Contrary to studies touting its therapeutic value, a new report says that vitamin C does not reduce uric acid levels in patients with gout.
In a small study, researchers in New Zealand found that vitamin C supplements did not lower uric acid (urate) levels to a significant degree.
“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, a professor at the University of Otago in Christchurch, New Zealand.
“Though vitamin C may reduce risk of developing gout, our data does not support using vitamin C as a therapy to lower uric acid levels in patients with established gout.”
Gout is an inflammatory arthritis that causes excruciating pain and swelling, triggered by the crystallization of uric acid in the joints. Attacks can last from several days to weeks, and each subsequent attack becomes more painful. More than 8 million Americans suffer from gout.
Long-term gout management often requires treatment with the drug allopurinol to lower urate levels by inhibiting uric acid production or by increasing uric acid excretion through the kidneys with medications like probenecid.
Nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen are often used to control the inflammation and pain, along with corticosteroids like prednisone.
In the New Zealand study, published in the American College of Rheumatology journal, Arthritis & Rheumatism, researchers recruited 40 gout patients who had high urate levels. All were given a 500 mg dose of vitamin C (ascorbate) daily, along with allopurinol.
Researchers analyzed blood levels of vitamin C, creatinine and uric acid at baseline and after 8 weeks. They found that vitamin C dose did not lower urate levels to a clinically significant degree, but it did increase ascorbate levels.
The results differ from previous research which found that vitamin C reduced urate levels in healthy individuals without gout, but had high levels of uric acid.
Stamp and her team report that reduction of uric acid was significantly less in gout patients taking vitamin C compared to those who started or increased their dose of allopurinol.
Last September, a study also published in Arthritis & Rheumatism found that patients who ate a daily serving of cherries over a two day period lowered their risk of a gout attack by 35 percent.
Researchers believe that the health benefit is derived from the urate-lowering effects and anti-inflammatory properties found in cherry products.