Vitamin D2 is actually one of two forms of vitamin D. It occurs naturally in plants. Vitamin D2 is also called ergoalcifediol. The compounds that make up D2 are actually broken down in the liver and kidneys before the body can use them. They're used to make hormones in the parathyroid gland and regulate calcium and phosphorus in the blood, two elements that build strong bones and teeth.
Facts About D2
When reading about vitamin D, most sources don't break out the two forms of vitamin D - D2 and D3 - but speak about vitamin D as a whole. Vitamin D is actually quite complex, with several forms of the vitamin available in nature.
The Differences Between D2 and D3
The Vitamin D Council, which provides education and information about this important vitamin, makes the following distinctions between vitamin D2 and D3:
| Vitamin D2 | Vitamin D3 |
| Manufactured by a fungus on plants | Manufactured by the human body when skin is exposed to sunlight |
| Body breaks it down into various substances, which some researchers believe to be harmful | Body breaks it down into calcitrol, which may have anti-cancer properties |
| Supplements made from plants | Supplements made from animals, specifically lambs' wool |
| Frequently added to foods as a fortifying agent | Not usually added to foods, but available as a pill or liquid |
Controversy
Some controversy exists among those who caution against using vitamin D, and others who believe it's fine to take D2 as a supplement.
Cautions
Many people take vitamin D supplements in the hopes of warding off certain diseases or improving other conditions. Because D2 is easier to make, many supplements contain vitamin D2. Some researchers do not believe that this is a good thing and think people should not take vitamin D supplements made with D2.
In a paper published by the American Journal of Clinical Nutrition, researchers Lisa A. Houghton and Reinhold Vieth caution that D2 should not be considered an equivalent supplement to D3. They make the cases that D2 does not behave the same way in the body. It metabolizes differently, and creates different by products. Some of these by products may be hard for the body to eliminate. Vitamin D2 also has a much shorter shelf life than vitamin d3, which diminishes its potency and usefulness as a supplement. When choosing vitamin D supplements, look for supplements that specify they contain D3 or the word "cholecalciferol", which indicates the presence of vitamin D3.
Just Fine
Yet other researchers think that these findings aren't true. In a press release issued in January 2008 from Boston University, researchers there came to the conclusion that D2's main actions are the same as D3. Michael Holick, P.h.D. and M.D., the lead researcher on the study, stated that, "One thousand IU of vitamin D2 daily was as effective as 1,000 IU of vitamin D3 in maintaining serum 25-hydroxyvitamin D levels and did not negatively influence serum 25-hydroxyvitamin D levels. Therefore, vitamin D2 is equally as effective as vitamin D3 in maintaining 25-hydroxyvitamin D status." Simply put, both D vitamins were equally as effective in maintaining the level of vitamin D in the body. Neither vitamin appeared to be more or less useful to the human body in the study Dr. Holick supervised.
Vitamin D Conclusions
Vitamin D is one of the more complex vitamins the human body needs for healthy growth and development. Unlike other vitamins, this fat-soluble vitamin is actually the precursor to various hormones and chemicals. The human body has to break down the compounds in vitamin D in the liver and kidneys to create what it can use. Whether making parathyroid hormone and helping to maintain metabolism, or adjusting the delicate balance of calcium and phosphorus in the bloodstream, vitamin D is critical for health. If you're concerned about the type of vitamin D to take, choose products that specify D3 or cholecalciferol, which some scientists thinks is closer to the body's natural vitamin D production and therefore more beneficial.
Blood tests can indicate vitamin D deficiency symptoms. It's easy to get adequate amounts with judicious exposure to the sun. Just 15 minutes a day of sun exposure for most months of the year will give the majority of people enough vitamin D. Eating healthy food with vitamin D, such as eggs and various types of fish, provides a good amount of vitamin D without sun exposure. Just don't go overboard with the supplements, since you can also overdose on vitamin D.
