Table 1.
Baseline characteristics of the study population according to tertiles of Mediterranean diet adherence.
| Variables | 1st Tertile n = 30 MD score ≤3 | 2nd Tertile n = 49 MD score 4–5 | 3rd Tertile n = 27 MD score ≥6 | P-value |
|---|---|---|---|---|
| MD score*; median [Pc25-Pc75] | 3 [2–3]a | 4 [4–5]b | 6 [6–7]c | <0.001 |
| Demographic parameters | ||||
| Age (years); mean (±SD) | 24.1 (±4.5) | 24.1 (±4.6) | 26.3 (±4.8) | 0.100 |
| Energy (kcal); mean (±SD) | 2418 (±701)a | 2860 (±836)b,c | 3192 (±720)c | 0.001 |
| BMI (kg/m2); mean (±SD) | 22.5 (±2.3)a | 24.3 (±3.7)b,c | 24.4 (±2.5)c | 0.021 |
| Waist circumference (cm); mean (±SD) | 78.4 (±5.6)a | 81.5 (±9.3)a,b | 84.6 (±6.8)b | 0.014 |
| Systolic blood pressure (mmHg); mean (±SD) | 126.3 (±11.4) | 129.0 (±9.3) | 127.0 (±11.0) | 0.571 |
| Diastolic blood pressure(mmHg); mean (±SD) | 72.6 (±7.0) | 72.1 (±9.1) | 72.7 (±7.7) | 0.946 |
| Blood parameters | ||||
| Plasma glucose (mg/dl); mean (±SD) | 88.0 (±9.3) | 87.1 (±7.2) | 88.5 (±9.1) | 0.759 |
| Total cholesterol (mg/dl); median [Pc25-Pc75] | 170.8 [150.8–182.3] | 170.8 [147.5–192.0] | 169.0 [149.0–188.0] | 0.878 |
| HDL-c (mg/dl); median [Pc25-Pc75] | 57.7 [54.8–66.3] | 56.0 [47.5–66.0] | 56.0 [48.0–59.0] | 0.467 |
| LDL-c (mg/dl); median [Pc25-Pc75] | 96.7 [76.8–105.5] | 96.7 [73.5–106.0] | 93.0 [79.0–108.0] | 0.911 |
| VLDL-c (mg/dl); median [Pc25-Pc75] | 14.1 [11.0–16.3] | 15.0 [9.5–19.5] | 13.0 [12.0–18.0] | 0.827 |
| Triglycerides (mg/dl); median [Pc25-Pc75] | 75.0 [56.5–81.6] | 76.0 [48.5–99.0] | 66.0 [59.0–88.0] | 0.739 |
| Plasma insulin (mcUI/ml); mean (±SD) | 6.1 (±3.7) | 6.8 (±5.5) | 6.2 (±5.7) | 0.794 |
| C-reactive protein (mg/dl); median [Pc25-Pc75] | 0.2 [0.2–0.2] | 0.2 [0.2–0.2] | 0.2 [0.2–0.2] | 0.985 |
| Folate (ng/ml); median [Pc25-Pc75] | 6.6 [5.7–8.9] | 6.3 [4.7–6.9] | 6.2 [4.6–8.1] | 0.150 |
| Semen/sperm parameters | ||||
| pH; median [Pc25-Pc75] | 8.0 [8.0–8.5]a | 8.0 [8.0–8.5]a,b | 8.5 [8.0–8.5]a,c | 0.023 |
| Volume (ml); median [Pc25-Pc75] | 2.8 [1.9–4.5] | 3.0 [1.9–4.6] | 3.3 [2.1–4.4] | 0.852 |
| Volume <1.5 ml; n (%) | 3 (10) | 8 (16.3) | 4 (14.8) | 0.731 |
| Total sperm count (x106); median [Pc25-Pc75] | 76.6 [30.8–139.5] | 65.0 [24.8–126.0] | 79.0 [43.5–101.0] | 0.675 |
| Total sperm count <39 × 106 spz; n (%) | 9 (30) | 19 (38.8) | 6 (22.2) | 0.321 |
| Sperm concentration (x106); median [Pc25-Pc75] | 27.6 [9.1–53.7] | 23.6 [10.0–38.1] | 25.2 [16.1–35.6] | 0.669 |
| Sperm concentration <15 × 106 spz/ml; n (%) | 11 (36.7) | 19 (38.8) | 5 (18.5) | 0.175 |
| Vitality (%); median [Pc25-Pc75] | 79.2 [69.4–82.2] | 79.3 [72.7–84.2] | 78.9 [72.7–87.9] | 0.662 |
| Vitality <58%; n (%) | 3 (10) | 2 (4.1) | 3 (11.1) | 0.451 |
| Total motility (%); median [Pc25-Pc75] | 54.5 [38.8–72.4]a | 64.4 [43.8–72.7]a,b | 73.2 [64.7–82.2]c | 0.009 |
| Total motility <40% motile; n (%) | 8 (26.7) | 7 (14.3) | 2 (7.4) | 0.127 |
| Progressive motility (%); median [Pc25-Pc75] | 40.8 [20.9–58.8]a | 41.8 [25.9–53.5]a,b | 52.2 [43.3–62.3]c | 0.013 |
| Progressive motility <32% motile; n (%) | 10 (33.3) | 17 (34.7) | 4 (14.8) | 0.160 |
| Non-progressive motility (%); median [Pc25-Pc75] | 11.1 [6.3–14.4] | 12.1 [8.6–16.1] | 12.1 [7.9–15.3] | 0.674 |
| Immotility (%); median [Pc25-Pc75] | 34.3 [25.6–53.0]a | 35.6 [27.3–56.2]a,b | 29.0 [20.1–35.9]a,c | 0.045 |
| Morphology (%); median [Pc25-Pc75] | 6.4 [4.4–8.0] | 6.5 [5.6–7.9] | 6.3 [5.0–8.0] | 0.762 |
| Morphology <4% normal; n (%) | 5 (16.7) | 5 (10.2) | 2 (7.4) | 0.515 |
| Seminogram abnormality; n (%) | 19 (63.3) | 32 (65.3) | 11 (40.7) | 0.094 |
Abbreviations. BMI: Body-mass-index, HDL-c: High-density lipoprotein cholesterol, LDL-c: Low-density lipoprotein cholesterol, MD: Mediterranean diet, n: number of subjects, Pc: percentile, spz: spermatozoa, VLDL-c: very-low-density lipoprotein cholesterol, SD: standard deviation.
*MD score (Trichopoulou et al.)18.
Continuous variables were presented as means (±SD) or medians [25th-75th percentiles (Pc)] and categorical variables are presented as number (n) and percentages (%). Differences in variables across tertiles of MD adherence were tested using ANOVA test or Kruskal–Wallis test for continuous variables. Same superscripts in different columns denote non-significant differences, while different superscript letters denote statistically significant differences in a paired comparison (after multiple comparison post-hoc Bonferroni test). Pearson chi-squared test (Fisher’s exact test) was used to compare categorical variables.