Ann Surg. 1977 Jul; 186(1): 97-100.

Comparison of the fecal microflora of Seventh-Day Adventists with individuals consuming a general diet. Implications concerning colonic carcinoma.

Goldberg MJ, Smith JW, Nichols RL.

Qualitative and quantitative fecal microflora was studied in a double blind fashion in 28 subjects. Fourteen were Seventh-Day Adventists, who were strict vegetarians, while the remaining 14 subjects were individuals consuming a general western diet. No statistically significant differences were identified in the fecal microflora of the two groups. The bacteriologic analysis included total aerobes and total anaerobes as well as each of the major fecal aerobes and anaerobes. This study seems to indicate that the dietary intake of animal fat and protein does not significantly alter the fecal microflora, a possibility which has previously been suggested as being part of the explanation for the higher incidence of colonic carcinoma in those who consume meat compared with vegetarians. It does not, however, invalidate the concept that dietary animal fat does increase bile acid degradation within the gastrointestinal tract, a factor which has been related to colon cancer. Future studies should be directed at identifying the factors that may be present in the gastrointestinal tracts of vegetarians which modify the ability of their colonic microflora to degrade bile acids, an essential step in the production of intraluminal carcinogens or co-carcinogens.