The Vitamin D Question Nobody Asks Their Doctor

Vitamin D occupies a strange place in modern medicine. It is prescribed for bone health, tested at every annual visit, and sold in doses that range from sensible to astonishing. Yet the evidence behind much of this is thinner than most patients — and many clinicians — assume.

What we know: severe deficiency matters. Very low vitamin D is associated with bone loss, muscle weakness, and falls in older adults. Correcting a true deficiency is reasonable and supported. What we do not know with the same certainty is whether pushing a normal level higher with high-dose supplementation changes anything meaningful for the average older adult.

The large trials of the last decade have been humbling. Broad supplementation has not delivered the reductions in fracture, heart disease, or cancer that observational studies once hinted at. The benefit, where it exists, appears concentrated in people who were genuinely deficient to begin with.

So the question worth asking your doctor is not 'What is my level?' but 'Given my level, my risk, and the medications I take, does supplementing change anything for me?' That is a different conversation — and a better one — than reaching for the highest dose on the shelf.

More is not a strategy. The right amount, for the right person, is.

— Gregory D. Adams, MD