Vitamin D is a fat-soluble vitamin that is used by the body for many different functions. Vitamin D is most well-known for preventing rickets (children) and osteomalacia (adults) by helping the body absorb calcium for strong bones and teeth, but it has many other uses in the body as well. Reasearch strongly supports the benefits of vitamin D to prevent osteoporosis, aid in tooth retention, and decrease risk for multiple sclerosis, bronchitis, respiratory tract infections, heart failure, and dental cavities. There has been conflicting research on the efficacy of vitamin D to prevent cancer, cardiovascular disease, and tuberculosis. More research is needed, but vitamin D has also shown promise in treating or preventing Alzheimer’s disease, asthma, chronic kidney disease, dementia, chronic obstructive pulmonary disease, cognitive function, diabetes, fibromyalgia, low birth weight, periodontal disease, premenstrual syndrome, rheumatoid arthritis, seasonal affective disorder, and weight loss. While more studies are necessary to establish a relationship between vitamin D deficiency and specific diseases, we can confidently say vitamin D helps build strong bones, regulate the immune system and neuromuscular system, and plays a role in the cell life cycle.
There are two important forms of vitamin D, ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Ergocalciferol comes from plant sterols and yeast and is less potent then cholecalciferol but this s a good choice if you are vegan. Cholecalciferol is formed when a cholesterol precursor (see, cholesterol isn’t all bad!) in the skin is exposed to sunlight and then converted to the active form of vitamin D by the liver and kidneys. Dietary sources of vitamin D include fish such as salmon or mackerel, eggs, fortified milk, mushrooms, and vitamin D fortified foods such as yogurt, cereal, and orange juice. By far the easiest way to get your vitamin D is sun exposure, but it can be difficult here in the Northwest. Thirty minutes of sun exposure, without sunscreen, at least twice a week should give you plenty of vitamin D but during the winter months we can’t get enough sunlight with our grey clouds, so either increase your consumption of vitamin D-rich foods or supplement.
Vitamin D deficiency symptoms are often subtle and include: getting sick often, excessive fatigue, bone (ex. Legs, ribs, and joints) and back pain, depression, slow wound healing, muscle pain, hair loss, and reduced bone density. People who are elderly, have dark skin, are overweight or obese, don’t eat much fish or dairy, don’t go outside much, have a disease that decreases vitamin D absorption by the digestive tract, and live far from the equator are more susceptible to vitamin D deficiency. Talk with your doctor about doing a 25-hydroxyvitamin D blood test if you have noticed any of these symptoms or are in an at-risk group. Also make sure to talk with your doctor about vitamin D supplementation before starting any new supplements.