Confusion Says: Diet Linked to Breast and Ovarian Cancer

This Reuters report got me excited—diet tied to breast and ovarian cancer risks—but when I started reading it, right away I found problem. Can you spot it? Take a look:
Women who eat diets rich in meat and dairy may have a decreased risk of breast cancer, while those who bulk up on fiber, fruits and vegetables show a lower risk of ovarian cancer.

The findings, published in the International Journal of Cancer, add to questions surrounding the role of diet in women's risk of the cancers…

…Using detailed dietary questionnaires, the researchers identified four common dietary patterns in the study group: an "animal product" pattern, which was heavy in meat and saturated fat, but also zinc, calcium and certain other nutrients; a "vitamins and fiber" pattern, which besides fiber was rich in vitamin C, beta-carotene and other nutrients found in fruits and vegetables; an "unsaturated fat" pattern that contained high amounts of vegetable and fish oils, as well as vitamin E; and a "starch-rich" pattern high in simple carbohydrates, vegetable protein and sodium.

Overall, the study found, women who followed a pattern rich in vitamins and fiber had a 23 percent lower risk of ovarian cancer than women who consumed the lowest amounts of those foods and nutrients.

On the other hand, the animal-product pattern was linked to a similar reduction in breast cancer risk.
Meat and dairy decrease cancer-risk—since when! Uh hello, The China Study? Here’s a quote from The China Study. Author T. Colin Campbell, PhD drops the hammer on milk:
What protein consistently and strongly promoted cancer? Casein, which makes up 87% of cow’s milk protein, promoted all stages of the cancer process. What type of protein did not promote cancer, even at high levels of intake? The safe proteins were from plants, including wheat and soy.
Okay, let’s see what he has to say about animal protein in general. My guess is the cattle ranchers of the world are going to be just a wee bit upset. More from Dr. Campbell:
Indian researchers had studied two groups of rats. In one group, they administered the cancer causing aflatoxin, then fed a diet that was composed of 20% protein, a level near what many of us consume in the West. In the other group, they administered the same amount of aflatoxin, but then fed a diet that was only composed of 5% protein. Incredibly, every single animal that consumed the 20% protein diet had evidence of liver cancer, and every single animal that consumed a 5% protein diet avoided liver cancer.
Make no mistake about it. Animal products are no friend to cancer-prevention. Now, Dr. Fuhrman and Dr. Campbell are friends, so, here’s Dr. Fuhrman’s take on all this:
Humans are genetically adapted to expect a high intake of natural and unprocessed plant-derived substances. Cancer is a disease of maladaptation. It results primarily from a body’s lacking critical substances found in different types of vegetation, many of which are still undiscovered, that are metabolically necessary for normal protective function.
Trust me, he’s not kidding. Plants are strong medicine! Take green vegetables for example. Leafy green or cruciferous vegetables are potent cancer-fighters. Check it out:
These vegetables also contain indole-3- carbinol (I3C). Indole-3-carbinol has been shown to reduce the risk of breast cancer by decreasing estrogen activity. Important recent studies have shown that cruciferous vegetables and the compounds they contain can do the following:
  • Halt the growth of breast cancer cells2
  • Dramatically reduce the risk of colon cancer3
  • Prevent the replication of prostate cancer cells and induce death of cancerous cells4
  • Inhibit the progression of lung cancer.5
Good stuff and the sooner you start eating lots of veggies—the better! Consider the plight of young women and breast cancer-risk. More from Dr. Fuhrman:
Higher consumption of produce and protein-rich plant foods such as beans and nuts is associated with a later menarche, and the higher consumption of protein-rich animal foods—meat and diary—is associated with an earlier menarche and increased occurrence of adult breast cancer.6
The newswires are a virtual ping-pong of what’s good for you and what’s not—drawn your own conclusions—here, this might help. From the European Journal of Cancer Prevention:
The aim of this study was to investigate whether polymorphisms in N-acetyl transferase 1 and 2 modify the association between meat consumption and risk of breast cancer. A nested case-control study was conducted among 24 697 postmenopausal women included in the 'Diet, Cancer and Health' cohort study (1993-2000). Three hundred and seventy-eight breast cancer cases were identified and matched to 378 controls. The incidence rate ratio (95% confidence interval) for breast cancer was 1.09 (1.02-1.17) for total meat, 1.15 (1.01-1.31) for red meat and 1.23 (1.04-1.45) for processed meat per 25 g daily increment in intake. Compared with slow acetylators, the IRR (95% confidence interval) among fast N-acetyl transferase 1 acetylators was 1.43 (1.03-1.99) and 1.13 (0.83-1.54) among intermediate/fast N-acetyl transferase 2 acetylators. Interaction analyses revealed that the positive associations between total meat intake and red meat intake and breast cancer risk were confined to intermediate/fast N-acetyl transferase 2 acetylators (Pinteraction=0.03 and 0.04). Our findings support an association between meat consumption and breast cancer risk and that N-acetyl transferase 2 polymorphism has a modifying effect on the association, indicating that the association is confined to only genetically susceptible women.
Alright, since we’ve already crossed over into nerd territory. Let’s look at one more study. It appeared in the International Journal of Cancer. Here’s the abstract:
Meat intake has been positively associated with risk of digestive tract cancers in several epidemiological studies, while data on the relation of meat intake with cancer risk at most other sites are inconsistent. The overall data set, derived from an integrated series of case-control studies conducted in northern Italy between 1983 and 1996, included the following incident, histologically confirmed neoplasms: oral cavity, pharynx and esophagus (n = 497), stomach (n = 745), colon (n = 828), rectum (n = 498), liver (n = 428), gallbladder (n = 60), pancreas (n = 362), larynx (n = 242), breast (n = 3,412), endometrium (n = 750), ovary (n = 971), prostate (n = 127), bladder (n = 431), kidney (n = 190), thyroid (n = 208), Hodgkin's disease (n = 80), non-Hodgkin's lymphomas (n = 200) and multiple myelomas (n = 120). Controls were 7,990 patients admitted to hospital for acute, non-neoplastic conditions unrelated to long-term modifications in diet. The multivariate odds ratios (ORs) for the highest tertile of red meat intake (7 times/week) compared with the lowest (3 times/week) were 1.6 for stomach, 1.9 for colon, 1.7 for rectal, 1.6 for pancreatic, 1.6 for bladder, 1.2 for breast, 1.5 for endometrial and 1.3 for ovarian cancer. ORs showed no significant heterogeneity across strata of age at diagnosis and sex. No convincing relation with red meat intake emerged for cancers of the oral cavity, pharynx and esophagus, liver, gallbladder, larynx, kidney, thyroid, prostate, Hodgkin's disease, non-Hodgkin's lymphomas and multiple myeloma. For none of the neoplasms considered was there a significant inverse relationship with red meat intake. Thus, reducing red meat intake might lower the risk for several common neoplasms.
Ultimately it’s your call, but I think the evidence is clear, eat more veggies and less meat. So, when you read headlines like this, you got to dig deeper and THEN see if you believe it.
1. UK Department of Health, Working Group on Diet and Cancer of the Committee on Medical Aspects of Food and Nutrition Policy. Nutritional aspects of the development of cancer. London: Her Majesty’s Stationary Office, 1998.

