Zonulin Testing and Leaky Gut: Does It Work?

Medically reviewed and written by Dr Zeeshan Afzal (MBBS), Medical Content Lead at Welzo. Last updated: August 2026.

The zonulin test is currently one of the most heavily marketed "leaky gut" tests in the UK. It is sold as a blood or stool test that tells you whether the junctions between your intestinal cells have loosened, and it is often bundled into private functional medicine panels costing £70 to £200. The promise is appealing: one number that explains bloating, fatigue, brain fog, joint aches and skin flare-ups. The reality is more complicated, and it is important that anyone spending money on this test understands why. Zonulin itself is a genuine protein with a genuine role in gut barrier regulation. But the laboratory assays used to measure it in commercial tests have been repeatedly shown to be measuring something else entirely. In this guide I will explain what zonulin does, how zonulin testing works, what the peer-reviewed evidence actually says about its accuracy, which tests are more useful, and what you can practically do to support your gut health whether or not you test. If you have arrived here because you suspect your gut barrier is compromised, these Welzo resources are the most relevant starting points: how the gut barrier actually works, is leaky gut real?, the complete UK guide to gut health, gut dysbiosis and the best supplements for leaky gut in the UK. For products, the most commonly used categories are our probiotics range, Akkermansia muciniphila, modified citrus pectin powder, Welzo Ultra Purity Berberine and Welzo Ultra Purity TUDCA.

Table of contents

• Key takeaways
• What is zonulin?
• What is a zonulin test and how is it done?
• Does a zonulin test work? What the evidence shows
• What do zonulin test results mean?
• Zonulin test vs other intestinal permeability tests
• Is leaky gut real?
• Should you get a zonulin test? A practical framework
• What to do instead: evidence-based gut barrier support
• Red flags: when to see a GP
• Frequently asked questions
• References

Key takeaways

• Zonulin (identified as pre-haptoglobin-2) is a real human protein and the only known physiological regulator that reversibly opens intestinal tight junctions.
• The problem is not the protein, it is the measurement. Two independent laboratory investigations found that widely used commercial zonulin ELISA kits do not detect pre-haptoglobin-2 at all, instead binding proteins such as complement C3 and properdin.
• There is no validated reference range, no agreed cut-off and no clinical guideline in the UK that recommends a zonulin test for diagnosis or monitoring.
• A raised zonulin result cannot confirm "leaky gut syndrome", and a normal result cannot rule out gut disease.
• Tests that genuinely change clinical decisions include coeliac serology, faecal calprotectin, FIT, H. pylori testing and breath testing for SIBO.
• Diet, alcohol, medication review, sleep and stress management have far more supporting evidence for gut barrier function than any single supplement or test.
• This article is health information, not a diagnosis. Persistent or alarming digestive symptoms should always be assessed by a GP.

What is zonulin?

Your small intestine is lined by a single layer of cells. That layer is only about one cell thick, yet it has to absorb nutrients while keeping bacteria, bacterial fragments and undigested food proteins out of your bloodstream. The cells are stitched together by protein complexes called tight junctions, made up of claudins, occludin and zonula occludens proteins.

Zonulin was described by Alessio Fasano's group in 2000 after they studied zonula occludens toxin, a toxin from Vibrio cholerae that prises tight junctions open. The team reasoned that a bacterial toxin would not have evolved a receptor unless the human body had its own equivalent molecule, and they went looking for it. Zonulin was later identified as pre-haptoglobin-2, the precursor form of haptoglobin-2. It remains the only known human protein that reversibly and physiologically modulates intestinal tight junctions (Sturgeon & Fasano, Tissue Barriers, 2016).

How zonulin opens tight junctions

When zonulin is released from the intestinal lining, it binds receptors on the surface of neighbouring cells and triggers a signalling cascade involving protein kinase C and rearrangement of the actin cytoskeleton. The practical effect is that the tight junction proteins disassemble and the paracellular space between cells widens. Larger molecules can then pass between cells rather than through them. This is a normal, reversible physiological process, not automatically a disease state — it is part of how the gut samples its environment and mounts immune responses.

What triggers zonulin release

Two stimuli are consistently described in the research literature as the most potent triggers of zonulin release: exposure of the small intestine to large numbers of bacteria, and gliadin, the gluten fraction responsible for coeliac disease (Fasano, F1000Research, 2020). This is one reason the zonulin pathway is so frequently discussed in the context of coeliac disease versus gluten intolerance, gluten intolerance and small intestinal bacterial overgrowth (SIBO).

