Most supplement-for-brain claims collapse under a good trial — but the COSMOS program is the rare exception, finding a daily multivitamin modestly improved cognition in older adults. Here’s what the trials actually found, how big the effect really is, who it applies to, and the conflicting evidence that keeps it honest.
Low vitamin D is linked to worse cognition — but does supplementing help? The honest “signal vs hype” answer: correcting a genuine deficiency is worthwhile, yet supplement trials in already-replete people came up empty. Test first, correct if low, don’t megadose.
Magnesium glycinate is the internet’s favourite sleep supplement — but does it work? The honest evidence, what the 2025 trial found, correct dosing, safety cautions, and who benefits most.
