It seems odd to be talking about the sunshine vitamin in the middle of a Florida summer, but on my last visit to the Rheumatologist’s office I had a low blood level of vitamin D. This diagnosis is more common than you might think: it’s been estimated that 70 percent of children and adults in the U.S. are vitamin D deficient.
With the exception of egg yolks, mushrooms and fatty fish, food sources of Vitamin D have been fortified. For most of our lives our Vitamin D came from exposure of skin to sunlight. Your body stores one form of previtamin D, called dehydrocholesterol, in the skin. When your skin absorbs sunlight, it is transformed into previtamin D3 (cholecalciferol). This previtamin form is then activated by the liver and kidney to Vitamin D3. With an increased focus on prevention of skin cancer, protections from sun exposure like clothing and sunblocks decrease production of vitamin D in the skin.
Debate continues as to whether D is just a vitamin, or is it a hormone. Yes, it is required for the absorption of calcium to prevent osteoporosis. But with receptor sites on every cell in the body, Vitamin D certainly behaves like a hormone. Studies have suggested that Vitamin D deficiency is linked with the risk of cancer, rheumatoid arthritis, lupus and MS. It has also been implicated in the pain associated with musculoskeletal conditions such as neuropathy and migraine headaches. And low vitamin D levels may contribute to the depressed mood associated with seasonal affective disorder.
I should have done a better job in researching the potential for nutrient-drug interactions in the medications that I was prescribed. Hydroxychloroquine, or Plaquenil, and corticosteroids, which both can be prescribed for the treatment of rheumatoid arthritis, can affect absorption of vitamin D.
So, how much is enough? Accordng to the National Academy of Science/Institute of Medicine the Daily Recommended Intake for adults is 600 international units daily. In my practice I recommend 1000 units/day for adults over 65 years of age. Your physician may prescribe a large dose (50,000 units) once a week for 8-12 weeks to correct a deficiency.