The results of a pooled analysis of 1,760 women confirmed that having higher levels of the vitamin D metabolite serum 25-hydroxyvitamin D is associated with a lower risk of breast cancer. The finding was reported at the 97th Annual Meeting of the American Association for Cancer Research held April 1-5, 2006 in Washington DC.
Cedric Garland, Dr PH, and Edward Gorham, PhD, of the University of California, San Diego, and their colleagues evaluated data from cancer studies conducted by Elizabeth R. Bertone-Johnson and colleagues at Harvard, and L.C. Lowe and associates at Saint George’s Hospital Medical School in London to arrive at their conclusion. "There is a strong inverse dose-response relationship between the serum concentration of 25-hydroxyvitamin D and the risk of breast cancer," Dr Garland stated. "It's a close fit to a linear model."
The research team found that having a serum vitamin D level of 52 nanograms per milliliter was associated with a 50 percent reduction in breast cancer risk.
To attain this level of the vitamin, it would be necessary to consume at least 1,000 international units (IU) of vitamin D per day--more than 2 1/2 times the daily value. The daily value was established as the minimum requirement to avoid a disease due to deficiency of that nutrient. Somehow it has been misinterpreted as a target value for health, rather than the absolute minimum to avoid death or disease directly due to deficiency.
Although the National Academy of Sciences has established 2,400 IU per day as the upper limit for vitamin D intake, there have been no toxic effects associated with up to 3,800 IU per day. "There is no substantial downside to a serum level of 52 nanograms per milliliter of Vitamin D," Dr Gorham noted. "Such levels are common in sunny climates. There is no known adverse effect of serum levels below 160 nanograms per milliliter."
The researchers recommend that at least 1,000 IU per day vitamin D3 be consumed until further studies are conducted.
Garland C, Gorham E; 97th Annual Meeting of the American Association for Cancer Research, April, 2006