The latest research suggests that vitamin D may play a more important role in health than had been suspected. But many of us do not get enough vitamin D. In this article from our Health After 50 newsletter, Johns Hopkins experts explain why you need vitamin D – and how to get it.
Your need for some nutrients, especially those affecting your bones, increases as you get older. One of these nutrients is vitamin D -- the only vitamin your own body can manufacture.
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Sunlight stimulates the production of vitamin D in the skin -- a mixed blessing, since the ultraviolet rays of the sun can also damage skin. But you also need to get vitamin D from food and supplements. From age 50 to 70, the recommended intake of vitamin D is 400 IU per day -- the amount in 4 cups of fortified milk. After age 70, you need 600 IU per day. The new U.S. dietary guidelines endorse much higher amounts -- 800 to 1,000 IU daily. Studies show that vitamin D deficiency is common, especially in people over 60.
Why do you need vitamin D? It is essential for bones and teeth. Without vitamin D, your ability to absorb calcium is reduced, and calcium is essential for strong bones and teeth. Vitamin D is also vital for muscle strength, and a deficiency may lead to falls and fractures. Thus, lack of vitamin D causes fractures in two ways: Weakened muscles lead to falls that result in fractures of thin bones.
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The latest research suggests that vitamin D may play a more important role in health than had been suspected. Healthy bones may not be the only function of vitamin D. Shortages may also be linked to multiple sclerosis, diabetes, and rheumatoid arthritis, as well as to breast and prostate cancers. All these disorders are more common in northern regions where people get less sun -- and lower vitamin D levels may be part of the explanation.
Getting your vitamin D -- Adults often drink too little milk -- a real dietary loss because both soy and cow's milk are fortified with vitamin D. (Not all milk products are good sources -- yogurt and cottage cheese are NOT made from fortified milk.)
Fish is also a good source of vitamin D; eggs have a small amount of vitamin D. But you should not eat fish every day, and those following heart-healthy diets have to limit eggs.
The typical multivitamin pill has 400 IU of vitamin D. Some calcium supplements also contain vitamin D, so you might buy one of these if you are taking calcium. But keep in mind that vitamin D can be harmful in dosages above 2000 IU daily. Avoid cod liver oil. It is very rich in vitamin D -- you could overdose, particularly if you are taking supplements. Cod liver oil also contains high levels of vitamin A, which can weaken bones.
