Wednesday, 14 January 2015

2. Diet and Prostate Cancer

The synopsis below is from the report on Prostate Cancer and Nutrition, by  Stanley A Brosman, MD  Clinical Professor, Department of Urology, University of California in Medscape, (updated October 2014).

     Prostate cancer has become such a frequently diagnosed condition that much research has been undertaken to understand its etiologic factors and how its onset can be prevented or delayed. Although the primary risk factor for developing prostate cancer is aging, the role of diet and nutrition in the development and progression of this and other cancers has received increasing attention.
     In 2002, the American Institute for Cancer Research published a study concluding that 200,000 of the 600,000 cancer deaths in the United States each year could be prevented through a combination of dietary changes, adequate physical activity, and maintenance of appropriate body weight. The report also noted that avoidance of tobacco and alcohol could prevent an additional one third of cancers. The study was carried out by a panel of 16 experts, who reviewed 4500 studies related to diet and cancer.
     In 1982, The National Academy of Science presented convincing evidence concerning the relationship between dietary fat and cancer. Dietary factors identified as having an etiologic role in prostate cancer include excessive fat intake, obesity, excessive intake of estrogens and phytoestrogens, and the consumption of burned or charred foods.
     The principal message from nutritional studies and cancer in humans has been an endorsement of the benefits of a diet consisting mainly vegetables, fruits, grains, and fish, combined with restricted caloric intake and exercise. Such a diet provides multiple micronutrients packaged in their most effective form. For example, whole-grain bread provides fiber, iron, vitamin E, and folate. Fruit juices such as pomegranate juice provide antioxidants.
A set of dietary principles derived from areas in which evidence of a dietary influence on cancer risk in general is substantial, even if not conclusive, have been agreed:  
1.  Limit or avoid dairy products.  
         2.  Avoid grilled, fried or broiled meat.  
               3.  Emphasise fruit and vegetables in diet.

     Dietary modifications, coupled with exercise and lifestyle modifications, may affect cancer growth rates. These measures can be used in concert with currently accepted therapy. Relying on diet alone to treat prostate or any other cancer is unrealistic.  

Dr Brosman's report is necessarily cautious and reflects current medical thinking. The apparent benefits of a diet consisting mainly of vegetables, fruits, grains and fish combined with restricted caloric intake and exercise is acknowledged and endorsed. However cancer prevention, treatment or cure through a dietary regime is not accepted, presumably because the such dietary effects have yet to be verified by controlled medical research. The report emphasizes the difficulty of such research, "given the inherent heterogeneity of any study population, the variations in individual lifestyles, and the quantitative and qualitative complexity in food and food products"  To this can be added the very long time factor and cost such research would entail, which means that such a research project is not going to happen. 

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