Gut Health Supplements

The Evidence-Based Guide

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The gut microbiome — trillions of bacteria, fungi and other microorganisms in the digestive tract — influences digestion, immune function, inflammation, metabolism and even mental health. Hill et al. (2014) consensus statement defined probiotics and prebiotics. Gut health supplements include probiotics (live beneficial bacteria), prebiotics (food for beneficial bacteria), digestive enzymes, fibre supplements and L-glutamine. The evidence varies: probiotics have strong evidence for antibiotic-associated diarrhoea and IBS; prebiotics and fibre have strong evidence for overall gut health; enzymes are condition-specific.

The food-first principle applies strongly to gut health: a diverse, high-fibre diet with fermented foods supports a healthy microbiome more effectively than supplements. Sonnenburg and Sonnenburg (2019) showed that dietary fibre diversity drives microbiome diversity — the strongest predictor of gut health.

Strong evidence

• Probiotics for antibiotic-associated diarrhoea
• Probiotics for IBS (specific strains)
• Fibre supplements for constipation
• Prebiotics for microbiome diversity
• Enzymes for diagnosed deficiencies

Weak/no evidence

• Probiotics for “general health” (vague claims)
• Cleanses and detox products
• Colostrum for gut healing
• L-glutamine for “leaky gut” (in healthy people)
• Multi-strain “everything” probiotics

The gut health hierarchy

1. Diet (diverse fibre, fermented foods, polyphenols). 2. Lifestyle (sleep, stress, exercise). 3. Supplements (probiotics/prebiotics for specific needs). A diverse diet with 30+ plant foods per week drives microbiome diversity more than any supplement. Start with food; add supplements for specific conditions.

1 Hill C, Guarner F, Reid G, et al. Expert consensus document: the International Scientific Association for Probiotics and Prebiotics. Nat Rev Gastroenterol Hepatol. 2014;11(8):506-514.

2 Sonnenburg ED, Sonnenburg JL. The ancestral and industrialized gut microbiota. Cell Metab. 2019;30(2):302-314.

Probiotics are live microorganisms that confer a health benefit when consumed in adequate amounts. Hill et al. (2014) and McFarland et al. (2018) provide the evidence. The key: strain specificity matters. Different strains help different conditions — there is no “one probiotic for everything.” Lactobacillus rhamnosus GG and Saccharomyces boulardii have the strongest evidence for antibiotic-associated diarrhoea. Bifidobacterium strains show benefit in IBS.

Antibiotic-Associated Diarrhoea

Strong evidence. Lactobacillus rhamnosus GG or Saccharomyces boulardii during and 1-2 weeks after antibiotics reduces diarrhoea risk by ~40%. McFarland et al. (2018). Take 2 hours apart from the antibiotic dose. This is the clearest probiotic benefit.

Irritable Bowel Syndrome (IBS)

Moderate evidence. Specific strains (Bifidobacterium infantis 35624, Lactobacillus plantarum) reduce bloating, pain and irregularity in some IBS sufferers. Ford et al. (2014) meta-analysis. Effects are individual — what works for one person may not work for another. Try for 4-8 weeks.

General “Gut Health”

Weak evidence for vague claims. Taking a random probiotic for “general gut health” or “immunity” has limited evidence. Fermented foods (yoghurt, kefir, sauerkraut, maas) provide diverse live cultures and may be more effective than single-strain supplements.

Colic and Infant Health

Some evidence for Lactobacillus reuteri reducing infant colic. Always consult a paediatrician before giving probiotics to infants.

SA fermented food sources

Maas (amasi) — traditional fermented milk, naturally probiotic. Kefir — diverse probiotic cultures, growing in SA. Yoghurt with live cultures. Sauerkraut and kimchi. These provide diverse live cultures often more effectively than supplements — and are part of SA food culture.

1 Hill C, Guarner F, Reid G, et al. Expert consensus document. Nat Rev Gastroenterol Hepatol. 2014;11(8):506-514.

2 McFarland LV, Evans CT, Goldstein EJC. Strain-specificity and disease-specificity of probiotic efficacy. Clin Infect Dis. 2018;66(suppl_2):S144-S150.

