Dr. Kumar’s Take
This randomized trial shows that a simple daily dose of vitamin C can lower uric acid in the blood, which is one of the main drivers of gout. The reduction was modest but consistent across different groups of people. While vitamin C alone may not replace prescription gout medications, it could be an inexpensive and safe addition to a prevention strategy. In my practice, patients at risk for gout or urate-related problems are reasonable candidates for adding more vitamin C through diet or supplements, as part of a broader plan.
Key Takeaways
✔ Vitamin C at 500 mg/day lowered serum uric acid by a mean of 0.5 mg/dL, while placebo did not.
✔ The effect was consistent across age, sex, race, BMI, chronic illness, diuretic use, and baseline vitamin C levels.
✔ Participants in the highest quartile of baseline uric acid saw the largest drop: a net mean change of 1.0 mg/dL.
✔ Vitamin C increased estimated glomerular filtration rate compared with placebo.
✔ The authors concluded vitamin C might be useful in preventing and managing gout and other urate-related diseases.
Actionable Tip
If you are at risk of gout or have borderline high uric acid, talk to your doctor about adding 500 mg of vitamin C per day, either through diet or a supplement. Pairing this with lifestyle changes like reducing sugary drinks and alcohol is a reasonable approach, though this trial tested the supplement alone.
Study Summary
This randomized, double-blind, placebo-controlled trial enrolled 184 nonsmokers for 2 months. Participants were randomly assigned to receive either 500 mg of vitamin C per day or a placebo. At the end of the trial, the vitamin C group showed a significant reduction in serum uric acid, mean change 0.5 mg/dL (95% CI 0.6 to 0.3), while the placebo group showed a mean change of 0.09 mg/dL (95% CI 0.05 lower to 0.2 higher), with a difference between groups at p < 0.0001. The same pattern held across nearly every subgroup examined.
Study Design
- Population: 184 nonsmoking adults, studied in research units affiliated with an academic institution.
- Intervention: 500 mg/day vitamin C supplement for 2 months.
- Control: Placebo.
- Design: Double-blinded, placebo-controlled, randomized.
- Endpoints: Change in serum uric acid, with serum ascorbic acid and estimated glomerular filtration rate also assessed.
Results
- Uric acid: Mean change of 0.5 mg/dL downward (95% CI 0.6 to 0.3) in the vitamin C group; the placebo group changed by 0.09 mg/dL (95% CI 0.05 lower to 0.2 higher), p < 0.0001.
- By baseline uric acid quartile: From lowest to highest quartile, net mean changes with vitamin C were 0.4 (95% CI 0.8 lower to 0.01 higher), 0.5 (95% CI 0.9 to 0.2), 0.5 (95% CI 0.8 to 0.2), and 1.0 (95% CI 1.6 to 0.4) mg/dL downward, with p values of 0.06, 0.005, 0.003, and 0.002.
- Kidney function (eGFR): Increased with vitamin C compared with placebo.
- Consistency: The same pattern of results appeared in subgroups defined by age, sex, race, body mass index, chronic illness, diuretic use, and quartiles of baseline serum ascorbic acid.
How Vitamin C Helps Lower Uric Acid
Vitamin C has been proposed to act on uric acid in two ways:
- Increased kidney filtration: This trial found that vitamin C increased estimated glomerular filtration rate compared with placebo, and more filtration means more urate presented for excretion.
- A uricosuric effect: Earlier work cited by the authors suggested vitamin C promotes urinary excretion of uric acid rather than reabsorption in the kidney.
The trial measured the uric acid and filtration changes. The transporter-level explanation remains a proposed mechanism.
Strengths and Limitations
Strengths:
- Randomized, double-blinded, placebo-controlled design.
- The same pattern of results appeared across a wide range of subgroups.
- Included the participants most likely to benefit, those in the highest baseline uric acid quartile.
Limitations:
- Short duration, 2 months.
- Only one dose tested, 500 mg/day.
- The endpoint was serum uric acid, not gout flares or other clinical events.
- Nonsmokers only, so the findings may not extend to smokers.
Related Studies and Research
Cherries and Gout Prevention: Highlights how cherry intake can lower risk of recurrent gout flares.
Coffee, Uric Acid, and Gout Risk: Looks at how coffee may impact uric acid metabolism and gout risk.
Diet and Gout Risk: NEJM Study: Large cohort study evaluating how diet impacts gout incidence.
Podcast: How to Make Gout Disappear from Your Life: A comprehensive look at modern and ancient gout science, and how to beat it.
Frequently Asked Questions
How much vitamin C is needed to lower uric acid?
This trial tested 500 mg/day for 2 months and found a significant reduction in serum uric acid at that dose. It is the only dose the study examined.
Can vitamin C replace gout medications?
No. This trial measured a change in a blood level, not gout flares, and the average reduction was 0.5 mg/dL. I treat it as an adjunct to standard care, not a substitute for prescription urate-lowering therapy.
Does vitamin C help people with the highest uric acid most?
In this trial, the highest quartile of baseline uric acid had the largest net reduction, 1.0 mg/dL (95% CI 1.6 to 0.4), and the lowest quartile had the smallest, 0.4 mg/dL, which did not reach statistical significance (p = 0.06).
Should everyone with high uric acid take vitamin C?
Vitamin C is an essential nutrient that the body cannot make, so everyone needs some at baseline. Whether to add a 500 mg supplement is a decision to make with your own physician, especially if you have kidney disease or a history of stones.
Bottom Line
Vitamin C at 500 mg/day for 2 months lowered serum uric acid in this randomized, placebo-controlled trial, with the largest effect in those who started with the highest levels. The authors concluded it might be beneficial in preventing and managing gout and other urate-related diseases. It should not replace standard gout treatment, but it is an inexpensive option worth discussing with your doctor.
