Leaky gut is an inflammatory condition of the small intestines in which the mucosal barrier shows increased permeability. This inner surface, approximately 400 m², forms a selectively permeable membrane between the contents of the gut and the blood so that nutrients can pass through to the liver; however, increased permeability allows the absorption of undigested food particles, micro-organisms, and toxins (i.e. lipopolysaccharide) which trigger an immune reaction.

The inflammatory response can then affect other organ systems in the body, particularly in those people with constitutional vulnerability. Leaky gut is associated with the development of  seasonal allergies, irritable bowel syndrome, metabolic syndrome, adult-onset coeliac disease, migraine, chronic fatigue syndrome, eczema, autoimmune conditions, Alzheimer’s disease, autism, cancer, and mood disorders.

The intestinal barrier is protected by a thick coating of mucus which lubricates the food and hinders large molecules or micro-organisms from directly contacting the cell walls (epithelium). Gastric acid also forms part of the barrier, sterilising food in the stomach, while bile has additional bactericidal properties. In addition, Paneth cells secrete enzymes, peptides and defensins into the intestines which can kill bacteria, fungi and viruses, while plasma cells synthesise secretory immunoglobulins (sIgA) which hinder the adherence of bacteria.

The single-celled epithelium performs its absorptive function by allowing nutrients to diffuse through the cells, or to travel via the spaces between them. These cellular spaces are bound with structural proteins called desmosomes, adherins, and tight-gap junctions. Tight-gap junctions are regulated by a protein called zonulin, which is a key regulator of permeability, along with several other proteases. Zonulin determines the size and nature of the particles which can pass through, purposely allowing some to contact gut-associated lymphoid tissue (GALT).

The GALT contains diverse immune cells which monitor the digestive contents for potential allergens and pathogens, and then mount responses to them before they are absorbed. These cells include dendritic cells, macrophages, T-regulatory cells, lymphocytes, and plasma cells. Exposure assists in the development of immune tolerance.

While inflammation adversely affects the integrity and permeability of tissues as a whole, including the gut epithelium, zonulin is affected by specific substances. For example, zonulin is upregulated or damaged in all people by the gliadin in wheat, aka gluten, and not just those with coeliac disease (gliadin causes zonulin release).

Intestinal immunological responsiveness is also determined by genetics, through a pathway called the major histocompatibility complex (MHC). This mechanism encodes surface proteins on cells which can recognise specific antigens and then present them to immune cells. This is part of the reason why there are individual variations in susceptibility to certain specific diseases that can be triggered by a general state of chronic inflammation arising from leaky gut and the resultant autointoxication.

Furthermore, a complex inter-relationship exists between the immune cells, nutrients, and commensal gut flora (bacteria, fungi, archaea), beginning as the infant passes through the birth canal. Chronic inflammation, whether induced by diet or disease will adversely affect the gut flora and produce a state of immune hyper-responsiveness that is evident in many chronic diseases, and is  called the ‘inflammabiome.’

The gut flora can influence barrier integrity, in turn, via the direct stimulation of epithelial growth as well as the synthesis of short chain fatty acids which nourish epithelial cells. They also regulate motility, nutrient absorption (vitamin K, B12), metabolise lactose, detoxify drugs and carcinogens, and help recycle bile salts. An altered state where the species present reflect active disease processes rather than health is called dysbiosis.

Leaky gut may be caused by a poor diet, dysbiosis, low stomach acid, infection, parasites, pharmaceutical drugs (NSAIDs, antibiotics), excess alcohol consumption, exposure to environmental toxins, endurance sport, menopause (low oestrogen), or chronic stress. The symptoms are typical of digestive system disorders generally: indigestion, halitosis, bloating, nausea, flatulence, altered bowel habit, fatigue, headaches, joint pains, food sensitivities, allergy, skin conditions, and mood disorders.