3 Ford AC, Quigley EM, Lacy BE, et al. Efficacy of prebiotics, probiotics, and synbiotics in IBS. Am J Gastroenterol. 2014;109(10):1547-1562.

Prebiotics are non-digestible fibres that feed beneficial gut bacteria, stimulating their growth and activity. Gibson et al. (2017) consensus updated the definition. The main prebiotic types: inulin (from chicory root), fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS) and resistant starch. Slavin (2013) confirmed that dietary fibre is the most important determinant of microbiome diversity. Prebiotic supplements can be useful, but food sources (onion, garlic, leek, asparagus, banana, oats, legumes) are preferred.

Food Sources (Preferred)

Onion, garlic, leek, asparagus, banana (especially slightly green), oats, barley, legumes (lentils, chickpeas), apples, flaxseed. A diet with 30+ plant foods per week provides diverse prebiotics. Sonnenburg and Sonnenburg (2019) showed dietary fibre diversity drives microbiome diversity.

Inulin and FOS Supplements

2-5g daily, gradually increasing (sudden high doses cause gas and bloating). Gibson et al. (2017). May increase Bifidobacterium populations. Useful for those who cannot tolerate high-fibre foods, but food sources are equally effective and provide additional nutrients.

Resistant Starch

Found in cooked-and-cooled rice, potatoes and green bananas. Resists digestion, feeds beneficial bacteria in the colon, and produces butyrate (a short-chain fatty acid that nourishes the gut lining). Easily incorporated by cooking rice/potatoes ahead and reheating.

Start slowly with prebiotics

If your current fibre intake is low, increasing prebiotics suddenly causes gas, bloating and discomfort. Increase gradually over 2-4 weeks, drink plenty of water, and allow your microbiome to adapt. Target: 25-38g total fibre per day (most South Africans get under 15g).

1 Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: the International Scientific Association for Probiotics and Prebiotics. Nat Rev Gastroenterol Hepatol. 2017;14(8):491-502.

2 Slavin J. Fiber and prebiotics. Nutrients. 2013;5(4):1417-1435.

3 Sonnenburg ED, Sonnenburg JL. The ancestral and industrialized gut microbiota. Cell Metab. 2019;30(2):302-314.

Digestive enzymes break down food into absorbable components. The body produces its own (amylase, protease, lipase, lactase), but supplements can help with specific intolerances or deficiencies. Lactase for lactose intolerance, alpha-galactosidase (Beano) for bean/vegetable gas, and pancreatic enzymes for diagnosed pancreatic insufficiency. Broad-spectrum enzyme supplements for “digestion” in healthy people have weak evidence — your body already produces adequate enzymes if you are healthy.

Lactase (For Lactose Intolerance)

Lactose intolerance is common in South Africans (especially after childhood). Lactase enzyme tablets (taken with dairy) break down lactose, preventing gas, bloating and diarrhoea. Evidence is strong. Also: lactose-free dairy, hard cheeses (naturally low lactose), and maas/kefir (bacteria pre-digest some lactose).

Alpha-Galactosidase (For Bean/Vegetable Gas)

Breaks down the complex sugars in beans, lentils and cruciferous vegetables that cause gas. Taken before meals with these foods. Evidence is moderate. Particularly useful for those transitioning to higher-fibre/plant-based diets.

Broad-Spectrum Enzymes (Weak Evidence)

Marketed for “general digestion support.” In healthy people with normal pancreatic function, additional enzymes provide no benefit — your body produces adequate amounts. Only useful for diagnosed pancreatic insufficiency (prescribed by a doctor) or specific intolerances.

Digestive symptoms deserve investigation

Chronic bloating, gas, diarrhoea or abdominal pain should be investigated by a doctor — not self-treated with enzyme supplements. These symptoms can indicate IBS, coeliac disease, inflammatory bowel disease, SIBO or other conditions requiring proper diagnosis and treatment. Enzyme supplements mask symptoms without addressing the root cause.

