Dietary microbial modulation for colorectal cancer prevention in the Hong Kong Chinese population

A patient's risk for CRC may be determined through microbial profiling, with recent evidence showing that altered microbiome environment, or dysbiosis, in the gut and pathogenic bacterial colonies overgrowth has implications for cancer development.4 5 Some gut microbiomes—known as CRC microbial markers—have been identified as promoting colorectal tumorigenesis.5 Certain unfavourable bacteria, including Fusobacterium nucleatum, Escherichia coli, Bacteroides fragilis, Clostridium hathewayi,and Bacteroides clarus have been identified to be more abundant in patients with CRC,6 7 whereas beneficial bacteria are less abundant.8 Moreover, dysbiosis is observed in patients with CRC, among a cluster of chronic diseases, such as, inflammatory bowel disease, diabetes mellitus, and obesity.9 10The commonality among these diseases is chronic inflammation, which is an important factor in the development of CRC. [...]contemporary diets in Hong Kong and other developed regions are low in fibre, high in processed foods including food additives, refined sugar, and hydrogenated fats.14 15 In a study comparing the cancer risk in rural Africans with that in African Americans, the higher fibre, lower animal fat, and lower protein in the rural African diet were associated with reduced cancer risk.16 17 Ou et al16 also reported that microbial metabolites moderated by dietary intake can influence CRC risk. The current literature on microbial-diet-host interaction is diverse and includes metabolic cross-feeding of microbes, substrate degradation of dietary fibres, and microbiome as moderators of host physiology and behaviour.18 Traditional Chinese diet One dietary approach in lowering CRC risk involves restoring beneficial gut microbiota, thus strengthening intestinal barrier against pathogenic bacteria, increasing intestinal motility, and lowering a pro-inflammatory state.19 20 This can be achieved by adopting a diversified diet such as the Mediterranean diet, which is high in vegetables and legumes; high in fruits; high in grains; moderate in plant protein rather than animal protein; and moderate in dairy.