Multivitamins against ageing? New Nature study causes a stir

A big-name research team, a prestigious journal, plenty of media buzz - and, in the end, a picture that’s far more nuanced than the headlines suggest.

Over recent days, an eye-catching claim has circulated internationally: taking a daily multivitamin can measurably slow ageing - at least in people aged over 70. The story stems from the COSMOS project, with new analyses published in Nature Medicine. Read beyond the splashy summaries, though, and the findings look less like an “anti-ageing breakthrough” and more like a careful, intriguing data point in a much bigger question: what do dietary supplements actually achieve in later life?

What the COSMOS study (Cocoa Supplement and Multivitamin Outcomes Study) actually involved

COSMOS is short for the Cocoa Supplement and Multivitamin Outcomes Study. The work is led by researchers at Brigham and Women’s Hospital in Boston, a major centre known for prevention-focused medicine. The broad aim is straightforward: can multivitamins and/or cocoa extracts influence health outcomes - and, in this specific analysis, markers linked to biological ageing?

The sub-study now being discussed included just under 1,000 participants, roughly half women and half men, all aged 70 or older. Participants were randomly assigned to one of four daily regimens for two years:

• a commercial multivitamin plus 500 mg cocoa powder (including 50 mg epicatechin, an antioxidant)
• cocoa plus placebo
• multivitamin plus placebo
• placebo only (no active ingredients)

Crucially, neither the participants nor the researchers knew who was in which group until the end. This is the classic robust set-up used in drug research: randomised, controlled, double-blind.

What was measured: “epigenetic age” using epigenetic clocks and DNA methylation

Rather than tracking wrinkles, strength, or blood pressure, the researchers focused on something far more granular: epigenetic clocks, which estimate epigenetic age from patterns of DNA methylation - tiny chemical tags on DNA that change over time and, in population studies, tend to correlate with ageing and mortality risk.

The study examined five different epigenetic clocks measured in blood, used as biological markers associated with ageing.

Blood samples were taken at baseline, 12 months, and 24 months. The team then assessed whether participants’ expected “biological ageing” appeared to speed up or slow down across five pre-specified epigenetic clocks.

COSMOS multivitamin findings: the key results in plain numbers

After two years, a consistent pattern emerged - the one that fuelled the headlines:

• Participants taking a daily multivitamin showed signals in all five epigenetic clocks suggesting slightly slower ageing.
• Two clocks that are more tightly linked to mortality shifted most clearly.
• The effect appeared most pronounced in people who looked biologically “older” than their chronological age at the start.
• Translated into time, the difference worked out to roughly four months of epigenetic-age advantage over two years, compared with the placebo group.
• For the cocoa component, this analysis found no clear benefit.

A four-month shift over two years is, viewed soberly, modest - more of a gentle nudge than anything resembling rejuvenation. The study authors themselves make that point.

Why experts urge caution when interpreting the Nature Medicine paper

In the Nature coverage and in the original Nature Medicine paper, the researchers’ tone is markedly more restrained than many reports. They describe the effect as statistically significant, while also emphasising how limited its real-world meaning may be.

The data suggest a possible small advantage, but they do not show whether this leads to noticeable health benefits.

Put plainly: yes, epigenetic clocks tick very slightly more slowly with a multivitamin in this study. But this sub-study does not demonstrate that participants had fewer heart attacks, remained independent for longer, or lived longer.

The authors argue that follow-up work needs to answer questions such as:

• How tightly do epigenetic clocks truly track specific diseases in older age?
• If interventions shift these markers, do they translate over time into fewer illnesses or longer life?
• How do lifestyle factors - diet, activity levels, smoking - compare with a capsule?

Multivitamin supplements versus a healthy diet: the more meaningful comparison

Study lead Howard Sesso notes that multivitamins should not be viewed in isolation. The bigger, more practical question is how supplementation stacks up against genuinely improving diet quality.

A realistic comparison might look like this: one group of older adults takes multivitamins, while another receives structured support to follow a Mediterranean-style pattern - more vegetables, wholegrains, pulses, and unsaturated oils. Whether a multivitamin adds any measurable extra benefit on top of that kind of dietary improvement remains unknown.

The limitations of epigenetic clocks as a health measure

The researchers also openly acknowledge a central weakness: epigenetic clocks are promising, but they are not yet fully validated as decision-making tools for clinical care. They correlate with age and mortality risk, but the underlying biology is still only partly understood.

