Written by Dr Zeeshan Afzal (MBBS) — Medical Doctor & Medical Content Lead, Welzo
Medically reviewed · Evidence-based · Aligned with UK clinical guidance
Last updated: July 2026 · Reading time: ~13 minutes
Everything attributed to Dr Hyman comes from his own books, podcast, website and company materials, or from published reporting. Where a position is contested within medicine, we say so and set out both sides.
Mark Hyman is the only figure in this series who is an actual practising physician, which changes what is at stake. Much of what he advocates is mainstream good sense. Some of it goes further than the evidence supports. Distinguishing the two is the point of this article.
Mark Hyman is an American family physician, a fifteen-time New York Times bestselling author, and the most prominent public advocate of functional medicine. He founded the UltraWellness Center, previously led the Cleveland Clinic Center for Functional Medicine, hosts The Doctor's Farmacy podcast, and co-founded Function Health, where he is chief medical officer.
His health interest began personally: he has described a period of chronic ill health he attributes to mercury exposure, which conventional consultations failed to explain. That experience shaped his emphasis on looking for underlying causes rather than treating symptoms alone.
Asprey sells coffee. Greenfield sells amino acids. Hyman is a licensed physician whose recommendations carry the authority of a medical qualification — and he also sells supplements and diagnostics. That combination means his claims deserve close reading, and it also means criticism should be specific and sourced rather than sweeping. We have tried to hold to that.
Hyman has spent two decades arguing that diet, sleep, movement and stress are central to chronic disease rather than peripheral to it, and that ultra-processed food is a major driver of population ill health. That was a minority position when he started making it. It is now close to consensus, and reflected in UK dietary guidance. His food-policy advocacy has been substantive and largely aligned with the evidence.
He is unusually clear that supplements come second to diet. His stated baseline — what he suggests for most adults — is modest:
Beyond that baseline he has discussed a longer and more experimental list at various points, including NMN, senolytic compounds used cyclically, and various targeted formulas. He also adjusts his own intake according to his blood results, which is at least internally consistent with his testing philosophy.
His main argument for universal supplementation is soil depletion and declining food nutrient density. There is genuine evidence that the nutrient content of some crops has fallen over decades. But the leap from that to "therefore most people need a daily multivitamin" is larger than the data supports. Large trials of multivitamins in well-nourished populations have generally not shown reductions in cardiovascular events or mortality.
The more defensible position — and the one this article recommends — is that supplementation should follow an identified gap, with vitamin D in a British winter as the main exception.
Hyman's dietary framework combines paleo and vegan principles: roughly three quarters of the plate as vegetables and fruit, adequate protein, generous healthy fats, low glycaemic load, minimal processed food, and attention to food quality.
Strip away the branding and the Pegan diet is close to what most dietitians would recommend: mostly plants, minimal ultra-processed food, low added sugar, sufficient protein, whole-food fats. It is flexible, it is not extreme, and the emphasis on quality over calorie-counting suits many people better than macro tracking.
The diet is frequently described as "detoxifying" and "hormone balancing". Those are marketing terms rather than physiological ones. Your liver and kidneys perform detoxification continuously and do not need dietary assistance; no food pattern "balances hormones" in any meaningful clinical sense. The underlying diet is sound. The claims attached to it are not always.
Function Health offers members over a hundred laboratory tests annually for a flat fee, with AI-generated interpretation, and options extending to multi-cancer detection tests and whole-body imaging. It has grown very fast and was valued at $2.5 billion in late 2025.
This is the section where we have to be most careful, because we sell blood tests too.
It is real. Many people cannot easily access testing, chronic disease is often detected late, and a baseline panel can identify genuinely actionable things — iron deficiency, thyroid dysfunction, undiagnosed diabetes, high cholesterol, vitamin D deficiency. Knowing your numbers is not a fad.
Testing a hundred markers in an asymptomatic person has predictable statistical consequences. Reference ranges are typically set so that around 5% of healthy people fall outside them. Run enough tests and abnormal results become near-certain by chance alone. That generates anxiety, repeat testing, and sometimes invasive follow-up investigation for findings that were never going to cause harm.
