Higher Vitamin D Levels Could Prevent 600,000 Cases of Breast and Colorectal Cancer Annually
Readers of Life Extension Update may recall the February 6, 2007 issue which reported the results of meta-analyses conducted by Cedric F. Garland, DrPH of the University of San Diego and colleagues that found a strong protective effect for higher serum vitamin D levels against breast and colorectal cancer. A new report coauthored by Dr Garland, published in the August, 2007 issue of Nutrition Reviews, builds on this work, and concludes that higher levels of vitamin D could prevent breast and colorectal cancers in over half a million people.
The current research determined the dose-response relationship between serum vitamin D levels and cancer. The study is the first to utilize satellite measurements of sunshine and cloud cover in 15 countries in which wintertime serum vitamin D levels among the populace were also measured. (Vitamin D is obtained from sun exposure, as well as by dietary means.) The information was used to estimate the average serum level of 25-hydroxyvitamin D [25(OH)D], a vitamin D metabolite, in 177 countries.
The team determined that higher vitamin D levels were related to a lower worldwide incidence of colorectal and breast cancer. Protective effects began to be observed at 24 to 32 nanograms per milliliter serum 25-hydroxyvitamin D (the average US late winter average is 15-18 ng/mL). The authors conclude that in North America, a 50 percent reduction in breast cancer incidence would require an intake of 3,500 IU vitamin D3 per day, and the same reduction in colon cancer incidence would require 2,000 IU. They estimate that 250,000 cases of colorectal cancer and 350,000 cases of breast cancer per year could be prevented if vitamin D levels were increased to 55 ng/mL worldwide, a level found to confer optimal protective benefits in Dr Garland’s previous research.
“For the first time, we are saying that 600,000 cases of breast and colorectal cancer could be prevented each year worldwide, including nearly 150,000 in the United States alone,” Dr Garland announced.
“The message is, depending on where you live, you may need to consider taking in considerably higher levels of vitamin D3 than those currently recommended,” he advised. “I’d recommend discussing vitamin D needs with a health care professional, who may order and interpret a simple blood test for a vitamin D metabolite [25(OH)D], and provide a dosage recommendation that’s appropriate for the individual’s needs.”
Vitamin A and vitamin D3 inhibit breast cancer cell division and can induce cancer cells to differentiate into mature, noncancerous cells. Vitamin D3 works synergistically with tamoxifen (and melatonin) to inhibit breast cancer cell proliferation. Preclinical studies demonstrated that vitamin D compounds could reduce breast cancer development in animals. Furthermore, human studies indicate that both vitamin D status and genetic variations in the vitamin D3 receptor (VDR) may affect breast cancer risk. Findings from cellular, molecular and population studies suggest that the VDR is a nutritionally modulated growth-regulatory gene that may represent a molecular target for chemoprevention of breast cancer (Welsh et al. 2003).
Daily doses of vitamin A, 350,000 to 500,000 IU were given to 100 patients with metastatic breast carcinoma treated by chemotherapy. A significant increase in the complete response was observed; however, response rates, duration of response and projected survival were only significantly increased in postmenopausal women with breast cancer (Israel et al. 1985).
Breast cancer patients may take between 4000 to 6000 IU, of vitamin D3 every day. Water-soluble vitamin A can be taken in doses of 100,000-300,000 IU every day. Monthly blood tests are needed to make sure toxicity does not occur in response to these high daily doses of vitamin A and vitamin D3. After 4-6 months, the doses of vitamin D3 and vitamin A can be reduced.
Two New Studies Back Vitamin D for Cancer Prevention
Researchers Report Levels Needed To Cut Breast, Colon Cancer Risk
February – 2007
Two new vitamin D studies using a sophisticated form of analysis called meta-analysis, in which data from multiple reports is combined, have revealed new prescriptions for possibly preventing up to half of the cases of breast cancer and two-thirds of the cases of colorectal cancer in the United States. The work was conducted by a core team of cancer prevention specialists at the Moores Cancer Center at University of California, San Diego (UCSD), and colleagues from both coasts.
The breast cancer study, published online in the current issue of the Journal of Steroid Biochemistry and Molecular Biology, pooled dose-response data from two earlier studies – the Harvard Nurses Health Study and the St. George's Hospital Study – and found that individuals with the highest blood levels of 25-hydroxyvitamin D, or 25(OH)D, had the lowest risk of breast cancer.
