RTM: Grant: meat & breast cancer in 35 nations 2.8.2 rmforall
Diet Called Most Important Breast Cancer Risk Factor
A unique study of breast cancer mortality rates and dietary factors for 35 countries published January 1 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; available online at this URL.)
(Reference: 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.)
[Contact: William B. Grant Ph.D. firstname.lastname@example.org ] 04-Jan-2002
Cancer 2002 Jan 1;94(1):272-81
An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates.
Newport News, Virginia, USA. email@example.com
BACKGROUND: The role of diet in the etiology of breast carcinoma has been debated for decades. The ecologic approach generally finds that dietary fat is highly associated with breast carcinoma mortality, with fish intake 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, nonfat dietary, environmental, genetic, lifestyle, and reproductive factors to be important.
METHODS: An ecologic study was conducted using breast carcinoma 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 intake (risk reduction), were found to explain 80% of the variance of breast carcinoma 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 carcinoma because they are associated with greater amounts of insulin-like growth factor-1 and lifetime doses of estrogen. Vegetable products contain several risk reduction components including antioxidants and phytoestrogens. The association with latitude is very likely because of solar UV-B radiation and vitamin D. Alcohol modulates estrogen's effects on breasts.
Fish intake is 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 assessed in well designed cohort studies. Copyright 2002 American Cancer Society. PMID: 11815987
Rich Murray, MA Room For All firstname.lastname@example.org
1943 Otowi Road, Santa Fe NM USA 87505 505-986-9103
Ralph W. Moss, Ph.D. Weekly CancerDecisions.com
Newsletter #62 11/21/02
Sun: Friend or Foe?
There is a widespread belief that sunlight is bad for you -- in fact, that it promotes cancer. I remember once reading a book titled "The Sun Is My Enemy." Most of us have come to regard the sun as our enemy. We are told to lather on sunscreens in order to prevent various kinds of cancer. But more recent evidence suggests that sunlight and the vitamin D it forms in our bodies are protective against cancers of many kinds.
Throughout most of history, people have regarded sunlight as healthful. The ancient Greeks and Romans had special temples where they worshipped the Sun God. This may be why the early Christians identified sunbathing with paganism. It was not until the Enlightenment that Westerners once again deliberately exposed themselves to the rays of the sun.
A recent article in Cancer (the journal of the American Cancer Society) examined cancer mortality in the United States and found that deaths from a wide range of cancers were double in sun-starved New England compared to the sunny Southwest. (The diets of the two regions did not show significant differences.)
According to W.B. Grant, author of the study, "The geographic distributions for five types of cancer are related inversely to solar radiation." Exposure to ultraviolet-B (UV-B) radiation (the kind blocked by commercial sunscreens) was associated with a reduced risk of cancer of the breast, colon, ovary, and prostate as well as non-Hodgkin lymphoma. Furthermore, people who had high UV-B exposure had fewer deaths from bladder, esophageal, kidney, lung, pancreatic, rectal, stomach, and uterine (endometrial) cancer.
Grant concluded that 21,700 Americans die prematurely each year as a result of low exposure to full sunlight. "Many lives could be extended through increased careful exposure to solar UV-B radiation," he wrote, "and more safely, vitamin D3 supplementation, especially in nonsummer months."
Ten years ago, geographers at the University of North Carolina made a similar discovery. The authors examined prostate cancer death rates in the 3,073 counties of the contiguous United States and found a big difference in prostate cancer rates depending on where one lived. The more sunlight (i.e., UV-B radiation) that a county received, the lower the percentage of its inhabitants who succumbed to prostate cancer. "These data lend support to the hypothesis
that UV radiation may protect against clinical prostate cancer," they wrote.
Excessive exposure to sunlight is associated with an increased risk of skin cancer, including melanomas. However, according to Joseph Mercola, DO, an increased risk of skin cancer with exposure to sunlight is not inevitable. First of
all, the greatest danger comes from burning the skin, not moderate tanning.
"Skin cancers are more likely related to the large distortion most people have in their omega-6 to omega-3 fat ratio. The high excess of omega-6 fats in most people's diet puts them at a much higher risk of developing skin cancer when exposed to excess sun." Thus, increasing one's omega-3 intake by eating fish several times per week (or taking a daily fish oil supplement) should be protective against this kind of cancer.
--Ralph W. Moss, Ph.D.
New Light on an Old Problem
Light therapy aids lung cancer patients. BBC News Online,
November 2, 2002.
Sun: Friend or Foe?
Grant WB. An estimate of premature cancer mortality in the
U.S. due to inadequate doses of solar ultraviolet-B
radiation. Cancer 2002;94:1867-75.
Hanchette CL and Schwartz GG. Geographic patterns of
prostate cancer mortality. Evidence for a protective effect
of ultraviolet radiation. Cancer 1992;70:2861-9.
Mercola J. Sunlight actually prevents cancer.
The news and other items in this newsletter are
intended for informational purposes only. Nothing in
this newsletter is intended to be a substitute for
professional medical advice.