Multivitamin

No — and this is the most important thing to be honest about. The largest, longest randomized trial (the Physicians' Health Study II, 14,641 men over 11+ years) found that a daily multivitamin produced NO reduction in major cardiovascular events, heart attack, stroke, or cardiovascular death (Sesso 2012, PMID 23117775). It is not a heart-disease drug and not a proven longevity intervention. What the same trial DID find was a modest 8% reduction in total cancer incidence (Gaziano 2012, PMID 23162860) — real, but small, and accrued over more than a decade. Buy a multivitamin as cheap insurance for dietary gaps, not as a longevity pill.

For many people, yes — as insurance, not as a drug. National data show large fractions of US adults fall short of the requirement for everyday nutrients like vitamin D, vitamin E and magnesium (Reider 2020). A multivitamin is the cheapest, simplest way to close those gaps in forms your body can use. The realistic payoff is correcting real shortfalls (which matters if you have them), a modest cancer-incidence edge over many years, and — the newest signal — a memory and cognition benefit in older adults (COSMOS-Mind, Baker 2022; COSMOS-Web, Yeung 2023). If you already eat a varied, nutrient-dense diet with no gaps, the marginal benefit is small. The honest summary: worthwhile insurance for people with dietary gaps, oversold as a wellness panacea for everyone.

It's the single clearest quality tell in the whole category. Methylfolate (L-5-MTHF) is the active, circulating form of folate your body uses directly; folic acid is a cheap synthetic that has no coenzyme activity until your body enzymatically converts it — a conversion many people perform inefficiently (Pietrzik 2010, PMID 20608755). Methylfolate works regardless of your conversion efficiency, which is why the better multivitamins (Thorne, Pure Encapsulations, Ritual, MegaFood, NOW ADAM) use it and the budget ones (Opti-Men, Kirkland) use folic acid. It's not a dealbreaker if cost is your constraint and you convert folate well — but if you're choosing on quality, methylfolate is the better form.

It depends entirely on who you are. Menstruating women lose iron monthly and often genuinely need it, so most women's multivitamins (like Ritual, #2, and Garden of Life Women's, #4) include it. Most men and post-menopausal women do NOT need supplemental iron and can accumulate too much over time, so men's and unisex formulas (Thorne, the Garden of Life Men's, the NOW and Optimum men's multis) are deliberately iron-free. Taking iron you don't need can cause GI upset and, long-term, iron overload. Rule of thumb: iron-free unless you're a menstruating woman, pregnant, or have diagnosed low iron — and if you suspect deficiency, get a blood test rather than guessing.

Not quite — read it carefully. The COSMOS-Mind (Baker 2022) and COSMOS-Web (Yeung 2023) trials found that a daily multivitamin improved memory and global cognition in adults aged 60-65 and older, over three years, by a modest amount — COSMOS-Web estimated the memory benefit as roughly three years of age-related change. That's a genuinely encouraging and well-conducted result, and it's the most promising direction for multivitamins. But it is specific to OLDER adults, the effect size is modest, and it's about slowing age-related decline, not boosting a young, healthy brain into being 'smarter.' For older adults it's a real point in the multivitamin's favour; for a 25-year-old it is not evidence of a cognitive edge.

Both can be good; the label matters more than the marketing word. 'Whole-food' multivitamins (like Garden of Life Vitamin Code, #4/#5, and MegaFood, #6) deliver nutrients in a food matrix with added probiotics or enzymes, and they typically use folate rather than folic acid — a genuine plus. The trade-offs are usually a higher pill count (four capsules for some) and lower per-nutrient potencies by design. Synthetic clinician-grade multis (Thorne #1, Pure Encapsulations #3) can match or beat them on form quality (methylated folate, chelated minerals) in fewer pills. Don't pick on the 'whole-food' label alone — check the actual forms (methylfolate vs folic acid), the dosing (sensible, not megadosed), and whether it's third-party tested.