Diet changes due to urbanization in South Africa are linked to microbiome and metabolome signatures of Westernization and colorectal cancer

Transition from traditional high-fiber to Western diets in urbanizing communities of Sub-Saharan Africa is associated with increased risk of non-communicable diseases (NCD), exemplified by colorectal cancer (CRC) risk. To investigate how urbanization gives rise to microbial patterns that may be amenable by dietary intervention, we analyzed diet intake, fecal 16 S bacteriome, virome, and metabolome in a cross-sectional study in healthy rural and urban Xhosa people (South Africa). Urban Xhosa individuals had higher intakes of energy (urban: 3,578 ± 455; rural: 2,185 ± 179 kcal/d), fat and animal protein. This was associated with lower fecal bacteriome diversity and a shift from genera favoring degradation of complex carbohydrates (e.g., Prevotella) to taxa previously shown to be associated with bile acid metabolism and CRC. Urban Xhosa individuals had higher fecal levels of deoxycholic acid, shown to be associated with higher CRC risk, but similar short-chain fatty acid concentrations compared with rural individuals. Fecal virome composition was associated with distinct gut bacterial communities across urbanization, characterized by different dominant host bacteria (urban: Bacteriodota; rural: unassigned taxa) and variable correlation with fecal metabolites and dietary nutrients. Food and skin microbiota samples showed compositional differences along the urbanization gradient. Rural-urban dietary transition in South Africa is linked to major changes in the gut microbiome and metabolome. Further studies are needed to prove cause and identify whether restoration of specific components of the traditional diet will arrest the accelerating rise in NCDs in Sub-Saharan Africa.

The association of fasting plasma sulfur-containing compounds with BMI, serum lipids and apolipoproteins

BACKGROUND AND AIM

Sulfur amino acids are recognized as potent modulators of lipid metabolism. Plasma total cysteine (tCys) is associated with fat mass, obesity and serum LDL-cholesterol and apolipoprotein (Apo)-B in large population studies. It is not known how fasting plasma concentrations of cysteine precursors and products relate to these associations in humans, given that sulfur-containing compounds (SCC) influence rodent weight gain and serum lipids.

METHODS AND RESULTS

We investigated the cross-sectional associations of fasting plasma SCC (methionine, total homocysteine, cystathionine, tCys, taurine and total glutathione) with BMI and fasting serum lipids and apolipoproteins in 854 men and women with and without cardiovascular disease (CVD). In multiple linear regression analysis adjusted for age, gender, CVD and other SCC, neither methionine, taurine, nor total glutathione was associated with BMI. Plasma taurine was, however, inversely related to HDL-cholesterol (partial r = -0.12, p = 0.004) and its associated apoA1 (partial r = -0.18, p < 0.001). Plasma cystathionine correlated positively with triglycerides and BMI, while tCys positively correlated with total cholesterol, LDL-cholesterol (partial r = 0.20, p < 0.001) and its associated apoB. The associations of SCC with serum lipids were independent of BMI. tCys was also independently associated with BMI (partial r = 0.20, p < 0.001) after adjustment for other SCC, glucose, lipids and apolipoproteins.

CONCLUSIONS

Fasting tCys is associated with BMI independently of metabolically related SCC. Elevation of plasma SCC is generally associated with an unfavorable lipid profile. The negative relations of plasma taurine with HDL-C and apoA1 deserve further investigation.