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Unhealthy dogma means unhealthy food
Part 3: Low-fat dairy and cancers
Skim milk and prostate cancer
Around 1975, scientists noted an apparent strong correlation between milk intake and deaths from prostate cancer. Since then, there have been growing suspicions of a causal link between the two which two studies published in 2007 appeared to confirm. The first was the CLUE II study which involved nearly 4,000 men in Washington County, Maryland.[1] This study found that men who consumed five or more servings a week of dairy foods were more likely to suffer from prostate cancer than those who ate a serving of one or less. The second study involved over 29,000 Finnish men taking part in the Alpha-tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) which ran for 17 years.[2] This also found that the more dairy consumed, the higher the risk of prostate cancer.
The first thing to be blamed for such an association, as it always seems to be, was the saturated fat in the cream.[3] But mounting evidence suggests that the truth is quite different because full-cream milk does not increase prostate cancer risk, only skim milk does. It was the stripping of fat from the milk — to make it ‘healthier' — which actually increased the risk.
The Physicians' Health Study involving over 20,000 men with 11 years of follow-up found that all the increased risk of prostate cancer associated with dairy intake was attributable entirely to skimmed milk.[4]
In 2005, the first National Health and Nutrition Examination Epidemiologic Follow-up Study (NHEFS), involving more than 3,600 men and 10 years of follow-up arrived at a similar conclusion. They found that men with the highest intakes of dairy were more than twice as likely to develop prostate cancer as men with the lowest intakes. But the risk was higher only with low-fat milk — not with whole milk or any other dairy. In fact, whole milk actually seemed to protect against prostate cancer.[5]
Similar results were found in other countries: A Norwegian study of more than 25,000 men,[6] and an analysis of milkdrinking and diet in 41 countries,[7] found that prostate-cancer death rates were associated only with the drinking of low-fat or skimmed milk.
Low-fat milk increases women's cancers too
Women are presently encouraged to consume dairy products as a source of calcium to prevent osteoporosis. And, because of the fat scare and the fact that all the calcium is in the milk, not in the cream, the milk women are advised to drink is skimmed.
Studies have looked at dairy intake and rates of ovarian cancer and found an increased ovarian cancer risk with milk drinking. But just as in the case with prostate cancer in men, there is no increased risk with whole milk; only with low-fat milk and skimmed milk. The Iowa Women's Health Study investigated the association of epithelial ovarian cancer with dietary ingredients in a study of 29,083 postmenopausal women.[8] They found that skimmed milk, but not whole milk, was significantly associated with an increased risk of cancer of the ovaries.
An even larger study published 6 years later confirmed the Iowa results. In the Brigham and Women's Hospital Nurses' Health Study, in which more than 80,000 women participated, those who consumed just one or more servings of skimmed or low-fat milk products per day had a 32% higher risk of any type of ovarian cancer, and a 69% higher risk of the most widespread form — serous ovarian cancer — compared with women who had three or fewer servings monthly. Yet again, whole milk did not increase the risk.[9]
The CLA connection
Another possible explanation is that stripping the fat from milk also removes other important anti-cancer components such as conjugated linoleic acid (CLA). CLA was identified as a component of milk and dairy products over 20 years ago, and studies have shown it to be a powerful anti-cancer agent. In the laboratory, when human breast and colon cancer cells were bathed in high-CLA milk fat from cows raised on pastureland, the number of cancer cells was reduced by between 58% and 90%.[11] [12]
And women who consumed four or more servings a day of high-fat dairy foods were half as likely to develop colorectal cancer as women who ate less than one serving a day. Low-fat dairy had no such protective effect.[13]
And, as we shall see next, cancers weren't the only consequence of eating low-fat diary.
References
[1]. Rohrmann S, Platz EA, Kavanaugh CJ, et al. Meat and dairy consumption and subsequent risk of prostate cancer in a US cohort study. Cancer Causes Control 2007; 18: 41-50.
[2]. Mitrou PN, Albanes D, Weinstein SJ, et al. A prospective study of dietary calcium, dairy products and prostate cancer risk (Finland). Int J Cancer 2007; 120: 2466-73
[3]. Willett WC. Nutrition and cancer. Salud Publica Mex 1997; 39: 298–309.
[4]. Chan JM, Stampfer MJ, Ma J, et al. Dairy products, calcium, and prostate cancer risk in the Physicians' Health Study. Am J Clin Nutr 2001; 74: 549-54
[5]. Tseng M, Breslow RA, Graubard BI, Ziegler RG. Dairy, calcium, and vitamin D intakes and prostate cancer risk in the National Health and Nutrition Examination Epidemiologic Follow-up Study cohort. Am J Clin Nutr 2005; 81: 1147-54
[6]. Veierod MB, Laake P, Thelle DS. Dietary fat intake and risk of prostate cancer: a prospective study of 25,708 Norwegian men. Int J Cancer 1997; 73: 634-8.
[7]. Grant WB. An ecologic study of dietary links to prostate cancer. Altern Med Rev 1999; 4: 162-9.
[8]. Kushi LH, Mink PJ, Folsom AR, et al. Prospective study of diet and ovarian cancer. Am J Epidemiol 1999; 149: 21-31.
[9]. Fairfield KM, Hunter DJ, Colditz GA, et al. A prospective study of dietary lactose and ovarian cancer. Int J Cancer 2004; 110: 271-7
[10]. Schwartz GG, Hulka BS. Is vitamin D deficiency a risk factor for prostate cancer? (Hypothesis). Anticancer Res 1990; 10: 1307-11.
[11]. Miller A, Stanton C, Murphy J, Devery R. Conjugated linoleic acid (CLA)-enriched milk fat inhibits growth and modulates CLA-responsive biomarkers in MCF-7 and SW480 human cancer cell lines. Br J Nutr 2003; 90: 877-85.
[12]. O'Shea M, Devery R, Lawless F, et al. Milk fat conjugated linoleic acid (CLA) inhibits growth of human mammary MCF-7 cancer cells. Anticancer Res 2000; 20: 3591-601.
[13]. Larsson SC, Bergkvist L, Wolk A. High-fat dairy food and conjugated linoleic acid intakes in relation to colorectal cancer incidence in the Swedish Mammography Cohort. Am J Clin Nutr 2005; 82: 894-900.
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