription drugs will kill the infection throughout your body. They only kill the infection flare-up in a localized area. But don’t be fooled, the infectious germs are still living inside your body, waiting to flare-up again once the localized antifungal treatment dissipates.”

Athlete’s foot is a disease of skin. It does not go deeper.

If this were true, then clearing up athlete’s foot or candida would invariably lead to its recurrence after a short while. There may be re-infection or the original infection may not have been properly cleared but usually the infection does not return. They finish with:

“Many doctors will diagnose a person with other illnesses and treat them with drugs and antibiotics, which actually make the fungal infection worse. After all, your doctor won’t make much money if she/he can’t treat you. Plus your doctor doesn’t like to say, ‘sorry, but I can’t help you’.”

The quacks accuse doctors of fraud!

Now they are accusing doctors of telling patients lies to sell services and treatments that are of no value. This is like the purveyors of fake news who accuse others of the crime. They are the ones telling lies to sell useless remedies. The website also includes a question and answer section, some of which is most illuminating:

“Cancer is a deficiency disease. We have known this for years, but have not known, until now, why we have been becoming so deficient in vitamins and minerals.”

Cancer as a deficiency disease is news. They continue:

“An invasive candidiasis infection consumes the nutrients we eat before they have a chance to feed our body cells. When cells become deficient of nutrients, cancer (and other diseases) occur.”

This is utter rubbish, but it does not end here.

“The fungal infection infects the knee joints and feeds on the tissues and bones. It continues to live there year after year causing arthritis symptoms and joint degeneration.”

We are not offered any evidence that fungal infection causes arthritis. We have seen Koch’s postulates in the chapter A Very Brief History of Science And Medicine. They represent a basic guidance for attributing a certain infectious cause to a disease. They do not apply fully to all diseases and AIDS and leprosy are amongst the exceptions. However, they are good guidelines and for this assertion to have any credulity it would be necessary to show that arthritic joints contain fungi. They might be seen under the microscope or grown in culture. It would help if eradication of the infection reversed the disease and if it could be produced in laboratory animals by injecting the organism. How people can make such totally unfounded claims is amazing. What is even more astounding is that some people will accept them without question. Apparently the way to clear the candida infection is with “antiseptic foods” such as onions, celery and garlic. There is no point in asking if there is any evidence that such foods have cleared any infection when there is no evidence that there was any infection there originally.

According to the website, common symptoms of candida infection include:

  • abdominal bloating
  • flatulence (gas)
  • abdominal pain
  • diarrhoea
  • constipation
  • foul smelling stools
  • bowel irritation
  • joint and muscle pain
  • heartburn
  • headaches
  • itching
  • bad breath
  • fluid retention
  • food sensitivities
  • allergies
  • sugar cravings
  • mental confusion (brain fog)
  • fatigue
  • feeling chilled after a bath or shower
  • malaise (general ill feeling)

This seems reminiscent of the character in Jerome K Jerome’s “Three Men in a Boat” who had “everything in the medical dictionary except housemaid’s knee”. Some of these abdominal symptoms suggest irritable bowel syndrome and diet can usually help in this. I am sure that “mental confusion (brain fog)” is essential for anyone to take this sort of thing seriously.

These utterly absurd claims are not limited to a single rogue source. A search for “systemic candidiasis” found several website promoting similar fantasies. One such site is called ezine articles.4Ezine articles. The Symptoms of Systemic Candidiasis The story is similar and the alleged symptoms are similar but by no means identical. They are:

  • Gastro Intestinal problems such as: bloating, gas, intestinal cramps, chronic diarrhoea, constipation, or heartburn
  • Chronic fatigue, especially after eating
  • Depression
  • Poor memory
  • Lack of concentration
  • Muscle pains
  • Rectal itching
  • Allergies (including both food and air born) (“air born” is their spelling, not mine!)
  • Severe pre-menstrual syndrome
  • Impotence
  • Memory loss, severe mood swings, and feeling mentally “disturbed”
  • Recurrent fungal infections such as “jock itch”, athlete’s foot, or ringworm
  • Extreme sensitivity to chemicals, perfumes, smoke, or other odours
  • Recurrent vaginal or urinary infections
  • Prostatitis
  • A feeling of being light headed or drunk after minimal wine, beer, or certain foods
  • Aching joints
  • Irritability
  • Acne

Many of these symptoms suggest not just irritable bowel syndrome but depression too. IBS often occurs with anxiety and depression and they are very responsive to any placebo effect.

