A 2004 study seemed to show that vitamin D in the form of cod liver oil had only a mild effect on reducing upper respiratory tract infections in young children. This result was surprising, considering that it has been known since at least 1926 that vitamin D can significantly reduce respiratory infection, colds, and flu. In fact, vitamin D plays a pivotal role in the immune system. The explanation likely comes from the fact that vitamin D in cod liver oil does not exist in isolation -- it comes with a high dose of vitamin A. Vitamin A and vitamin D compete for each others function. For example, even the vitamin A in a single serving of liver can impair vitamin D's rapid intestinal calcium response. Unfortunately, Americans tend to consume multivitamins or cod liver oil that contain disproportionately small amounts of vitamin D, but detrimental quantities of vitamin A. One manufacturer sells cod liver oil containing only 3 to 60 IU of vitamin D, but between 3,000 and 6,000 IU of vitamin A. Sunlight is still the best way to obtain vitamin D -- it is your body's natural method of creating the substance. But in winter months, sometimes it is not possible to receive enough sunlight. If you do supplement your vitamin D, make sure get it from a good source.
Why Sunlight is the Best Source of Vitamin D
Tuesday, November 18, 2008
Cod Liver Oil, Vit D and Vit A Connection
Dr. Mercola
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