Other factors that have been linked with increased intestinal permeability in human studies include high alcohol intake, non-steroidal anti-inflammatory drugs such as ibuprofen, prolonged psychological or physical stress, strenuous endurance exercise, chemotherapy, and acute gastrointestinal infection (Camilleri, Gut, 2019).

What is a zonulin test and how is it done?

A zonulin test is a laboratory assay that attempts to quantify how much zonulin is present in a sample. In the UK, three broad versions are sold, almost always through private laboratories rather than the NHS.

Serum or plasma zonulin test (blood)

This is the most common format. It is usually a finger-prick blood spot kit posted to your home, or a venous blood sample taken at a private clinic. The laboratory runs an enzyme-linked immunosorbent assay (ELISA) and reports a concentration in ng/mL. Turnaround is typically five to fifteen working days.

Faecal (stool) zonulin test

Stool zonulin is offered as a standalone marker or, more often, as one line item within a large comprehensive stool test or gut microbiome test. Advocates argue that faecal zonulin reflects local intestinal release rather than systemic levels. The same assay specificity concerns apply, and stool zonulin has been studied less than serum zonulin.

Zonulin antibody tests

Some panels measure IgA or IgG antibodies to zonulin and to other tight junction proteins such as occludin and actomyosin, rather than zonulin itself. These are marketed as "intestinal antigenic permeability screens". They are less well studied again, and there is no consensus on what an elevated antibody titre means for an individual patient.

How the test is taken

1. Order the kit online or through a private clinic.
2. Collect a finger-prick blood spot, a venous sample or a stool sample according to the instructions.
3. Return the sample by post, usually within 24 hours of collection.
4. Receive a PDF report with a number, a reference range and, frequently, a supplement recommendation.

That last step is worth pausing on. A large proportion of zonulin tests sold direct to consumers are supplied by companies that also sell the protocol recommended off the back of the result. That is a commercial conflict of interest, and it should factor into how much weight you give the report.

Does a zonulin test work? What the evidence shows

This is the core question, and the honest answer is that the evidence does not currently support using a zonulin test to diagnose or monitor increased intestinal permeability in an individual. There are five distinct problems, and they compound.

Problem 1: the commercial assays may not be measuring zonulin

This is the most serious issue. In 2018, a German group at the University of Leipzig measured serum zonulin in 376 people using a widely used commercial ELISA kit, and also genotyped every participant for haptoglobin. Because zonulin is pre-haptoglobin-2, results should have tracked haptoglobin genotype. They did not. The team then used antibody capture experiments, mass spectrometry and Western blotting to work out what the kit was actually binding, and concluded that it was not pre-haptoglobin-2 but structurally related proteins, with properdin the most likely candidate (Scheffler et al., Frontiers in Endocrinology, 2018).

A year later an Australian team at Monash University ran an independent check on two different commercial kits, from CUSABIO and Immundiagnostik. Using immunoprecipitation followed by mass spectrometry, the top protein matches were haptoglobin and complement C3 for one kit and complement C3 for the other. Their conclusion was direct: current commercial zonulin assays are not detecting pre-haptoglobin-2, and clinicians should be cautious about using serum zonulin as a marker of mucosal barrier integrity until assay methodology improves (Ajamian et al., PLOS ONE, 2019).

Two independent laboratories, different continents, different kits, same finding. That is a substantial problem for a test being sold on the high street.

Problem 2: not everyone can even produce zonulin

Pre-haptoglobin-2 can only be produced by people who carry the haptoglobin-2 allele. Roughly a fifth of the population carries the HP1-1 genotype and therefore should produce no pre-haptoglobin-2 at all. Yet commercial assays return measurable "zonulin" values in essentially everybody, irrespective of genotype. Either the biology is wrong or the assay is measuring a different protein. The published laboratory work points firmly to the latter.

Problem 3: no validated reference range

Different laboratories quote different normal ranges, use different units and different sample types. There is no internationally agreed cut-off separating "normal" from "leaky", no validated sensitivity or specificity figures for diagnosing a defined condition, and no external quality assurance scheme of the kind that underpins NHS biochemistry. Two samples from the same person sent to two labs can produce results that lead to opposite conclusions.