I moved on to the webpage “cure your yeast infection naturally”. At least they did not pretend that there is no medical cure for fungal infection. They did mention difluconazole, the anti-fungal that can be taken by mouth. They suggest that it is used too often and this is causing a problem of resistant fungi. The scientific literature reports that some resistance to fluconazole does occur. However, this is rare and unlike bacterial resistance to antibiotics, it is not a problem. Most papers relate to very ill patients in intensive care units or those with immune compromise. There is no evidence of significant resistance in the community. If people who use such websites are finding that their yeast infection is not responding to difluconazole, they need to ask if they really had a yeast infection at all. Laboratories can grow Candida without difficulty and could test for resistance to anti-fungal drugs just as they test bacteria for antibiotic resistance and offer advice on the best one to use. This is not usually done as antifungal resistance is uncommon.

There are a number of other sites in a similar vein. Most of them are American rather than British. However, before leaving the topic there is something that arose at times that merits investigation.

Leaky Gut Syndrome

I had never heard of “leaky gut syndrome”. There is a British website that expands on this although the spelling is American and it often refers to American sources. According to this website:

“The symptoms of Leaky Gut Syndrome are many and varied and include: abdominal pain, heartburn, insomnia, bloating, anxiety, gluten intolerance, malnutrition, muscle cramps and pains, poor exercise tolerance, food allergies.”

Again there is such an array of symptoms that scepticism is required. It also states that:

Wrong again!

“Leaky Gut Syndrome has also been linked with many conditions, such as: Coeliac Disease, Multiple Sclerosis, Fibromyalgia, Autism, Chronic Fatigue Syndrome, Irritable Bowel Syndrome, Eczema, Dermatitis, Ulcerative Colitis.”

Again, this list produces a credibility gap. Gluten intolerance is what causes coeliac disease. In fact, coeliac disease is associated with a leaky gut but it is the result rather than the cause. They give a number of possible causes for this alleged condition including candidiasis.

The small intestine has finger-like villi which greatly increase the surface area to absorb nutrients as in A. Allergy to gluten leads to flattening of the villi in B and with it comes malabsorption, causing weight loss and diarrhoea. Avoidance of gluten will let the villi grown back and all will be normal as long as gluten is strictly avoided.

Never having heard of “leaky gut syndrome” I turned to PubMed to see just how much medical literature there is about it. A search for “leaky gut syndrome” produced just 14 papers. This is a very small number. Of those an astounding eight were reviews. Were they all reviewing the other six papers? To put this into perspective, a similar search for irritable bowel syndrome produced 7,108 papers of which 1,768 (25%) were reviews. Of all the papers on “leaky gut syndrome”, three were published in a journal I had never heard of called “Neuroendocrinology letters”. Calling it “letters” seems strange. Letters in journals, rather than papers, are usually comments on recently published papers or relating to medico-political matters. If they are reporting new findings it is not normally completed research. Neuroendocrinology is a small niche area and seems a strange one for these publications. I have looked at its provenance and it is published by The Society of Integrated Sciences in Stockholm. “Integrated Sciences” is usually a term for pseudoscience that no respected scientist would even consider. It claims to publish peer reviewed papers but letters are not usually peer reviewed. I have looked at a number of the papers that they publish and there was no neuroendocrinology that I could find. This is to do with nerves and hormones, to keep it simple. Superficially they are cloaked in scientific jargon and pseudoscience that gives a false sense of respectability.

