Milk Products and Prostate Cancer
According to the Third Expert Report by the World Cancer Research Fund and the American Institute for Cancer Research, there is no strong evidence that dairy products and diets high in calcium increase the risk of prostate cancer. While some studies have suggested an association between dairy products or calcium and an increased risk of prostate cancer, this evidence is limited and does not support a convincing or probable association.
Highlights
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Basic Facts on Prostate Cancer
Prostate cancer is the most common cancer among Canadian men (excluding non-melanoma skin cancers). About 1 in 7 men will develop prostate cancer (it is most often diagnosed after the age of 65). There is no single cause for prostate cancer, but factors known to increase the risk for developing it include:1
- Family history;
- African ancestry.
The Evidence
According to the Third Expert Report published in 2018 by the World Cancer Research Fund and the American Institute for Cancer Research, there is no strong evidence that dairy products or diets high in calcium increase the risk of prostate cancer.2 The report upheld the conclusion of the 2007 Second Expert Report3 that for a higher consumption of dairy products, the evidence suggesting an increased risk is limited. In addition, the evidence on the association between diets high in calcium and an increased risk of prostate cancer is now considered “limited suggestive”, as compared to the 2007 report, where it was considered to be strong evidence.
Potential Mechanisms
Vitamin D
Some studies have found that vitamin D deficiency could be linked to an increased risk of prostate cancer. To date, the potential association between vitamin D and prostate cancer remains unclear.4
IGF-1 (Insulin-like Growth Factor-1)
IGF-1 is a hormone needed for proper growth and development. IGF-1 is part of a multi-component IGF system, which regulates the proliferation, differentiation and apoptosis of both normal and prostate cancer cells.4
The level of IGF-1 is increased by the intake of any type of protein, whether animal or vegetable. In addition, although it has been found that the intake of one serving of milk products daily can increase IGF-1 levels, this was no longer the case after controlling for overall protein intake.5
Studies in animals and cell lines have hypothesized that IGF-1 may stimulate the rapid growth of prostate cells and inhibit cell death. However, from experimental and epidemiological data, it appears that high serum levels of IGF-1 may be a tumour marker, rather than an etiological factor for prostate cancer.4
Dietary fat
Early ecological studies have demonstrated that average total fat intake per capita was correlated to prostate cancer mortality. Since then a meta-analysis of prospective cohort studies and more recent large-scale prospective cohort studies have not found an association between dietary fat intake and the risk of prostate cancer.4
Conclusion
The totality of the scientific evidence to date does not support a strong association between dairy product consumption or calcium intake and increased risk of prostate cancer.
References
- Canadian Cancer Society. 2018. Prostate cancer. Available at www.cancer.ca . Accessed September 27, 2018.
- World Cancer Research Fund / American Institute for Cancer Research. Diet, Nutrition, Physical Activity and Cancer: a Global Perspective, Continuous Update Project Expert Report 2018. Available at dietandcancerreport.org Accessed September 27, 2018.
- World Cancer Research Fund/American Institute for Cancer Research. Food, nutrition, physical activity, and the prevention of cancer: a global perspective. Washington, DC: AICR. 2007.
- Parodi PW. Dairy product consumption and the risk of prostate cancer. Int Dairy J 2009;19:551-565.
- Giovannucci E et al. Nutritional predictors of insulin-like growth factor 1 and their relationships to cancer in men. Cancer Epidemiol Biomarkers Prev 2003;12:84-89.
Keywords: prostate cancer , cancer , calcium
