When you're in the midst of a migraine, the bright light of the sun can be excruciating. But hiding from its rays on a regular basis may contribute to these headaches' development. Low levels of vitamin D—which your body produces when exposed to sunlight—have been implicated in migraines and other types of headaches. Effects Beyond the Bones At one time, low vitamin D levels were thought to cause only the bone-weakening disease rickets. Now, increasing evidence suggests low levels affect almost every system of the body, including the brain. Though research to prove that low vitamin D causes migraine is ongoing, several recent studies shed some light on the link. A report presented at a meeting of the American Headache Society found that 40% of people with migraines had low vitamin D levels. Those with deficiencies also developed migraines earlier in life. Another study, in the Journal of Headache Pain, shows migraines are more common at higher latitudes. This fact, and the pattern of migraine pain by season, suggests that the headaches strike where sun exposure is decreased and vitamin D levels reduced. Population studies report that about 42% of US adults have abnormally low levels of Vitamin D. Hitting It on the Head Scientists recently discovered that several brain areas—including the hypothalamus, which has been implicated in some types of headache disorders—have receptors for vitamin D, as well as enzymes that help convert it into a form your body can use. This helps explain why running low on this vital nutrient could contribute to head pain. If the association is proven to be cause-and-effect, vitamin D supplements could become another treatment option for people with migraine. In fact, one researcher successfully treated two postmenopausal women who had chronic migraines with vitamin D and calcium supplements. Clearly, a broader clinical trial can validate this theory. An Important Health Check If you suffer from chronic migraines, talk with your doctor about your vitamin D levels. He or she may recommend a blood test to determine your 25-hydroxyvitamin D levels. If you have less than 20 ng/ml, you are deficient. Levels of 20 to 30 ng/ml are slightly low, and 30 to 74 ng/ml is the normal range. Because we're urged to protect our skin from the sun by staying indoors and wearing sunscreen or protective clothing, it can be hard for our bodies to produce enough vitamin D. The government currently recommends 600 IU of vitamin D daily for teens and adults up to age 70. Good food sources include fortified milk, mushrooms, and fatty fish such as salmon and tuna. If your levels are low, your doctor may recommend a vitamin D supplement.