Colorectal Cancer in Africa: Causes, Dietary Intervention, and Lifestyle Change

Abstract

Colorectal cancer (CRC) is a menace in the global public health system. According to GLOBOCAN reports, colorectal cancer is the second most diagnosed cancer in the world with more than 1.9 million cases and 935,000 deaths in 2020 alone. Diet plays a key role in exposing humans to environmental carcinogens and anti-carcinogens, consequently mitigating or aiding in the development of various cancers. CRC is most prevalent in western countries with a high intake of saturated fats, refined carbohydrates, and processed meat. CRC was an extremely rare disease in Africa some decades ago, but the situation is fast changing. The traditional African diet consists of leafy, roots and cruciferous vegetables, fruits, roots, tubers and plantains, legumes, whole grains, and spices, all of which have been shown to possess protective effects against CRC. However, the effect of urbanization has contributed to the shift of dietary choices among the African population to consuming more ultra-processed foods with high levels of unhealthy components that have originated from colorectal cancer prevalent regions. This review evaluates the current nutritional challenges of the African diet to colorectal cancer and the potential roles of the traditional African diets and lifestyle modification in the prevention and management of colorectal cancer.

Dietary risk factors for colorectal cancer in Uganda: a case-control study

“…These staple foods have substances with anticarcinogenic properties such as polyphenols, minerals and vitamins. A high content of non-digestible carbohydrates (NDCs) such as fibre and resistant starch are found in roots and tubers [ 41 ]. Our study showed that consumption of potatoes at a frequency of two to three times/weekly was associated with a reduced likelihood of CRC.…”

“…Studies have shown that compared to potato starch, resistant starch from maize, produces more butyrate, which is preferable for colonocytes [ 42 ]. Our findings showed that the consumption of potatoes 2-3x/weekly, was protective against CRC, as it is a high-fibre food which produces short-chain fatty acids, particularly butyrate which is preferable for colonocytes and this high-fibre food also produces antioxidants [ 41 ]. The Ugandan diet tends to consist of a variety of potatoes, millet-based meals, maize and cassava, and hence, these high-fibre foods tend to be protective against CRC.…”

“…Our study showed that consumption of potatoes at a frequency of two to three times/weekly was associated with a reduced likelihood of CRC. These staple crops contain starch and nonstarch polysaccharides which are anaerobically fermented to short-chain fatty acids such as butyrate, acetate and propionate [41]. The production of butyrate from the fermentation of resistant starch is more protective against CRC than the nonstarch polysaccharides of dietary fibre [32,[41][42][43][44][45][46].…”

“…These staple crops contain starch and nonstarch polysaccharides which are anaerobically fermented to short-chain fatty acids such as butyrate, acetate and propionate [41]. The production of butyrate from the fermentation of resistant starch is more protective against CRC than the nonstarch polysaccharides of dietary fibre [32,[41][42][43][44][45][46].…”

“…To minimize this bias, controls were recruited from the surgery departments of four different specialized hospitals with diseases that had no association with dietary factors. The cases and controls recruited from private hospitals may have had a higher socioeconomic status compared to those recruited from government hospitals; however, studies have shown an inverse association between the risk of CRC and the consumption of vegetables and fruits among individuals of different socioeconomic status [68]. Similar results from controls recruited from different hospital sources suggest that their selection did not affect the results [68].…”