Low vitamin D levels may be cause of some health complaints so make sure you get your safe quota of sunshine.
By Pamela Stuppy
We hear a lot about concern about getting enough calcium for our bones, but vitamin D often takes a back seat when it comes to recommendations.
Vitamin D plays a crucial role in bone health. Not only can it reduce the risk of osteoporosis (bone brittleness), but can also reduce the chance of osteomalacia (a softening of bone). Vitamin D deficiency can draw calcium out of the bone.
Health-care professionals are starting to realize that some health complaints are related to low vitamin D levels. The aching bones and muscles, characteristic of a vitamin D deficiency, are often diagnosed as "growing pains" in children, fibromyalgia in adults, or trouble moving about by some nursing home patients.
Researchers and health care providers have identified a surprisingly high percentage of children and adolescents in the Boston area with vitamin D deficiencies. Many individuals in nursing homes and hospitals are also deficient.
What does vitamin D do?
One of its major roles is to absorb calcium from the intestinal tract into the bloodstream and move it from the bloodstream into the bones. It also helps regulate the excretion of calcium by the kidneys. When vitamin D levels are below normal, the uptake of calcium is reduced and bones are not maximally benefited.
Where do we get vitamin D?
Ultraviolet radiation from the sun reacts with our skin to create a precursor for active vitamin D. This precursor then goes through two activation stages, one in the liver and the other in the kidney. The final product is the form of vitamin D that can take action. Any interference with this process can reduce the level of vitamin D in the blood.
Sunscreen effectively blocks UV rays so the skin is unable to produce the vitamin. People with darker skin (which protects the skin like sunscreen) have more difficulty producing adequate vitamin D in most parts of the United States. Many African-Americans living in the northern parts of the country have been identified as vitamin D deficient. The farther away you get from the equator, the lower the level of UV exposure.
In New England, we can get vitamin D from the sun May through October (a good reason to head for a warmer climate on vacation in the winter!). A daily dose is about five to 10 minutes of hand and face exposure before applying sunscreen. This limits the concern of skin cancer from extended sun exposure, but allows for the needed production of vitamin D.
Older adults often have reduced levels because their skin produces D at only about 25 percent that of younger adults. They may also have less efficient livers and kidneys, tend to use more sunscreen, wear more clothing, and get outside less often. People with medical conditions that reduce nutrient absorption in the intestine (such as Crohn’s disease or untreated celiac disease), are also at risk for vitamin D deficiency.
Besides sunlight, the other sources of vitamin D are foods - generally those which have been fortified - or supplements. Food sources continue to change because of the current trend to add nutrients to much of our food supply. Milk, fish liver oils, and liver contain D, as well as some yogurt, orange juice, soy milk, cereals, and others.
The deficiencies seen in children and adolescents can be blamed on lower intakes of milk, the use of sunscreen, and/or more time spent indoors on the computer or watching television. Some children stay inside because of living in unsafe neighborhoods.
How much vitamin D do we need?
Recommendations vary depending on who you ask. About 200-400 IU is a general goal for most children, adolescents and adults. At about 50 years of age, intake should be at least 400 IU and over 70 years old, at least 600 IU. For people with osteoporosis or using a medication that depletes bone (like prednisone), intake should be at least 800 IU. If a person is on medication for osteoporosis, adequate intakes of both calcium and vitamin D are important so that the medication can be maximally effective.
However, some researchers believe that the recommendations for all age groups are much too low. They advocate taking a supplement above the level found in most multiple vitamins. Since it is a stored vitamin, people with diagnosed deficiencies are being treated under a physician’s care, to levels as high as 50,000 IU weekly, but blood levels need to be monitored.
Survey research shows that at least 90 percent of the U.S. population does not get adequate vitamin D. Obviously, some populations are at greater risk. Making sure you are getting adequate vitamin D is a good investment for your bones.
Pamela Stuppy, MS, RD, LD, is a registered, licensed dietitian with nutrition counseling offices in York, Maine, and at Whole Life Health Care in Newington. She is also the nutritionist for Phillips Exeter Academy.
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