Modest Effects on Cognitive Decline from Multivitamin Use
Setting aside cases of vitamin deficiency, the consensus on supplement use (including vitamins) in essentially healthy individuals is that it does little to nothing, or is even mildly harmful to long-term health. That mild harm might include use of antioxidants that diminish the beneficial response to exercise that is mediated in part by oxidative stress. As a counterpoint to the consensus, researchers here provide evidence for multivitamin use to modestly improve cognitive function in later life. Whether this result will hold up in other study populations is a question, and we'll likely be waiting a while on the answer. It tends to take a long time for studies involving hundreds or thousands of participants to be organized, conducted, and analyzed.
The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) is a large-scale, nationwide, randomized trial rigorously testing cocoa extract and multivitamin supplements. Two previously published studies of cognition in COSMOS suggested a positive effect for a daily multivitamin. COSMOS researchers now report the results of a third study of cognition in COSMOS, which focused on participants who underwent in-person assessments, together with the results of a combined analysis from the three separate studies.
In the in-clinic study the researchers administered detailed, in-person cognitive assessments among 573 participants in the subset of COSMOS known as COSMOS-Clinic. In their prespecified analyses of data from COSMOS-Clinic, investigators observed a modest benefit for the multivitamin, compared to placebo, on global cognition over two years. There was a statistically significant benefit of multivitamin supplementation for change in episodic memory, but not in executive function/attention. The team also conducted a meta-analysis based on the three separate studies, with non-overlapping COSMOS participants (ranging 2-3 years in treatment duration), which showed strong evidence of benefits for both global cognition and episodic memory. The authors estimate that the daily multivitamin slowed global cognitive aging by the equivalent of two years compared to placebo.