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Nutrition for A Healthy Gut

24 May 2019

Bloating, belching, flatulence, nausea, indigestion, abdominal cramps, heaviness after meals, diarrhoea, constipation….These are just some of a myriad of debilitating gastro-intestinal (GI) symptoms that are all too common nowadays. In fact, they are so prevalent that one survey of 500 British people found that as many as 10% suffers from these types of symptoms almost every day.

GI symptoms can be due to medical conditions like celiac disease, Crohn’s disease or colitis. But in other cases, medical tests can find no organic cause, meaning that you can be left without a clear direction of how to improve your health. Such cases are what are known as Functional Gastro-Intestinal Disorders (FGID). 40 or more FGIDs have been named and classified, including functional dyspepsia and IBS. This article gives some suggestions on things you could consider to improve the health of your gut.

The best results come when working with an experienced and appropriately qualified nutrition practitioner - hence it would be best to see a Registered Nutritional Therapist in order to find out exactly what functional disorders are causing your symptoms, and get a personalised nutrition programme that may include the types of interventions outlined below:

What, when and how we eat significantly affect how our digestive tracts work.


Elimination diets are often prescribed for digestive problems. Food components that commonly trigger symptoms include gluten, lactose, excessively high-fat foods, hot spices and/or sugars and starches that are poorly absorbed in the gut (commonly known as ‘FODMAPs).

FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) are highest in gluten grains (except spelt), beans, pulses, dairy and many fruits and vegetables. These can be problematic for people with microbial imbalances in the gut (dysbiosis), whether in the colon or the small intestine (SIBO). This is because FODMAPs are food for microbial overgrowths. There is very good evidence for the low-FODMAP diet improving IBS symptoms like wind, bloating, dyspepsia and alternating constipation and diarrhoea. It may also help individuals with inflammatory bowel disease.

Elimination diets can be extremely helpful. But it’s important to remember that the key to long-term digestive health is microbial diversity; and that this arises from eating as wide a range of plant foods as possible. (Experts suggest 30 different types of plant a month.) Thus it may be best to use elimination diets for limited periods only, so that a wide range of vegetables, fruits, beans, pulses, nuts, seeds and whole grains can soon be reintroduced.


‘Grazing’, or ‘eating little and often’ can be helpful in stabilizing blood glucose levels. But our digestive tracts do better when they are allowed longer periods of rest. Fasting 12 hours overnight and 4 hours between meals can help to prevent microbial overgrowths because it allows optimal functioning of a the migrating motor complex (MMC). The MMC is a system of electrical waves in the GI smooth muscle that sweeps the digestive tract clean of residual microbes and food particles.  It occurs only during fasting and is interrupted by eating, including snacking. Poor MMC function has been associated with SIBO, gastroparesis and intestinal pseudo-obstruction. So try to eat just 2-3 times a day, with fasting in between.


The gut and the brain are closely connected by the vagus nerve and other neurological pathways.  Hence why feeling tense, angry, depressed or stressed can be detrimental to gut health and vice versa.

If you live a stressful life, it can be helpful to keep a food and mood/stress journal, to identify any stress triggers that may be affecting digestion. Insufficient sleep (quality and quantity) are also thought to compromise digestion, so aim to get 7-9 hours a night.

At mealtimes, focus on the eating – aim not to be reading, watching TV, working or driving at the same time. Eat sitting down, in a calm, relaxed state. Try taking some long breaths at the start of the meal.  And aim to chew each mouthful 30 times before swallowing.

Addressing the causes – relevant nutrients

Functional causes of gut problems include microbial imbalances ('dysbiosis'), low levels of digestive secretions, leaky gut, sluggish bile flow and disordered muscle contractions (peristalsis) in the intestines  Remember that working with a Registered Nutritional Therapist will enable you to identify which particular causes to address to get the best improvement of your symptoms.)

