What is leaky gut o intestinal permeability? What is the recommended diet to alleviate leaky gut symptoms? How can the intestinal lining be repaired?
What is the intestinal barrier?
The intestinal barrier is the largest surface area of contact with the external environment with an approximate size of 200 square meters.
Nutrients, water and electrolytes are absorbed by the intestinal epithelium.
It is also the first line of defence against pathogens, allergens and potentially harmful substances present in the intestine.
The connection between the microbiota and the intestinal barrier
The intestinal epithelium is covered by the intestinal mucosa, where thousands of bacteria compose the microbiota. This monolayer of epithelial cells is formed mainly by enterocytes. They contain immune cells and cells specialized in the secretion of hormones and neuropeptides.
These bacteria participate in the digestion and influence the development and functioning of the immune system by strengthening the intestinal barrier.
What exactly is leaky gut?
The alteration of the intestinal barrier promotes the passage of substances into the internal environment that would normally be excluded, resulting in immune response with an inflammatory process.
In fact, this is a situation of intestinal hyperpermeability, also known as a leaky gut syndrome.
The leaky gut syndrome is associated with an imbalance in the microbiota called dysbiosis.
Intestinal hyperpermeability is linked to various pathologies
Intestinal hyperpermeability is linked to inflammatory diseases of the gastrointestinal system such as celiac disease, food intolerance, inflammatory bowel disease or irritable bowel syndrome (IBS).
It is also linked to extra digestive or autoimmune diseases such as allergies, dermatitis, obesity, diabetes, multiple sclerosis, rheumatoid arthritis, lupus and psoriasis (Dieterich, 2018).
What factors can alter intestinal permeability?
Diet, stress and the intake of certain medications are the factors that can also further disturb the microbiota and intestinal permeability.
The Importance of foods rich in fibre and polyphenols
A diet consisting of an excess of processed foods rich in sugar, salt, processed fats and food additives damages the microbiota and increases intestinal permeability.
On the other hand, a diet rich in plant-based foods with an abundance of dietary fibre and bioactive compounds such as polyphenols reduces intestinal hypermeability (leaky gut).
For example, vegetables, fruits, legumes, whole grains and cereals, nuts and turmeric reduce inflammation and promote good intestinal health.
Impact of certain drugs on intestinal permeability
The negative effect of antibiotics on the microbiota is well known. But there is also evidence that other drugs have an impact on intestinal hyperpermeability.
A recent study confirms that proton pump inhibitors (PPI antacids), metformin (antidiabetic), some NSAIDs, antidepressants and statins can induce intestinal dysbiosis (Le Bastard, 2018).
How to improve the intestinal barrier with food?
Probiotics can help restore the balance of the intestinal microbiota and modulate the immune system.
They can also promote the barrier function against pathogenic microorganisms by producing bacteriocins or competing with them for nutrient availability and in their adhesion to the mucosa.
It is important to know that the activity of probiotics is strain and dose-dependent.
Among the most popular fermented foods are kombucha, kefir, yoghurt, sauerkraut, kimchi, miso and tempeh.
These types of foods and drinks contain live bacteria that are still active once they are in our bodies. They thus contribute to the diversity of the intestinal microbiota. This is why it is very important to consume non-pasteurized fermented foods.
In addition, these fermented foods may contain organic acids that are used by bacteria as a substrate to produce short-chain fatty acids (Marco, 2017).
Prebiotics – Fibre
Dietary fibre itself improves intestinal health by increasing stool volume and stimulating peristalsis.
In addition, certain types of fibre can be used by probiotic bacteria as food. Indeed, they increase the population of bacteria and also allow the synthesis of short-chain fatty acids such as butyric acid.
The production of short-chain fatty acids is the result of the bacterial fermentation of complex carbohydrates. These fibres are called prebiotic or fermentable fibres.
They are found, for example in carrots, apples, oats, mushrooms, chia and flax seeds, seaweed, chicory root, leeks, onions, asparagus, artichokes, bananas, legumes and tubers. Tubers are an important source of starch when cooked and then cooled in the refrigerator.
Postbiotics – Short-Chain Fatty Acids
Short-chain fatty acids (SCFAs) like butyrate, propionate and acetate are produced in the colon during the fermentation of dietary fibres.
At the intestinal level, butyrate acts as a nutrient for the enterocyte.
Butyrate stimulates the formation of the mucous membrane by improving the gut’s barrier function against pathogens and allergens. It also acts as an immunoregulator by inducing the formation of regulatory T-lymphocytes that counteract chronic inflammation.
Intestinal permeability (leaky gut) and constipation
Butyrate is particularly indicated to reduce diarrhoea and constipation caused by intestinal inflammation
Inflammation of the gut
Butyrate may also be recommended for the comfort of patients with inflammatory bowel disease such as Crohn’s disease or ulcerative colitis, irritable bowel syndrome, and diverticulitis (Rios-Covian, 2016; Manrique, 2017).
Recent studies highlight the role of short-chain fatty acids (SCFAs) in the microbiota-intestine-brain axis and relate butyrate to neurotransmitter production and blood-brain membrane integrity (Toribio-Mateas, 2018; Gómez-Eguílaz, 2019).
Glutamine is an amino acid that improves the function of the intestinal barrier by acting as an energy source for the epithelial cells of the small intestine.
It helps to reduce leaky gut symptoms. Indeed, glutamine increases the proteins that form the tight junctions between enterocytes and improves intestinal permeability.
Although glutamine is readily available in our usual diet, it must be supplemented in some cases to improve intestinal function.
omega-3 DHA is a structural component of the cell membranes of all organs and tissues of our body, especially for the nervous system, brain and visual function.
Similarly, DHA is essential for the integrity of the intestinal membrane. So we must ensure an adequate supply of omega-3 through our diet.
Typical omega-3 DHA rich foods are fatty fishes like tuna, mackerel, wild salmon, anchovies, sardines, and some crustaceans.
Unfortunately, fatty fishes accumulate mercury and other environmental toxins and their consumption might no be recommended for certain populations like pregnant women.
Therefore, dietary supplements made from microalgae oil not originating from the sea are an excellent option to cover the needs of this nutrient.
Recent publications highlight the immunomodulatory and anti-inflammatory activity of vitamin D in the intestinal barrier.
Vitamin D deficiency is linked to intestinal hyper-permeability.
People suffering from inflammatory bowel disease and other autoimmune conditions often present a moderate of severe deficiency of vitamin D.
Therefore, improving vitamin D levels improves the integrity of the intestinal barrier, the immune response and the rate of relapse (Yamamoto, 2020; Fletcher, 2019; Li, 2018; Tabatabaeizadeh, 2018).
Curcumin is the main active ingredient in the rhizome of Curcuma longa. Curcumin shows powerful anti-inflammatory and antioxidant capacity.
In fact, curcumin acts by inhibiting the activity of the enzyme cyclooxygenase-2 (COX-2) and the nuclear transcription factor NF-kB. This is why turmeric is of great interest in inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease.
Curcumin supplementation in these patients has been shown to improve the intestinal barrier, reduce the symptoms and duration of acute episodes and significantly improve their quality of life (Burge 2019, Mazieiro 2018, Brumati 2014).
A varied diet and a selected food supplementation contribute to improving leaky gut symptoms. A well-balanced diet, rich in fibre, fermented foods, essential nutrients such as vitamin D and omega-3 fatty acids supports the microbiota diversity, and gut health in general.
Author: Anna Paré Vidal
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