Problem 4: biological variability

Zonulin release is dynamic. It rises and falls in response to meals, infections, exercise and stress. A single snapshot taken on a single morning does not describe your baseline barrier function any more than one blood pressure reading describes your cardiovascular risk. Serial testing would be needed to say anything meaningful, which multiplies the cost of an already unvalidated test.

Problem 5: association is not diagnosis

Elevated zonulin has been reported in cohorts with coeliac disease, type 1 diabetes, inflammatory bowel disease, obesity, non-alcoholic fatty liver disease, depression and several other conditions. A systematic review and meta-analysis in Nutrients found higher zonulin-related permeability markers in children with certain mental health diagnoses compared with controls (Nutrients, 2020). But group-level differences in research cohorts are a completely different thing from a test that can tell one individual whether they have a specific, treatable problem. Blood pressure differs at group level between many disease populations too; that does not make it a diagnostic test for those diseases.

What the other side of the argument says

In fairness, some laboratories now claim to have developed assays with monoclonal antibodies specific to pre-haptoglobin-2 that do not cross-react with mature haptoglobin. If that is validated independently and published in peer-reviewed literature, the picture could change. Zonulin biology is also being actively pursued as a therapeutic target — larazotide acetate, a zonulin receptor antagonist, has been trialled in coeliac disease, and animal work has explored zonulin blockade in arthritis (Tajik et al., Nature Communications, 2020). Research interest in zonulin is legitimate. Selling an unvalidated version of that research as a consumer diagnostic is a separate matter.

An editorial letter in Gut summarised the field's concern bluntly, arguing that the shortcomings of zonulin as a biomarker are actively misleading intestinal permeability research (Gut, 2021).

What do zonulin test results mean?

Given everything above, results should be interpreted with real caution. Here is a realistic reading of the common scenarios.

The false-negative scenario is the genuinely dangerous one. If someone with iron-deficiency anaemia, weight loss and diarrhoea is told their gut barrier is fine on the basis of a zonulin number, and therefore delays coeliac serology or referral, that is real clinical harm. If you want a structured way of describing your bowel pattern to a clinician, the Bristol stool chart is far more useful than any private biomarker.

Zonulin test vs other intestinal permeability tests

If the zonulin test is unreliable, what else exists? Several methods have better validation, though it is important to say that none of them is a routine NHS test for "leaky gut" either — most are research tools or are used to investigate a specific disease rather than permeability itself.

Lactulose–mannitol and multi-sugar tests

You drink a measured dose of sugars that the body does not metabolise, then collect urine over a set period. Mannitol is absorbed through cells; lactulose is much larger and mainly crosses between them. A raised lactulose to mannitol ratio suggests increased paracellular permeability. This is the closest thing to a reference method in humans, and a validated multi-sugar protocol using timed urine collections can separate small intestinal from colonic permeability (Khoshbin et al., Gastroenterology, 2021). However, results are affected by gastric emptying, renal function, collection accuracy and the assay method used, and even proponents accept it rarely changes what a clinician does next.

Faecal calprotectin

This is a genuinely validated stool marker. It measures neutrophil-derived protein and reflects intestinal inflammation, and NICE recommends its use to help distinguish inflammatory bowel disease from irritable bowel syndrome in people with lower GI symptoms (NICE diagnostics guidance DG11). It does not measure permeability, but it answers a far more clinically important question. We cover this in detail in our guide to the calprotectin test in the UK.

Blood barrier markers: LPS, LBP and I-FABP

Lipopolysaccharide binding protein, soluble CD14 and intestinal fatty acid binding protein are studied as circulating markers of barrier failure and bacterial translocation. A comparative study in American Journal of Physiology – Gastrointestinal and Liver Physiology assessed several of these alongside established permeability tests and found associations, but again these remain research tools rather than validated individual diagnostics (AJP-GI, 2021). A broader review of faecal and circulating permeability biomarkers reaches similar conclusions (PubMed, 2023).

Endoscopy, biopsy and confocal endomicroscopy

Direct visualisation and tissue sampling remain the gold standard for diagnosing disease of the intestinal lining. Confocal laser endomicroscopy can visualise epithelial gaps and shedding in real time during endoscopy. These are hospital procedures used to answer specific diagnostic questions, not screening tools.

Comparison at a glance

Is leaky gut real?

This is where a lot of confusion sits, so it is worth separating two things clearly.

Increased intestinal permeability is real. It is measurable, it is described in peer-reviewed gastroenterology, and it is documented in coeliac disease, Crohn's disease, ulcerative colitis, following gastrointestinal infection, in critical illness and after NSAID exposure.

