Table 1.
Participants’ characteristics in all four seasons
| Seasona | pb | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Winter (n = 81) | Spring (n = 84) | Summer (n = 83) | Autumn (n = 85) | |||||||
| Sex, n (%) | Male | 55 | 67.9 | 56 | 66.7 | 55 | 66.3 | 56 | 65.9 | |
| Female | 26 | 32.1 | 28 | 33.3 | 28 | 33.7 | 29 | 34.1 | ||
| Smoking status, n (%)c | Never-smoker | 53 | 65.4 | 56 | 66.7 | 55 | 66.3 | 56 | 65.9 | |
| Past-smoker | 14 | 17.3 | 15 | 17.9 | 14 | 16.9 | 15 | 17.6 | ||
| Smoker | 14 | 17.3 | 13 | 15.5 | 14 | 16.9 | 14 | 16.5 | ||
| Age (years)c | 43.4 | 9.4 | 43.4 | 9.4 | 43.4 | 9.4 | 43.3 | 9.4 | ||
| Physical activity (METs•h/day)c | 10.6 | 6.8 | 10.7 | 7.0 | 10.8 | 6.9 | 10.7 | 6.9 | ||
| BMI (kg/m2) | 23.3 | 3.8 | 23.0 | 3.8 | 22.9 | 3.6 | 23.0 | 3.4 | 0.18 | |
| Fasting blood glucose (mg/dL) | 91.8 | 8.9 | 91.3 | 7.7 | 91.6 | 8.5 | 90.4 | 8.5 | 0.20 | |
| HbA1c (%) | 5.3 | 0.3 | 5.3 | 0.2 | 5.3 | 0.2 | 5.3 | 0.2 | 0.23 | |
| Insulin (μU/mL) | 5.8 | 4.5 | 5.6 | 4.3 | 5.3 | 4.6 | 6.5 | 9.2 | 0.55 | |
| HOMA-IR | 1.3 | 1.1 | 1.3 | 1.1 | 1.2 | 1.2 | 1.5 | 2.2 | 0.66 | |
| Shannon diversity indexd | 2.72 | 0.27 | 2.61 | 0.23 | 2.62 | 0.22 | 2.6 | 0.22 | < 0.001 | |
| Energy intake (kcal/day) | 1975 | 390 | 1899 | 470 | 1906 | 442 | 1953 | 461 | 0.06 | |
| Ethanol intake (g/day) | 0.6 | 0.2, 6.0 | 0.4 | 0.1, 9.9 | 0.5 | 0.2, 8.9 | 0.4 | 0.1, 4.5 | 0.25 | |
| Green tea (mL/day)d | 443 | 417 | 341 | 365 | 333 | 333 | 372 | 358 | < 0.01 | |
| Catechins (mg/day) | 67.8 | 23.2, 150.1 | 61.2 | 1.1, 176.6 | 84.9 | 0.6, 184.9 | 90.7 | 25.4, 250.1 | 0.34 | |
| EGCG (mg/day) | 9.5 | 0.9, 26.9 | 7.6 | 0.1, 27.6 | 8.3 | 0.1, 37.3 | 18.2 | 4.5, 49.8 | 0.046 | |
| Green tea (mL/1,000 kcal)e | 229 | 226 | 186 | 195 | 179 | 180 | 200 | 196 | 0.049 | |
| Catechins (mg/1,000 kcal) | 35.0 | 11.6, 75.6 | 29.4 | 0.8, 116.5 | 43.4 | 0.3, 127.9 | 42.4 | 11.2, 146.1 | 0.51 | |
| EGCG (mg/1,000 kcal) | 5.3 | 0.5, 13.9 | 3.7 | 0.04, 14.6 | 3.8 | 0.1, 17.3 | 9.8 | 2.1, 29.5 | 0.09 | |
METs, metabolic equivalents; BMI, body mass index; HbA1c, glycated hemoglobin A1c; HOMA-IR, homeostatic model assessment index of insulin resistance; EGCG, epigallocatechin-3-gallate
aContinuous data are expressed as mean and standard deviation or median and interquartile range, while categorical data are expressed as number and percentage
bFor comparisons between the seasons, p values were estimated by repeated-measures analysis of variance, and p values of < 0.05 are shown in bold
cThe following variables were measured only in the first season (winter), and their values were used as representative values for the remaining three seasons: age, smoking status, and physical activity
dLower in spring, summer, and autumn compared with that in winter (Dunnett’s multiple comparisons test p < 0.05)
eLower in summer compared with that in winter (Dunnett’s multiple comparisons test p < 0.05)