TABLE 3.
Associations between plasma vitamin C concentration (insufficient: <50 μmol/L and sufficient: ≥50 μmol/L) and skeletal muscle mass in men and women aged 42–82 y1
| Dietary vitamin C | Plasma vitamin C | FFM% | FFMBMI | |||||
|---|---|---|---|---|---|---|---|---|
| Vitamin C categories | Mean ± SD | Median | Mean ± SD | Median | Unadjusted | Adjusted | Unadjusted | Adjusted |
| Men (n = 5853) | ||||||||
| Insufficient (n = 2035) | 72.9 ± 39.7 | 63.4 | 35.9 ± 10.8 | 39.0 | 75.9 ± 0.131 | 75.9 ± 0.126 | 2.29 ± 0.006 | 2.30 ± 0.006 |
| Sufficient (n = 3818) | 99.0 ± 53.3 | 88.0 | 68.1 ± 16.5 | 64.0 | 77.2 ± 0.090 | 77.2 ± 0.092 | 2.35 ± 0.004 | 2.34 ± 0.004 |
| Absolute difference2 | — | — | — | — | 1.29 (0.980, 1.59) | 1.25 (0.943, 1.56) | 0.060 (0.046, 0.073) | 0.047 (0.033, 0.061) |
| % difference3 | — | — | — | — | 1.70 | 1.65 | 2.61 | 2.05 |
| P value | — | — | — | — | <0.001 | <0.001 | <0.001 | <0.001 |
| Women (n = 7212) | ||||||||
| Insufficient (n = 1212) | 73.1 ± 40.6 | 63.8 | 37.1 ± 10.1 | 40.0 | 59.3 ± 0.260 | 59.3 ± 0.235 | 1.53 ± 0.008 | 1.54 ± 0.007 |
| Sufficient (n = 6000) | 98.2 ± 51.0 | 88.4 | 75.4 ± 21.4 | 72.0 | 61.3 ± 0.103 | 61.3 ± 0.104 | 1.60 ± 0.003 | 1.60 ± 0.003 |
| Absolute difference2 | — | — | — | –– | 2.03 (1.53, 2.54) | 2.03 (1.53, 2.54) | 0.068 (0.052, 0.084) | 0.060 (0.044, 0.076) |
| % difference3 | — | — | — | — | 3.43 | 3.43 | 4.43 | 3.91 |
| P value | — | — | — | — | <0.001 | <0.001 | <0.001 | <0.001 |
1
Values are means ± SEMs. P values were calculated using ANCOVA comparing the 2 categories. Adjusted model includes age, smoking status, physical activity, corticosteroid use, menopausal status, hormone replacement therapy use, statins use, and social class. FFMBMI, fat-free mass standardized by BMI; FFM%, fat-free mass percentage.
2
Absolute difference calculates the absolute difference between means of the 2 categories, with 95% CIs.
3
% difference calculates the percentage difference between means of the 2 categories.