Vitamin D After 40: The Muscle Number Your Blood Test Hides
There’s a number hiding on the blood panel most men over 40 skip reading. It’s not cholesterol, not HbA1c, not testosterone. It’s vitamin D — and if it’s low, it’s quietly doing more damage to your muscle than you think. Here’s the catch, and it’s the entire point of this post: vitamin D is not a supplement that makes you stronger. It’s a deficiency marker. Below a threshold it’s associated with weaker muscles and worse physical function. Above that threshold, taking more does almost nothing. The supplement industry wants you to forget that distinction, because “take this to get jacked” sells better than “check this one number so you know you’re not deficient.” ...