(CNN) - They call it the sunshine vitamin. That's because vitamin D, unlike other vitamins and minerals, doesn't always come from food. The best source of this supplement is the sun.
But some people lack vitamin D because many won't stay in the sun for long periods of time, fearing they may develop skin cancer. According to the National Institutes of Health, one out of three Americans aren't getting enough of the supplement in their diet, which can lead to health problems.
When vitamin D levels get too low, our bones weaken and the risk of heart disease, high blood pressure, dementia and certain types of cancer goes up. Low vitamin D levels can also lead to fatigue.
So nutritionists recommend eating your vitamin D. You can find it in oily fish, fortified milk and egg yolks. Doctors recommend people from ages 1 to 70 get 600 international units a day of vitamin D to get the full benefits.
Copyright 2014 CNN. All rights reserved.