While previous research touted vitamin C’s benefit in moderating gout risk, a new study indicates that vitamin C supplements are not effective in reducing uric acid (urate) levels to a clinically significant degree in patients with established gout. Vitamin C supplements, alone or in combination with allopurinol (a drug used to prevent gout attacks), appear to have a weak effect on lowering uric acid levels in gout patients, according to the results published in the American College of Rheumatology (ACR) journal, Arthritis & Rheumatism.
Once thought to be a disease of royals and the very rich, gout is an inflammatory arthritis that causes excruciating pain and swelling triggered by the crystallization of uric acid within the joints. Uric acid comes from the breakdown of substances called purines, which are found in all your body’s tissues. They are also in many foods, such as liver, dried beans and peas, and anchovies. Normally, uric acid dissolves in the blood, passes through the kidneys and out of the body in urine. But it can build up in the blood when the body increases the amount of uric acid it makes, the kidneys do not get rid of enough uric acid and a person eats too many foods high in purines.
Estimates from the ACR report that more than 8.3 million Americans suffer with gout. Long-term management of the disease involves treatment with medications that lower urate levels by inhibiting uric acid production (allopurinol) or increasing uric acid excretion (probenecid) through the kidneys.
While current treatments are successful in reducing the amount of uric acid in the blood, there are many patients who fail to reach appropriate urate levels and need additional therapies, said lead author Lisa Stamp of the University of Otago in Christchurch, New Zealand. Vitamin supplementation is one such alternative therapy and the focus of our current study, which looked at the effects of vitamin C on urate levels in patients with gout.
Researchers recruited 40 gout patients who had urate levels greater than the ACR treatment target level. Of the 40, 20 patients already on allopurinol were given an additional 500 mg dose of vitamin C daily or had the dose of allopurinol increased. The 20 patients who were not taking allopurinol prior to the study were put on allopurinol or vitamin C (500 mg/day). Researchers analyzed blood levels of vitamin C, creatinine and uric acid at baseline and week eight.
Study findings show that taking 500 mg/day of vitamin C for eight weeks did not lower urate levels to a clinically significant degree in gout patients. The results differ from previous research which found that vitamin C reduced urate levels in healthy individuals without gout who had high levels of uric acid (hyperuricemia). Most people with hyperuricemia do not develop gout. But if excess uric acid crystals form, gout can develop.
In fact, the Stamp study found that reduction of uric acid was significantly less in gout patients taking vitamin C than in those who started or increased their dose of allopurinol.