Vitamin D deficiency: An emerging public health problem
In a strict sense, Vitamin D is not really a “vitamin” because our body can produce this chemical even in the absence of dietary ingestion.
The human skin, when exposed to sunlight, can chemically produce Vitamin D from cholesterol-like precursor molecules. Most of us work indoors, however, and even our children are liberally protected from cancer-causing solar radiation by sunscreens, hats and long sleeves. Individuals with darker skin pigmentation may also be more prone to Vitamin D deficiency.
Low bone density results when calcium levels decline and Vitamin D allows our bodies to effectively absorb and utilize calcium in our diet. Maintaining adequate Vitamin D intake is essential for maintaining bone health and avoiding osteoporosis. Osteoporosis, in fact, afflicts more than half of Americans over the age of 50, with rates approaching 80 percent in women and 20 percent in men.
A recent study also demonstrated that calcium combined with Vitamin D may decrease unsteadiness and fall risk in women after age 70. At the other end of the life spectrum, Vitamin D deficiency in kids may lead to pain in the legs that we used to call “growing pains.” It seems that maintaining healthy intake of Vitamin D and calcium is essential throughout the life span.
Beyond musculoskeletal health, Vitamin D is emerging as a protective factor for heart disease. For example, the Third National Health and Nutrition Examination Survey, a federally funded research trial, found that nearly a third of persons with Vitamin D deficiency also had coronary artery disease, compared to a level closer to one-fifth among those with adequate Vitamin D stores.
Preliminary evidence suggests that Vitamin D may protect against some cancers, including those of breast, colon, ovary, uterus and kidneys, though more studies are needed to verify these results. Also intriguing is the recent observation that low Vitamin D levels predict cognitive impairment and depression in the elderly. Among incarcerated persons, Vitamin D deficiency may be prevalent even at a young age, as inmates spend hours in dark cells. Both economically and physiologically, preventing Vitamin D deficiency makes sense. Treating end-stage diseases, such as osteoporosis, is like chasing down a horse that already escaped from the barn.
Vitamin D is found in oily fish such as tuna, herring and salmon. Dairy products are also supplemented with Vitamin D.
On a practical basis, however, it is a challenge to obtain adequate dietary Vitamin D intakes. We also produce less natural Vitamin D in our skin as we age, with a 30 percent decline in natural production by age 70. Moreover, the elderly spend more time indoors away from Vitamin D-inducing sunlight. Some home-bound elderly adopt what has been called a “tea and toast” level bereft in Vitamin D and calcium. We also take more medications as we age. Some of these drugs may lower Vitamin D levels in our bloodstreams. Prednisone, for example, is often used to treat rheumatoid arthritis or asthma, though it may potentially lead to low Vitamin D levels.
Vitamin D levels can be measured in laboratories, and a level between 30 and 40 nanograms per mL is generally necessary to optimize health.
If a patient is deficient, supplementation may require initial intensive treatment with a type of Vitamin D called Ergocalceferol, at doses of up to 50,000 units a week for up to six weeks. Eventually, once the deficiency is corrected, a maintenance dose of a related compound called Cholecalciferol is instituted, at around 2,000 units per day. The recommended dose of Vitamin D for healthy persons without deficiency states may be considerably lower, however. Check with your doctor for details.
Together we can fight Vitamin D deficiency . . . throughout the lifespan.
Scott T. Anderson, M.D., Ph.D. is Clinical Professor at UC Davis Medical School (stamdphd@comcast.net). This article is for informational purposes, and does not constitute medical advice.
Short URL: http://www.dailyrepublic.com/?p=129677
Posted by Scott Anderson
on Jan 28 2012.
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