The Great Vitamin D Debate

It’s been hailed as a lifesaving wonder supplement. But recent research throws some shade on the “sunshine vitamin.”

- Andrea Atkins

REMEMBER WHEN VITAMIN D was merely the patron saint of strong bones (and defender against that Dickensian affliction, rickets)? That started to change about two decades ago, when studies began to show that people with lower levels of vitamin D in their blood could be at higher risk for cancer, heart disease, and diabetes. At the same time, Americans concerned about the dangers of sun exposure were continuing to slather on sunscreen. Since our body makes D when our skin is exposed to sunlight (in addition to absorbing it from certain foods; see “D-licious,” page 71), people living at every latitude began to fear that they weren’t getting enough, and sales of the vitamin skyrocketed. Medicare claims for vitamin D tests increased 445 percent between 2007 and 2016. Some experts started advising that all people load up on D: In 2011, the Endocrine Society even published guidelines recommending supplementation. And today consumers take more D than any other supplement, according to a 2018 survey from ConsumerLab.com.

Now, on the basis of an important long-term trial, it seems our D mania wasn’t entirely justified.