Key gaps include:

• clear thresholds for what counts as a clinically meaningful change
• long-term datasets showing whether altering these markers changes disease trajectories
• head-to-head comparisons with established measures such as fitness, muscle strength, and cognitive performance

So, if someone sees their “epigenetic age” on a lab report, it is not the equivalent of a pass/fail MOT certificate for health - it is closer to a developing risk indicator whose implications are still being worked out.

Who funded COSMOS - and why sponsorship matters

As is often the case, the most sensitive details sit low down in the paper: the funding and sponsors. Alongside public bodies such as the US National Institutes of Health, several industry-linked organisations were involved.

Sponsor	Area
Mars / Mars Edge	Food manufacturer; nutrition and functional foods division
Pfizer Consumer Healthcare (now Haleon)	Producer of over-the-counter products and dietary supplements
Foxo Technologies	Company offering epigenetic testing
American Pistachio Growers	Trade association for pistachio producers
Council for Responsible Nutrition	Lobby group for the dietary supplement industry

The researchers state they worked independently and that sponsors did not influence the study. Formally, that supports the claim of no direct conflict of interest. Still, it is reasonable to ask whether the study would be viewed differently - or designed differently - if funding had come solely from neutral public sources.

The Council for Responsible Nutrition, in particular, has faced criticism historically over perceived indirect influence (for instance, travel funding, fees, or other benefits to researchers). Such ties do not automatically invalidate results, but they do justify extra scrutiny - especially when findings could make a commercially attractive product look better.

What this means in practice for people aged 70+ considering multivitamins

If you are over 70, already taking multiple prescriptions, and seeing adverts for “anti-ageing vitamins”, the natural question is: is it worth it? The COSMOS data do not provide a simple yes/no.

However, a few practical takeaways are reasonable:

• Multivitamins may help plug micronutrient gaps, particularly where appetite is poor or diets are very limited.
• The observed slowing of epigenetic age is small, and it cannot currently be translated directly into guaranteed health gains.
• A balanced, fibre-rich diet, regular movement, and stopping smoking have far stronger evidence for improving health and life expectancy.
• If you have existing conditions or take several medicines, discuss any supplement with a GP or pharmacist because interactions and contraindications are possible.

Multivitamins are best seen as a supplement, not a miracle cure - they do not replace a good diet or an active lifestyle.

Risks and common misconceptions about “harmless” vitamins

Many people assume vitamins are safe in any quantity because they are sold without prescription. That is not true. Fat-soluble vitamins - A, D, E, and K - can accumulate in the body. High-dose products can be risky for some people, depending on their medical history, and may contribute to problems such as kidney stones or liver strain.

There is also a behavioural trap: relying on a pill can delay harder but more powerful changes. A daily walk, cutting back on alcohol, or adding an extra portion of vegetables typically does far more for blood vessels, brain health, and metabolism than reaching for another tablet.

A UK-specific note: regulation, quality, and targeted supplementation

In the UK, supplements are regulated as foods rather than medicines in most cases, which means quality and dosing can vary between brands. If you do choose a multivitamin, it is sensible to avoid megadoses, stick close to reference intakes, and buy from reputable manufacturers that provide transparent labelling.

It is also worth remembering that the most useful supplements in older age are often targeted rather than all-in-one. For example, vitamin D is commonly discussed in the UK because sunlight exposure can be limited for much of the year - but the right approach depends on individual circumstances and should be guided by a clinician where relevant.

How to judge future health headlines about studies like COSMOS

This COSMOS analysis is a good example of how complex data can be turned into simple promises. A few questions help keep perspective whenever you read a big claim:

• Does the study measure hard outcomes (heart attacks, disability, death), or surrogate markers (blood values, epigenetic clocks)?
• How large is the effect in real terms (months, percentages), not just “statistically significant”?
• Who paid for the work, and do funders have a financial stake in the outcome?
• Do the authors speak cautiously - or like marketers?

For multivitamins, the most accurate summary right now is: there are interesting signals of small laboratory effects on epigenetic clocks. Whether that translates into noticeably better health or longer independent living for older adults remains unproven. If your goal is healthier ageing, the best-supported foundations are still the basics: nutritious food, regular movement, strong social ties, and - where needed - clinically guided, targeted supplementation rather than blindly taking high-dose combination products.