TABLE 3.
Effect of GlyNAC supplementation and withdrawal on mitochondrial fuel oxidation, respiratory quotient, and energy expenditure. OA received GlyNAC supplementation for 24 weeks, and GlyNAC was stopped for 12 weeks from week 24 to Week 36. Data are reported as means ± SD and median (IQR). Means are significantly different at p < 0.05
| Outcome measure | Young adults: 0‐week | Older adults: 0‐week | Older adults: after 12‐weeks on GlyNAC | Older adults: after 24‐weeks on GlyNAC | Older adults: 36‐weeks (12‐weeks after stopping GlyNAC) |
|---|---|---|---|---|---|
| YA v OA 0‐week | OA‐0‐week v OA‐12‐weeks | OA‐0‐weeks v OA‐24‐weeks | OA‐24‐weeks v OA‐36‐weeks | ||
| Fasting respiratory quotient (RQ) | 0.77 ± 0.01 | 0.84 ± 0.03 | 0.79 ± 0.04 | 0.77 ± 0.03 | 0.83 ± 0.03 |
| 0.76 (0.0) | 0.86 (0.0) | 0.80 (0.1) | 0.78 (0.0) | 0.84 (0.0) | |
| p = 0.0008 | p = 0.02 | p = 0.0000 | p = 0.0003 | ||
| Fasting mitochondrial fatty‐acid oxidation (mg/kgLM/min) | 1.7 ± 0.2 | 0.8 ± 0.3 | 1.4 ± 0.2 | 1.5 ± 0.2 | |
| 1.7 (0.3) | 0.8 (0.4) | 1.4 (0.2) | 1.5 (0.3) | ||
| p = 0.0004 | p = 0.0018 | p = 0.0002 | |||
| Fasting mitochondrial carbohydrate oxidation (mg/kgLM/min) | 1.3 ± 0.5 | 2.0 ± 0.5 | 1.7 ± 0.8 | 1.2 ± 0.5 | |
| 1.1 (0.8) | 2.1 (0.8) | 1.6 (1.2) | 1.2 (0.5) | ||
| p = 0.034 | p = 0.26 | p = 0.0026 | |||
| Energy expenditure (kcal/d) | 1530 ± 284 | 1319 ± 198 | 1280 ± 212 | 1291 ± 205 | 1252 ± 249 |
| 1535 (355) | 1294 (367) | 1202 (247) | 1269 (262) | 1242 (229) | |
| p = 0.041 | p = 0.51 | p = 0.63 | p = 0.65 |