Bacterial imbalance (dysbiosis) in the colon or the small intestine (SIBO)

Antimicrobial phytochemicals:

Extracts from plants like olive leaf, cinnamon bark, oregano oil and fennel seed contain bioactive compounds that can help to rebalance gut microbial populations by inhibiting overgrowths.

Oregano, for example, contains the phenol carvacrol, which has broad-spectrum antimicrobial activity, as well as being an antioxidant and antispasmodic. A study of 104 patients found that a course of antimicrobial plant extracts including oregano oil and olive leaf was as effective in clearing a SIBO as the most commonly used antibiotic therapy.


Ginger can be helpful where the cause of microbial overgrowths is slow motility in the gut. Ginger’s active phenols gingerol and shogaol support the MMC, which regularly sweeps the intestine clean.

Live Bacteria

Certain strains of bacteria naturally found in the human gut (like Lactobacilli Acidophilus and Bifidobacterium) can be useful in reseeding the large intestine after a course of antibiotics, as well as in other cases of colonic dysbiosis.

Saccharomyces Cerevisiae Boulardii

This probiotic yeast has been shown to maintain and restore the flora in the large and small intestine, and has been found effective in reducing diarrhea in children and adults associated with antibiotic use, foreign travel and infections of Clostridium difficile and other common viruses and bacteria.


FOS is a prebiotic fibre that selectively stimulates the growth of beneficial bacteria in the gut. Just 8g of FOS a day for 2 weeks has been found to produce a ten-fold increase in Bifidobacteria. Not only does this rebalance the gut microflora, it also increases the production of n-butyrate and other short chain fatty acids that keep the colonocytes healthy and have powerful anti-inflammatory effects. Studies have shown FOS to improve IBS symptoms by increasing commensal microbes and reducing the toxic load of pathogens. It has also been shown to enhance magnesium absorption in the gut, so may be a useful adjunct to magnesium supplementation.

It’s best to use naturally-derived FOS (from chicory) rather than the synthetic form (often extracted from sugar beet) because the latter can contain fructose and other sugars.

In SIBO, it may be helpful to use antimicrobials and dietary measures before considering prebiotic fibre.

Fungal overgrowths in the colon and/or small intestine (SIFO)

Saccharomyces Cerevisiae Boulardii

S Boulardii is sometimes referred to as a ‘yeast against yeasts’ because of its ability to rebalance fungal overgrowths like Candidiasis. S Boulardii also improves the gut’s innate and adaptive immune systems, so that pathogens are less able to colonize and produce toxic products that cause inflammation.

Live Bacteria

Live bacteria such as Lactobacillus and Bifidobacteria can be helpful where opportunistic yeasts have taken hold following antibiotic therapy.


Garlic extract has long been used for its antifungal activity and recent research indicates that common yeast overgrowths like Candida Albicans are disrupted by the activity of the sulphur compounds in garlic, in particular alliin, which is converted to the active allicin in the human body.

(Best avoided in SIBO because of garlic’s fermentable sugars.)

Low Digestive Secretions


Hydrochloric acid (HCl) is produced in the stomach to break down food, liberate minerals and disable unwanted microbes that have been ingested. It also activates a powerful protease called Pepsin that breaks down protein and releases vitamin B12 from food. The food then passes into the small intestine, where it is further digested for absorption.

HCl can decline with age and also with stress, leading to incomplete digestion and many gut symptoms.

Supplemental HCl and pepsin is commonly prescribed to replace some of the lost acidity in the short-term, while the underlying cause of low stomach acid is investigated and addressed.

(Not to be taken in cases of GI inflammation or ulceration.)


Zinc is the limiting cofactor in the biosynthesis of hydrochloric acid, meaning that if HCl levels are insufficient, zinc depletion could be the cause. Zinc also keeps the taste buds healthy, enabling us to get more pleasure from healthy, wholefoods.

Digestive Enzymes

Digestive enzymes are secreted by the pancreas and the villi in the small intestine, in order to break down food matter into its component nutrients. These can then be absorbed across the gut wall into the blood stream. If this enzyme system does not work effectively, undigested food will be fermented by the resident bacteria, causing flatulence, bloating and sometimes diarrhoea.

