Bill Harris, M.D. | Q&A

Vitamin D3?
Q&A with Bill Harris, M.D.

Q. I have been informed by a collegue that the vitamin supplement D3 used to fortify milk actually comes from pigs. Is there any truth to this, and how can the FDA allow interspecia mingling in food products?

A. Dear Marty,

It's very likely true but you're asking a complicated question of a person who thinks there's no such thing as "vitamin D". The stuff in question is actually a hormone synthesized in the body from cholesterol and activated by sunlight under normal conditions. While inadequate exposure to sunlight can cause "vitamin D deficiency" it's really sunlight deficiency and the logical step is to spend more time outdoors.

If you can't do that then you do have to take "vitamin D" but be aware that it's notoriously toxic when taken in excess and that it comes in two forms. Cholecalciferol ("vitamin D3") comes from animals and since cow's milk fresh from the teat only contains about 55 IU/quart it is usually supplemented with D3 (400 IU/quart) from slaughterhouse by-products. Another form is ergocalciferol ("vitamin D2") which comes from fungus and yeast and which does the same job. However, that is no longer added to milk apparently for economic reasons. You may be interested to know that the second highest content of D(2) is found in shiitake mushrooms right below cod liver oil (D3).

As for how anyone in any branch of our government gets away with doing anything, I haven't a clue.


-William Harris, M.D.

William Harris MD received a degree in physics from the University of California Berkeley, where he earned Phi Beta Kappa honors. He received his degree in medicine from the University of California at San Francisco, and received his postgraduate training at San Diego County Hospital. He holds a Medical License in the State of Hawaii. He has been an Emergency Department physican since 1963, and the Director of the Kaiser Permanente Vegan Lifestyle Clinic on Oahu until his retirement in 1998. Dr. Harris is the author of The Scientific Basis of Vegetarianism.

In addition, he was the 1950 Big Ten Trampoline Champion, is an accomplished hangglider and commercial pilot, and at age 70 became a skydiver with 108 jumps to date. Dr. Harris has been vegetarian since 1950, and vegan since 1963.

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