"Leaky gut syndrome" as a standalone diagnosis is not a recognised medical condition. The Cleveland Clinic describes it as a hypothetical condition that is not currently a recognised medical diagnosis (Cleveland Clinic), and the Gastrointestinal Society takes a similar position, noting that increased permeability generally appears as a feature of established disease rather than as its root cause (Gastrointestinal Society). Guts UK, the national charity for the digestive system, is currently funding research at King's College London into barrier dysfunction in inflammatory bowel disease, which tells you the science is live but not settled (Guts UK).

The unresolved question is direction of causality. Does barrier failure drive chronic disease, or does chronic disease damage the barrier? For most conditions the evidence is currently consistent with permeability being a consequence, or at best a contributing factor within a wider picture, rather than a single root cause. We explore this in more depth in is leaky gut real? and gut health and autoimmune conditions.

Should you get a zonulin test? A practical framework

When a zonulin test is unlikely to help

• You have undiagnosed symptoms and want a shortcut to an answer. It will not give you one.
• You want to rule out something serious. It cannot.
• You want to track whether a supplement is "working". The assay variability is too high for this to be meaningful.
• You have red flag symptoms (see below). Testing privately here risks delay.

When it might be reasonable

• A clinician you trust is using it as one small input within a broader assessment, and you understand its limitations.
• You are participating in research.
• You have already completed appropriate NHS investigation and are exploring, with informed consent, on a curiosity basis with money you are happy to spend.

Tests that will more reliably change your management

• Coeliac serology — tTG-IgA plus total IgA, taken while still eating gluten, as set out in NICE guideline NG20. See our coeliac test guide.
• Faecal calprotectin to help distinguish IBD from IBS.
• FIT and, where indicated, bowel cancer screening.
• H. pylori testing if you have dyspepsia — see H. pylori testing in the UK.
• Breath testing where SIBO is suspected — see SIBO testing.
• Full blood count, ferritin, B12, folate, CRP and thyroid function — covered in our gut health blood test guide.

What to do instead: evidence-based gut barrier support

Here is the practical upside. Almost everything that plausibly supports gut barrier function is worth doing regardless of what a zonulin test says, which is a strong argument for skipping the test and starting the work.

Fibre and plant diversity

Fermentable fibre feeds bacteria that produce short-chain fatty acids, particularly butyrate, which is the primary fuel for colonocytes and is involved in tight junction regulation. Most UK adults fall well short of the recommended 30g of fibre per day. Practical guides: how to increase fibre without bloating, high fibre foods in the UK, the 30 plants a week target and resistant starch. Greater microbiome diversity is one of the more consistent markers associated with metabolic and digestive health.

Polyphenols and fermented foods

Berries, olive oil, cocoa, green tea, herbs and coffee supply polyphenols that are metabolised by gut bacteria. Regular intake of fermented foods such as live yoghurt, kefir, sauerkraut and kimchi has been associated with improved microbial diversity and lower inflammatory markers in controlled feeding studies.

Reduce the things that damage the barrier

Alcohol, regular NSAID use, smoking and diets dominated by ultra-processed foods are all associated with barrier disruption. Some artificial sweeteners have shown effects on the microbiome in experimental studies. If you take long-term acid suppression, our guide to the long-term effects of omeprazole is worth reading — but never stop prescribed medication without speaking to your prescriber.

Sleep, stress and the gut–brain axis

Experimental work has shown that acute psychological stress and corticotropin-releasing hormone increase intestinal permeability in humans through a mast cell–dependent mechanism. That makes stress management a legitimate part of gut care rather than an afterthought. See the gut–brain connection, the vagus nerve and the gut and gut health and sleep.

Supplements: what is reasonable to consider

No supplement is a treatment for "leaky gut", and no supplement should replace investigation of persistent symptoms. Within those limits, the options most often discussed, with varying levels of evidence, include:

• Probiotics — strain-specific effects; see our probiotics collection, how to choose a probiotic and the best probiotics in the UK.
• Akkermansia muciniphila — a mucin-degrading species studied for its relationship with the mucus layer; see Welzo Akkermansia and pasteurised Akkermansia.
• Butyrate and prebiotics — see butyrate supplements and prebiotic supplements.
• Modified citrus pectin — a soluble fibre; see citrus pectin powder and modified citrus pectin vs standard pectin.
• Zinc carnosine, L-glutamine and colostrum — see zinc carnosine, glutamine vs collagen and colostrum.
• Berberine — studied mainly for metabolic effects and with meaningful drug interactions; see Welzo Ultra Purity Berberine and berberine interactions.
• TUDCA — a bile acid studied in liver and bile flow contexts; see Welzo Ultra Purity TUDCA and TUDCA side effects.

