Here’s How Vitamin D — No, Not Vitamin C — Helps Your Immune System

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You already know that vitamin D is good for you. Now, new research from the University of Edinburgh in Scotland suggests that vitamin D boosts the immune system and could potentially stave off autoimmune diseases. Previous studies have already indicated that people living in higher latitudes where there is less sunlight might be more likely to develop multiple sclerosis, an autoimmune disease characterized by inflammatory attacks on the central nervous system. This new study, published in the journal Frontiers in Immunology, states that vitamin D deficiency could indeed be connected to the onset of autoimmune diseases like MS, Science Daily reported in a news release.

The research focused on how vitamin D affects the body's immune system, specifically its ability to produce T cells, which help fight infections. By studying cells from both mice and people, researchers discovered that "vitamin D caused dendritic cells to produce more of a molecule called CD31 on their surface and that this hindered the activation of T cells," the news release explained. "CD31 prevented the two cell types from making a stable contact — an essential part of the activation process — and the resulting immune reaction was far reduced."

The findings are important in understanding how vitamin D deficiency affects the immune system and potentially makes people more susceptible to autoimmune diseases. Making sure you're getting enough vitamin D can help keep your immune system healthy and strong. According to the national Institutes of Health, the recommended daily dose of vitamin D for healthy adults between the ages of 19 and 50 is 600 IU.

When I moved from Maine (a state with very little daylight during the winter) to California, I had my vitamin D levels tested and I was deficient. If you're worried you're not getting enough vitamin D, particularly because you live in a cold, cloudy climate, there are definitely things you can do to get more of it.

Not sure how to tell whether or not you're getting enough vitamin D? Signs of vitamin D deficiency include depression, anxiety, fatigue, weakness, muscle cramps, joint pain, or getting sick often, according to Jami Cooley, RN, on the website University Health News. Get your vitamin D levels tested by your doctor if you suspect a deficiency.

If you're not able to get enough sunlight to boost your vitamin D levels naturally, all is not lost. Cooley noted that you can opt to sit in front of a light box for 30 minutes each morning. In addition, you can also take a vitamin D supplement. That being said, deciding which vitamin or supplement is best for you can be overwhelming.

When doing research, you might notice that there is more than one kind of vitamin D — D2 and D3. According to a study published in the journal Mayo Clinic Proceedings, there is no definitive evidence about which one is better, though the study did find that vitamin D3 stays in your body longer, which means you need to take it less often.

If your vitamin D levels are normal and you just want to make sure you're maintaining adequate levels of vitamin D, you can also get it from foods. Incorporate things like fatty fish (such as tuna and salmon), fortified foods like dairy, orange juice, soy milk and cereals, cheese, egg yolks, and mushrooms into your diet, Medical News Today advised.

What's more, with vitamin D, there can be too much of a good thing. The Vitamin D Council reported that symptoms of vitamin D overload can include feeling ill, loss of appetite, excessive thirst, urinating more frequently, constipation or diarrhea, abdominal and bone pain, confusion, and fatigue. If you're healthy, stick to the recommended dosage, get outside or in front of a light box for 30 minutes every day, and eat vitamin D rich foods. If you suspect your vitamin D levels are too low or too high, see your doctor before starting a vitamin D regimen.