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However, a mountain of new evidence suggests that the vitamin may have a more versatile role than previously thought, particularly when it comes to maintaining a healthy immune system and boosting mood.
Low levels have been associated with more severe asthma, colds, seasonal affective disorder, depression, and even chronic pain or fibromyalgia.
So does that mean that taking more vitamin D (or spending a bit more time in the sun) can combat fibromyalgia? Not just yet.
Studies have found that pain patients, including those with fibromyalgia, are more likely to be vitamin D deficient than their pain-free peers. However, it’s not clear which came first; people in pain may get less sun (presumably because they may be more likely to stay inside, due to pain), which could lead to a vitamin D deficiency, rather than vice versa—a vitamin D deficiency leading to pain.
And it’s also not clear if making sure you have adequate levels of the vitamin will help relieve pain or other fibromyalgia symptoms, such as lack of energy or difficulty sleeping.
What’s known about vitamin D
Our bodies make vitamin D naturally when exposed to sunlight. It only takes 10 to 15 minutes a day outside (without sunscreen) to make an adequate amount, but according to studies, about half of adults and 70% of children don’t get enough. In a 2003 study, 93% of pain patients had low levels of vitamin D. The current dietary reference intake for people up to age 50 is 200 international units (IU) per day of vitamin D. Adults ages 51 to 70 need 400 IU/day, and those older than 70 need 600 IU/day, with an upper limit of 2,000 IU/day deemed safe.
But some experts suggest raising that upper limit. Toxicity levels, they say, are closer to 10,000 IU/day, and 2,000 may be closer to the baseline of what healthy bodies need. Current recommendations were established by the Institute of Medicine in 1997 to promote optimal bone health and are under review to possibly be revised in the summer of 2010.
Screening for vitamin D deficiency is as easy as a blood test, and deficiency can be righted with a few minutes of sunscreen-free time in the sun, supplemental pills, or by incorporating foods like eggs, mushrooms, and salmon—all natural carriers of vitamin D—into a healthy diet.
Getting vitamin D from natural sources can stop you from getting too much of the vitamin, since the body makes only what it needs.
Although it’s hard to overdose on vitamin D, it is possible if you take megadoses of the vitamin, which can cause hypercalcemia, an above-average concentration of calcium in the blood that can lead to kidney failure and nervous system problems, and hyperphosphatemia, an increase in levels of phosphates in the blood, which can affect bone density and increase the risk of osteoporosis.
Many who lack vitamin D—especially during the dark and dreary winter months when sunlight isn’t abundant—do turn to supplements. In 2008, Americans spent $235 million on vitamin D supplements, up from $40 million in 2001.