Of the papers I found, one seemed to be a protocol for a trial about to be done in people with AIDS to test gut permeability. Another was about gut permeability in heart failure and again not really relevant. One was in a psychiatry journal. Two were about permeability of the bowel in different circumstances and so were not really relevant. As four of the papers were not really about “leaky gut syndrome” this means that there were ten publications. Three were in journals of complementary and alternative medicine. This is not an impressive array.

Even Nobel laureates have gone over to the dark side

The original website that I accessed about “leaky gut syndrome” is now for sale, but there are plenty of similar ones, making similar claims. This one is headed511 Signs You Have Leaky Gut Syndrome The author is advertised as “Amy Myers, M.D., is a renowned leader in functional medicine and New York Times best-selling author of The Autoimmune Solution and The Thyroid Connection.” The MD suggests that she is a proper doctor but Darth Vader is not the only one to have gone over to the dark side. A book can be a best-seller, by whatever criteria, and still be unbelievable rubbish. Some of the best-sellers on nutrition are utter fantasy.

Leaky gut syndrome is covered on the NHS website.6“Leaky gut syndrome” from the NHS They say that some people attribute certain chronic diseases to it, including chronic fatigue syndrome and multiple sclerosis. The site above names several other conditions, including autism. Parents of autistic children are bombarded with fake causes and remedies for their children’s illness and they may be desperate enough to turn to them. However, there is no evidence to support any of this.

Since I wrote this chapter, I have come across “leaky gut” in the medical literature on several occasions and a PubMed search gives far more results than the last time I looked. Interest in it is fairly new and I have no reason to retract the criticisms above of those on the fringes of medicine who who purvey this disease.

A review called 7Leaky Gut, Leaky Brain? from December 2018 says that leaky gut has long been associated with coeliac disease. He says that some psychiatric problems, including depression, can occur with coeliac disease. However, he points out that the only people who benefit from gluten exclusion from the diet are the 1% of the population who have coeliac disease. There are those who use jargon-loaded terms such as terms as oxidative stress, superoxide oxidative burst or cytokine stress without understanding the complex mechanisms involved. On the subject of CAM he says, “I like to keep an open mind. However, not so open a mind that my brains fall out or, in this case, leak out.”

Another review on ‘leaky gut’ for clinicians discussed the components of the intestinal barrier, the diverse measurements of intestinal permeability, abnormalities in non-inflammatory “stressed states” and the impact of treatment with diet. 8Leaky gut: mechanisms, measurement and clinical implications in humans Information on “healthy” or “leaky” gut in the public domain requires confirmation before endorsing dietary exclusions, replacement with non-irritating foods (such as fermented foods) or use of supplements to repair the damage. “Stress” disorders such as endurance exercise, non-steroidal anti-inflammatory drugs administration, pregnancy and surfactants (such as bile acids and dietary factors such as emulsifiers) increase permeability. Dietary factors can reverse intestinal leakiness and mucosal damage in the “stress” disorders. Whereas inflammatory or ulcerating intestinal diseases result in leaky gut, no such disease can be cured by simply normalising intestinal barrier function. It is still unproven that restoring barrier function can improve clinical features of diseases. Clinicians should be aware of the potential of barrier dysfunction in GI diseases and of the barrier as a target for future therapy. Unfortunately, this review is not available without charge.

Gluten sensitivity is covered further in the chapter Diets and Nutrition for Health and Fitness. Sales of gluten-free products suggest that they are eaten by 6% of the population although only 1% has coeliac disease. A double-blind randomized placebo controlled trial of healthy volunteers showed that gluten exclusion did not have any benefit in those who do not have coeliac disease.9Gluten Does Not Induce Gastrointestinal Symptoms in Healthy Volunteers: A Double-Blind Randomized Placebo Trial However, it was interesting that when they screened subjects before the trial, they had to exclude two as they had previously undiagnosed coeliac disease. If you think that you are gluten sensitive, have it checked. There is one other disease that does benefit from gluten exclusion. It is a very rare skin disorder called dermatitis herpetiformis. It causes blistering, it is very rare and I have never seen a case.