Enzyme function can be enhanced by supplementing with broad-spectrum enzymes, preferably plant-sourced because quality control is assured and contamination is far less likely than when animal sources are used. Natural plant enzymes are highly bioavailable in the human digestive tract.


Lactase is synthesised in the intestine to digest lactose the sugar in dairy products. The most common cause of dairy intolerance is lactase deficiency. This may be the result of diarrhoea and/or leaky gut, as damaged intestinal villi cannot produce the enzyme, but it can also be genetic, with an estimated 75% of the world’s population being lactose deficient.

Supplementing lactase may aid the digestion of small to moderate portions of dairy. Tip: longer-fermented foods are naturally lower in lactose.

Fat malabsorption/sluggish bile


Eating fat in the diet triggers the release of bile from the gallbladder into the duodenum, where it emulsifies the fat, making it ready for digestion by lipase enzymes. Sluggish bile flow can impede this process, leading to fat malabsorption.

A key component of bile in fat digestion is lecithin, containing phosphatidyl choline (PC). Supplemental lecithin may therefore aid fat digestion where bile flow is compromised. It has been found to increase the bile secretion and solubility and even to reduce elevated serum cholesterol levels as a result.

Digestive Enzymes

Emulsified fats are further broken down in the intestine by the digestive enzyme lipase. Lipase deficiency causes malabsorption of fats and fat-soluble vitamins. (Drugs that inhibit lipases have become the main pharmacological intervention for obesity.) Plant enzyme supplements that contain good levels of lipases can aid fat absorption and may be a useful adjunct to lecithin in some cases.


Globe artichoke is well-known for its ability to stimulate bile production, thanks to its flavonoid constituent cynarin. Its choleretic properties have led to it being named in the scientific literature as one of the more evidence-supported plants for enhancing digestion. Studies have found it to increase fecal bile acids and to reduce the nausea, vomiting, flatulence and abdominal pain of functional dyspepsia and dyspepsia associated with biliary disease. This makes it an especially important intervention where there is impaired fat digestion, often referred to as fatty meal intolerance.

What’s more, artichoke helps to protect the liver and may even help liver cells to regenerate.

Disordered peristalsis (fast or slow GI transit time)


FOS draws moisture into the colon. This helps to keep waste matter soft and bulky, encouraging it to move through the digestive system faster and helping to promote regular bowel movements.

FOS has been found to improve colonic transit time, faecal mass and frequency in cases of constipation. To avoid excessive fermentation, remember to start with the lowest dose possible.


Ginger is a prokinetic spice, meaning that it stimulates gastric contractions and gastric emptying and is therefore used to promote digestive motility and peristalsis. It does this by acting on the serotonin and choline receptors in the gut to normalise muscle contractions. These properties have led to ginger’s long history of use in indigestion, nausea and vomiting, including where such symptoms arise from pregnancy or chemotherapy.


Peppermint is known as a calminative, helping to relax a spasmodic intestine and calm down uncomfortable spasms and cramps. The key active ingredients are the menthol and other volatile oils, although these are likely enhanced by other compounds in the whole leaf.

(Best not recommended in cases of oesophageal reflux.)


Animal studies have found curcumin (derived from turmeric) to help normalise urgency and loose bowels in IBS by regulating neurotransmitters that control peristalsis.

Its anti-inflammatory effects may also help to calm down an over-active, irritated bowel. Low-grade inflammation in the GI tract can be a feature of IBS, especially if pathogenic microbes are part of the picture.


Artichoke leaf can improve constipation because of its bile-enhancing properties. Bile stimulates peristaltic muscle contractions, improving colon transit time. As a result, many people with stubbornly slow bowels find relief with artichoke extract, as long as it contains sufficient levels of active cynarin.

Slow transit time can also cause bloating, flatulence and abdominal discomfort and pain (dyspepsia). In one study, an amazing 85% noted an improvement with artichoke extract. Another study found improvements in as little as six weeks of starting the course.

