Those are the basic facts, but some questions might remain: How should you get vitamin D? How much should you get and when should you worry about your levels? In light of these common questions, our Yale Medicine doctors help clear up some confusion about vitamin D, separating fact from fiction. “The body can use each perfectly fine,” says Dr. In case you were wondering, it doesn’t matter if you’re getting D2 or D3, and the sunlight-generated kind isn’t better than the nutritional variety.

Through a process called hydroxylation, the liver and kidneys turn the stored vitamin D into the active form the body needs (called calcitriol). Here it remains inactive until it’s needed. How does the body process vitamin D?Īfter vitamin D is absorbed through the skin or acquired from food or supplements, it gets stored in the body’s fat cells. They are generally recommended for people with fat absorption issues, lactose intolerance, milk allergies, as well as for people with darker skin tones or with certain medical conditions that prevent them from going outdoors. Leffell, MD, chief of Dermatologic Surgery.Īnother avenue to get vitamin D is by taking supplements. “We each have vitamin D receptor cells that, through a chain of reactions starting with conversion of cholesterol in the skin, produce vitamin D3 when they’re exposed to ultraviolet B (UVB) from the sun,” says Yale Medicine dermatologist David J. When exposed to the sun, your skin can manufacture its own vitamin D.

(Since the 1930s, manufacturers have voluntarily enriched these foods with vitamin D to help reduce the incidence of nutritional rickets.)

That’s why foods like milk, cereal and some orange juices are vitamin D2- and D3-fortified. But because we don’t consume large enough quantities of these foods, they can’t be our sole source of vitamin D. There are two main kinds of vitamin D-vitamin D2 and vitamin D3-which you can get from (and occur naturally in) certain foods like salmon, tuna, mackerel and beef liver and egg yolks. The short answer is from food, the sun or supplements.

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