If you are starting from scratch, our structured gut reset protocol and best foods for gut health are more useful than a test result. Always check interactions with prescribed medicines, and speak to a pharmacist or GP if you are pregnant, breastfeeding, immunocompromised or taking anticoagulants.

Red flags: when to see a GP rather than order a test

Arrange an urgent GP appointment if you have any of the following. These symptoms need clinical assessment, not a private biomarker.

• Blood in your stool, or black tarry stools
• Unintentional weight loss
• A persistent change in bowel habit lasting more than three weeks, particularly if you are over 50
• Difficulty swallowing or persistent vomiting
• An abdominal or rectal mass
• Iron deficiency anaemia without an obvious cause
• Waking at night with pain or diarrhoea
• Fever with abdominal pain
• A family history of bowel cancer, coeliac disease or inflammatory bowel disease alongside new symptoms

More detail is in our guide on when to see a GP about stomach symptoms.

Frequently asked questions about zonulin testing

Is a zonulin test accurate?

Not reliably. Two independent laboratory investigations, published in Frontiers in Endocrinology in 2018 and PLOS ONE in 2019, found that widely used commercial zonulin ELISA kits do not detect pre-haptoglobin-2, the protein zonulin was identified as. They appear to bind other proteins including complement C3 and properdin. Until assay specificity is independently validated, a zonulin test should not be used to diagnose or exclude anything.

Can I get a zonulin test on the NHS?

No. Zonulin testing is not part of NHS pathways because it is not validated for clinical decision-making and "leaky gut syndrome" is not a recognised NHS diagnosis. NHS testing for gut symptoms focuses on coeliac serology, faecal calprotectin, FIT, blood tests and, where indicated, endoscopy.

How much does a zonulin test cost in the UK?

Standalone private zonulin tests typically cost around £70 to £130, and bundled "intestinal permeability" or comprehensive stool panels that include zonulin usually run from £150 to £400. Prices vary by provider and change frequently, so check current pricing directly with the laboratory.

What is a normal zonulin level?

There is no internationally agreed normal range. Different laboratories publish different reference intervals using different sample types, units and kits, which is itself a sign the test is not standardised. A result described as "normal" by one lab could be flagged as raised by another.

Is stool zonulin better than blood zonulin?

There is no good evidence that it is. Faecal zonulin is argued to reflect local intestinal release rather than systemic levels, but it faces the same assay specificity questions and has been studied less extensively than serum zonulin.

Can zonulin levels be lowered?

Studies have reported changes in measured zonulin after dietary change, weight loss, gluten withdrawal in coeliac disease and some probiotic interventions. Because of the assay problems, it is difficult to know whether those changes reflect zonulin itself. The interventions involved — better diet, more fibre, less alcohol, treating underlying disease — are worth doing on their own merits.

Does a high zonulin result mean I have leaky gut?

No. It means a protein was detected above that laboratory's threshold. It does not confirm increased intestinal permeability, does not identify a cause and does not constitute a diagnosis. Any result should be interpreted alongside your symptoms and validated tests by a qualified clinician.

What is the best test for leaky gut?

There is no single validated clinical test for leaky gut. The best-validated research method for measuring intestinal permeability is a timed multi-sugar urine test such as lactulose–mannitol, but even that rarely changes management. In practice the more useful question is what underlying condition is causing your symptoms, which is answered by coeliac serology, faecal calprotectin, FIT, H. pylori testing and, where indicated, endoscopy.

Do probiotics affect zonulin?

Some randomised trials have reported reductions in measured zonulin with specific probiotic strains, but findings are inconsistent, sample sizes are often small and the assay concerns apply. Probiotics may be worth trialling for symptoms such as bloating or IBS, where strain-specific evidence is stronger — see our guides on supplements for IBS and supplements for bloating.

Should I take supplements based on a zonulin test result?

Basing a supplement regimen on an unvalidated test is not a sound approach, particularly when the test is sold by a company that also sells the recommended protocol. If you want to support your gut, focus on fibre intake, plant diversity, fermented foods, alcohol reduction, sleep and stress — and use targeted supplements as an addition rather than a substitute for diagnosis.

