Table 1.
Clinical trials examining the effect of vitamin C supplementation upon serum uric acid, ordered by year of study.
| Source (year) | Country | Population | Size | Mean Age, y (SD) | % Male | Study Design†† | Study Duration, d* | Intervention (per day) | Control | Baseline Uric Acid (mg/dL)** | Pretreatment Plasma Ascorbic Acid (μmol/L)*** | Uric Acid Measurement | Completing Trial (%) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Naziroglu et al(25), 2009† | Turkey | Postmenopausal & Diabetic Women | 40 | 51 (45 - 65) | 0 | PO | 42 | Vit C 1000mg, Vit E 600mg, Estradiol 0.625mg, Medroxyprogesterone 5mg | Estradiol 0.625mg, Medroxyprog esterone 5mg | 3.6 (1.1) | - | Routine kits, autoanalyzer | 100 |
| Teixeira et al(26), 2009 | Portugal | Athletes | 20 | 19.7 (3.6) | 70 | PD | 28 | Vit C 400mg, Vit E 272mg, β-carotene 30mg, Lutein 2mg, Selenium 400μg, Zinc 30mg, Magnesium 600mg | Placebo | 4.9 (1.0) | 56.2 (24.0) | Enzymatic method at 550 nm using commercial kit (Horiba ABX A11A01670) | 100 |
| Huang et al(10), 2005† | USA | Adult Nonsmokers | 184 | 58.2 (13.7) | 45 | FPT | 60 | Vit C 500mg | Placebo | 5.2 (1.5) | 62.2 (15.5) | Hitachi 917 autoanalyzer Roche Diagnostics; uricase-peroxidase method with ascorbate oxidase incubation | 92 |
| Polidori et al(27), 2005 | Italy | Acute Ischemic Stroke | 59 | 77.0 (7.2) | 53 | PO | 90 | Vit C 200mg, Aspirin 300mg | Aspirin 300mg | 2.9 (0.9) | 27.0 (4.5) | High performance liquid chromatography with Supelco columns | 100 |
| Van Hoydonck et al(28), 2004 | Belgium | Healthy Male Smokers | 42 | 52 (12) | 100 | XD | 28 | Vit C 500mg | Placebo | - | 45 (20) | Enzyme-linked calorimetric assay (Roche, Basel, Switzerland) | 81 |
| Vrca et al(29), 2004† | Croatia | Patients with Graves’ Disease | 57 | - | 9 | PO | 28 | Vit C 200mg, β-carotene 6mg, Vit E 36mg, Selenium 60μg, Methimazole at varying doses | Methimazole at varying doses | 3.5+ | - | Olympus AU500 Analyser | 100 |
| Yanai et al(30), 2004 | Japan | Healthy, Nonsmoking male athletes | 8 | 20.4 (1.6) | 100 | PS | 21 | Vit C 1000mg | Placebo | 5.2 (0.8) | - | Uricase calorimetric method | 100 |
| Nieman et al(31), 2002† | USA | Ultramarath on Runners | 29 | 47.7 (12.1) | - | PD | 7 | Vit C 1500mg | Placebo | - | - | Hematology Laboratory | 97 |
| Martinez-Abundis et al(32), 2001 | Mexico | Obese male volunteers | 16 | 26.5 (6.3) | 100 | PD | 28 | Vit C 1000mg | Placebo | 7.0 (1.2) | - | Enzymatic methods | 100 |
| Hamilton et al(33), 2000† | UK | Healthy Adults | 32 | 35 (9) | 50 | XD | 42 | Vit C 500mg | Vit E 73.5mg as placebo | 4.4 (0.9) | 63.6 (12.5) | Commercial kits on a Cobas Fara (Roche Dianostic Systems) | 94 |
| Rokitzki et al(34), 1994 | Germany | Male Athletes | 24 | 38.5 (8.5) | 100 | PD | 31.5 | Vit C 200mg, Vit E 400 IU | Placebo | 5.9 (1.0) | 46.3 (12.8) | Enzymatic test | 92 |
| Maxwell et al(35), 1993 | UK | Healthy Students | 16 | 19.6 (1.5) | 67 | PO | 21 | Vit C 400mg | Vit E 400mg | 4.8 (1.0) | 77.7 (19.3) | Automated uricase-peroxidase system | 100 |
| Kyllastinen et al(36) (a), 1990 | Finland | Long-stay Hospital Patients | 29 | 81+ (68 - 93) | 0 | XD | 42 | Vit C 200mg | Placebo | - | - | Routine laboratory methods | 93 |
| Kyllastinen et al(36) (b), 1990† | Finland | Long-stay Hospital Patients | 29 | 81+ (68 - 93) | 0 | XD | 42 | Vit C 2000mg | Placebo | - | - | Routine laboratory methods | 93 |
†
Trials reporting significant baseline reductions in Uric Acid
††
F is factorial; P is parallel; X is crossover; T is triple blind; D is double blind; S is single blind; O is open
*
1 Month = 30 days
**
Uric acid converted from μmol/L to mg/dL by dividing by 59.48
***
Vitamin C converted from mg/dL to μmol/L by multiplying by 56.776
+
Median value.