The great protector: Vitamin D
By Marilyn Wiley
Vitamin D is a fat-soluble vitamin found in food and is the only vitamin that is manufactured in the skin by the action of ultraviolet rays from the sun. If you live in northern states like Massachusetts, your skin cannot make Vitamin D from about November through March, because of the low angle of the sun’s rays, fewer hours of sunlight, and the tendency to stay indoors through the cold short days of winter. Sunscreen with a sun protection factor (SFP) of eight or greater will block the ultraviolet rays that produce Vitamin D, but it is still important to routinely use sunscreen to help prevent skin cancer. An exposure to sunlight 10 to 15 minutes twice per week is adequate to produce Vitamin D; then sunscreen should be applied to protect the skin.
Vitamin D’s main function is to maintain normal blood levels of calcium and phosphorus. By helping calcium absorption, Vitamin D helps form and maintain strong bones. Vitamin D also works with other vitamins and minerals to promote bone mineralization. A deficiency of Vitamin D results in thin, brittle bones and increases fractures especially as people age. It is estimated that 30 to 40% of seniors with hip fractures have low levels of Vitamin D in their bodies. Recent research has found that low levels of Vitamin D are associated with an increased risk of Type 1 Diabetes, muscle and bone pain, and cancers of the breast, colon, prostate, ovaries, and esophagus. Also, Vitamin D may help lower blood pressure and protect against multiple sclerosis.
Fortified foods are common sources of Vitamin D and include milk fortified with 100 I.U. of Vitamin D per cup. Other dairy products such as cheese and ice cream are generally not fortified with Vitamin D. Breakfast cereals are sometimes fortified with Vitamin D, but the amount is usually only 40 I.U. for each serving. Foods high in Vitamin D include cod liver oil, which some you may remember from childhood. Also fatty fish such as salmon, mackerel, tuna, and sardines canned in oil are good food sources of Vitamin D. Soy milk is often fortified with Vitamin D and can be used by those who want a lactose free substitute.
Vitamin D researchers are recommending higher levels of Vitamin D than those recommended by the government. About 1000 I.U. is often recommended to maintain optimum blood levels of Vitamin D, and even with foods high in Vitamin D and sunlight during the summer months, it is usually necessary to add a Vitamin D supplement to your diet.
Since Vitamin D is a fat-soluble vitamin, it is stored in the body; therefore, the upper limit recommendation is 2000 I.U. per day, because large amounts of Vitamin D can be toxic.
Remember, Vitamin D is needed by all ages to protect against poor bone mineralization and help prevent some types of cancer.
Marilyn Wiley is a Registered Licensed Dietician and Consulting Nutritionist for Elder Services of Berkshire County.
