Are You Getting Enough Vitamin D?
Vitamin D is an essential nutrient that promises great health benefits, yet most adults fall short.
Best Sources of Vitamin D
The sun is an excellent source of vitamin D, but it is hard to quantify how much vitamin D you get from time in the sun and the risk of skin cancer may outweigh the benefits. Food first, says Baylor College of Medicine dietitian Keli Hawthorne. "Supplements can fill in the gaps but it is always better to try to meet your nutritional needs with foods that contain fiber, phytonutrients, and so much more," Hawthorne says.
Unless you enjoy a diet that includes fatty fish or fish liver oils, it may be hard to get enough vitamin D naturally without eating fortified foods or taking a supplement. "The major dietary source of vitamin D comes from fortified diary, along with some yogurts and cereals," Hawthorne says. Mushrooms, eggs, cheese, and beef liver contain small amounts.
Reading Food Labels
Daily Values (DV) are on nutrition fact panels to help consumers compare nutrients in products and to choose a healthy diet. The DV for vitamin D is currently set at 400 IU by the FDA, which is less than the recommended 600 IU.
Hawthorne's advice: "Do the math: When one serving says it meets 100% DV, you still need an additional 200 IU to satisfy your requirement."
Amount of vitamin D in sample food sources:
- 1 Tbsp cod liver oil: 1,360 IU
- 3 oz. salmon: 800 IU
- 8 oz. fortified milk:100 IU
- 8 oz. fortified orange juice: 100 IU
- 3 oz. irradiated mushrooms: 400 IU
How Much Is Too Much?
Vitamin D is a fat-soluble vitamin. Fat-soluble vitamins can build up in the body and are not as easily excreted as water-soluble vitamins. The IOM committee set a level of 4,000 IU as the ‘tolerable upper limit' or the maximum amount that is safe to consume daily.
Vitamin D researcher and Creighton University professor Robert Heaney, MD, agrees with the new level but would like to see it even higher.
"I am delighted the upper limit for vitamin D has been doubled to 4,000 IUs per day, although this is a conservative level, considering the body of scientific evidence indicating it should be 10,000 IU," Heaney tells WebMD. "However, few people need more than 4,000 IUs, which will meet the needs of most healthy people, give physicians confidence to recommend supplementation, and allow research at higher vitamin D levels."
In July 2011, the Endocrine Society Practice Guidelines published recommendations for the evaluation, treatment, and prevention of vitamin D recommending an upper limit of 10,000 IU/day.
"There is a potential to cause harm if you overdose on supplements above 4,000 IU/day but there is no fear of overdosing from the sun because your skin acts like a regulatory system, only allowing production of the amount of vitamin D you need," Brannon says.