Table 2.

Effects of age groups and various potential confounders on gut microbiome compositional differences

Factor	R2 value	p-value
Age groups	0.028	0.098
Age	0.015	0.089
Sex	0.012	0.399
BMIa	0.016	0.155
Race	0.025	0.435
Smoking status	0.029	0.117
Dietary intakeb
Total energy	0.015	0.211
Total protein	0.015	0.218
Total fat	0.014	0.222
Saturated fatty acids  Monounsaturated fatty acids  Polyunsaturated fatty acids	0.016 0.014 0.011	0.131 0.279 0.718
Total carbohydrate	0.015	0.214
Starch  Sugar	0.014 0.017	0.306 0.079
Total fiber	0.014	0.299
Vitamin A	0.013	0.436
Vitamin C	0.013	0.510
Calcium	0.015	0.251
Iron	0.014	0.301
β-carotene	0.011	0.727
Thiamin	0.014	0.290
Riboflavin	0.015	0.210
Potassium	0.014	0.270
Zinc	0.013	0.464

All datasets were first transformed using centered log-ratio transformation to account for compositionality. The Euclidean distance was then used for permutational multivariate analysis of variance (PERMANOVA). The R² value indicates the effect size, while p-value < 0.05 is considered significant. ^aCalculated based on 75 samples. ^bCalculated based on 79 samples