Can a Daily Multivitamin Help Protect Your Brain? Here’s What One of the Largest Studies Ever Done Found

Medically reviewed by Reshma Patel, Consultant Dietitian and Georgie Murphy, Assoc. Registered Nutritionist and Gut Health Expert
A woman in profile with an illustration of the brain over her head

By Dr Mandy Leonhardt, General Practitioner and Menopause Specialist

If you’ve ever wondered whether a daily multivitamin is “worth it,” you’re not alone. For years, the honest answer from science has been a bit of a shrug. But one of the largest, longest-running, and most respected studies on multivitamins has now turned up a finding that’s hard to ignore - and it’s about your brain.

The Study: COSMOS

COSMOS is a large, independent, placebo controlled, randomised clinical trial (RCT) - the gold standard of research design - that followed over 21,000 older adults for several years. The researchers set out to answer a big question: can a daily multivitamin help prevent cancer and heart disease?1

The honest answer? Not really. The scientists running the study have been refreshingly transparent about that. This isn’t a study with an agenda to sell supplements; it’s independent research that reports what it finds, good or bad.2

But Then Something Interesting Happened

While COSMOS wasn’t designed to look at brain health first, several follow-up studies (called “ancillary studies”) dug into cognition specifically - memory, focus, and how sharp participants’ thinking stayed as they aged. And here’s where it gets exciting:3

  • Participants who were taking the multivitamin had higher cognitive test scores after 3 years, compared to the participants in the placebo group.
  • The investigators estimated that taking the daily multivitamin slowed cognitive aging by approximately 60%.
  • Compared to the placebo group, the participants in the multivitamin group “showed improved global cognition, which reflects overall ability across multiple cognitive domains, such as recall, recognition, and learning”.4
  • Memory and executive function (the mental skills you use to plan, focus, and make decisions) were both significantly better in the multivitamin group.

These weren’t one-off results either. Multiple independent research teams, using different types of cognitive tests (phone-based, computer-based, and in-person), all found the same pattern: people taking a daily multivitamin had better memory outcomes than those on placebo.5

Why This Matters

SISTERLY was built around the idea that daily nutritional support should do more than just “fill gaps” - it should actively support how you think, feel, and function day to day.

COSMOS is one of the strongest pieces of independent evidence to date that a daily multivitamin can genuinely support memory and cognitive health as we age.

That’s not a marketing claim - it’s a finding from a large, peer-reviewed, independent research programme, and it’s exactly the kind of outcome a potent multivitamin was designed to support.

It’s also a good reminder of why we believe in transparency: real science doesn’t confirm every hope we might have for a product, but when it does find something - like a meaningful, repeated, cross-study benefit for memory - that’s worth paying attention to.

It’s Not Just About Cognition

COSMOS is a great example of what a daily multivitamin can do for the brain - but it’s worth remembering that many of the individual nutrients in SISTERLY’s multivitamins have their own, separate body of established science behind them, beyond this one study:

  • Energy: B-complex vitamins (B1, B2, B3, B5, B6, B12) are directly involved in how your cells convert food into usable energy, and CoQ10 plays a central role in energy production within cells.
  • Immunity: Vitamin C, vitamin D, zinc, and selenium all have well-documented roles in normal immune system function.
  • Hormone balance: Magnesium and vitamin B6 are both linked to hormone regulation, and are commonly studied in relation to PMS and menstrual cycle symptoms.

None of this is new or unique - it’s well-established nutritional science. But it’s a useful reminder that a good multivitamin isn’t a one-trick pony: the same formula that may support long-term brain health is also doing daily, practical work for energy, immunity, and hormonal balance.67

The Takeaway

A daily multivitamin isn’t a cure-all. But according to one of the best-designed, most transparent studies we have, it may genuinely help protect your memory and cognitive sharpness as you get older. That’s a compelling reason to make a quality daily multivitamin, like SISTERLY, part of your routine.

This article has been fact checked by the SISTERLY expert team, but as always, we encourage you to read the original research yourself - links to the source studies are in the footnotes.

References

  1. Original COSMOS, COSMOS-Mind, COSMOS-Web, and COSMOS-Clinic study publications, and Physicians’ Health Study II. pubmed.ncbi.nlm.nih.gov/38244989
  2. COSMOS was designed primarily to test other health outcomes, and results there were mixed. It’s a good example of how findings can evolve and vary across different, larger, more diverse trial populations, and of a study reporting honestly on what it did and didn’t find.
  3. Two further ancillary studies backed this up: COSMOS-Web (3,562 participants, computer-based testing) found significantly better memory at both 1 and 3 years in the multivitamin group; COSMOS-Clinic (573 participants, in-person neuropsychological testing) found improved episodic memory over 2 years, though not executive function or attention. A combined meta-analysis of all three ancillary studies (over 5,000 participants total) confirmed improved global cognition and episodic memory with multivitamin use.
  4. These are general, well-established nutrient functions supported by a broad base of nutrition science (independent of the COSMOS study itself), not new claims.
  5. A good summary of the current findings on multivitamins can be found here. ods.od.nih.gov/factsheets/MVMS-HealthProfessional
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