Vitamin D is an essential nutrient your body requires primarily to build strong bones and for overall good health. A fat-soluble vitamin that functions like a steroid hormone in the body, vitamin D comes in two forms in your diet, D2 and D3, and can also be produced in your skin when exposed to sunlight. It helps your body absorb and maintain adequate levels of calcium and phosphate, which are both important to bone health.
We primarily get vitamin D from sunlight and proper nutrition. Certain foods contain vitamin D, like milk, fortified cereals, and fatty fish such as salmon, tuna and mackerel. Adults should consume 400-800 international units (or 10 to 20 mcg) of vitamin D daily.
Unfortunately, about 42% of the US population is vitamin D deficient with some populations having even higher levels of deficiency, including premenopausal women, those with poor nutrition habits, people over age 65, Caucasians who avoid even minimal sun exposure, and those who take prescription medication long term for heartburn, acid reflux, and constipation. Studies show people with darker skin, such as African Americans and Latinos, are also at risk for lower vitamin D levels because high amounts of melanin in skin reduce the body’s ability to produce vitamin D from sunlight. In addition, certain chronic conditions—such as celiac disease, bariatric surgery, obesity, and chronic kidney or liver disease—can contribute to deficiency.
The latest research links vitamin D deficiency to mood swings, depression, lack of energy, chronic skin conditions, and other chronic diseases.
Summer is naturally a great time to take in more vitamin D through your skin. Yet, this has to be balanced with protection from extended sun exposure, which leads to an increased risk of skin cancer. Susan Blum, MD, MPH, an assistant clinical professor in the department of preventive medicine at the Icahn School of Medicine at Mount Sinai, found that being in direct sunlight daily for up to 20-30 minutes (arms and legs exposed) before applying sunscreen can help improve vitamin D levels. Also, Dr. Blum discouraged discontinuing prescribed vitamin D supplements during summer months.
Pinpointing a healthy vitamin D level for yourself is tricky. If you think you may be vitamin D deficient, discuss any concerns or symptoms with your primary care physician, who can order testing, if appropriate. Normal vitamin D levels are usually between 20-80 NG/ML. If supplementation is recommended, remember to take it with a meal and on a full stomach to help absorption. For more information on Vitamin D, one helpful resource is the book, The Vitamin D Solution, by Michael F. Holick, MD.