How vitamin D strengthens bones — and why too much is risky

Vitamin D is essential for strong bones, a stable mood, and overall health — yet many people have a deficiency without knowing it. Sunlight provides most of our vitamin D, while food offers only a small share. Low levels can weaken bones, raise the risk of stress fractures, and worsen osteoporosis. A daily low dose supplement can help, but high doses should only be taken under medical supervision.