You might have heard that vitamin D helps to lower the risk for multiple sclerosis (MS). Or that it helps lessen symptoms in people who already have the disease. Evidence suggests that getting enough of this vitamin might protect against MS by holding back your immune system from attacking your own nerve cells.
But the link between vitamin D and MS isn't proven yet.
The MS-Vitamin D Link
Those protective actions are important in autoimmune diseases like MS where your body turns against itself. In MS, cells of your immune system attack the coating around nerve fibers, called myelin, and leads to such hallmark symptoms as numbness, weakness, and blurry vision.
Research finds that vitamin D might help repair myelin and guards your nerves from damage.
Can Vitamin D Prevent or Slow MS?
Researchers aren’t sure if vitamin D can keep you from getting MS in the first place. Your body makes most of the vitamin D it needs from sunlight on your skin. People in northern climates like Scotland and Scandinavia are more likely to have MS compared with those who live in much sunnier climates. Studies show that people who get more sunlight and more vitamin D in their diets have a lower risk for MS overall.
There's some evidence that vitamin D might slow MS and make the disease less severe. Studies have found a link between higher vitamin D levels in the blood and less active disease, fewer lesions in their brain and spinal cord, and fewer relapses of symptoms.
In other studies, people with MS who had higher vitamin D levels had less severe disease and disability.
Do I Need More Vitamin D?
It's common for people with MS to be low on this vitamin. It may be hard for you to get outside to get sun often enough. Low vitamin D can also be a side effect of corticosteroids and other MS medications.
Your doctor can run a blood test to check your vitamin D level. You might be able to make up the difference by eating more fatty fish, eggs, and other foods that are high in vitamin D. Or, your doctor might suggest you take a supplement.
It's not clear whether taking a daily vitamin D supplement protects people from getting MS, or slows the disease in those who already have it. Studies suggest it might help, but this hasn't been proven. But since supplements are usually safe to take, it may not hurt to try them.
What Dosage Is Best?
Experts can’t say how much vitamin D is needed to prevent or slow MS. Different medical groups disagree on the ideal amount.
Official recommendations for adults is 400 to 600 international units (IUs) of vitamin D daily.
Ask your doctor what’s right for you. Be careful not to overdo it. Vitamin D helps your body absorb calcium, and you might end up with too much of that mineral. High calcium levels can weaken bones, damage the heart, and increase the risk for kidney stones.
If you already have MS, your doctor can check whether your vitamin D levels are too low. If so, it might make sense for you to take a supplement.