References

1. Sturgeon C, Fasano A. Zonulin, a regulator of epithelial and endothelial barrier functions, and its involvement in chronic inflammatory diseases. Tissue Barriers. 2016;4(4):e1251384. https://pmc.ncbi.nlm.nih.gov/articles/PMC5214347
2. Scheffler L, Crane A, Heyne H, et al. Widely used commercial ELISA does not detect precursor of haptoglobin2, but recognizes properdin as a potential second member of the zonulin family. Frontiers in Endocrinology. 2018;9:22. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5807381/
3. Ajamian M, Steer D, Rosella G, Gibson PR. Serum zonulin as a marker of intestinal mucosal barrier function: may not be what it seems. PLOS ONE. 2019;14(1):e0210728. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0210728
4. Massier L, Chakaroun R, Kovacs P, Heiker JT. Blurring the picture in leaky gut research: how shortcomings of zonulin as a biomarker mislead the field of intestinal permeability. Gut. 2021. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8355880/
5. Camilleri M. Leaky gut: mechanisms, measurement and clinical implications in humans. Gut. 2019;68(8):1516–1526. https://pubmed.ncbi.nlm.nih.gov/31076401/
6. Fasano A. All disease begins in the (leaky) gut: role of zonulin-mediated gut permeability in the pathogenesis of some chronic inflammatory diseases. F1000Research. 2020;9:F1000 Faculty Rev-69. https://f1000research.com/articles/9-69/v1
7. Khoshbin K, Khanna L, Maselli D, et al. Development and validation of test for "leaky gut" small intestinal and colonic permeability using sugars in healthy adults. Gastroenterology. 2021;161(2):463–475. https://www.gastrojournal.org/article/S0016-5085(21)00642-9/fulltext
8. National Institute for Health and Care Excellence. Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel. NICE diagnostics guidance DG11. https://www.nice.org.uk/guidance/dg11
9. National Institute for Health and Care Excellence. Coeliac disease: recognition, assessment and management. NICE guideline NG20. https://www.nice.org.uk/guidance/ng20
10. Cleveland Clinic. Leaky gut syndrome: symptoms, diet, tests and treatment. https://my.clevelandclinic.org/health/diseases/22724-leaky-gut-syndrome
11. Gastrointestinal Society. Debunking the myth of 'leaky gut syndrome'. https://badgut.org/information-centre/a-z-digestive-topics/leaky-gut-syndrome/
12. Guts UK. Understanding 'leaky gut syndrome' in people with inflammatory bowel disease — research funding award, King's College London. https://gutscharity.org.uk/
13. Tajik N, Frech M, Schulz O, et al. Targeting zonulin and intestinal epithelial barrier function to prevent onset of arthritis. Nature Communications. 2020;11:1995. https://www.nature.com/articles/s41467-020-15831-7
14. Meira de-Faria F, Bednarska O, Ström M, et al. Biomarkers for assessment of intestinal permeability in clinical practice. American Journal of Physiology – Gastrointestinal and Liver Physiology. 2021. https://journals.physiology.org/doi/full/10.1152/ajpgi.00113.2021
15. Fecal and circulating biomarkers for the non-invasive assessment of intestinal permeability. Diagnostics. 2023. https://pubmed.ncbi.nlm.nih.gov/37296827/
16. Zonulin-dependent intestinal permeability in children diagnosed with mental disorders: a systematic review and meta-analysis. Nutrients. 2020;12(7):1982. https://www.mdpi.com/2072-6643/12/7/1982

About the author

Dr Zeeshan Afzal (MBBS) is a qualified doctor and Medical Content Lead at Welzo. He reviews Welzo's digestive health content for clinical accuracy and alignment with UK guidance, including NICE guidelines and NHS pathways. This article was written and medically reviewed by Dr Afzal in August 2026 and is scheduled for annual review.

Medical disclaimer

This article is provided for general information only and does not constitute medical advice, diagnosis or treatment. It should not be used as a substitute for consultation with a qualified healthcare professional. Do not delay seeking medical advice, or stop or change prescribed treatment, on the basis of anything you have read here. If you have persistent digestive symptoms, blood in your stool, unexplained weight loss or any of the red flag symptoms described above, contact your GP. In an emergency, call 999 or attend your nearest A&E department.