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What's so special about vitamin D?

Created date

August 9th, 2010

Vitamin D saves lives, says Rasa Kazlauskaite, M.D., endocrinologist and director of the Rush University Prevention Center in Chicago. A large-scale study published in 2008 showed that people who took a placebo were more likely to die earlier than people who took vitamin D supplements. There are many places throughout the body where vitamin D may have a life-sustaining effect. Vitamin D can make your muscles stronger, which may prevent falls, says Austin Welsh, M.D. , medical director at Tallgrass Creek. According to the Centers for Disease Control and Prevention, falls are the leading cause of injury deaths among older adults. Vitamin D is also essential for promoting calcium absorption in your bones and, thus, may protect you from bone fractures. Research suggests that vitamin D may also have other health benefits. Vitamin D helps boost your immune system, Welsh says. My patients who have adequate vitamin D levels report having fewer colds and flu. Vitamin D has also been associated with healthy hearts, and it may have a protective effect against certain cancers, Kazlauskaite adds. In addition, emerging research is revealing that vitamin D might play a role in the prevention and treatment of diabetes, hypertension, multiple sclerosis, and other medical conditions.

Many seniors are D-deficient

According to the National Institutes of Health, vitamin D deficiency is quite common among seniors. There are a number of reasons why older people can t maintain normal vitamin D levels, Welsh says. As you age, your skin cannot synthesize vitamin D efficiently and your kidneys are less able to process it into its active form. [caption id="attachment_13488" align="alignright" width="280" caption="Salmon, milk, orange juice and fortified cereal are all great sources of Vitamin D. (File photos)"][/caption] People are designed to make vitamin D when the skin is exposed to sunlight, but factors such as geographic latitude, ozone levels, time of year, time of day, and whether or not you re wearing sunscreen all affect how much vitamin D you actually get from sun exposure. Most seniors don t get enough sun exposure to have sufficient vitamin D levels. And those who do get a lot of sunlight may either be wearing sunscreen or have a tan, Kazlauskaite says. A tan prevents the sun s rays from reaching the cells that make vitamin D. Your vitamin D levels may also be lower if you have certain medical conditions like liver disease or Crohn s disease. Extra weight can also contribute. Fat tends to trap vitamin D and then it s not available to the rest of your body, Kazlauskaite says. Despite the importance of the sun to vitamin D production, the American Academy of Dermatology advises that you take protective measures (including wearing sunscreen and protective clothing) when you are outdoors due to the risk of skin cancer.

Fortified foods: not what they seem

Vitamin D is measured in international units (IUs), a standard measurement for certain vitamins. The U.S. Food and Nutrition Board recommended intake is 400 IUs/day for adults 51-70 and 600 IUs for adults age 71 and over. Some experts, however, think even 1,000 IUs/day may be too little for some older adults. Very few foods naturally contain vitamin D. Fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources. See the sidebar for food sources of vitamin D. Fortified foods provide most of the vitamin D in the American diet, but people typically get less than 100 IUs per day of vitamin D from food, Kazlauskaite says. Studies show that amounts in fortified milk can vary from gallon to gallon. That s because vitamin D, which is an oil, is added to large vats of milk and may not dissolve evenly. And many foods that you would expect to be fortified are not like cheese, ice cream, and many yogurts marketed to adults.

Multivitamins and supplements

Most multiple vitamins have a relatively low dose of vitamin D about 400 IUs, Kazlauskaite says. Many of my patients have insufficient levels of vitamin D even though they take multivitamins, Welsh says. Vitamin D is absorbed better if it is taken with food and not with a bunch of other pills. Even if you are already taking osteoporosis medications or calcium/vitamin D supplements, you still may be vitamin D deficient. Symptoms that can indicate deficiency like bone pain and muscle weakness can be subtle and go undetected. Your primary care doctor or endocrinologist can do a simple blood test to check your vitamin D levels and recommend supplements if needed, Kazlauskaite says.

Health risks

On rare occasions, vitamin D can be toxic if taken in very high levels, Welsh says. Seniors should be under a doctor s supervision when taking vitamin D to make sure levels aren t too low or too high. In addition, vitamin D supplements have the potential to interact with several types of medications like steroids, some cholesterol-lowering drugs, and some seizure medications.