A massive NIH study of nearly 400,000 adults over 20 years found that daily multivitamin users had a 4% higher mortality risk compared to non-users. The research showed no mortality benefit whatsoever—contradicting the belief that multivitamins serve as health “insurance”. Interestingly, multivitamin users typically had healthier lifestyles overall, yet still showed increased risk.
For healthy adults without diagnosed deficiencies, the healthiest nutrients come from food sources, not processed pills. Some specific concerns include potential buildup of excess iron or niacin from daily use. This reinforces that supplementation should be targeted and evidence-based, not indiscriminate.

With any association study, there’s always the risk of reverse causation, that people take multivitamins because they’re unhealthy.
Or that people who take vitamins stress out more about their health (as well as everything else, probably) and that could be a factor.
A good study would account for it, but corporate news can’t be bothered to vet for things like that, so you have to read the study yourself, assuming you’re not paywalled from it.
I wish everyone understood this.
I still have a hard time wrapping my head around Bayes’ theorem 🤷
With “observational” studies, yes, but a formal study which has control over the study objects, and a vetting process to throw out dishonest samples accounts for that.
No. This does not fix the issue