This is why the UK National Screening Committee applies strict criteria before recommending population screening: the condition must be important, the test accurate, and — crucially — earlier treatment must actually improve outcomes. Most markers on a broad panel do not meet that bar for asymptomatic people.
Multi-cancer early detection tests are not currently recommended for population screening in the UK, and evidence that they reduce cancer mortality is not established. They can produce both false reassurance and false alarms.
Whole-body imaging in asymptomatic people reliably produces incidental findings — harmless anomalies that then require investigation to rule out something serious.
Function Health has been criticised for cross-promoting supplements alongside test results. When the same organisation identifies the problem and sells the solution, the incentive to find problems is structural rather than personal. That criticism is fair, and it applies to us as much as to them — which is why our position is that a test should be ordered because you have a question, not because a panel exists.
Hyman is the most visible face of functional medicine, and it remains genuinely contested within the profession. It is worth setting out both sides accurately rather than picking one.
The criticism. When CBS News hired Hyman as a contributor, physicians objected publicly. One told The Guardian that functional medicine functions as "a pipeline that moves disenchanted healthcare providers away from evidence-based care" and towards the wellness industry. Specific practices associated with the field — IgG food intolerance testing, some heavy-metal protocols, extensive unvalidated functional panels — lack good evidence.
The defence. The core proposition of functional medicine — that nutrition, sleep, movement and stress are foundational to chronic disease management — is not fringe and is increasingly built into mainstream guidelines. As one integrative practitioner put it in a balanced assessment, critics painting the whole field as divorced from evidence are cherry-picking specific claims, while Hyman himself sometimes shows "a tendency toward absolutist thinking" that outruns the nuance of the research.
That framing is about right. The foundational insight is sound; some of the specific practices and much of the certainty are not.
| Claim | Status |
|---|---|
| Recommends multivitamin, vitamin D, omega-3 and magnesium as a baseline | Confirmed |
| Follows and promotes the Pegan diet | Confirmed — his own book |
| Co-founder and CMO of Function Health | Confirmed |
| Targets 7–8 hours sleep; eats around three hours before bed | Confirmed |
| Sells his own supplement line | Confirmed |
| Exact personal doses across his full stack | Partly reported — varies and is adjusted to his results |
| A diet can "detoxify" or "balance hormones" | Not supported as stated |
| Multivitamins reduce disease risk in well-nourished adults | Not supported by large trials |
| Broad untargeted panels improve outcomes in asymptomatic people | Not established |
The dietary core. Mostly plants, minimal ultra-processed food, low added sugar, adequate protein. This is where the great majority of the benefit sits and it aligns with UK guidance.
Vitamin D through autumn and winter. UK guidance recommends supplementation for the general population, because sunlight at British latitudes is insufficient in those months. Note that Hyman's typical suggestion is well above the UK's 10 µg (400 IU); higher doses are better guided by a blood test, since vitamin D accumulates.
Sleep and eating window. Seven to eight hours, and not eating close to bedtime, are both sensible and well supported.
Omega-3 and magnesium: reasonable, with modest effect sizes. Targeted probiotics for specific symptoms, where the strain matches the outcome studied.
Routine multivitamins in well-nourished adults. NMN and senolytics in humans. "Detox" framing. Broad untargeted panels as a route to better health outcomes.
Unlike some others in this series, there is little in Hyman's routine that could hurt you directly. The realistic harms are over-investigation — anxiety, unnecessary follow-up, occasionally invasive procedures for findings that were never dangerous — and cost.
Vitamins A, D, E and K accumulate. Stacking a multivitamin with separate high-dose vitamin D and a cod liver oil can push intake into ranges where harm becomes plausible. Count your total across all products.
Analytical studies summarised in a 2023 review of supplement adulteration found that between 14% and 50% of sampled sports supplement products contained undeclared prohibited substances. Third-party testing is the minimum standard.
What to look for on a label
Every active listed with its own quantity — never a proprietary blend, which is how under-dosing is hidden. Doses stated in the form that matters. And third-party batch testing with a published certificate of analysis you can actually read.
