July 22, 2008
Vitamin D: The New Superstar?: As Scientists Find Out More About This Nutrient, It May Be Time for You to Step Up Your Intake of It.
By Karen Shideler, The Wichita Eagle, Kan.
Jul. 22--If you keep up with health headlines, you know vitamin D is a bit of a celebrity lately:
Low vitamin D levels are common in otherwise healthy children, putting them at risk of rickets, or soft bones.
High vitamin D levels seem to reduce the risk of breast cancer.
Low vitamin D levels are associated with high death rates from breast and colon cancer and kidney disease.
Low vitamin D levels are associated with a higher risk of death overall and death from cardiovascular causes.
Men with low vitamin D levels are at increased risk of heart attack.
Is it time to boost your intake?
Probably, says Rebecca Kirby, who is both a physician and a registered dietitian at the Oliver W. Garvey Center for Healing Arts. It's part of Wichita's Center for the Improvement of Human Functioning.
The center focuses on nutritional medicine, and measuring vitamin D levels is a routine test. Kirby says most patients have a low-average level at best.
"I think most Kansans have low vitamin D levels," she says.
Why? Because Kansas is sort of in the middle for sunlight exposure, we wear sunscreen and we don't eat enough fish, among other possibilities.
Vitamin D is made when unprotected skin is exposed to sunlight and is found in foods such as fatty fish. It's not really a vitamin, Kirby says; it's a prohormone, or chemical precursor of hormones. Receptors for it are found in all kinds of tissue and cells in our bodies, so it may have even broader effects than we already know about:
It helps our bodies absorb calcium, and low levels can result in muscle pain and weakness. Low levels may predispose people to diabetes, rheumatoid arthritis and other diseases. It may play a role in balance, gum disease and depression.
So boost away, using the tips here.
The 'sunshine vitamin'
Vitamin D is created when skin is exposed to ultraviolet-B rays. About 10 minutes of sun, two or three times a week, is enough to produce all the vitamin D you need.
You don't have to get all 10 minutes at once, but the optimal time is between 11 a.m. and 2 p.m.
If you're depending on the sun for vitamin D, don't use sunscreen during that time.
Light-skinned people make vitamin D more easily than those with dark skin.
People who live south of a line from Los Angeles to Columbia, S.C., get enough sunlight for vitamin D production throughout the year. That line runs through Oklahoma City, so Kansans come up a little short in winter.
If you're getting vitamin D from the sun, keep exposure times to a minimum -- you'll be balancing D production with increased risk of skin cancer. And melanoma rates have increased significantly, especially among young women.
Vitamin D sources
Vitamin D also is available from food sources and supplements. These are good food sources:
Milk and some brands of yogurt, soy milk and rice milk (cheese and ice cream often aren't made with fortified milk)
Fortified orange juice
Fish that swim in cold water, such as salmon, tuna, sardines and mackerel
Cod liver oil
Vitamin D, in supplements and fortified foods, comes in two forms: D2 (ergocalciferol) and D3 (cholecalciferol). Choose D3, Kirby says, because it is more biologically active. Many supplement makers have switched to D3, but read the labels. Check multivitamin labels as well.
The recommended "adequate intake" is what's needed to maintain bone health and normal calcium metabolism in healthy people:
200 international units (IUs) for people 50 or younger.
400 IUs for those 51 to 70.
600 IUs for those older than 70.
Physician-dietitian Rebecca Kirby says studies have shown it takes 700 to 800 IUs to make an impact on decreasing the risk of fractures.
A study under way by the National Institute on Aging theorizes that older women may need 4,400 IUs daily to prevent osteoporosis.
But use caution _ too much vitamin D from supplements can be toxic.
Reach Karen Shideler at 316-268-6674 or [email protected]
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Copyright (c) 2008, The Wichita Eagle, Kan.
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