Vitamin D sources

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(Host) With our short summers, are we in the North getting enough sunshine Vitamin D? Commentator Ruth Page suggests some ways to make sure you get enough of that essential vitamin.

(Page) A few weeks ago, when I did a commentary about using sunblock to protect your skin from the sun, I should have said, “Don’t wear sunblock with an SPF higher than 8, if you want to absorb vitamin D from sunlight.” You get D from ultraviolet rays, and they’re just what the sunblock stops. The National Institutes of Health recommend that you expose unprotected skin to the sun for no more than ten or fifteen minutes at a time, since overexposure not only burns, it can lead to skin cancer.

The NIH emphasizes that people who live in the northern U.S., including New England, may be at risk of Vitamin D deficiency. NIH reports, for instance, that in Boston, from November through February, the average amount of sunlight doesn’t provide adequate vitamin D for our needs.

So what do we do? There aren’t many sources of D: it is available from some fish oils (especially cod liver oil), fortified breads and cereals, and Vitamin D-fortified milk. Unless you consume a full quart of milk a day, for 400 International Units, or IUs, of vitamin D, you need sunshine and other backup sources. Persons over seventy need 600 IUs of D every day — a blockbuster forty-eight ounces of milk. (Don’t count cheese, yogurt and ice cream; many are not made with D-fortified milk.)

Because Vitamin D helps your body absorb calcium, it is vital in maintaining strong bones and avoiding osteoporosis. A study showed that fully half of a group of women hospitalized for hip fractures from osteoporosis had Vitamin D deficiency.

There’s another disease adults can suffer from insufficient vitamin D: osteomalacia, which leads to muscle weakness as well as weak bones. Persons taking steroids for chronic conditions need to discuss with their doctors the possibility of the steroids interfering with vitamin D metabolism; steroids can also decrease calcium absorption.

The Institute of Medicine points out that mothers’ milk does not contain enough vitamin D and suggests mothers talk with a doctor about it. Usually if the baby gets a little sun-exposure in addition to mom’s milk, it’s enough. Just remember that babies’ tender skin burns very, very easily; so be careful in using that as a backup source for nursing infants.

How about getting too much vitamin D? That can be serious too. You’re not likely to get too much from diet alone, unless you’re downing a lot of cod liver oil. But don’t overdo the supplements. The top safe upper intake level for all of us older than babies is two thousand International Units. For infants, the top is one thousand Internationaal Units.

This is Ruth Page, passing on some useful nutrition reminders from the National Institutes of Health.

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