Bowel, 'leaky'

'Leaky gut syndrome' is a proposed condition some health practitioners claim is the cause of a wide range of long-term conditions, including chronic fatigue syndrome and multiple sclerosis (MS).

Proponents of 'leaky gut syndrome' claim that many symptoms and diseases are caused by the immune system reacting to germs, toxins or other large molecules that have been absorbed into the bloodstream via a porous ("leaky") bowel.

There is little evidence to support this theory, and no evidence that so-called "treatments" for "leaky gut syndrome", such as nutritional supplements and a gluten-free diet, have any beneficial effect for most of the conditions they are claimed to help.

While it is true that certain factors can make the bowel more permeable, this probably does not lead to anything more than temporary mild inflammation of an area of the bowel.

This page:

explains what we know about the bowel lining – including how this can become more permeable, the effect this has and the few cases where treatment is warranted
explains why we should be sceptical about "leaky gut syndrome"
provides advice for anyone suffering unexplained symptoms and links to reliable information that might help you

The bowel lining: what we know

The inside of the bowel is lined by a single layer of cells that make up the mucosal barrier (the barrier between the inside of the gut and the rest of the body).

This barrier is effective at absorbing nutrients, but prevents most large molecules and germs passing from inside the bowel into the bloodstream and potentially irritating the bowel lining.

Effect of alcohol and certain painkillers

Alcohol, aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen are well-known irritants of the bowel lining. They damage the seals between cells, allowing water-soluble substances to pass through the gaps and into the bloodstream.

Gastroenterologists (specialists in diseases of the gut) generally agree that these irritants do not usually cause anything more than just mild inflammation of a particular area of the bowel, and the bowel lining becomes even more porous as a result. At the very worst, the inflammation might be bad enough to cause ulcers in the bowel lining.

The vast majority of people who consume lots of alcohol or regularly take aspirin or ibuprofen have none of the widespread symptoms or health conditions that proponents of "leaky gut syndrome" mention – health problems you would expect if the theory was true.

Effect of certain bowel diseases and treatments

The following diseases and treatments are also known to damage the seals in the bowel lining:

inflammatory bowel diseases – such as Crohn's disease
infections of the intestines – such as salmonella, norovirus and giardiasis
coeliac disease
chemotherapy drugs
chronic kidney disease
radiotherapy to the abdomen
immunosuppressants (drugs that weaken the immune system)
HIV/AIDS
cystic fibrosis
type 1 diabetes

Generally, only in these situations might treatment for a "leaky" bowel be necessary. For example, people with Crohn's disease usually benefit from medication to reduce the bowel inflammation, and may also benefit from a liquid diet (read more about the treatment of Crohn's disease).

Why we should be sceptical about 'leaky gut syndrome'

Unproven theory

Exponents of "leaky gut syndrome" – largely nutritionists and practitioners of complementary and alternative medicine – believe the bowel lining can become irritated and 'leaky' as the result of a much wider range of factors, including an overgrowth of yeast or bacteria in the bowel, a poor diet and the overuse of antibiotics.

They believe that undigested food particles, bacterial toxins and germs can pass through the "leaky" gut wall and into the bloodstream, triggering the immune system and causing persistent inflammation throughout the body. This, they say, is linked to a much wider range of health problems and diseases, including:

food allergies
migraine
tiredness and chronic fatigue syndrome
asthma
autoimmune diseases (where the body's immune system attacks its own tissues) such as lupus, multiple sclerosis (MS) and rheumatoid arthritis
skin diseases like scleroderma
autism

The above theory is vague and still largely unproven.

'Treatments'

Some scientists and sceptics believe that people who promote "leaky gut syndrome" are either misguided and read too much into the theory, or are deliberately misleading the public to make money from the "treatments" they sell.

The sorts of products sold online include diet books, nutritional supplements (containing probiotics, for example), gluten-free foods and other special diets, such as low sugar or antifungal diets. These have not been proven to be beneficial for many of the conditions they are claimed to help.

Some websites even promote various nutritional "treatments" for autism, despite conflicting evidence. A 2006 review explored the potential effect of manipulating the diet of people with autism, concluding that the dietary treatments were "cumbersome" and not proven to be effective.

Generally, eliminating foods from the diet is not a good idea unless it's strictly necessary (for example, if you have coeliac disease), as it can lead to nutritional deficiencies.

Advice and further information

If you have symptoms that are not explained by a diagnosis, it may help to read our page on medically unexplained symptoms. Such mystery symptoms are surprisingly common, accounting for a fifth of all GP consultations in the UK.

If you have been diagnosed with a particular health condition, you can look it up in our A-Z index of treatments and conditions, where you will find reliable, evidence-based information about its treatment.

Generally, it is wise to view "holistic" and "natural health" websites with scepticism – do not assume that the information they provide is correct or based on scientific fact or evidence.