WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
Vitamin D has major health benefits. The best source of vitamin D is from the sun, but you also see many foods fortified with Vitamin D. Unfortunately, milk and other foods fortified with vitamin D often contain a synthetic form called ergocalciferol, or vitamin D2.
This synthetic form isn't as potent and doesn't last as long in your body. In fact, synthetic vitamin D becomes toxic in your body at far lower levels. Too much synthetic vitamin D2 may be linked to health problems. A number of studies link synthetic vitamin D2 to irritation of the lining of blood vessels.