It’s no secret that vitamin D is a crucial ingredient for overall health, glowing skin, and strong bones, but most people don’t get enough of this fat-soluble vitamin that helps muscles, heart, lungs, and brain function properly.
Research has shown that 3/4 of U.S. teens and adults are “D-ficient.” This is a scary number, considering the number of health woes the lack of the vitamin has been linked to: Obesity, cancer, heart disease, diabetes, and certain autoimmune diseases, to name a few.
The Institute of Medicine recommends infants get 400 International Units (IU) a day, adults get 600 IU, and people older than 70 get 800 IU. You can calculate – using this page for latitude and longitude numbers – how long it will take you to stay outside in order for the body to produce 25 mcg (the equivalent of 1,000 International Units) of vitamin D. You may need 15 minutes or three hours. However, the best way to know exactly how much vitamin D you need is to test your blood.
Sunlight is the best known source of Vitamin D, but the body has to convert it to active Vitamin D and not everyone has that ability, Maria Bohland, a registered dietician and founder of DietAustin.com, says. The parathyroid gland, she adds, produces active vitamin D, unless it has been damaged. Other organs, such as the kidney, are also involved in producing D’s active form.
The body needs enough calcium to convert vitamin D. “Calcium and Vitamin D are like a married couple,” Bohland adds. “They need each other and you need both for optimal bone health.”
Sources of Vitamin D that don’t require you to absorb sun include supplements and, surprisingly, a lot of foods. It naturally occurs in a few, Bohland says, but it is added to many processed foods – some are actually good for you – such as milk and fortified cereal.