Are You Getting Enough Vitamin D?

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Thirty percent of Americans use vitamin and mineral supplements every day, yet most adults have low vitamin D levels — and new research shows this one vitamin, which is also a hormone, protects against far more than weak bones.

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More than strong bones

Thirty percent of Americans use vitamin and mineral supplements every day. Yet most adults have low vitamin D levels, with an estimated 10 million Americans over age 50 diagnosed with osteoporosis. Vitamin D has long been known as the vitamin that cured rickets, but scientists today know that vitamin D does much more than just make our bones strong. New research is showing that vitamin D also helps protect us against cancer, diabetes, arthritis, multiple sclerosis, and even cardiovascular disease.

Where vitamin D comes from

Vitamin D is not abundant in most Americans' diets, so we get most of it from sun exposure and multivitamins. The problem is that not everyone gets enough sun exposure. The season, time of day, color of your skin, age and use of sunscreen all affect your skin's ability to produce vitamin D. Also, most multivitamins contain vitamin D2, which does not deliver the same amount of the vitamin to your body as the more desirable D3 form.

The vitamin that is also a hormone

Vitamin D is the only vitamin that is also a hormone. After vitamin D is made by your skin or eaten, the kidneys and liver convert it into an active hormone. As a hormone, it controls calcium absorption to build strong bones and teeth, and helps to maintain muscle strength. When your vitamin D levels are low, your bones break down to supply calcium to the rest of your body.

Most people living in South Carolina can get enough vitamin D by getting about 10–15 minutes of sun exposure on their arms and face a few times a week — as long as they don't use sunscreen, which blocks some of the UV rays necessary to make the vitamin. Since darker skin pigment reduces the skin's ability to synthesize vitamin D by 95%, darker skinned people need 5–10 times as much sun exposure to synthesize enough vitamin D. As long as sun exposure is for short periods of time, it will not increase the risk of serious skin cancer such as melanoma.

How much do you need?

The current recommended intake of vitamin D is 200 IUs (international units) for those up to age 50; 400 IUs for people 51–70; and 600 IUs for those older than 70. Requirements increase with age because older skin produces less vitamin D. But these recommendations date back to 1997. According to the Institute of Medicine Dietary Reference Intakes, the safe upper limit for vitamin D is 2,000 IUs for children, adults, and pregnant and lactating women. But since vitamin D is a fat-soluble vitamin that is stored in the body, there's some concern it can be harmful in large doses.

Studies published recently show the effectiveness of higher levels of vitamin D and that the current recommendations are not adequate to protect against osteoporosis or reduce the risk of common cancers, diabetes, multiple sclerosis, rheumatoid arthritis, and inflammation associated with cardiovascular diseases. The need for higher vitamin D is especially important for older, dark-skinned, and housebound people.

Finding out — and boosting your D

Chances are you are not getting enough vitamin D for optimal health, so ask your doctor if you have a vitamin D deficiency. Vitamin D deficiency can be diagnosed on the basis of a simple blood test that measures 25-vitamin D. Until then, boost your D with safe sun exposure, supplement your diet with 1,000 IUs of vitamin D3 a day, and be sure to eat a variety of foods rich in vitamin D such as fortified milk, yogurt and cereals, catfish, salmon, tuna and egg yolks. By reducing the frequency of vitamin D deficiency, it is likely that many common, serious health disorders will lessen in frequency and severity.

About the author

Allen Smolenski, M.D.

Emergency Medicine physician and founder of Coastal Medical Clinic in Surfside Beach (2009). After losing nearly 60 pounds himself — and placing third in his class at the 2008 NPC Natural Northern USA Bodybuilding Contest — he completed a fellowship in Anti-Aging and Regenerative Medicine through the A4M, and now helps patients across the Grand Strand optimize their hormones, metabolism, and long-term health.

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