1 Suchy FJ, Brannon PM, Carpenter TO, et al. NIH consensus development conference: lactose intolerance. NIH Consens State Sci Statements. 2010;27(2):1-27.

2 Ianiro G, Pecere S, Giorgio V, et al. Digestive enzyme supplementation. Therap Adv Gastroenterol. 2016;9(6):842-854.

Fibre is the most evidence-backed “gut health supplement” — adequate fibre (25-38g/day) supports regularity, microbiome diversity, cholesterol reduction, blood sugar control and satiety. Slavin (2013) and the EFSA confirm these benefits. Most South Africans get under 15g/day. Food sources are preferred (whole grains, fruit, vegetables, legumes, nuts, seeds), but fibre supplements (psyllium, acacia fibre, inulin) can help bridge the gap for those who struggle to meet targets through food.

Psyllium Husk (Ispaghula)

The most evidence-backed fibre supplement. 5-10g with water, 1-3 times daily. Effective for constipation, IBS (mixed type), cholesterol reduction and blood sugar control. McRorie and Faergeman (2015). Start low and increase gradually. Must drink plenty of water — psyllium can cause blockage if taken without adequate fluid.

Acacia Fibre (Gum Arabic)

Soluble fibre from acacia trees. Gentler on the gut than psyllium (less gas/bloating). 5-10g daily. Also acts as a prebiotic, feeding Bifidobacterium. Good option for sensitive guts.

Inulin and FOS

Prebiotic fibre (see Prebiotics section). 2-5g daily, gradually increasing. Feeds beneficial bacteria. Can cause gas at higher doses. Also found naturally in onion, garlic, banana and asparagus.

Food fibre first

Fibre supplements are useful for bridging gaps, but food sources provide additional vitamins, minerals, polyphenols and diverse fibre types that supplements cannot match. Aim for 25-38g/day from: whole grains (oats, brown rice, wholewheat bread), fruit (apple, banana, berries), vegetables (broccoli, spinach, morogo), legumes (lentils, beans, chickpeas), nuts and seeds. Use supplements to top up, not replace.

1 Slavin J. Fiber and prebiotics. Nutrients. 2013;5(4):1417-1435.

2 McRorie JW, Faergeman O. Insights into the fiber fermentability. Adv Nutr. 2015;6(1):57-67.

3 European Food Safety Authority. Scientific opinion on dietary reference values for carbohydrates. EFSA Journal. 2010;8(3):1462.

L-glutamine is the most abundant amino acid in the body and the primary fuel for intestinal cells. Rao et al. (2016) and Pugh et al. (2020) studied intestinal permeability (“leaky gut”). The concept: increased intestinal permeability allows toxins and undigested proteins to enter the bloodstream, potentially driving inflammation. L-glutamine supplementation (5-15g/day) may support gut barrier integrity in specific conditions (post-surgical, critical illness, IBD). However, “leaky gut” as a broad diagnosis in healthy people is controversial, and L-glutamine for general gut health has weak evidence.

When it may help

Post-surgical intestinal recovery, inflammatory bowel disease (under medical supervision), and possibly in heavy-training athletes (intense exercise increases intestinal permeability acutely). Costa et al. (2017) documented exercise-induced GI syndrome, where glutamine may play a supportive role.

When it is overhyped

“Leaky gut syndrome” as a broad diagnosis for fatigue, brain fog and general symptoms is not a recognised medical diagnosis. L-glutamine for these vague complaints has no evidence. The body produces adequate glutamine, and dietary protein provides additional amounts. Do not self-diagnose “leaky gut” — consult a gastroenterologist for digestive symptoms.

The 'leaky gut' controversy

Increased intestinal permeability is a real phenomenon in specific conditions (IBD, coeliac, post-surgery, intense exercise). But "leaky gut syndrome" as a broad diagnosis for general symptoms is not recognised by mainstream gastroenterology. Be cautious of practitioners diagnosing "leaky gut" and selling glutamine supplements. For persistent digestive symptoms, see a gastroenterologist for proper diagnosis.

