Daily Multivitamins: Do They Actually Help You Live Longer?

The logic behind a daily multivitamin seems intuitive: since diet rarely delivers exactly optimal amounts of every vitamin and mineral, one pill "just in case" should close any gaps and, at worst, do no harm. This belief has fueled a multivitamin market worth billions of dollars annually for decades, even though hard data on its effect on hard endpoints like mortality was, for a long time, fragmentary.

Two large cohort studies — one published in 2024 in JAMA Network Open, the other back in 2011 in Archives of Internal Medicine — provide data that calls this intuitive assumption into question.

The most recent and largest of these studies is the work of Loftfield and colleagues, published in 2024 in JAMA Network Open, analyzing data from three large, prospective US cohorts with a follow-up period spanning nearly three decades.

This result isn't isolated — a similar direction of association was described over a decade earlier in the 2011 study by Mursu and colleagues, published in Archives of Internal Medicine, covering older women participating in the Iowa Women's Health Study.

Correctly interpreting these results matters. The effect sizes are very small — an HR of 1.04-1.06 means a risk increase of just a few percent, not a dramatic health hazard. Both studies are observational, not experimental, meaning they can't definitively prove causation — reverse causation is possible (people already worried about their health for some reason may be more likely to take a multivitamin), as are other confounding factors that couldn't be fully controlled for.

It's also worth remembering these studies concern the general adult population without specific, diagnosed deficiencies. People with a confirmed deficiency in a specific vitamin or mineral (e.g., a vitamin D3 deficiency, which we cover in more depth in our vitamin D3 entry) represent a completely different clinical scenario than preventive multivitamin use by someone without diagnosed deficiencies.

In practice, this means a healthy person without diagnosed deficiencies has no strong justification in this data to treat a daily multivitamin as a life-extending measure. This doesn't mean you need to immediately stop taking one — but it's worth checking whether your motivation for taking it rests on real, diagnosed needs or on the general belief in a "safe insurance policy."

It's rare for such a popular, routinely used supplement to get a study covering nearly 400,000 people followed for 27 years — and rarer still for that study's result to diverge so clearly from the widespread belief in its benefits. This isn't a reason for panic, but it's a solid argument for treating a daily multivitamin as a choice that requires justification, not a default, cost-free "insurance policy."

If you're considering multivitamin supplementation, it's worth asking yourself (and ideally a doctor) whether it's backed by a specific, diagnosed need or by a general cultural belief — the data suggests that in the latter case, the benefit is at best uncertain.