A cross-sectional study observing the association of psychosocial stress and dietary intake with gut microbiota genera and alpha diversity among a young adult cohort of black and white women in Birmingham, Alabama.

BACKGROUND: The relationships between psychosocial stress and diet with gut microbiota composition and diversity deserve ongoing investigation. The primary aim of this study was to examine the associations of psychosocial stress measures and dietary variables with gut microbiota genera abundance and alpha diversity among young adult, black and white females. The secondary aim was to explore mediators of psychosocial stress and gut microbiota diversity and abundance. METHODS: Data on 60 females who self-identified as African American (AA; n = 29) or European American (EA; n = 31) aged 21-45 years were included. Cortisol was measured in hair and saliva, and 16S analysis of stool samples were conducted. Discrimination experiences (recent and lifetime), perceived stress, and depression were evaluated based on validated instruments. Spearman correlations were performed to evaluate the influence of psychosocial stressors, cortisol measures, and dietary variables on gut microbiota genus abundance and alpha diversity measured by amplicon sequence variant (ASV) count. Mediation analyses assessed the role of select dietary variables and cortisol measures on the associations between psychosocial stress, Alistipes and Blautia abundance, and ASV count. RESULTS: AA females were found to have significantly lower ASV count and Blautia abundance. Results for the spearman correlations assessing the influence of psychosocial stress and dietary variables on gut microbiota abundance and ASV count were varied. Finally, diet nor cortisol was found to partially or fully mediate the associations between subjective stress measures, ASV count, and Alistipes and Blautia abundance. CONCLUSION: In this cross-sectional study, AA females had lower alpha diversity and Blautia abundance compared to EA females. Some psychosocial stressors and dietary variables were found to be correlated with ASV count and few gut microbiota genera. Larger scale studies are needed to explore the relationships among psychosocial stress, diet and the gut microbiome.

Body fat percentage assessment using skinfold thickness agrees with measures obtained by DXA scan in African American and Caucasian American women.

Dual-energy x-ray absorptiometry (DXA) is considered to have high accuracy in estimating fat mass; however, DXA is not always available. We hypothesized that the equations most commonly used for predicting body fat percentage (BF%) using skinfold thickness agree with direct measures of BF% obtained by DXA scan in African American (AA) and Caucasian American (CA) women. Data from 42 women from Alabama who were 21 to 45 years of age, who self-identify as AA (n = 20) or CA (n = 22) were included. BF% was estimated using DXA scan and through 6 different skinfold thickness equations. Agreement between DXA-BF% and BF% based on the skinfold thickness equations was assessed following the Bland-Altman method (bias and agreement limits). Agreement analysis showed in both AA and CA women that the BF%-Siri equation reflects better agreement and lower mean differences (bias) with BF%-DXA than the BF%-Brozek equation after applying 4 body density (BD) equations. Limits showed that BF%-Siri and BF%-Brozek predictive equations overestimate BF% compared with DXA-BF% in both AA and CA women. In AAs, equations that overestimated less were Wilmore and Behnke-Siri (by 1.81%) and Durnin and Womersley-Siri (by 2.5%) equations. Regarding CAs, equations that overestimated less were Durnin and Womersley-Siri (by 2.74%) and Wilmore and Behnke-Siri (by 3.11%) equations. The results of this study show that the BF%-Siri equation is a more accurate alternative than the BF%-Brozek equation for the calculation of BF%. In the calculation of BD, the Wilmore and Behnke equation in AA women and Durnin and Womersley in CA women were those that overestimated BF% to a lesser degree.