A bottle on almost every household table, and a market worth billions. So what does the largest study ever conducted on them say?
The study
Researchers analysed data from 390,124 generally healthy US adults followed for more than 20 years — and found no evidence that taking a daily multivitamin lowers the risk of death[1],[2]. The study was led by scientists at the US National Cancer Institute and published in JAMA Network Open[1].
people
And not the only study
A rapid review of meta-analyses found that randomised controlled trials show multivitamin and mineral supplementation does not affect all-cause mortality, with no benefit across primary or secondary prevention populations[3].
But the picture isn't entirely bleak
The same review noted that randomised trials indicated multivitamin use improved global cognition, episodic memory and immediate recall in older or cognitively intact adults, reduced psychological symptoms in healthy individuals, and lowered systolic blood pressure in at-risk populations[3].
The precise conclusion: healthy adults with adequate dietary intake may not benefit, but multivitamins might still be useful for specific populations and age groups[3].
And who are those groups here specifically?
- People deficient in vitamin D — the majority in Saudi Arabia (67% per one study).
- Women deficient in iron — 30–56% per the national survey (details).
- After bariatric surgery — lifelong monitoring (why).
- Pregnant and breastfeeding women — on medical prescription.
The rule
Treat a proven deficiency confirmed by a test — not an assumed one. A "just in case" multivitamin for someone who eats well is spending without documented return. A specific supplement after a specific test is a genuine investment.