Can Daily Multivitamins Improve Cognition?

It's been a few years since we've done a video on multivitamins, but now's the perfect time, thanks to a recent study about them that got a lot of attention. That's the topic of this week's healthcare triage. Taking a daily multivitamin may help prevent dementia, at least according to a health news headline, but you know I'm about to issue a hard disagree on that. These headlines were based off a recent randomized placebo-controlled trial assessing the effects of cocoa, or multivitamins, on cognitive function in older adults. And before I begin, I just have to get one small point on the table. The findings are presented as proof that multivitamins can improve cognitive function, when in fact they were looking at whether they could slow cognitive decline, and that's an important difference. The study didn't find any effects of cocoa on cognition, but they did find an effect of multivitamins, and you know how much I love randomized controlled trials, so you may be surprised to hear that I'm not all that excited about this one. I'm always talking about the difficulties of conducting nutritional research, and research on multivitamins isn't much of an exception. People were indeed randomized into groups here, and that's a good thing, but lots of other problems still exist. For one, they simply self-report that they religiously took these vitamins every day for three years. No one was following them around to make sure they never forgot, or if they did forget, that they were willing to tell the researchers who called them up occasionally to ask. In that vein, no one was following the placebo group around to make sure they never took up multivitamins in that three-year period. Secondly, the researchers didn't measure baseline vitamin levels, meaning levels at the beginning of the study before supplementation started. Thus, they weren't able to rule out anyone with real deficiencies who could very reasonably have benefited. Even then, though, actual deficiencies aren't that common in the developed world, and supplementing with extra vitamins is like trying to put more gas in your car's tank than it can hold, it just results in wasted overflow. But we're curious around here, so we took a look at the results. The graphs do indeed show that participants taking a multivitamin had improved scores on cognitive tests over the course of three years. However, they also showed that participants taking a placebo improved their scores over that time period as well. This is called the practice effect. Taking the same test multiple times usually helps you get better at it. Researchers generally expect this to happen, and just have to be sure to compare the placebo and multivitamin group directly to understand if there was improvement beyond this practice effect. The authors did make this comparison, and there was a small difference, but looking at the graphs, I would be hard-pressed to say there's a meaningful difference between the placebo and multivitamin groups. A difference of a single point in scores could translate to statistical significance, but is not likely to be clinically significant, meaning not likely to make an actual difference in a patient's life and day-to-day function. There was a bigger difference between the groups in a subset of people with cardiovascular disease, but that's a whole other ball of wax to get into. I can't say it's impossible that vitamin supplementation plays a role in healthy aging, but it would depend on factors that weren't assessed for here, and I truly think that any potential role it might play will be incredibly difficult to parse apart in the enormous puzzle of nutrition and health. Hey, did you enjoy this episode? You might enjoy this previous episode on vitamin D supplements continue to be unnecessary. We'd appreciate it if you'd like the video, subscribe to the channel below, maybe go on over to patreon.com slash healthcare triage, where you can help support the show, make it bigger and better. We'd especially like to thank our research associates, James Glasgow, Joe Sevitz, Edward Littleholm, and Brian Nam, and of course, our Surgeon Admiral, Sam.