Sex, Body Mass Index, and Dietary Fiber Intake Influence the Human Gut Microbiome

<div><p>Increasing evidence suggests that the composition of the human gut microbiome is important in the etiology of human diseases; however, the personal factors that influence the gut microbiome composition are poorly characterized. Animal models point to sex hormone-related differentials in microbiome composition. In this study, we investigated the relationship of sex, body mass index (BMI) and dietary fiber intake with the gut microbiome in 82 humans. We sequenced fecal 16S rRNA genes by 454 FLX technology, then clustered and classified the reads to microbial genomes using the QIIME pipeline. Relationships of sex, BMI, and fiber intake with overall gut microbiome composition and specific taxon abundances were assessed by permutational MANOVA and multivariate logistic regression, respectively. We found that sex was associated with the gut microbiome composition overall (p=0.001). The gut microbiome in women was characterized by a lower abundance of Bacteroidetes (p=0.03). BMI (>25 kg/m²<i>vs</i>. <25 kg/m²) was associated with the gut microbiome composition overall (p=0.05), and this relationship was strong in women (p=0.03) but not in men (p=0.29). Fiber from beans and from fruits and vegetables were associated, respectively, with greater abundance of Actinobacteria (p=0.006 and false discovery rate adjusted q=0.05) and Clostridia (p=0.009 and false discovery rate adjusted q=0.09). Our findings suggest that sex, BMI, and dietary fiber contribute to shaping the gut microbiome in humans. Better understanding of these relationships may have significant implications for gastrointestinal health and disease prevention.</p></div

Sweetened Beverages, Coffee, and Tea and Depression Risk among Older US Adults

<div><p>Sweetened beverages, coffee, and tea are the most consumed non-alcoholic beverages and may have important health consequences. We prospectively evaluated the consumption of various types of beverages assessed in 1995–1996 in relation to self-reported depression diagnosis after 2000 among 263,923 participants of the NIH-AARP Diet and Health Study. Odds ratios (OR) and 95% confidence intervals (CI) were derived from multivariate logistic regressions. The OR (95% CI) comparing ≥4 cans/cups per day with none were 1.30 (95%CI: 1.17–1.44) for soft drinks, 1.38 (1.15–1.65) for fruit drinks, and 0.91 (0.84–0.98) for coffee (all <i>P</i> for trend<0.0001). Null associations were observed for iced-tea and hot tea. In stratified analyses by drinkers of primarily diet versus regular beverages, the ORs were 1.31 (1.16–1.47) for diet versus 1.22 (1.03–1.45) for regular soft drinks, 1.51 (1.18–1.92) for diet versus 1.08 (0.79–1.46) for regular fruit drinks, and 1.25 (1.10–1.41) for diet versus 0.94 (0.83–1.08) for regular sweetened iced-tea. Finally, compared to nondrinkers, drinking coffee or tea without any sweetener was associated with a lower risk for depression, adding artificial sweeteners, but not sugar or honey, was associated with higher risks. Frequent consumption of sweetened beverages, especially diet drinks, may increase depression risk among older adults, whereas coffee consumption may lower the risk.</p></div

Population Characteristics.

<p>¹All characteristics were compared by sex using either Chi square or Mann-Whitney-Wilcoxon tests. All analyses were carried out using SAS software (version 9.3).</p><p>²Race was grouped as White and Other for Chi square test.</p><p>Population Characteristics.</p

Odds ratios^a and 95% confidence intervals of depression according to types of sweetener added to coffee or tea in the NIH-AARP Diet and Health Study, 1995–2006.

<p>Abbreviations: CI, confidence interval; OR, odds ratio;</p>a<p>Adjusted for age at baseline, sex, race, education, marital status, smoking, alcoholic beverage intake, physical activity, body mass index, and energy intake.</p

Odds ratios^a and 95% confidence intervals of depression according to baseline beverage consumption in the NIH-AARP Diet and Health Study, 1995–2006.

<p>Abbreviations: CI, confidence interval; OR, odds ratio;</p>a<p>Adjusted for age at baseline, sex, race, education, marital status, smoking, alcoholic beverage intake, physical activity, body mass index, and energy intake.</p>b<p>Numbers may not add up to total due to missing.</p

Odds ratios^a and 95% confidence intervals of depression according to baseline consumption of regular or diet sweetened beverages in the NIH-AARP Diet and Health Study, 1995–2006.

<p>Abbreviations: CI, confidence interval; OR, odds ratio.</p>a<p>Adjusted for age at baseline, sex, race, education, marital status, smoking, alcoholic beverage intake, physical activity and body mass index, and energy intake.</p>b<p>Numbers may not add up to total due to missing.</p

Gut microbiome according to BMI in women and men separately.

<p>Unweighted principal coordinate analysis plot of the first two principal coordinates categorized by BMI (<25 kg/m², ≥25 kg/m²) in (A) women and (B) men. Ellipses were added to plots using the R package, latticeExtra (R version 2.15.3). Alpha rarefaction plots of Shannon diversity indices grouped by normal weight (<25 kg/m²; open circles) and overweight/obese (≥25 kg/m²; red circles) status for women (C) and for men (D). Statistical significance was assessed by non-parametric Monte Carlo permutations (QIIME). (E) Relative abundance of Firmicures and Bacteroidetes. Mann-Whitney-Wilcoxon test was used to test for overall differences using SAS software (version 9.3).</p

Odds ratios^a and 95% confidence intervals of depression according to baseline consumption of caffeinated or decaffeinated beverages in the NIH-AARP Diet and Health Study, 1995–2006.

<p>Abbreviations: CI, confidence interval; OR, odds ratio.</p>a<p>Adjusted for age at baseline, sex, race, education, marital status, smoking, alcoholic beverage intake, physical activity, body mass index, and energy intake.</p>b<p>Numbers may not add up to total due to missing.</p

PERMANOVA¹ analysis of personal factors with the unweighted UniFrac distance matrix.

<p>¹Adonis, which uses permutational multivariate analysis of variance (PERMANOVA), was used to test statistical significances of association of overall composition with personal factors. All analyses were carried out using the QIIME pipeline.</p><p>²BMI was categorized as normal weight (<25 kg/m²) versus overweight or obese (≥25 kg/m²).</p><p>³Total and specific sources of dietary fiber were categorized as low (quartiles 1–3) versus high (quartile 4) intake.</p><p>PERMANOVA<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124599#t002fn001" target="_blank">¹</a> analysis of personal factors with the unweighted UniFrac distance matrix.</p

Gut microbiome according to sex.

<p>(A) Unweighted principal coordinate analysis plot of the first two principal coordinates categorized by sex. Ellipses were added to plots using the R package, latticeExtra (R version 2.15.3). (B) Relative abundance of the three major phyla. Mann-Whitney-Wilcoxon test was used to test for overall differences using SAS software (version 9.3). Nominal p-values are listed below each phylum.</p