Breast Cancer Links to Diet and Sunlight

Press release on breast cancerFor immediate release

UNIQUE DIETARY CANCER STUDY SHOWS BREAST CANCER DRAMATICALLY INCREASED BY ANIMAL PRODUCTS AND REDUCED BY VEGETABLE PRODUCTS, SUNLIGHT, AND VITAMIN D

A unique study of breast cancer mortality rates and dietary factors for 35 countries being published January 1, 2002 in the journal Cancer presents strong evidence that diet is the most important risk factor for breast cancer. Specifically, the data from the study shows that the fraction of daily calories derived from animal products exhibits a very strong correlation with increased mortality by this cancer, while the fraction derived from vegetable products shows an equally strong correlation with a decreased mortality.

This new study finally solves the mystery of why almost all such correlation type studies find a very strong link between dietary fat and the incidence of breast cancer, while other types of cancer studies, such as those involving case-control or the examination of cohorts do not show this effect. The increase is due to the fact that those females living in countries with high-fat diets generally eat a higher fraction of animal products, drink more alcoholic beverages, and eat less fish (a source of vitamin D) than those women living in countries with low-fat diets. Thus, over their lifetime, they produce more estrogen and more insulin like growth factor (IGF-1). Both of these compounds are known to be strong factors associated with increased risk of breast cancer, and alcohol increases the effects of estrogen.

The study also confirms surprising and important results about the relationship between the mortality from breast cancer and ultraviolet-B (UV-B) radiation, the type of sunlight that produces vitamin D (and is also associated with tanning and skin cancer). The results clearly show that exposure to UV-B actually reduces the mortality from breast cancer quite substantially. For example, breast cancer mortality rates in the southwestern part of the U.S. are only half what they are in the northeast, and, in Europe, the breast cancer mortality rates are found to increase with increasing latitude as long as corrections are made for diet. Thus, the most cost-effective way to reduce breast cancer mortality rates for adult women in the U.S. and Europe is likely by sufficient UV-B radiation without burning and the use of vitamin D supplements, especially in winter in the NE U.S. and northern Europe.

The study was conducted by William B. Grant, Ph.D., an independent research scientist who studies dietary and environmental links to chronic diseases. Using correlation analyses based on the sophisticated tools developed to study the effects of atmospheric pollution, Dr. Grant, in 1997, published the first paper linking a high-fat, high-caloric diet to the development of Alzheimer's disease. (W.B. Grant, Dietary links to Alzheimer's disease. Alzheimer's Disease Review 2, 42-55, 1997 http://www.mc.uky.edu/adreview/default.htm )

W.B. Grant, An ecologic study of dietary and solar UV-B links to breast cancer mortality rates. Cancer, 94, 272-281, Jan. 1, 2002.

Abstract from Background. The role of diet in the etiology of breast cancer has been debated for decades. The ecologic approach generally finds that dietary fat is highly associated with breast cancer mortality, with fish and solar ultraviolet-B (UV-B) radiation, a source of vitamin D, inversely associated. Case-control and cohort studies generally find a variety of chemical, non-fat dietary, environmental, genetic, lifestyle, and reproductive factors to be important.

Methods. An ecologic study was conducted using breast cancer mortality rates (1989-1996), dietary supply data, and latitude (an index of solar UV-B radiation) from 35 countries.

Results. The fraction of energy derived from animal products (risk) combined with that from vegetable products (risk reduction), followed by solar UV-B radiation and, to a lesser extent, energy derived from alcohol (risk) and fish (risk reduction), were found to explain 80% of the variance of breast cancer mortality rates. Dietary fat contributed insignificantly in regressions involving the other factors.

Conclusions. It is hypothesized that animal products are associated with risk for breast cancer since they are associated with greater amounts of insulin-like growth factor-I (IGF-I) and lifetime doses of estrogen. Vegetable products contain a number of risk-reduction components including antioxidants and phytoestrogens. The association with latitude is very likely due to solar UV-B radiation and vitamin D. Alcohol modulates estrogen's effects on breasts. Fish are associated with risk reduction through vitamin D and n-3 oils. These results are consistent with those of many case-control and cohort studies, but should be should be assessed in well-designed cohort studies.

