Vitamin D Only Seems to Slow Aging Markers If You Were Low to Begin With

Vitamin D talks directly to your genes, switching them on and off in ways that overlap with how aging works. But this review of the evidence found that big trials of vitamin D pills alone show little benefit for healthy aging. The clearest effects showed up in people who were actually deficient, and when supplements were paired with exercise and better nutrition. The authors also point to a J-shaped curve, meaning too much can be as unhelpful as too little.