Need some vitamin D? You could just go outside
Consumer surveys find that vitamin D now outsells all other supplements, including fish oil, probiotics and even multivitamins.
That’s rather surprising given that vitamin D is actually one of the few vitamins we can make on our own. All we need is to expose our skin to the sun, and our bodies take care of the rest. But the D boom isn’t a scam, necessarily — it’s just rife with confusing science and misinformation.
Vitamin D is essential for healthy bones: We need it to absorb calcium, among other minerals. It is also being investigated as a possible preventive player in conditions including asthma, cardiovascular disease, hypertension, autoimmune diseases like Type 1 diabetes and, of course, cancer. Although none of these associations has been proved, breathless headlines provide enough intrigue to drive market growth above 10 percent a year.
The other factor driving growth is that many of us don’t get direct exposure to the sun — either because we wear sunblock or be- cause we’re indoors all day. And with the exception of fish liver, very few foods are naturally rich in vitamin D. Instead, the vitamin D in most foods and supplements is created by irradiating lanolin (the greasy substance in sheep’s wool).
If you don’t eat fortified foods, you’re probably not getting much vitamin D through your diet.
Here’s the catch: It’s not clear how much is enough.
Despite all this uncertainty, it’s still possible to make an intelligent decision about whether to take a vitamin D supplement. You just need to ask yourself some questions:
Do you spend 15 minutes or more in the sun without sunscreen or protective clothing several times a week? If so, you’re likely to be in good shape in terms of vitamin D for most of the year. (Our bodies know when to stop making vitamin D, so there’s no risk of overdose from the sun.)
Are you breast-feeding? If so, you likely will want to give supplemental vitamin D to your baby. There is little vitamin D in breast milk, further evidence that we have evolved to meet our requirements with the help of the sun, not food.