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Shedding light on vitamin D

Vitamin D is sometimes called “the sunshine vitamin” because sunlight causes your body to produce it. However, you can get some vitamin D from your diet too.

Vitamin D is an essential nutrient produced by your body when your skin is exposed to sunlight. It is also found in foods and available in dietary supplements. Vitamin D helps your body absorb calcium and also keeps calcium and phosphate available to help your bones form and grow. Emerging research suggests vitamin D might control cell growth, immunity, and nerve and muscle function, as well as reduce inflammation.

Sun exposure

There is no general answer to how much sun exposure you need to achieve and maintain an adequate vitamin D level. The amount of sun exposure (minutes per day) you need depends on where you are, the time of year, time of day, the weather, your age, skin type, clothing, use of sunscreen, activity, and environment. The American Academy of Dermatology recommends using sun protection. For more information about the risks and benefits of sun exposure as a source of vitamin D, read this fact sheet from the Office of Dietary Supplements.

How much vitamin D?

The Recommended Dietary Allowance of vitamin D is 600 IU (15 micrograms or mcg) for adults up to 70 years of age. This amount has been determined sufficient to maintain bone health and normal calcium metabolism. However, the debate continues as to whether this amount is sufficient.

Vitamin D from foods

Unlike other nutrients, vitamin D occurs naturally in very few foods, which is why some foods are “fortified” with vitamin D; that is, they have vitamin D added. The most common fortified food is milk, but some cereal products, yogurt, orange juice, margarine, and other foods also are fortified. Foods that naturally contain vitamin D include cod liver oil, mackerel, swordfish, salmon, tuna, sardines, beef liver, and egg yolks. On the new Nutrition Facts panel manufacturers must declare the actual amount of vitamin D in mcg, in addition to the percent Daily Value (DV) of vitamin D. With this labeling, consumers will be able to track some of their vitamin D intake to ensure they’re consuming enough.

Vitamin D supplements

People who are deficient of this nutrient sometimes need vitamin D supplements, as determined by their healthcare provider. It’s important to consult a healthcare provider before taking a vitamin D supplement, because excess vitamin D can be stored in your body, putting you at risk for toxicity. Over time, too much vitamin D can lead to irregular heart rhythms, kidney damage, and other serious health problems. At this time there is no consistent recommendation for general supplementation for those without a known deficiency.

The bottom line

Vitamin D is an essential nutrient. Recommended intakes usually can be obtained through food and sunshine. For those with a known deficiency who are being treated by a healthcare provider, vitamin D supplementation is typically an option. For more detailed information about vitamin D, read this fact sheet from the National Institutes of Health’s Office of Dietary Supplements.

Posted 12 July 2017