In spite of numerous studies that demonstrate a profound reduction in risk of cancer with increased sunlight exposure and vitamin D supplementation, a new study appears to completely contradict the idea that vitamin D has anti-cancer properties, especially for breast cancer. 
Don’t be deceived. The researchers obviously have not kept up on vitamin D research, or they have deliberately conducted a study with the express intention of misleading the public, meaning that the so-called “research” falls somewhere between incompetence and deception.
First of all, the amount of supplementation used was 400 IU daily. That miniscule amount is like feeding a starving woman nothing more than a daily peanut! 400 IU is barely sufficient to prevent rickets, much less stave off cancer. More than a year ago, another study, this one done by researchers who understood vitamin D, showed that supplementing about 1,100 IU along with calcium for four years reduced the risk of all cancers in women by 60-77%.
Summer sunlight can stimulate the skin to produce up to 20,000 IU of vitamin D in 20 minutes of full-body exposure. As I stated, 400 IU is almost NOTHING. In winter, most men and women need at least 3-5,000 IU daily to maintain healthful summer levels, and nursing mothers need at least 6,400 IU to maintain adequate serum levels for both themselves and their infants. This research is no secret, and yet the researchers who conducted this new study used 400 IU. It makes one wonder if they even bother to read the research. A short time ago I posted the following material on vitamin D and breast cancer, and it bears repeating here:
There has been a concerted effort by the “Powers of Darkness” to ensure that children avoid that most natural of childhood activities—playing outdoors in the sun. Yet, it is known that girls who have the greatest exposure to sunlight during the ages of 10-19 have a 35% decreased risk of cancer as adults when compared to those who had the least exposure. Sunlight is essential for optimal human health and it is criminal to deprive children and adults of mankind’s most healthful friend. It is likely that much of sunlight’s cancer-preventive properties are mediated by vitamin D.
Adult habits of sun exposure also make a profound difference in the risk of breast cancer. Dr Esther John and colleagues conducted research on the sun-exposure habits of women and correlated those habits to the risk of developing breast cancer. Those women who had the greatest exposure to sunlight were 65% less likely to develop breast cancer. Isn’t it interesting that the most potent anti-cancer agent may be something that the cancer societies have defined as a carcinogen (something that causes cancer)? That anti-cancer agent is sunshine, which produces vitamin D. Research shows that women with a combination of a genetically susceptible tendency to breast cancer and a low blood level of vitamin D (less than 20 ng/ml) have nearly seven times the breast cancer rate as those without a family history of susceptibility genetics and a blood level above 20 ng/ml. Another investigation pointed out that those women with the highest serum levels of vitamin D had a 69% reduced risk when compared to those with the lowest levels. There was a striking dose-response relationship between higher vitamin D and lower breast-cancer risk.
Vitamin D also makes a terrific difference in the progression and spread of breast cancer after it is diagnosed. Blood levels of vitamin D at the time of diagnosis of breast cancer accurately predict a woman’s survival. The cancer is much more aggressive in those whose serum vitamin D levels are low; they are 94% more likely to have the cancer metastasize (spread to other tissue) and 73% more likely to die within ten years of diagnosis.
So what is the bottom line? Another analysis estimated that maintaining a vitamin D blood level of 55ng/ml would prevent the breast-cancer deaths of 85,000 US women yearly and that the deaths prevented worldwide would be 350,000; still another showed that moderate sunlight exposure combined with 2,000 IU of vitamin supplementation would be sufficient to produce the levels necessary to achieve such a reduction in breast-cancer risk and death. It is likely that the combination of supplementation and sunlight furnishes at least 3,000 IU daily. Is it any wonder that 400 IU made no difference in breast cancer rates? We must no longer ignore the beneficial health influences of sunlight and vitamin D on breast cancer or any of the other myriad disorders such as heart disease and osteoporosis that correlate so closely to vitamin D deficiency.
 Chlebowski R, et al. Calcium Plus Vitamin D Supplementation and the Risk of Breast Cancer. JNCI Published online 11-11- 2008.
 Lappe, J. et al. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr 2007;85:1586–91.
 Heaney, R. et al. Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr 2003;77:204-10.
 Wagner C. et al. High-dose vitamin D3 supplementation in a cohort of breastfeeding mothers and their infants: a 6-month follow-up pilot study. Breastfeed Med 2006;1:59-70.
 Knight J. et al. Vitamin D and reduced risk of breast cancer: a population-based case-control study. Cancer Epidemiol Biomarkers Prev 2007;16:422-9.
 John, E. et al. Vitamin D and breast cancer risk: The HANES 1 epidemiologic follow-up study, 1971-1975 to 1992. Cancer Epidemiology Biomarkers and Prevention 1999;8:399-406.
 Lowe L. et al. Plasma 25-hydroxy vitamin D concentrations, vitamin D receptor genotype and breast cancer risk in a UK Caucasian population. Eur J Cancer 2005;41:1164-699.
 Abbbas, S et al. Serum 25-hydroxyvitamin D and risk of post-menopausal breast cancer--results of a large case-control study. Carcinogenesis. 2008;29:93-9
 Goodwin, P. et al. quoted in Medical Health Articles Sept 26, 2008 (http://google-sina.com/2008/09/26/low-vitamin-d-levels-raise-breast-cancer-death-risk-by-75-percent/)
 Garland, C et al. What is the dose-response relationship between vitamin D and cancer risk? Nutrition Reviews 2007;65:S91-5.
 Garland, C. et al. Vitamin D and prevention of breast cancer: pooled analysis. J Steroid Biochem Mol Biol. 2007;103:708-11.