HOME
Diet and Breast Cancer Information
Part 3: Fruit, veg and soya don't help; sunlight is beneficial in breast cancer
It has been claimed that eating more fruit and vegetables reduces the risk of breast cancer. To test this, 20 named researchers investigated 7,377 incident invasive breast cancer cases and a wide variety of fruit and vegetable intakes among 351,825 women at 17 cancer research centres in the USA, Germany, Netherlands, and Sweden. They found no association for green leafy vegetables, 8 botanical groups, and 17 specific fruits and vegetables. They concluded:
"These results suggest that fruit and vegetable consumption during adulthood is not significantly associated with reduced breast cancer risk".[i]
Soya
Soya is promoted as a preventative of breast cancer. But a review of 18 studies of research carried out at several medical centres in the USA found no statistical benefit with breast cancer. The authors say that inconsistencies and limitations among the studies cast doubt on the potential protective effects of the foodstuff in preventing breast cancer.[ii]
Sunlight
The same team found that lack of exposure to UV sunlight could place some populations at higher risk of breast cancer. Annual age-adjusted mortality rates for breast cancer varied from 17-19 per 100,000 in the South and Southwest to 33 per 100,000 in the Northeast. Risk of fatal breast cancer in the major urban areas of the United States increased as intensity of local sunlight decreased.[iii] They found the same pattern across the USSR.[iv]
A low blood level of vitamin D is known to increase the risk for the development of breast and colon cancer,[v] pancreatic cancer,[vi] and may also accelerate the growth of melanoma.[vii] Because of this, Dr Gordon Ainsleigh in California believes that sunscreens cause more cancer deaths than they prevent. He estimated that the 17% increase in breast cancer observed between 1991 and 1992 may be the result of sunscreen use over the past decade.[viii] He also estimated that 30,000 cancer deaths in the United States alone could be prevented each year if people adopted a regimen of regular, moderate sun exposure.
Dr William Grant found that deaths from a range of cancers of the reproductive and digestive systems were approximately twice as high in New England as in the southwest, despite a diet that varied little between regions. According to Dr. Grant's study, northern parts of the United States may be dark enough in winter that vitamin D synthesis actually shuts down completely. Based on his US findings, Dr Grant estimates a quarter of breast cancer deaths in the UK are a result of vitamin D deficiency.[ix]
Dietary breast cancer treatment
Although surgery, radiation and chemotherapy are used to treat breast cancer, an important adjuvant breast cancer treatment is eating the correct diet. As animal fats and a low-carb diet help to prevent breast cancer, any breast cancer treatment should also include such a dietary regime.
Sugars are considerably worse than starches as far as damage to the immune system is concerned. There is also evidence that the same may apply in the case of cancer. A study of rats fed diets with equal amounts of calories from sugars or starches found the animals on the high-sugar diet developed more cases of breast cancer than those on the high-starch diet.[x] The Glycaemic Index (GI) can a useful tool in guiding the breast cancer patient toward a healthier diet, but it has flaws. It seems advisable that breast cancer patients should avoid not only all processed foods whatever their GI, but fresh foods with a GI over 40, as well as all fruit. Fresh green leafy vegetables may be eaten freely and some of the starchier root vegetables with a low GI, such as carrot, may be eaten in moderation. Foods from animal sources, with their fat, which have a GI of zero, should, of course, form the basis of all meals.
And do get out into the sun in the middle of the day and without sunscreen. It doesn't have to be for long: about 15 minutes all over, or longer if you are partially dressed. People with dark skins may need considerably longer.
References
[i]. Smith-Warner SA, et al. Intake of Fruits and Vegetables and Risk of Breast Cancer: A Pooled Analysis of Cohort Studies. JAMA 2001; 285: 769-776.
[ii]. Trock BJ, Hilakivi-Clarke L, Clarke R. Meta-Analysis of Soy Intake and Breast Cancer Risk. JNCI 2006; 98: 459-471.
[iii]. 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.
[iv]. Gorham ED, Garland FC, Garland CF. Sunlight and breast cancer incidence in the USSR. Int J Epidemiol 1990; 19: 820-4.
[v]. Martinez ME, Willett WC. Calcium, vitamin D, and colorectal cancer: a review of the epidemiologic evidence. Cancer Epidemiol Biomarkers Prev 1998; 7: 163-8.
[vi]. Skinner HG, Michaud DS, Edward Giovannucci E, et al. Vitamin D Intake and the Risk for Pancreatic Cancer in Two Cohort Studies. Cancer Epidemiol Biomarkers Prev 2006; 15: 1688?95.
[vii]. Ainsleigh HG. Beneficial effects of sun exposure on cancer mortality. Prev Med 1993; 22: 132-40.
[viii]. Holborow P. Melanoma and fatty acids. NZ J Med 1991; 104: 19.
[ix]. Grant W. An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B radiation. Cancer 2002; 94: 1867-75.
[x]. Hoehn SK, et al. Complex versus simple carbohydrates and mammary tumors in mice. Nutr Cancer 1979; 1: 27.
Last updated 1 August 2008
