Differences in Fecal Gut Microbiota, Short-Chain Fatty Acids and Bile Acids Link Colorectal Cancer Risk to Dietary Changes Associated with Urbanization Among Zimbabweans.

The incidence of colorectal cancer (CRC) is gradually rising in sub-Saharan Africa. This may be due to dietary changes associated with urbanization, which may induce tumor-promoting gut microbiota composition and function. We compared fecal microbiota composition and activity in 10 rural and 10 urban Zimbabweans for evidence of a differential CRC risk. Dietary intake was assessed by a food frequency questionnaire. Fecal microbiota composition, metabolomic profile, functional microbial genes were analyzed, and bile acids and short chain fatty acids quantified. Animal protein intake was higher among urban volunteers, but carbohydrate and fiber intake were similar. Bacteria related to Blautia obeum, Streptococcus bovis, and Subdoligranulum variabile were higher in urban residents, whereas bacteria related to Oscillospira guillermondii and Sporobacter termitidis were higher in rural volunteers. Fecal levels of primary bile acids, cholic acid, and chenodeoxycholic acid (P < 0.05), and secondary bile acids, deoxycholic acid (P < 0.05) and ursodeoxycholic acid (P < 0.001) were higher in urban residents. Fecal levels of acetate and propionate, but not butyrate, were higher in urban residents. The gut microbiota composition and activity among rural and urban Zimbabweans retain significant homogeneity (possibly due to retention of dietary fiber), but urban residents have subtle changes, which may indicate a higher CRC risk.

Glucose tolerance study in low and normal birth weight young adults.

Objective: To determine blood glucose levels by conducting an oral glucose tolerance test in low and normal birth weight young black adults. Design: Acase control study was done. Seventy students in the College of Health Sciences who had neonatal clinic cards as proof of birth weight were recruited into the study. Blood glucose levels were measured before, during and after the oral glucose tolerance test. Setting: Department of Physiology, University of Zimbabwe, College of Health Sciences, Harare, Zimbabwe. Main Outcome Measures and Results: A total of 70 young adult participants, 47(67%) females and 23(33%)males with mean age 20.28±0.19 years were recruited. 30 had Low Birth Weight (LBW, 21 females and 9 males) and 40 had Normal Birth Weight (NBW,26 females and 14 males).LBW individuals had significantly elevated (p<0.05) mean blood glucose levels at 30minutes(9.41±0.91 for LBW and 7.24±0.28 for NBW, p=0.029) and 60 minutes (9.22±0.75 for LBW and 7.57±0.36 for NBW, p=0.035) after the oral glucose tolerance test. Oral glucose tolerance testing detected 1case of type II diabetes (LBW individual), 13cases of impaired glucose tolerance (9 LBW and 4 NBW individuals)and 1 case of impaired fasting glucose (LBW individual).LBW was associated with an odds ratio of 3.1 for impaired glucose tolerance and it was statistically significant, p<0.05 (p=0.027). Conclusion: Low birth weight was associated with glucose intolerance and significantly higher mean blood glucose levels at 30 and 60 minutes after glucose loading in young adults.