There are lots of opinions out there about Vitamin D. Should you take it or not? Do you need it or not? Does it just help your bones, or are there other effects? If you are out in the sun all day, is that enough? With all of these questions, and more, there seem to even more answers, on many sides of the discussion.
Although we like to think that sun exposure is the primary way we get Vitamin D, in fact, even in average dressed individuals, the importance of sunlight is not as high as one would think. The body makes vitamin D when skin is directly exposed to the sun by the conversion of cholesterol (you knew it was good for something!), and most people meet at least some of their vitamin D needs this way. Skin exposed to sunshine indoors through a window will not produce vitamin D. Cloudy days, shade, and having dark-colored skin also cut down on the amount of vitamin D the skin makes. Not only that, as we age our ability to produce Vitamin D from sunlight exposure goes down.
Having said that, it is still prudent to limit exposure of skin to sunlight in order to lower the risk for skin cancer. When out in the sun for more than a few minutes, wear protective clothing and apply sunscreen with an SPF (sun protection factor) of 8 or more. Clearly, in the case of those dressed for tznuit, modesty, the potential for Vitamin D deficiency is increased. Such people, both men and women, should likely include good sources of vitamin D in their diets or take a supplement under the direction of their physician. The often stated recommended intakes of vitamin D are set on the assumption of and average amount of sun exposure.
What foods provide vitamin D?
Very few foods naturally have vitamin D. Fortified foods provide most of the vitamin D in American diets.
· Fatty fish such as salmon, tuna, and mackerel are among the best sources.
· Beef liver, cheese, and egg yolks provide small amounts.
· Mushrooms provide some vitamin D. In some mushrooms that are newly available in stores, the vitamin D content is being boosted by exposing these mushrooms to ultraviolet light.
· Almost all of the U.S. milk supply is fortified with 400 IU of vitamin D per quart. But foods made from milk, like cheese and ice cream, are usually not fortified.
· Vitamin D is added to many breakfast cereals and to some brands of orange juice, yogurt, margarine, and soy beverages; check the labels.
A few words about milk. Children who worked in factories in the early part of the 20th century would develop a disease called rickets, with softening and bending of the bones, particularly in the legs. In the 1930s, it was recognized that Vitamin D would prevent rickets, and it was added to milk, a likely vehicle to get the vitamin into children. The amount added to milk then, and still today, is 400 units per quart. We now know that this is less than the daily requirement of Vitamin D, which for most adults is about twice that amount. That means that in order to get adequate Vitamin D from milk, one would have to drink a half-gallon of milk every day. And that's why supplements make more sense.
What kinds of vitamin D dietary supplements are available?
Vitamin D is found in supplements (and fortified foods) in two different forms: D2 (ergocalciferol) and D3 (cholecalciferol). Both increase vitamin D in the blood. Check with your physician to see if you are deficient in Vitamin D, and what level of supplementation you may need. If food is not sufficient for your needs, either over the counter or prescription levels of Vitamin D may be prescribed.
Some studies suggest that taking mega-doses of Vitamin D on an infrequent basis, such as monthly or even less often, increases the risk of side effects from the supplement. Taking a nominal amount daily would be more physiologic, and may have better results.
Do not just take extra Vitamin D just because you think you need it. Vitamin D is one of the fat soluble vitamins, which will accumulate in the body to toxic levels if taken to excess. So the first thing to do is ask your physician to test your Vitamin D level. Of course, one can never predict if your health insurance will cover such screening, it may not. And if the level is normal, you likely don't need to screen it again for many years. But if it is not normal, allow your physician to direct the dose and regimen of Vitamin D to replace your deficiency and keep you in the healthy level going forward.
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