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Milk Products and the Prevention of Colon Cancer

Parviz Ghadirian, Ph.D.

Director, Epidemiological Research Unit, Research Centre, Centre hospitalier de l’Université de Montréal (CRCHUM)-Hôtel-Dieu; Professor, Department of Nutrition, Faculty of Medicine, Université de Montréal

Colon cancer is the third most common cancer in males and females and the second leading cause of mortality in the Western World. It has been estimated that in Canada in 2009, a total of 22,000 individuals will develop colon cancer (12,100 males/9,900 females). The incidence rate of this cancer is higher among males than females (62 vs. 41 per 100,000 per year, respectively).1 Although genetics is a key factor, environmental factors including healthy eating and physical activity may play an even more important role in the prevention of cancer.2

The role of milk products in the etiology of colon cancer

A recent review of nutrition and cancer by the World Cancer Research Fund and the American Institute of Cancer Research concluded that: “milk probably protects against colorectal cancer.”2

A meta-analysis of 60 epidemiological studies (n >26,000) demonstrated a 22% risk reduction in adults who consumed higher quantities of milk (summary RR=0.78; 95% CI, 0.67-0.92) and a 16% risk reduction in individuals who consumed higher quantities of other milk products (summary RR=0.84; 95% CI, 0.75-0.95).3 Similarly, a recent large prospective cohort study (n>36,000) demonstrated a 28% colon cancer risk reduction in women who consumed higher quantities of milk products (RR=0.72; 95% CI, 0.61- 0.84; p<0.001) and a 15% risk reduction (RR = 85; 95% CI, 0.76-0.95; p=0.01) in men.4

Moreover, a pooled analysis of 10 prospective studies (n~5,000) from five countries also showed that individuals who consumed at least one glass of milk (250 mL) per day had a 15% lower risk of developing colon cancer (RR=0.85; 95% CI, 0.78-0.94; p=0.001) than individuals who drank little (<70 mL/day) or no milk. It is interesting to note that each additional intake of 500 mL of milk per day was associated with another 12% reduction in risk.5 A recent cohort study from Shanghai of >73,000 adult women also showed that milk intake is inversely associated with the incidence of colon cancer (RR=0.80; 95% CI, 0.4-1.3; ptrend=0.05).6

Multivariate RRs

Potential mechanisms

The components in milk products that may account for this beneficial effect include calcium, vitamin D, butyric acid, sphingolipids, probiotics, and conjugated linoleic acid (CLA).7 Research to date suggests a synergistic effect between calcium and vitamin D in preventing colon cancer.8 A study using the Swedish Mammography Cohort of 60,708 women that included approximately 15 years of follow-up suggests that consumption of higher fat milk products (especially cheese) and the CLA in dairy fat are also important factors in reducing risk. Women who consumed ≥4 servings of higher fat milk products had a 41% reduced risk of developing colorectal cancer compared to women who consumed <1 serving of higher fat milk products per day (RR=0.59; 95% CI, 0.44-0.79, ptrend=0.002); even after controlling for calcium and vitamin D intakes.9

Highlights

  • Good evidence suggests that milk and milk products may play a significant role in reducing colon cancer risk.
  • The greatest impact has been demonstrated in cancer of the distal colon.
  • Additional research will help clarify the mechanisms responsible for these benefits but, to date, calcium, vitamin D, and CLA appear to be important factors.

References

  1. Canadian Cancer Society. Statistics. 2009. http://www.cancer.ca/Canada-wide/About20%cancer/Cancer%20Statistics//Stats%20at%20grance/Colorectal%20cancer.aspx?sc_lang=en.
  2. World Cancer Research Fund/ American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer. A Global Perspective. Washington, DE: AICR, 2007.
  3. Huncharek M et al. Colorectal cancer risk and dietary intake of calcium, vitamin D, and dairy products: a meta-analysis of 26,335 cases from 60 observational studies. Nutr Cancer 2009;61(1):47-69.
  4. Park Y et al. Dairy food, calcium and risk of cancer in the NIH-AARP diet and health study. Arch Int Med 2009;169(4):391-401.
  5. Cho E et al. Dairy foods, calcium and colorectal cancer: a pooled analysis of 10 cohort studies. J Natl Cancer Inst 2004;96:1015-1022.
  6. Lee SA et al. Animal origin foods and colorectal cancer risk: a report from the Shanghai Women’s Health Study. Nutr Cancer 2008;61(12):194-205.
  7. Pufulete M. Intake of dairy products and risk of colorectal neoplasia. Nutr Res Rev 2008;21:56-67.
  8. Grau MV et al. Calcium supplementation and colorectal adenomas: results of a randomized trial. J Natl Cancer Inst 2003;95:1765-1771.
  9. Larsson SC et al. High-fat dairy food and conjugated linoleic acid intakes in relation to colorectal cancer in the Swedish Mammography Cohort. Am J Clin Nutr 2005;82:894-900.

Keywords: colon cancer, cancer prevention

Scientific Evidence Keywords

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