Researchers experimenting with Vitamin D in the treatment of prostate cancer warn the public about taking megadoses of the vitamin.
United States Food and Drug Administration, Health Canada and other authorities contend that the safe upper limit for daily intake of Vitamin D by adults is 2,000 International Units (I.U.'s) or less .
A team of researchers recently re-assessed the data on Vitamin D. One day of full body exposure to sunlight by an adult apparently results in the synthesis of 10,000 I.U.'s of Vitamin D. The "No observed adverse effect limit" of 2,000 I.U. per day "is too low by at least 5-fold." (Vieth R. "Vitamin D supplementation, 25-hydroxivitamin D concentrations, and safety," American Journal of Clinical Nutrition 1999;69:842-856)
Up to 10, 000 I.U. of Vitamin D daily appears to be safe.
Two eye diseases associated with Vitamin D and calcium deficiencies. Patients with retinitis pigmentosis treated with sufficient Vitamin D and calcium without exception improved. Most were of the very advanced type with very contracted fields. Karatoconus (conical cornea) successfully treated with Vitamin D and calcium. (Arhtur Alexander Knapp, MD. "Blindness: Forty Years of Original Research," Journal of the International Academy of Preventive Medicine, Volume 4, Number 1, July 1977; 57- 58)
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