Higher and Higher "Vitamin D definitely decreased the incidence of cancer." That was the quote heard 'round the world last summer, and it immediately branded vitamin D with a mainstream reputation as the anti-cancer vitamin. Researcher Joan Lappe of Creighton University spoke those words, also noting that a dose of 1,100 IU of vitamin D per day was required. But new research indicates a higher dosage may be necessary. So…how high should you go? I covered the Creighton research in the e-Alert "Flying Lessons" (7/24/07). And dosage was one of the key topics addressed. I noted that Dr. Michael Thun of the American Cancer Society told the Associated Press that we should stick with the lower recommended vitamin D dosage for now - 200 to 600 IU per day, depending on age. He added that 2,000 IU per day is considered dangerous, according to guidelines set in 1997. Welcome to 2008, Dr. Thun. The new research comes from the Bone Mineral Research Center in Mineola, NY, where researchers recruited more than 200 healthy, black, postmenopausal women. Writing in the American Journal of Clinical Nutrition (AJCN), the authors note that most vitamin D data has been collected from white subjects. People with dark skin tend to be at risk of vitamin D deficiency because their pigmentation impedes the process by which sunlight is absorbed to create vitamin D. STUDY PROFILE About half the subjects received 800 IU of vitamin D3 daily for two years, followed by an increase to 2,000 IU for one additional year (D3 is the same form of the vitamin that's produced in the skin after exposure to sunlight.) - Half the subjects received a placebo for three years
- At the outset of the study, the subjects' average vitamin D level was 47 nanomoles per litre (nmol/L) - 50 nmol/L is considered the low end of a "normal" level of D
- After just three months of supplementation, the average nmol/L in the intervention group had jumped to 71.4
- After three months of supplementation with 2,000 IU daily, the average nmol/L climbed to 87
- Sixty percent of the women in the intervention group reached a level of at least 75 nmol/L
So…how much daily D do you need? HSI Panelist Allan Spreen, M.D., has stated that he would have no fear taking 2,000 IU of D3 daily. And in the e-Alert "Sunny Side of the Street" (12/22/03), I told you about this recommendation from Jonathan V. Wright, M.D.: Between 1,600 and 2,000 IU of D3 daily, and as much as 4,000 IU for those over the age of 40. (He also recommends a consistent intake of dietary sources that contain vitamin D, including salmon, sardines, and cod liver oil - in addition, of course, to moderate daily exposure to direct sunlight). But some researchers believe we might go even higher with supplementary D dosage. In an editorial published in AJCN last year, 15 scientists from prominent research institutions signed an editorial calling for an international reassessment of our daily vitamin D requirements. They wrote that when a recent AJCN review applied the risk assessment method used by the Food and Nutrition Board to update the safe tolerable upper intake level (UL) for vitamin D "the conclusion was that the UL for vitamin D consumption by adults should be 10,000 IU/d." Keep in mind, that's a safe upper level, not a recommended dosage. Talk to your doctor before adding vitamin D3 supplements to your daily regimen. Sources:
"Dose Response to Vitamin D Supplementation Among Postmenopausal African American Women" American Journal of Clinical Nutrition, Vol. 86, No. 6, December 2007, ajcn.org
"Vitamin D and Calcium Supplementation Reduces Cancer Risk: Results of a Randomized Trial" American Journal of Clinical Nutrition, Vol. 85, No. 6, June 2007, ajcn.org
"The Urgent Need to Recommend an Intake of Vitamin D That is Effective" American Journal of Clinical Nutrition, Vol. 85, No. 3, March 2007, ajcn.org | 
