Table 2.
Association of α-diversity metrics with coffee and tea intake as categorical or continuous variables.
| Categorical | Continuous | ||||||
|---|---|---|---|---|---|---|---|
| β (95% CI)a | P-trendb | β (95% CI)a | P | ||||
| Coffee | None (n=129) |
<1 c/day (n=139) |
[1-3) c/day (n=354) |
≥3 c/day (n=316) |
Per cup per day | ||
| Richness | Ref. | −0.72 (−9.042, 7.602) | −3.752 (−10.982, 3.477) | −3.732 (−10.985, 3.521) | 0.218 | −0.216 (−1.038, 0.606) | 0.606 |
| Shannon index | Ref. | 0.021 (−0.138, 0.18) | −0.04 (−0.178, 0.099) | −0.029 (−0.168, 0.11) | 0.483 | 0.002 (−0.013, 0.018) | 0.777 |
| Evenness | Ref. | 0.005 (−0.012, 0.022) | −0.001 (−0.016, 0.014) | 0 (−0.015, 0.015) | 0.744 | 0.001 (−0.001, 0.002) | 0.528 |
| Tea | None (n=231) |
<1 c/day (n=498) |
[1-3) c/day (n=140) |
≥3 c/day (n=69) |
Per cup per day | ||
| Richness | Ref. | −0.883 (−6.408, 4.641) | 9.465 (2.052, 16.878) | 2.717 (−6.756, 12.189) | 0.065 | 1.473 (0.015, 2.931) | 0.048 |
| Shannon index | Ref. | −0.042 (−0.148, 0.064) | 0.166 (0.024, 0.308) | 0.143 (−0.038, 0.324) | 0.013 | 0.039 (0.011, 0.067) | 0.006 |
| Evenness | Ref. | −0.005 (−0.017, 0.006) | 0.011 (−0.004, 0.026) | 0.018 (−0.001, 0.037) | 0.024 | 0.004 (0.001, 0.007) | 0.009 |
a
Parameters are from linear regression models with specified α-diversity metric (averaged over 100 iterations of rarefied OTU table at 3,000 sequence reads/sample) as outcome. All models were adjusted for age, sex, study (CPS-IIa, CPS-IIb, PLCOa, PLCOb), current smoking, BMI (kg/m2), energy intake (kcal/day), ethanol intake (grams/day), and coffee or tea intake (cups/day; in tea and coffee models, respectively).
b
Trend tests across groups were done by entering the categorical variables into the models as continuous terms.