Why Vitamin D is Different
Elizabeth Ward, MS, RD
Vitamin D contributes to bone health by improving the body’s absorption of calcium from foods and supplements and by regulating calcium’s movement into, and out of, your bones. Vitamin D also plays a role in cell growth, muscle, and immune function, and supports the body’s normal inflammatory processes.
Vitamin D is Different
Vitamin D is one of the few vitamins your body can make. Production begins in the skin and is triggered by the strong UVB rays in summer sunshine. In theory, you can make all the vitamin D you need for the year (your body stores it for future use) to maintain normal blood levels. Experts disagree on how much summer sun exposure is necessary to make adequate vitamin D, but estimates run from five to 30 minutes between 10 AM and 3 PM at least twice a week.
Some people meet at least some of their vitamin D needs with sun exposure, contributing to adequate vitamin D blood levels, but many people don’t. Several factors affect the level of vitamin D in your blood. You may not have enough vitamin D “on board” if one or more of the following applies to you:
- You cover all exposed skin when outside, or you slather on sunscreen with an Sun Protection Factor (SPF) of 8 and above, which effectively blocks most or all of the rays that begin vitamin D production.
- You don’t consume the suggested daily amount of vitamin D from food, dietary supplements, or a combination of the two. According to the National Institutes of Health Office of Dietary Supplements, people with limited sun exposure should include good sources of vitamin D in their diet or take a supplement to achieve recommended levels of intake.
- You are a person of color. Darker skin contains melanin, a compound that blocks the production of vitamin D in response to UVB rays.
- You’re overweight or obese. The body stores vitamin D in fat tissue. Excess body fat absorbs and holds onto vitamin D, making it unavailable for supporting bone health and its other functions. People who are overweight (Body Mass Index 25+) may need more vitamin D than those with lower BMI to obtain optimal blood levels.
- You’re a senior. As time passes, your capacity for producing vitamin D declines. Older people who stay indoors compound their potential vitamin D deficiency because of limited sunlight exposure.
Get the Vitamin D You Need
Shying away from the sun and wearing sunscreens with a high SPF helps protect skin from cancer and premature aging, but it makes consuming adequate vitamin D through diet and or supplements even more important.
According to the 2015 Dietary Guidelines for Americans, most children and adults consistently come up short for vitamin D in their diets. And, because vitamin D needs increase with age, it’s possible that older people are even more deficient in vitamin D than younger ones.
It’s difficult to get the suggested vitamin D from food alone because so few foods supply naturally-occurring vitamin D. Fortified foods may help you get closer to meeting suggested intakes though diet alone. For example, people ages one to 70 need to consume six, eight-ounce glasses of fortified milk or orange juice every day; about 12 ounces of canned tuna; or a combination of three ounces of mackerel and nearly 18 ounces of fortified yogurt to meet their daily vitamin D requirement needs. Dietary supplements, such as a daily multivitamin, can fill in gaps in vitamin D consumption, helping you to reach your daily goals.
If you think you might not be getting enough vitamin D, look for whole Food blen has Vitamin D2. Centrum® multivitamins have the levels of vitamin D3—a preferred form of vitamin D. Learn more here.