LETTER TO THE EDITOR – JUNE 2002

I read an article that recommended a daily intake of 10 micrograms of vitamin-D3. What is vitamin D3 and how many IUs are in 10 micrograms? All the supplements in the health food store list the potency of vitamin D in IU.

WP, USA

Editor: Vitamin D3 (cholecalciferol) is the naturally derived form of vitamin D. Vitamin D2 (ergocalciferol) is synthetic and is far more toxic than vitamin D3. I would not use it myself so check the labels. The usually recommend daily dosage of vitamin-D is 10 micrograms or 400 IU. However, researchers at the University of Toronto recently concluded that 100 micrograms/day (4000 IU/day) is a safe and desirable intake – at least during the winter months.