Table 3.
Pharmacokinetic comparative bioavailability studies in humans.
| Subjects | Intervention | Study Design | Vitamin C Analysis | Plasma Uptake | Urinary Excretion | Reference |
|---|---|---|---|---|---|---|
| 9 non-smoking males 18–35 years | 200 mg vitamin C tablet | 8 h sampling; Crossover design (3 week washout) | HPLC-ECD | Kiwifruit comparable plasma vitamin C and AUC | Kiwifruit ↑ urinary vitamin C and AUC (relative to creatinine) | [89] |
| Gold kiwifruit (200 mg vitamin C) | ||||||
| 5 non-smoking males 22–27 years | 50 mg vitamin C solution; | 8 h sampling; Crossover design (4 week washout) | HPLC-ECD | Mashed potatoes ↓ plasma vitamin C (at 1 to 2.5 h); potato chips ↓ AUC | Mashed potatoes ↓ urinary vitamin C (at 3 h) | [84] |
| 282 g mashed potato (50 mg vitamin C) | ||||||
| 87 g potato chips (50 mg vitamin C) | ||||||
| Placebo | ||||||
| 5 non-smoking males 22–26 years | 50–500 mg vitamin C solution | 6 h sampling; Crossover design | HPLC-ECD | Acerola juice comparable plasma vitamin C and AUC | Acerola juice ↓ urinary vitamin C (at 1, 2 and 5 h) | [85] |
| 100 mL acerola juice (50 mg vitamin C) | ||||||
| 12 males 20–35 years | 284 mg vitamin C drink | 4.5 h sampling; Crossover design (1 week washout) | Colorimetric (TPTZ) | Orange juice comparable bioavailability (AUC/concentration) | ND | [86] |
| 590 mL orange juice (68 mg vitamin C) | ||||||
| Placebo (milk) | ||||||
| 7 non-smoking females | 150 mg vitamin C solution | 8 h sampling; Crossover design (2 week washout) | HPLC-UV | Orange juice comparable plasma vitamin C | ND | [87] |
| 300 mL orange juice (150 mg vitamin C) | ||||||
| Placebo | ||||||
| 7 non-smokers 26–59 years | 30 mg vitamin C solution | 4 h sampling; Crossover design (3–4 week washout) | Fluorometric (phenylene diamine) | Grape juice ↓ plasma vitamin C (at 16 to 28 min) | ND | [34] |
| 200 mL red grape juice (30 mg vitamin C) | ||||||
| 9 healthy subjects 19–41 years | 500 mg vitamin C tablet | 1 g/day vitamin C for 2 weeks pre-study; 8 h sampling; Crossover design (1 week washout) | Colorimetric (DNPH) | Bioflavonoids comparable AUC | Bioflavonoids comparable 24 h vitamin C excretion | [83] |
| Mixed bioflavonoids | ||||||
| Placebo | ||||||
| 12 non-smoking subjects 18–41 years | 500 mg vitamin C solution | Subgroup had 1 g/day vitamin C for 2 weeks pre-study; 8 h sampling; Crossover design (1 week washout) | Fluorometric | Citrus extract ↑ AUC | Citrus extract ↓ 24 h vitamin C excretion in non-saturated subjects and ↑ 24 h vitamin C excretion in saturated subjects | [81] |
| 2 g citrus extract | ||||||
| Placebo | ||||||
| 5 men 21–25 years | 500 mg vitamin C solution | 100 mg/day vitamin C for 1 month pre-study; 8 h sampling; Crossover design (1 week washout) | Colorimetric (Indophenol dye) | ND | Blackcurrant juice slight ↑ 8 h vitamin C excretion in saturated subjects | [82] |
| 500 mg vitamin C in blackcurrant juice | ||||||
| 15 normal subjects (4 smokers) 20–42 years | 70 mg/h vitamin C solution | Intestinal perfusion; Tandem design | Colorimetric (DNPH) | Orange juice comparable intestinal absorption | ND | [88] |
| Orange juice | ||||||
| 12 men (6 smokers) 23–44 years | 75 mg vitamin C solution | Pre- and post-saturation with 1 mg/day vitamin C; 2–24 h sampling; Crossover design (1 day washout) | Colorimetric | Orange juice and rutin ↓ plasma vitamin C (at 2 h) | Orange juice slight ↑ 24 h vitamin C excretion | [71] |
| 400 mg rutin | ||||||
| Orange juice (75 mg vitamin C) |
AUC: area under the concentration-time curve; ND: not determined; DNPH: 2,4-dinitrophenylhydrazine; TPTZ: 2,4,6-tris(2-pyridyl)-s-triazine.