Gut health is central to Hyman's framework, and it is one area where targeted supplementation has a growing evidence base. Akkermansia muciniphila is among the more interesting strains in that research.
Welzo Ultra Purity Akkermansia 60 Billion AFU
Two capsules daily with breakfast · 30 servings · every active listed with its quantity · published certificate of analysis
Note this is a multi-ingredient formula, not a single strain. Alongside the Akkermansia and L. acidophilus it contains 700 mg of berberine — a metabolically active compound that can interact with prescription medicines, including diabetes drugs. Check with a pharmacist first if you take any regular medication.
View product →Decide what you actually want to know before ordering anything. Tired? A tiredness and fatigue panel covering iron, thyroid and B12 answers that. Concerned about heart risk? A cholesterol test. Following a plant-based diet? A nutrition and vitamin panel. A hundred markers with no question attached mostly generates noise.
An abnormal number is a prompt for a conversation, not a diagnosis. This is the step most consumer testing skips, and it is the one that determines whether testing helps you.
Hyman is right about this and says so himself. Mostly plants, minimal ultra-processed food, adequate protein, low added sugar. No supplement compensates for its absence.
Vitamin D through the UK winter, omega-3 if you don't eat oily fish, and whatever your bloods actually flagged. Our minimal evidence-led stack guide sets out the reasoning.
His stated baseline for most adults is a multivitamin, vitamin D, omega-3 and magnesium. He has discussed a longer experimental list including NMN and senolytic compounds, and adjusts his own intake according to his blood results. He is consistent that supplements come second to diet.
A hybrid of paleo and vegan principles: roughly three quarters of the plate as vegetables and fruit, adequate protein, whole-food fats, low glycaemic load and minimal processed food. Stripped of the branding, it is close to standard dietetic advice and is a reasonable framework.
The underlying pattern is. The claims sometimes attached to it are not: no diet "detoxifies" you — your liver and kidneys do that continuously — and no food pattern "balances hormones" in a meaningful clinical sense.
Probably not without a specific question. Reference ranges are typically set so about 5% of healthy people fall outside them, so testing a hundred markers makes an abnormal result nearly certain by chance. That drives anxiety and follow-up investigation for findings that were never going to cause harm. Test with a question, and take results to a clinician.
Most well-nourished adults do not. Large trials have generally not shown reductions in cardiovascular events or mortality from multivitamins. Supplementing an identified gap is a better strategy, with vitamin D through the UK autumn and winter as the main exception.
UK guidance suggests 10 µg (400 IU) daily for the general population through autumn and winter. Higher doses such as those Hyman suggests are better guided by a blood test, since vitamin D is fat-soluble and accumulates.
Partly. Its core proposition — that nutrition, sleep, movement and stress are foundational to chronic disease — is mainstream and well supported. Specific practices associated with the field, such as IgG food intolerance testing and extensive unvalidated panels, are not well evidenced. Judge individual claims rather than the label.
They are not currently recommended for population screening in the UK and evidence that they reduce cancer mortality is not established. They can generate both false reassurance and false alarms. Follow the NHS screening programmes you are invited to, and discuss any additional testing with your GP.
Yes — he sells a supplement line and co-founded Function Health, a blood testing company where he is chief medical officer. That does not make his recommendations wrong, but it means each should be weighed on its own evidence rather than on his endorsement.
The dietary core, the emphasis on sleep, the insistence that food matters more than pills, and the instinct to look for causes rather than only manage symptoms. That is most of the value, and it is free.
Medical disclaimer. This article is for general information and is not medical advice. It is not a substitute for consultation with a qualified healthcare professional. Dr Mark Hyman has no connection to Welzo and does not endorse Welzo or any product mentioned. Nothing here should be taken as a claim that any supplement prevents, treats or cures any disease.
Blood tests are not a substitute for clinical assessment. Discuss any abnormal result with your GP. Speak to your GP or pharmacist before starting a supplement if you take prescription medication, are pregnant or breastfeeding, or have liver, kidney, thyroid or metabolic disease. If you have symptoms that concern you, see a doctor rather than ordering a test.
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