1 Rao RK, Samak G. Role of glutamine in protection of intestinal epithelial tight junctions. J Epithel Biol Pharmacol. 2016;6:1-7.

2 Pugh R, Grant C, Duggan S. Intestinal permeability and chronic disease. Adv Ther. 2020;37(10):4189-4200.

3 Costa RJS, Snipe RMJ, Kitic CM, Gibson PR. Systematic review: exercise-induced gastrointestinal syndrome. Aliment Pharmacol Ther. 2017;46(3):246-265.

Supplement	Evidence	Best For	Food Alternative
Probiotics (specific strains)	Strong	Antibiotic diarrhoea, IBS	Maas, kefir, yoghurt
Prebiotics (inulin, FOS)	Moderate	Microbiome diversity	Onion, garlic, banana, oats
Fibre (psyllium)	Strong	Constipation, cholesterol	Whole grains, fruit, veg
Lactase	Strong	Lactose intolerance	Lactose-free dairy
Alpha-galactosidase	Moderate	Bean/vegetable gas	Gradual fibre increase
L-glutamine	Weak (general)	Specific conditions only	Adequate dietary protein
Broad-spectrum enzymes	Weak	Nothing (healthy people)	Normal digestion
Colostrum	Weak	Nothing proven	Regular dairy

Probiotics in Immunocompromised

Probiotics are generally safe, but in severely immunocompromised individuals (chemotherapy, HIV/AIDS, premature infants), live bacteria can cause infections. Consult a doctor before using probiotics if immune function is compromised. Sarker et al. (2016) documented rare but serious probiotic infections in vulnerable populations.

SIBO and Probiotics

Small Intestinal Bacterial Overgrowth (SIBO) can be worsened by some probiotics (bacteria ferment in the wrong place). If you have SIBO symptoms (bloating, gas, pain soon after eating), get tested before taking probiotics. Certain probiotic strains may help; others may worsen symptoms. Work with a gastroenterologist.

“Leaky Gut” Self-Diagnosis

“Leaky gut syndrome” as a broad diagnosis for general symptoms is not a recognised medical diagnosis. Be cautious of practitioners (and supplement companies) diagnosing leaky gut and selling glutamine or other supplements. For persistent digestive symptoms, see a gastroenterologist for proper diagnosis — coeliac disease, IBD, IBS and SIBO require specific medical treatment.

Sudden High Fibre

Suddenly increasing fibre (from food or supplements) causes gas, bloating, cramping and discomfort. Increase gradually over 2-4 weeks, drink plenty of water (fibre needs fluid to work), and allow the microbiome to adapt. Those with IBS or IBD should be particularly careful with fibre increases.

When to see a professional

If you have persistent digestive symptoms (bloating, pain, diarrhoea, constipation, reflux), blood in stool, unexplained weight loss, or a family history of bowel cancer — consult a gastroenterologist or GP. These symptoms require proper diagnosis, not self-supplementation. An HPCSA-registered dietitian can help with diet-based gut health strategies once medical conditions are ruled out.

1 Sarker SA, Brüssow H, Vinner L, et al. Safety of probiotics in relation to infections. J Pediatr Gastroenterol Nutr. 2016;63(2):284.

2 Pimentel M, Saad RJ, Longstreth GF, et al. ACG clinical guideline: SIBO. Am J Gastroenterol. 2020;115(2):165-178.

Explore related: All Supplements · Gut Health Diets · Supplement Education

Quick Facts

Probiotics are strain-specific — L. rhamnosus GG and S. boulardii have the strongest evidence for antibiotic diarrhoea

Dietary fibre diversity drives microbiome diversity — aim for 30+ plant foods per week

Maas (amasi) is a natural SA probiotic — fermented foods often beat supplements

Most South Africans get under 15g fibre/day vs the recommended 25-38g

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Medical Disclaimer

This information is educational and not a substitute for professional advice. Persistent digestive symptoms require medical diagnosis. Probiotics may be risky in immunocompromised individuals. "Leaky gut syndrome" as a broad diagnosis is not medically recognised. Consult a gastroenterologist or dietitian.

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