It’s spring in the Pacific Northwest, and that means almost everyone I know is craving sunshine. That familiar cry of “gotta get my vitamin D!” echoes across campus. And it’s true. Our skin makes loads of vitamin D when it is exposed to the sun. However, since the latitude in the Pacific Northwest is northern, and we’re protecting our skin from harmful UV rays with sunscreen, the likelihood that we get enough vitamin D from sun alone is minimal. It turns out that most people use about 3,000 IU of vitamin D each day. And it would be very unusual to get that much from the sun.

Therefore, it’s a good thing that most of us also get vitamin D in our diet. Vitamin D comes from animal sources (meat, dairy) and is also supplemented in foods. I discovered a year ago that even though I eat meat, I didn’t get enough vitamin D to make a dent. I was still deficient. (You can have your blood tested if you are wondering if you’re deficient.) I started supplementing.

So why do we care about vitamin D levels? Usually we think about vitamin D working with calcium to effect the strength of our bones. But it does much more than that. More than 250 genes are controlled by vitamin D.

Researchers at Mount Sinai in New York recently examined the role of vitamin D in allergic rhinitis in kids.(1) For you non-medical people, allergic rhinitis is when allergies makes your nose run. These researchers took an unusual approach. They looked at whether mom ate vitamin D rich foods during pregnancy or supplemented with vitamin D affected whether their kids developed allergic rhinitis. By now you’ve guessed the punch line. Yes! If mom’s got more vitamin D in their diet (i.e. via food), it reduced the likelihood that their children would develop allergies by 20%.

Here’s an interesting caveat: vitamin D supplementation by mom didn’t reduce allergic rhinitis. What? If food can do it, why didn’t supplementation? Not all supplements are created equal. The researchers suspect that the women may have been taking vitamin D supplements that didn’t provide a bio-available form of vitamin D.

Certainly there are many other factors that play into childhood allergies – children being exposed to pets and other kids is well known to reduce allergies, for example. But vitamin D can also play a role.

So go out there and get your vitamin D!

1 Bunyavanich S, Rifas-Shiman SL, Platts-Mills TA, Workman L, Sordillo JE, Camargo CA Jr, Gillman MW, Gold DR, Litonjua AA. Prenatal, perinatal, and childhood vitamin D exposure and their association with childhood allergic rhinitis and allergic sensitization. J Allergy Clin Immunol. 2016 Apr;137(4):1063-1070.e2. doi: 10.1016/j.jaci.2015.11.031. Epub 2016 Feb 10