Atlas of Cancer Mortality for U.S. with maps of breast cancer mortality rates:http://cancer.gov/atlasplus/type.html

Selected references:( abstracts available at http://www.ncbi.nlm.nih.gov/pubmed/)6. Kaizer L, Boyd NF, Kruikov V, Tritchler D. Fish consumption and breast cancer risk: an ecological study. Nutr Cancer 1989;12:61-8.7. Garland FC, Garland CF, Gorham ED, Young JF. Geographic variation in breast cancer mortality in the United States: A hypothesis involving exposure to solar radiation. Prev Med 1990;19:614-22.8. Garland FC, Garland CF, Gorham ED. Calcium and vitamin D. Their potential roles in colon and breast cancer prevention. Ann NY Acad Sci 1999;889:107-19.9. Gorham ED, Garland CF, Garland FC. Acid haze air pollution and breast and colon cancer mortality in 20 Canadian cities. Can J Publ Health 1989;80:96-100.10. Gorham ED, Garland FC, Garland CF. Sunlight and breast cancer incidence in the USSR. Int J Epidemiol 1990;19:820-4.12. Willett W. Diet and breast cancer. J Intern Med 2001;249:395-411.13. Holmes MD, Callmer E, Hjalmar ML, Lidbrink E, Nilsson B, Skoog L. Association of dietary intake of fat and fatty acids with risk of breast cancer, JAMA 1998;281:914-20.14. Lee MM, Lin SS. Dietary fat and breast cancer. Annu Rev Nutr 2000;20:221-48.16. Janowsky EC, Lester GE, Weinberg CR, Millikan RC, Schildkraut JM, Garrett PA, et al. Association between low levels of 1,25-dihydroxyvitamin D and breast cancer risk. Public Health Nutr 1999;2:283-91.17. John EM, Schwartz GG, Dreon DM, Koo J. Vitamin D and breast cancer risk: the NHANES I epidemiologic follow-up study, 1971-1975 to 1992. National Health and Nutrition Examination Survey. Cancer Epidemiol Biomarkers Prev 1999;8:399-406.18. Willett WC, Stampfer MJ, Colditz GA, Rosner BA, Hennekens CH, Speizer FE. Moderate alcohol consumption and the risk of breast cancer. N Engl J Med 1987;316:1174-80.20. Smith-Warner SA, Speigelman D, Yuan SS, van den Brandt PA, Folsom AR, Goldbnohm A, et al. Alcohol and breast cancer in women, A pooled analysis of cohort studies. JAMA 1998;279:535-40.73. Fan S, Meng Q, Gao B, Grossman J, Yadegari M, Goldberg ID, et al. Alcohol stimulates estrogen receptor signaling in human breast cancer cell lines. Cancer Res 2000;60:5635-9.74. Mukutmoni-Norris M, Hubbard NE, Erickson KL. Modulation of murine mammary tumor vasculature by dietary n-3 fatty acids in fish oil. Cancer Lett 2000;150:101-9.76. Feldman D, Zhao XY, Krishnan AV. Editorial/mini-review: Vitamin D and prostate cancer. Endocrinology 2000;141:5-9.

Recent referencesSingletary KW, Gapstur SM. Alcohol and breast cancer: review of epidemiologic and experimental evidence and potential mechanisms. JAMA. 2001 Nov 7;286(17):2143-51. Review.

Rose DP. Dietary Fat, Fatty Acids and Breast Cancer. Breast Cancer. 1997 Mar 25;4(1):7-16.

Bartsch H, Nair J, Owen RW. Dietary polyunsaturated fatty acids and cancers of the breast and colorectum: emerging evidence for their role as risk modifiers. Carcinogenesis. 1999 Dec;20(12):2209-18. Review.

Related publications by W. GrantGrant, WB. An ecologic study of dietary links to prostate cancer, Altern Med Rev, 1999;4:162-169. http://www.thorne.com/altmedrev/.fulltext/4/3/162.html

Grant, WB. Dietary fiber and colorectal cancer, The Townsend Letter, 1999;192:112-3

Grant, WB. Fish consumption, cancer, and Alzheimer disease, Am J Clin Nutr, letter, 2000 Feb;71:599.http://www.ajcn.org/cgi/content/full/71/2/599