Some people find it especially useful when taken alongside FOS. However, it can also provide much needed benefit to individuals whose digestive system is not yet able to tolerate increased soluble fibre, perhaps because of microbial overgrowths.

Leaky gut

L glutamine

The amino acid L-glutamine is a major fuel for intestinal cells, meaning that deficiency can compromise barrier function. This can lead to IBS and especially urgency and loose bowels, as well as systemic inflammatory-like symptoms.

Supplemental l-glutamine can improve intestinal barrier function in cases of leaky gut caused by inflammation, chemotherapy and other damaging inputs. It restores tight junction proteins that keep toxins and other antigens from leaking out of the gut lumen into the underlying lymphoid tissue. And it can also reduce the activation of the inflammatory molecule NF-κB.

As many people with diarrhea have leaky gut, glutamine may help to reduce visceral hypersensitivity by improving barrier function.

S Boulardii

This beneficial yeast enhances the gut-associated innate and adaptive immune systems. It has been found to improve the integrity of the intestinal epithelial cells, protect tight junctions, prevent pathogens’ ability to adhere to gut wall and colonise, and act as a powerful anti-inflammatory. All of these mechanisms can help prevent and reverse leaky gut.


Several preclinical studies and uncontrolled clinical trials show that curcumin, the active ingredient of turmeric, improves gut inflammation, gut permeability and the brain-gut axis, especially in functional gut disorders like IBS. 

Vitamins A and D

Vitamin A is essential for the health of all mucous membranes, and deficiency predisposes to gut mucosal damage.

Vitamin A is often reported as inadequate in government nutrition surveys, partly because the main source in today’s diet is conversion from beta carotene. Not everyone can efficiently convert beta carotene into vitamin A, however, and direct food sources are less popular than they use to be (liver, oily fish and full fat dairy).

Vitamin D is a potent anti-inflammatory agent, and has also been found to improve the structure and function of tight junctions, and to reduce gut permeability and the translocation of bacterial lipopolysaccharides to the underlying immune system tissue. In this way, vitamin D helps to prevent endotoxicity from leaky gut


Zinc improves mucosal repair in patients with diarrhea and in inflammatory bowel disease; and has also been found to improve leaky gut situations and compromised absorption in animal studies.

Supplementing zinc with vitamin A has been found to improved LG and linear growth shortfalls in health compromised children.

Red Flags

While many gut disorders can be helped with these diet and supplemental strategies, it is important to see your GP if you suspect anything more serious, such as infection or inflammation. Symptoms to see your GP about include blood in the stool, unintended weight loss, acute pain, a sudden change in bowel habits and/or severe or persistent vomiting or diarrhoea.

Are you taking medications?

Many different types of medication, both those prescribed for digestive problems and some prescribed for other health issues, can significantly affect the health of the digestive tract. So it is worth considering whether symptoms are due to medication side-effects.

Proton pump inhibitors (given for acid reflux and gastric inflammation) can trigger episodes of wind and bloating because they prohibit optimal digestion and absorption, leaving more food free to feed microbes and promote bacterial and fungal overgrowths.  Antibiotics can cause diarrhoea due to their decimation of the intestinal flora. Probiotics can often help to avoid this problem. (They should be taken away from the antibiotics.)

What’s more, the therapeutic effects of some medications may be increased or reduced by some of the nutritional supplements outlined here. So be sure to check your doctor is happy with your supplements if you are taking prescribed medications. 

If you believe that some of these types of interventions may help you, book in for a consultation by going to '121 Consultations' in the menu bar. We'll work with you to identify the root cause of your symptoms, and then put in a gut-improvement programme that is personalised to your individual needs.

© 2019 Lorraine Nicolle

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Lorraine writes and edits nutrition books on how eating the right foods and nutraceuticals for your individual biochemistry can reduce the risk of chronic illness and lead to a healthier, happier life.

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