Lifestyle and Colorectal Cancer Risk
As per the World Health Organization GLOBOCAN database, in 2008 approximately 1.2 million new cases of CRC were diagnosed and 608,000 people died of CRC. Recent studies show that the risk of a colorectal cancer is associated with lifestyle related issues. The Cleveland Clinic colon cancer risk assessment surveyed around 27,000 volunteers all over the world. The study highlights the modifiable risk factors, such as diet and lifestyle behaviors, reported by patients without a personal history of colorectal cancer and polyps.
The survey results reflected that less than 10 percent of all respondents ate five or more servings of fruit, vegetables and grains per day and only about 25 percent undertook at least 30 minutes of exercise four times per week.
It is observed that the balance between genetic predisposition and these factors, including nutritional components and lifestyle behaviors, determines individual susceptibility to develop colorectal cancer.
Diet and lifestyle.
Earlier it was hypothesized that there is a close linkage between diet and bowel cancer based on the on the observation that in the areas of low incidence of this excrescency (Africa, Asia) the consumption of fiber is greater than in the Western world which in turn have a meat rich diet with added preservatives. A high-fiber diet consists mainly of vegetables, fruits, and grains. Their presence in meals contributes to decreased transit time through the gastrointestinal tract, dilution of colonic contents, and enhancement of bacterial fermentation, which leads to increased production of short-chain fatty acids (acetate, propionate, and butyrate). Moreover, these substances were found to induce apoptosis in CRC cells in rats. Dietary fiber has also been proved to have an anti-inflammatory function, decreasing the production of IL-6 and TNFα and cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) gene expression. Additionally, short-chain fatty acids interfere with numerous regulators of the cell cycle, proliferation, and apoptosis, such as β-catenin, p53, p21, Bax, and caspase 3 genes in an animal model of CRC. A meta-analysis based on 13 retrospective cohort studies presented by Howe et al. in 1992 indicated that the risk of CRC is reduced by approximately 50 % in individuals who consume a high-fiber diet in comparison with the general population.
Physical exercises also contribute in lowering the risk levels as the key mechanisms that explain the protective role of physical activity focus on increased insulin sensitivity, lower insulin levels, decreased body mass, and decreased adipose tissue volume, leading to reduction of chronic inflammation. This inflammation in turn makes cells carcinogenic.
References
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