Table 1.
Baseline characteristics according to quartiles of predicted serum vitamin D
| Quartiles of predicted serum vitamin D | p value* | ||||
|---|---|---|---|---|---|
| Q1 | Q2 | Q3 | Q4 | ||
| N | 4649 | 4648 | 4649 | 4648 | |
| Serum vitamin D predicted status (range, ng/mL) | 7.1;18.6 | 18.7;19.8 | 19.9;21.1 | 21.2;32.7 | |
| Age (years) (SD) | 41.9 (12.1) | 39.2 (11.6) | 36.4 (11.7) | 34.7 (12.1) | < 0.001 |
| Women (%) | 62.1 | 60.8 | 60.4 | 58.9 | 0.544 |
| Smoking status (%) | < 0.001 | ||||
| Never | 43.9 | 46.4 | 50.9 | 55.0 | |
| Current | 21.0 | 22.8 | 22.3 | 21.4 | |
| Former | 35.1 | 30.9 | 26.9 | 23.7 | |
| Marital status, married (%) | 61.1 | 55.3 | 45.6 | 38.1 | < 0.001 |
| Years of university (years) (SD) | 5.2 (1.6) | 5.2 (1.5) | 5.1 (1.5) | 4.9 (1.4) | < 0.001 |
| Body mass index (kg/m2) (SD) | 26.1 (3.9) | 23.5 (2.8) | 22.5 (2.8) | 21.9 (2.7) | < 0.001 |
| Weight change (%)a | 44.0 | 31.8 | 23.9 | 21.4 | < 0.001 |
| Physical activity (METs-h/wk) (SD) | 10.7 (11.8) | 15.1 (13.3) | 21.8 (16.4) | 39.7 (32.0) | < 0.001 |
| TV (hours/day) (SD) | 1.6 (1.1) | 1.6 (1.1) | 1.6 (1.1) | 1.7 (1.4) | < 0.001 |
| Siesta (hours/day) (SD) | 0.6 (0.5) | 0.6 (0.5) | 0.5 (0.5) | 0.5 (0.5) | < 0.001 |
| Sleeping hours (hours/day) (SD) | 7.2 (0.9) | 7.3 (0.8) | 7.3 (0.8) | 7.3 (0.9) | < 0.001 |
| Walking time (min/day) (SD) | 22.5 (18.4) | 25.5 (18.6) | 35.7 (23.5) | 65.7 (40.5) | < 0.001 |
| Summer sun exposure (h/day) (SD) | 0.6 (0.6) | 0.8 (0.7) | 1.2 (0.9) | 2.1 (1.8) | < 0.001 |
| Skin reaction after sun exposure (%) | < 0.001 | ||||
| Mild reaction | 74.8 | 98.3 | 99.1 | 99.3 | |
| Severe reaction | 25.2 | 1.7 | 0.9 | 0.7 | |
| Energy intake (kcal/d) (SD) | 2282 (620) | 2293 (601) | 2359 (601) | 2429 (625) | < 0.001 |
| Carbohydrate intake (% of energy) | 43.0 (7.8) | 43.3 (7.4) | 43.8 (7.3) | 44.0 (7.6) | < 0.001 |
| Protein intake (% of energy/d) | 18.5 (3.5) | 18.2 (3.3) | 18.2 (3.2) | 18.2 (3.2) | < 0.001 |
| Fat intake (% of energy) | 36.4 (6.8) | 36.4 (6.5) | 36.1 (6.4) | 36.0 (6.7) | 0.068 |
| Monounsaturated fatty acids intake (% of energy) | 16.0 (3.9) | 15.9 (3.7) | 15.7 (3.6) | 15.5 (3.7) | < 0.001 |
| Saturated fatty acids intake (% of energy) | 12.5 (3.2) | 12.6 (3.1) | 12.5 (3.2) | 12.3 (3.3) | < 0.001 |
| Polyunsaturated fatty acids intake (% of energy) | 5.2 (1.6) | 5.2 (1.6) | 5.2 (1.5) | 5.2 (1.6) | 0.999 |
| Trichopoulou’s 9-point score/Mediterranean dietary pattern (SD) | 4.2 (1.8) | 4.1 (1.8) | 4.2 (1.8) | 4.4 (1.8) | < 0.001 |
| Following special diet (%) | 10.5 | 7.0 | 6.2 | 7.5 | < 0.001 |
| Between-meal snacking (%) | 36.7 | 30.9 | 31.7 | 33.4 | < 0.001 |
| Alcohol intake (g/d) (SD) | 6.9 (11.2) | 6.7 (10.1) | 6.5 (9.3) | 6.4 (9.3) | 0.999 |
| Sugar-sweetened beverage (servings/day) | 0.2 (0.4) | 0.2 (0.4) | 0.2 (0.4) | 0.2 (0.4) | 0.68 |
| Total vitamin D intake (mcg/d)b | 6.1 (4.1) | 6.3 (4.4) | 6.9 (5.2) | 7.7 (7.5) | < 0.001 |
| Total dietary fiber intake (g/d) | 22.0 (10.1) | 21.6 (9.3) | 22.7 (9.6) | 23.9 (10.4) | < 0.001 |
| Family history of T2D (%) | 19.4 | 15.6 | 13.3 | 13.2 | < 0.001 |
| Prevalent hypertension (%) | 16.3 | 10.3 | 8.5 | 7.1 | < 0.001 |
| Prevalent CVD (%) | 1.5 | 1.3 | 1.4 | 1.5 | 0.999 |
| Prevalent cancer (%) | 3.4 | 2.8 | 2.4 | 1.9 | < 0.001 |
| Prevalent hypercholesterolemia (%) | 21.7 | 18.0 | 14.5 | 13.5 | < 0.001 |
| Prevalent hypertriglyceridemia (%) | 9.8 | 6.8 | 4.8 | 4.4 | < 0.001 |
Continuous variables are described as means (standard deviation) and categorical variables as percentages
*p values adjusted with Bonferroni’s method
aWeight gain prior baseline of 5 or more kgs
bTotal intake of dietary vitamin D and supplementation, energy adjusted by residual method (mcg/d)