Nearly one-third of persons over the age of one in the U.S. are at risk of inadequate vitamin D intake or vitamin D deficiency, per the Centers for Disease Control and Prevention. This is concerning, given insufficient vitamin D can lead to brittle, soft, thin bones, resulting in rickets in children and osteomalacia in adults. Further, low blood levels of the sunshine vitamin have been linked to higher risks of fractures and several medical conditions, including cancer, cardiovascular disease, high blood pressure, asthma, diabetes, and some autoimmune disorders. Supplemental use is common, with 37 percent of the population supplementing with vitamin D. So, should you join the crowd and supplement your diet with vitamin D? EN answers your questions.
VITAMIN D2 VS.D3
Supplemental vitamin D is found in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). There is debate over whether D3 is superior. The National Institutes of Health regards both forms as equivalent when it comes to raising blood levels and treating deficiencies. In high doses D3 is more potent, which could increase the likelihood of toxicity.
Vitamin D in the Diet
In the food supply, vitamin D is limited. It’s found naturally in fatty fish (salmon, tuna), fish liver oils (think cod liver oil), egg yolks, beef liver, and some mushrooms exposed to light. Dairy milk is fortified with vitamin D, as are many plant-based milks. Some foods, such as margarines, cereals, and orange juice are fortified. Fortunately, your body can make vitamin D when the skin is exposed to the sun. The sun is not always a reliable source, given that during winter months it is too low in the sky in northern parts of the country to trigger vitamin D production. Moreover, sunscreen blocks vitamin D synthesis in the skin, as does cloudy weather and heavy pollution. Ultimately it’s tough to know if you’re getting enough and whether you ought to turn to supplements.
Are You Low?
Before reaching for a supplement, it’s a good idea to have your blood level of vitamin D tested. If your levels are low or deficient, your physician can recommend an appropriate amount from a supplement. Vitamin D toxicity can occur from excessive supplementation, thus increasing the risk of kidney stones, and kidney, heart and blood vessel damage. All the more reason to be under the care of your physician when deciding whether to supplement.
—Andrea N. Giancoli, MPH, RD