Vitamin D, the “sunshine vitamin,” is best known for helping to build strong bones. But scientists are learning that it also promotes health in a wide variety of other ways. One may be reducing multiple sclerosis (MS) flare-ups. Your skin can make vitamin D after exposure to sunlight. The vitamin is also added to milk and certain brands of cereal, orange juice, yogurt, and other foods. Plus, it’s found naturally in fatty fish such as salmon, tuna, and mackerel. D Is for Decreased Risk Fifty years ago, scientists noticed something intriguing: People who lived closer to the equator, where there is a lot of sunlight, had a lower risk of developing MS than those who lived farther away. But why? Scientists suspected that the answer might involve vitamin D. If you have MS, your immune cells become active and start attacking myelin, the substance that forms a protective sheath around nerve fibers. Since vitamin D helps regulate the immune system, experts speculate that vitamin deficiency may play a role when the immune process goes awry. Observational studies suggest that scientists are on the right track. In a large study of nurses, for example, a higher vitamin D intake from supplements was associated with a lower risk of developing MS. But further study is needed for definitive proof of a connection. A different study suggested that otherwise healthy folks with abnormally low vitamin D levels in their system were twice as likely to develop MS. Less Vitamin D, More MS Flare-Ups If you already have MS, a low vitamin D level has been associated with an increase in the frequency and severity of disease flare-ups. On the flip side, research suggests that maintaining a healthy level of vitamin D might lessen MS symptoms. Consider a study published in Annals of Neurology in 2012. More than 400 people with MS received blood tests and MRI brain scans every year for five years. A higher level of vitamin D in the blood was associated with fewer characteristic changes of MS in the brain. In addition, vitamin D helps protect against osteoporosis, a condition in which bones become weaker and more likely to break. Some people with MS have a heightened risk for osteoporosis because of decreased physical activity or long-term treatment with steroids, such as prednisone (Deltasone, Orasone), prednisolone (Prelone), and dexamethasone (Decadron). Getting adequate amounts of vitamin D is even more important for them. Getting Your D Most people meet at least some of their vitamin D needs by spending time in the sun. But there’s a catch: The UV radiation in sunlight increases the risk for skin cancer. Doctors are still debating how to balance the benefits of sun exposure against the risks. A safer way to raise your vitamin D level may be to boost your intake of fatty fish and foods fortified with vitamin D, including lowfat or nonfat milk. Small amounts of vitamin D are also found in beef liver, egg yolks, and cheese. Your doctor may recommend taking a supplement, as well. Ask your doctor whether you need a blood test to check your vitamin D level.