TABLE 2.
Associations between Qs of dietary vitamin C and skeletal muscle mass in men and women aged 42–82 y1
| Vitamin C | FFM% | FFMBMI | ||||
|---|---|---|---|---|---|---|
| Mean ± SD | Median | Unadjusted | Adjusted | Unadjusted | Adjusted | |
| Men (n = 6350) | ||||||
| Q1 (n = 1270) | 36.6 ± 9.33 | 38.5 | 76.2 ± 0.169 | 76.3 ± 0.128 | 2.27 ± 0.007 | 2.30 ± 0.007 |
| Q2 (n = 1270) | 57.9 ± 5.38 | 57.7 | 76.9 ± 0.161** | 76.7 ± 0.124* | 2.32 ± 0.007*** | 2.32 ± 0.007* |
| Q3 (n = 1270) | 78.4 ± 6.64 | 78.3 | 76.8 ± 0.159* | 76.7 ± 0.124* | 2.33 ± 0.007*** | 2.33 ± 0.007** |
| Q4 (n = 1270) | 107 ± 10.1 | 106 | 76.8 ± 0.166** | 76.8 ± 0.125** | 2.34 ± 0.007*** | 2.34 ± 0.007*** |
| Q5 (n = 1270) | 170 ± 44.8 | 157 | 76.9 ± 0.156*** | 77.1 ± 0.125*** | 2.36 ± 0.007*** | 2.35 ± 0.007*** |
| Q5–Q1 difference2 | — | — | 0.694 (0.244, 1.14) | 0.763 (0.404, 1.121) | 0.088 (0.068, 0.108) | 0.052 (0.032, 0.071) |
| % difference3 | — | — | 0.910 | 1.00 | 3.88 | 2.25 |
| P-trend | — | — | 0.024 | <0.001 | <0.001 | <0.001 |
| Women (n = 7989) | ||||||
| Q1 (n = 1598) | 38.9 ± 9.41 | 40.6 | 60.1 ± 0.217 | 60.3 ± 0.166 | 1.55 ± 0.007 | 1.56 ± 0.006 |
| Q2 (n = 1598) | 62.6 ± 5.93 | 62.5 | 61.0 ± 0.208** | 60.9 ± 0.162* | 1.58 ± 0.007*** | 1.58 ± 0.006* |
| Q3 (n = 1598) | 83.9 ± 6.75 | 83.6 | 61.0 ± 0.207** | 60.9 ± 0.162* | 1.59 ± 0.006*** | 1.59 ± 0.006** |
| Q4 (n = 1598) | 112 ± 9.88 | 111 | 61.0 ± 0.198** | 60.9 ± 0.163* | 1.59 ± 0.006*** | 1.58 ± 0.006** |
| Q5 (n = 1597) | 171 ± 43.4 | 159 | 61.5 ± 0.201*** | 61.5 ± 0.164*** | 1.61 ± 0.006*** | 1.61 ± 0.006*** |
| Q5–Q1 difference2 | — | — | 1.40 (0.83, 1.97) | 1.14 (0.680, 1.61) | 0.064 (0.046, 0.082) | 0.050 (0.028, 0.062) |
| % difference3 | — | — | 2.33 | 1.90 | 4.17 | 2.89 |
| P-trend | — | — | <0.001 | <0.001 | <0.001 | <0.001 |
Values are means ± SEMs. The P-trend was calculated using ANCOVA. Adjusted model includes age, total energy, protein intake as a percentage of total energy, estimated energy requirement, smoking status, physical activity, corticosteroid use, menopausal status, hormone replacement therapy use, statins use, number of days participant filled out the food diary, and social class. *,**,***Significant difference with quintile 1, according to ANCOVA: *P < 0.05; **P < 0.01; ***P < 0.001. FFMBMI, fat-free mass standardized by BMI; FFM%, fat-free mass percentage; Q, quintile.
Q5–Q1 calculates the absolute difference between the means of Q5 and Q1, with 95% CIs.
% difference calculates the percentage difference between the means of Q5 and Q1.