2. Johnston N. Sulforaphane halts breast cancer cell growth. Drug Discov Today 2004;9(21): 908. Rose P, Huang Q, Ong CN, Whiteman M. Broccoli and watercress suppress matrix metalloproteinase- 9 activity and invasiveness of human MDA-MB-231 breast cancer cells. Toxicol Appl Pharmacol 2005;S0041-008X.

3. Seow A, Yuan JM, Sun CL, et al. Dietary isothiocyanates, glutathione S-transferase polymorphisms and colorectal cancer risk in the Singapore Chinese Health Study. Carcinogenesis 2002;23(12): 2055-261.

4. Wu HT, Lin SH, Chen YH. Inhibition of cell proliferation and in vitro markers of angiogenesis by indole-3-carbinol, a major indole metabolite present in cruciferous vegetables. J Agric Food Chem 2005:53(13):5164-5169. Singh SV, Srivastava SK, Choi S, et al. Sulphoraphane-induced cell death in human prostate cancer cells is initiated by reactive oxygen species. J Biol Chem 2005; 280(20):19911-19924. Xiao D, Srivastava SK, Lew KL, et al. Allyl isothiocyanate a constituent of cruciferous vegetables inhibits proliferation of human prostate cancer cells by causing G2/M arrest and inducing apoptosis. Carcinogenesis 2003;24(5):891-897.

5. Conaway CC, Wang CX, Pittman B, et al. Phenethyl isothiocyanate and sulforaphane and their n-acetylcysteine conjugates inhibit malignant progression of lung adenomas induced by tobacco carcinogens in A/J mice. Cancer Res 2005;65(18): 8548-8557.

6. UK Department of Health, Working Group on Diet and Cancer of the Committee on Medical Aspects of Food and Nutrition Policy. Nutritional aspects of development of cancer. London: Her Majesty’s Stationary Office, 1998.
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Josh - February 25, 2008 9:49 AM

I think reporting on these confusing news stories about nutrition is a great service. But when they appear, it would be most useful to get an explanation on specifically where, in Dr. Fuhrman's view, the new study or article went wrong. For example, were the study findings misinterpreted by a journalist? Was the study design flawed? Did the researchers misinterpret their own data? Simply quoting from contrary generalizations in works by T. Colin Campbell and Dr. Fuhrman isn't all that useful when faced with news reports that appear to offer more recent scientific evidence in support of a different understanding. Principles of nutritional excellence should reflect science, not dogma, and science is always an ongoing dialogue. I certainly don't intend to drop my Fuhrman-style diet because of this Reuters report, but I would love to know exactly why I shouldn't.

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