Leaky gut can be measured using a lactulose/ mannitol test in which both sugars are taken together, and their ratio is determined afterwards in the urine. Lactulose is a larger molecule than the more-easily absorbed mannitol, so a higher urinary excretion ratio of lactulose to mannitol reflects a mucosal barrier which is capable of ‘leaking’ larger molecules, such as undigested food proteins. Serum zonulin has also been trialled as a test for leaky gut but it is less reliable as a measure of damage than a test for the actual antibodies generated against zonulin. Other useful markers are faecal calprotectin, which is a measure of intestinal inflammation, and the serum ESR or CRP, which indicate inflammation in general.

Treatment

General

A lactulose mannitol test can indicate leaky gut or this sate can simply be assumed because of the gut symptoms, associated food sensitivities or other symptoms of immune system dysregulation. Regardless, the specific cause needs to be identified in the diet with either an old-fashioned elimination protocol or IgA/ IgG/ IgE tests. A stool test can add important information about inflammation, parasites, bile acids and pancreatic enzyme sufficiency. Pharmaceutical drugs such as PPIs, NSAIDS, steroids, and antibiotics will harm the gut so alternatives need to be found.

A lifestyle assessment must be made, as well as an audit of environmental allergens such as dust, pollen, pet dander, domestic or workplace chemicals and harmful electro-magnetic fields. A Hair Mineral Analysis will reveal any mineral deficiency or heavy metal exposure.

Chronic stress adversely affects the integrity of the whole gut along with its protective secretions and needs to be managed. This can be done with adequate rest, sleep, nutrients, exercise, meditation, yoga etc.

Diet

Factory foods consisting of refined sugars, trans fats and synthetic additives must be avoided while reactivity to certain substances needs to be identified (salicylates, yeast, mould, gluten, amines, histamine, glyphosate etc.). Even supposed beneficial wholefoods can trigger inflammation so formal testing or an elimination diet may be necessary.

A good diet to begin with is the traditional Mediterranean diet containing vegetables, fruit, sourdough bread, goat’s cheese, nuts, seeds, olive oil, and moderate meat. If this is not sufficient, a Paleo diet should be tried which avoids wheat, dairy and soy, the most problematic foods.

Any deficiency of protein, zinc, minerals or vitamins will cause loss of integrity in gut tissues or poor immune function. Glutamine is a key repair nutrient as are omega-3 oils, zinc, vitamin A, vitamin C, and polyphenols such as quercetin. Vitamin D is necessary for barrier immune function, and integrity. Avoid excess alcohol, coffee or tea consumption. The common food additive chitosan also increases permeability.

Dysbiosis is an important consideration in the aetiology of leaky gut. Good bacteria confer colonisation resistance to pathogens, they regulate immunity, and quieten inflammatory responses which lead to intestinal damage, increased  permeability and cause immune system reactivity. The diet should consist of wholefoods with plenty of fibre, and be supplemented with probiotic foods such as kefir, yoghurt or fermented vegetables. A probiotic supplement can be used in the transition.

Herbs

Herbs to soothe, protect and treat the gut while it heals are slippery elm, marshmallow, liquorice, plantain, marigold, and golden seal. Turmeric, chamomile and Aloe vera are anti-inflammatory and healing. Gotu kola builds tissue integrity.

Herbs to treat the immune system are garlic, echinacea, Siberian ginseng, and andrographis. Herbs for building stress-coping are oats, ashwagandha, schisandra, Korean ginseng, skullcap and rhodiola.

A detox can be undertaken with herbs such as yellow dock, nettle, burdock,  and clivers. The liver needs to be treated in chronic conditions with herbs such as milk thistle, dandelion, bupleurum, and chelidonium.

Cell Salts

Calc-fluor is for building tissue integrity. Ferrum-phos can be used to treat inflammation and anaemia. Mag-phos and Kali-phos are for the nervous system and stress adaptation.

Disclaimer: this article is intended for the purpose of general education only, and is not a substitute for diagnosis, treatment advice, or a prescription that is given in a consultation with a qualified physician.