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Sunny D

The role of vitamin D in the body is examined

February 1, 2011
By CHRISTOPHER DIEM Journal Staff Writer

MARQUETTE - In winter the sun is an infrequent guest to the Upper Peninsula, which may lead to vitamin D deficiency.

Furthermore, Patricia Smith, corporate/community dietitian with the Nutrition and Wellness/Diabetes Education Department at Marquette General Hospital, said Marquette is so far north of the equator that it only has sufficient sun to help our bodies produce vitamin D from late spring to early fall. Vitamin D can be produced in the skin as a result of ultraviolet rays from the sun.

Vitamin D maintains normal blood levels of calcium and phosphorous, electrolytes that are critical for bone growth in children and bone maintenance in adults. If someone is not getting enough calcium in their diet it can lead to osteomalacia or osteoporosis.

Article Photos

Alyssa Carlson and Aaron Baldini walk along Presque Isle Park trail in Marquette. (Journal file photo)

"Osteoporosis usually happens in older people but if the vitamin D is not sufficient and your body is not getting enough calcium the breakdown of bone can actually start even in your 40s," Smith said.

She said the body uses vitamin D at a fairly rapid rate so if people are not getting it from the sun, it's important they get it either from the food they eat or a supplemental source.

A good source of vitamin D is deep-water, cold-water, fatty fish and fish liver oils, such as cod liver oil. Eggs, beef liver, cheese and mushrooms also contain vitamin D, but not very much. Fortified foods, like fortified milk, cereals, grains, bread, pastries and some margarines also contain vitamin D.

There are also vitamin D supplements available in health food stores and the pharmacy sections of other stores.

Smith said vitamin D recommendations have been, until very recently, very low. She said the Institute of Medicine established new dietary requirements on Nov. 30 which increased the recommended amount of vitamin D.

The minimum daily amount for babies is 400 international units a day, for those age 1 to 70 the amount is 600 units a day, and people 71 and older should have 800 units a day.

However too much vitamin D can lead to health problems. The Institute of Medicine's report concluded that kidney stones have been associated with taking too much calcium from dietary supplements. Very high levels of vitamin D, above 10,000 international units per day - are known to cause kidney and tissue damage, according to the report.

The average adult should expose their face, arms and back to the sun at least twice a week for 15 minutes without sunscreen to get the vitamin D they need.

"That's very minimal and that's assuming the sun is at the correct angle. Here in Marquette the only time that would work at all is in the summer time. The rest of the year you can be in the sun all day and you're not going to produce any vitamin D," Smith said.

Tanning beds can provide vitamin D if a certain kind of ultraviolet light is used.

"Different tanning beds have different artificial light. It's something you can investigate," she said. "You would want to ask the people who were giving you the service."

People are advised to speak to their doctor if they think they be vitamin D deficient. Smith said people can ask their doctor about the 25-hydroxy vitamin D test as a way to measure how much vitamin D is in their body.

Christopher Diem can be reached at 906-228-2500, ext. 242. His e-mail address is



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