  • Systemic candidiasis can occur in people with severe compromise of their immune system but the alleged disease in people with a normal immune system is fictitious.
  • Leaky gut syndrome, as described, is not a disease with any basis.
These sites often look plausible with impressive pseudoscience

Before publication, I checked the two sources that I had used to refer to systemic candidiasis and leaky gut syndrome. The candidiasis website did not exist and the leaky gut site was for sale. That would be reason to rejoice but I have found other sites that peddle the same nonsense. The ezine article is still there. The NHS points out that whilst some medications and conditions can increase bowel permeability, “there is currently little evidence to support the theory that a porous bowel is the direct cause of any significant, widespread problems.” They are similarly scathing about the use of herbal remedies or diets to heal these conditions.

Leaky gut is an interesting, new field of investigation but it is really too soon to make any confident statement about it. However, it is essential to differentiate the real science from the nonsense that is purveyed under that title.

Further Resources


  1. Harding M. Candidiasis. PatientUK 2017
  2. Candida albicans- Habitat, Morphology, Cultural Characteristics, Life Cycle, Pathogenesis, Lab Diagnosis, Treatments, Prevention and Control. by Sagar Aryal 2017
  3. Dismukes WE. Introduction to antifungal drugs
  4. Ezine articles. The Symptoms of Systemic Candidiasis
  5. 11 Signs You Have Leaky Gut Syndrome
    Fantasy from someone who ought to know better
  6. “Leaky Gut Syndrome” from the NHS
  7. Obrenovich MEM. Leaky Gut, Leaky Brain? Microorganisms. 2018 Oct 18;6(4) [full text]
  8. Camilleri M. Leaky gut: mechanisms, measurement and clinical implications in humans. Gut. 2019 Aug;68(8):1516-1526.
  9. Croall ID, Aziz I, Trott N, Tosi P, Hoggard N, Sanders DS Gluten Does Not Induce Gastrointestinal Symptoms in Healthy Volunteers: A Double-Blind Randomized Placebo Trial. Gastroenterology. 2019 Sep;157(3):881-883 [full text]

Site Index

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.

1 Introduction
2 A Very Brief History of Science And Medicine
Fundamentals of Medical Science
3 Finding Good Medical Advice and Evidence Based Medicine
4 Randomised Controlled Trials
5 Cohort or Longitudinal and Epidemiological Studies
6 Qualitative Research
7 Basic Maths in Medical Research and Decision Making
8 How Good is the Evidence?
9 Ethics in Practice and Research
Public Health Issues
10 Screening Programmes
11 Fake News and Vaccine Scares
12 Electronic Cigarettes (E-Cigarettes)
13 Motor Vehicle Emissions, Air Pollution and Health
14 COVID-19. What You Need to Know
15 Who is at Risk from COVID-19
16 What We Must Learn from the COVID-19 Pandemic
17 Basics of Nutrition
18 Exercise, Obesity and Diets for Weight Loss
19 Diets and Nutrition for Health and Fitness
20 Supplements
Complementary and Alternative Medicine
21 Introduction to Alternative Healthcare
22 Homeopathy
23 Acupuncture
24 Manipulation of the Spine
25 Reflexology
26 Herbal Remedies
27 Other Natural Products
28 Chelation Therapy
29 Hypnosis
30 Other Modalities of Complementary and Alternative Medicine
Some Controversial Diseases
31 Fibromyalgia
32 Chronic Fatigue Syndrome (CFS) or Myalgic Encephalitis (ME)
33 Systemic Candidiasis and Leaky Gut Syndrome
34 Mobile Phones, Masts, Wi-Fi and Electro-sensitivity
The Environment
35 Global Warming and Climate Change
36 Alternative Energy
Some Final Thoughts
37 Still Searching for the Age of Reason