This vitamin C & uric acid investigation is a layman’s review of:
- The effects of vitamin C supplementation on serum concentrations of uric acid: Results of a randomized controlled trial.
- Huang HY, Appel LJ, Choi MJ, Gelber AC, Charleston J, Norkus EP, Miller ER 3rd.
- Arthritis Rheum. 2005 Jun;52(6):1843-7.
Vitamin C & Uric Acid Study
The purpose of this study is to determine the effects of vitamin C supplementation on uric acid concentrations in the blood. It follows from a number of previous studies that suggest that vitamin C may encourage uric acid excretion.1-4
Vitamin C & Uric Acid Study Methods
184 participants in the study were split into 4 groups:
- 500mg vitamin C plus placebo
- 400mg vitamin E plus placebo
- Vitamin C plus vitamin E
These supplements were taken for two months, with blood tests at the start and end of the trial. Statistical analysis was performed on the test results, taking into account age, sex, racial group, body mass index, chronic illness, and diuretic use.
Results were split into groups as follows:
- Hyperuricemia – two groups: above & not above 7mg/dL.
- Starting uric acid level – 4 groups with cut-off points at 4.2, 5.0, and 6.4 mg/dL. Note that these are statistical groups (quartiles) , and the cut-off points have no medical significance.
- Starting ascorbic acid levels – this is another name for vitamin C
Vitamin C & Uric Acid Study Results
All uric acid measurements in the published study are in the USA standard (mg/dL). I include some significant measurements in alternative scales using the GoutPal Uric Acid Concentration Calculator.
The average starting uric acid level was 5.2mg/dL (0.31mmol/L or 310μmol/L). No change in uric acid was recorded for the placebo and vitamin E groups. The data for the 4 original groups were reallocated, treating Vitamin E as placebo.5 This leads to the results comparing vitamin C with placebo, and shows the vitamin C group had an average reduction of 0.5mg/dL.
The published report includes a large table of different statistics, but the most relevant ones relate to the groups of different starting uric acid levels.
|1||21||3.6 (0.21)||0.3 (.02)|
|2||26||4.6 (0.27)||0.4 (.02)|
|3||20||5.5 (0.33)||0.4 (.02)|
|4||25||7.2 (0.43)||0.7 (.04)|
Vitamin C & Uric Acid Study Discussion
The authors note the strength of the report as a placebo-controlled randomized trial, and a fair cross-section of general population. However, they also note that no long-term tests were carried out, and only a single dose was tested.
The greater weaknesses for gout patients lie in the nature of the study itself. It is limited to uric acid concentrations, and whilst this is highly relevant to gout patients,9 it warrants further investigation. Nor does the study give any insight into why vitamin C & uric acid are related, though some possible explanations are included in the discussion.10-15
Vitamin C & Uric Acid Study Conclusion
The authors conclude:
supplementation with vitamin C at 500 mg/day for 2 months reduced serum uric acid concentration. This finding suggests that vitamin C might be beneficial in the prevention or management of gout and other urate-related diseases.
This study is widely quoted, and a leading American rheumatologist has concluded:
“Consider taking vitamin C supplements as vitamin C has been found to reduce serum uric acid in clinical trials (references to this and other studies) … Given the general safety profile associated with vitamin C intake, vitamin C may provide a useful option in the prevention of gout.”
Terkeltaub: Gout & Other Crystal Arthropathies: Expert Consult: Online and Print, 1e
Vitamin C & Uric Acid: Next Steps
My conclusion is, first, you should have a good gout treatment plan that includes uric acid monitoring by your doctor, or using a home uric acid test meter. If you have that, you should consider vitamin C supplementation, probably in conjunction with other natural gout cures to lower uric acid.
Vitamin C supplements are widely available from suppliers including Amazon.com, Amazon.co.uk, kalyx.com, and Walmart.com – if you try any of these, please share some feedback in the Gout Forum.
Vitamin C & Uric Acid References
- Stein HB, Hasan A, Fox IH. Ascorbic acid-induced uricosuria: a consequency of megavitamin therapy. Ann Intern Med 1976; 84: 385–8.
- Sutton JL, Basu TK, Dickerson JW. Effect of large doses of ascorbic acid in man on some nitrogenous components of urine. Hum Nutr Appl Nutr 1983; 37: 136–40.
- Berger L, Gerson CD, Yu TF. The effect of ascorbic acid on uric acid excretion with a commentary on the renal handling of ascorbic acid. Am J Med 1977; 62: 71–6.
- Mitch WE, Johnson MW, Kirshenbaum JM, Lopez RE. Effect of large oral doses of ascorbic acid on uric acid excretion by normal subjects. Clin Pharmacol Ther 1981; 29: 318–21.
- Huang HY, Appel LJ, Croft KD, Miller ER III, Mori TA, Puddey IB. Effects of vitamin C and vitamin E on in vivo lipid peroxidation: results of a randomized controlled trial. Am J Clin Nutr 2002; 76: 549–55.
- Levey AS, Bosch JP, Lewis JB, Greene T, Rogers N, Roth D, and the Modification of Diet in Renal Disease Study Group. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Ann Intern Med 1999; 130: 461–70.
- Gochman N, Schmitz JM. Automated determination of uric acid, with use of a uricase-peroxidase system. Clin Chem 1971; 17: 1154–9.
- McGown EL, Rusnak MG, Lewis CM, Tillotson JA. Tissue ascorbic acid analysis using ferrozine compared with the dinitrophenylhydrazine method. Anal Biochem 1982; 119: 55–61.
- Campion EW, Glynn RJ, deLabry LO. Asymptomatic hyperuricemia: risks and consequences in the Normative Aging Study. Am J Med 1987; 82: 421–6.
- Kang DH, Nakagawa T, Feng L, Watanabe S, Han L, Mazzali M, et al. A role for uric acid in the progression of renal disease. J Am Soc Nephrol 2002; 13: 2888–97.
- Sanchez-Lozada LG, Tapia E, Avila-Casado C, Soto V, Franco M, Santamaria J, et al. Mild hyperuricemia induces glomerular hypertension in normal rats. Am J Physiol Renal Physiol 2002; 283: F1105–10.
- Nakagawa T, Mazzali M, Kang DH, Kanellis J, Watanabe S, Sanchez-Lozada LG, et al. Hyperuricemia causes glomerular hypertrophy in the rat. Am J Nephrol 2003; 23: 2–7.
- Iseki K, Oshiro S, Tozawa M, Iseki C, Ikemiya Y, Takishita S. Significance of hyperuricemia on the early detection of renal failure in a cohort of screened subjects. Hypertens Res 2001; 24: 691–7.
- Syrjanen J, Mustonen J, Pasternack A. Hypertriglyceridaemia and hyperuricaemia are risk factors for progression of IgA nephropathy. Nephrol Dial Transplant 2000; 15: 34–42.
- Ohno I, Hosoya T, Gomi H, Ichida K, Okabe H, Hikita M. Serum uric acid and renal prognosis in patients with IgA nephropathy. Nephron 2001; 87: 333–9.