The researchers divided the 1,760 records of individuals in the two studies into five equal groups, from the lowest blood levels of 25(OH)D (less than 13 nanograms per milliliter, or 13 ng/ml) to the highest (approximately 52 ng/ml). The data also included whether or not the individual had developed cancer.
“The data were very clear, showing that individuals in the group with the lowest blood levels had the highest rates of breast cancer, and the breast cancer rates dropped as the blood levels of 25-hydroxyvitamin D increased,” said study co-author Cedric Garland, Dr.P.H. “The serum level associated with a 50 percent reduction in risk could be maintained by taking 2,000 international units of vitamin D3 daily plus, when the weather permits, spending 10 to 15 minutes a day in the sun.”
The colorectal cancer study, published online February 6 in the American Journal of Preventive Medicine, is a meta-analysis of five studies that explored the association of blood levels of 25(OH)D with risk of colon cancer. All of the studies involved blood collected and tested for 25 (OH)D levels from healthy volunteer donors who were then followed for up to 25 years for development of colorectal cancer.
As with the breast cancer study, the dose-response data on a total of 1,448 individuals were put into order by serum 25(OH)D level and then divided into five equal groups, from the lowest blood levels to the highest.
“Through this meta-analysis we found that raising the serum level of 25-hydroxyvitamin D to 34 ng/ml would reduce the incidence rates of colorectal cancer by half,” said co-author Edward D. Gorham, Ph.D. “We project a two-thirds reduction in incidence with serum levels of 46ng/ml, which corresponds to a daily intake of 2,000 IU of vitamin D3. This would be best achieved with a combination of diet, supplements and 10 to 15 minutes per day in the sun.”
Vitamin D3 is available through diet, supplements and exposure of the skin to sunlight, or ultraviolet B (UVB). In the paper, the researchers underscored the importance of limiting sun exposure such that the skin does not change color (tan) or burn. For a typical fair-skinned Caucasian individual, adequate vitamin D could be photosynthesized safely by spending 10 to 15 minutes in the noontime sun on a clear day with 50 percent of skin area exposed to the sun. Darker skinned individuals may require more time in the sun, such as 25 minutes. For people with photosensitivity disorders, or anyone with a personal or family history of nonmelanoma skin cancer, any amount of extra sun exposure would be inadvisable.
The meta-analysis on colorectal cancer includes data from the Women's Health Initiative, which had shown in 2006 that a low dose of vitamin D did not protect against colorectal cancer within seven years of follow-up. However, the researchers wrote, the meta-analysis indicates that a higher dose may reduce its incidence.
“Meta-analysis is an important tool for revealing trends that may not be apparent in a single study,” said co-author Sharif B. Mohr, M.P.H. “Pooling of independent but similar studies increases precision, and therefore the confidence level of the findings.”
The authors recommend further research to study individuals for the effect of vitamin D from sunlight, diet and supplements on the risk of cancer.
Co-authors on both the breast cancer and colorectal meta-analysis papers are Edward D. Gorham, MPH, Ph.D., Cedric F. Garland, Dr.P.H.; Frank C. Garland, Ph.D.; Sharif B. Mohr, MPH; William B. Grant, Ph.D; Martin Lipkin, M.D.; Harold L. Newmark, ScD; Edward Giovannucci, M.D., ScD; and Michael F. Holick, M.D., Ph.D. Co-author on the colorectal meta-analysis paper only was Melissa Wei, B.S. Authors' institutional affiliations are UCSD Department of Family and Preventive Medicine and Moores UCSD Cancer Center (Gorham, Garland, Garland); Naval Health Research Center, San Diego (Gorham, F.C. Garland, Mohr); SUNARC-Sunlight, Nutrition and Health Research Center, San Francisco (Grant); Strang Cancer Prevention Center of Rockefeller University, New York, NY (Lipkin); Rutgers–The State University of New Jersey and Cancer Institute of New Jersey (Newmark); Harvard Schools of Public Health and Medicine (Giovannucci, Wei); and Boston University School of Medicine (Holick). Funding for this research was provided by a Congressional allocation to the Hollings Cancer Center of the Medical University of South Carolina through the Department of the Navy.