The shifting research on vitamin supplements and cognitive decline

Back in 2019 we discussed reports that said not only do vitamins not help with cognitive decline, people who take them have a higher rate of all-cause mortality.  But in 2022 we heard that researchers publishing with the Alzheimer's Association were finding that maybe vitamin supplements help after all.  At least a little.  So that's confusing.

Recently, some of you told me that you'd read about new research supporting the use of multivitamins to fight cognitive decline.  The research was conducted at Massachusetts General Hospital and was published in The American Journal of Clinical Nutrition, January 18, 2024.  In the study, the memory and cognition of 573 individuals were tested at the beginning of the study, although only 492 were still available or willing to be tested at the end of the two-year study period.  The study was placebo controlled, although it wasn't clear to me how many were given the placebo.

The researchers concluded "daily multivitamin supplementation leads to a significantly more favorable two-year change in episodic memory.  [Other research studies] indicate that daily multivitamin use significantly benefits both global cognition and episodic memory.  These findings ... support the benefits of a daily multivitamin in preventing cognitive decline among older adults."  So that's good, although some commentators characterize the effect as "modest."  Some speculate that the multivitamins support the gut microbiome and the gut-brain axis, which we've discussed before.  Other experts believe that the multivitamins are simply making up for vitamin deficiencies that you would not otherwise have if you adhere to the Mediterranean diet.

Of course, the researchers did not believe their findings were sufficiently conclusive; more research needs to be done.

Incidentally, the research did not find a positive effect for executive function or attention, two deficits of brain function associated with Alzheimer's disease.  So I'm inclined to think the context for the benefits of multivitamin supplementation is more associated with slowing the effects of normal aging and less with slowing disease.