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In a study of three socio-economic groups in Hong Kong, the high income group had a high faecal concentration of bile acids, especially the dihydroxy bile acids, compared to the low income group. The faecal bile acids were also more highly degraded. The faecal flora contained more bacteroides and fewer eubacteria. Very few of the clostridia able to dehydrogenate the steroid nucleus were isolated. An epidemiological study based on street blocks indicated that the high income group also have a higher incidence of cancer of the large bowel and of the breast. The results are discussed in terms of theories on the aetiology of large bowel cancer.

A comparison of dietary intake and faecal characteristics in population samples from two areas of Denmark and Finland with 4-fold variation in colon-cancer incidence suggests that the aetiology of colon cancer may be multifactorial and is not associated in a simple manner with dietary fat, neutral steroids, acid steroids, or their bacterial metabolites. However, meat consumption was greater in the high-incidence areas. Higher intakes of dietary fibre and milk in the low-incidence area suggest a possible protective effect, unrelated to mouth-anus transit-time. Further careful dietary and metabolic studies are needed to clarify the relationships between possible carcinogenic and protective effects of diet.

The food consumption, including type and quantity of dietary fiber, of male population samples in Copenhagen, Denmark, and Kuopio, Finland, with a fourfold difference in incidence of colon cancer was studied. A cohort of male brewery workers in Copenhagen, who consumed approximately four times more beer than did the population at large, was investigated for the development of colorectal cancer. The results suggest that there is a protective effect of dietary fiber, which is not related to mouth to anus transit time, against the development of colon cancer. Beer consumption is unrelated to the development of colorectal cancer.

The cause of death in 1951-1977 and cancer morbidity in 1959-73 were determined in 1094 (99.6%) eligible spouses of 1716 persons in Sweden who died from colon and rectum cancer in 1961. The risk of colorectal cancer and other possibly aetiologically related diseases was no higher in the spouses than in a matched population.

The suggested association between high consumption of beer and an increased risk of death from cancer of the colon and rectum was investigated among blue-collar workers at a Dublin brewery, who consume more than average amounts of beer, usually in the form of stout. A study of their mortality between 1954 and 1973 showed that they had as good an expectation of life as all Dublin males, with no increased risk of death from cancer of the oesophagus, pharynx, liver or of cirrhosis of the liver, accidents or suicide, conditions normally associated with the high consumption of alcohol. They had significantly increased risk of death from cancer of the rectum and also from diabetes mellitus. Twenty per cent of the workers, differentiated by their place of work within the brewery, had a much higher risk of death from cancer of the rectum.

In samples of adult men from two Scandinavian populations with 4-fold differences in colon cancer incidence, a comparison was made of estimated food records over 4 days, defecation habits, mouth-to-anus transit time, and stool weight. The "high incidence" group consumed more white wheat breads and total meat and beer, but less potatoes and milk than the "low incidence" group. Defecation habits were similar. Transit time and stool weight had few significant correlations with diet and defecation habits, but stool weights were higher in the low incidence group. The results are consistent with a possible protective role of dietary fiber, unrelated to transit time.

Some 30 randomly selected men, aged 50-59 years, were investigated in each of 4 areas--Copenhagen, Them (rural Denmark), Helsinki, and Parikkala (rural Finland)--to determine the relationship of diet, gut transit time, fecal bulk, fecal bacteriology, bile acid concentration, and urinary volatile phenol production to large bowel cancer risk. Average daily fat intake was found to be high in all 4 areas, and no differences emerged between areas. Saturated fatty acid consumption was higher in low-incidence areas than in high-incidence areas. Intakes of nonstarch polysaccharides (the main component of dietary fiber), carbohydrate, and protein (mainly milk) were higher in the low-incidence area of Parikkala than in the high-incidence area of Copenhagen. The fecal bile acid concentration was higher in the high-incidence area than in the low-incidence area, with the other 2 areas having intermediate values. Fecal bulk showed an inverse association with colorectal cancer incidence. No differences were observed with regard to fecal bacteriology or mutagenic activity of the foods. These results indicate that a population can have a low risk of colorectal cancer despite a high intake of dietary fat, protein, and meat. Dietary carbohydrate and fiber may be considered protective. One mechanism limiting colorectal cancer risk could be the increase in fecal bulk resulting from such intakes, since increased fecal bulk dilutes the increased colonic bile acid concentrations of subjects on high-fat diets.