Vitamin C and gout: You may have heard that vitamin C can reduce the risk of gout. But what does the science say? Here I take a look at four studies whose findings may surprise you!
Does vitamin C really reduce uric acid in the bloodstream?
You may have heard that vitamin C — also known as ascorbic acid — can lower uric acid and so reduce the risk of gout. But what does the science say? Here I take a quick look at four studies carried out over the past few decades.
What do the studies show?
‘The effects of vitamin C supplementation on serum concentrations of uric acid: results of a randomized controlled trial’ — was published in 2005 in Arthritis & Rheumatology by Han-Yao Huang et al.
It was a double-blinded placebo-controlled randomized trial of 184 participants who were given either placebo or vitamin C supplements (500 mg/day) for 2 months.
The study concluded that:
Supplementation with 500 mg/day of vitamin C for 2 months reduces serum uric acid, suggesting that vitamin C might be beneficial in the prevention and management of gout and other urate-related diseases.
‘Vitamin C Intake and the Risk of gout in Men – A Prospective Study’ — the largest study I came across — was published in March 2009 in the Archives of Internal Medicine by Hyon K. Choi et al.
It followed a cohort of approx. 47,000 men between 1986 and 2006 with no history of gout at the beginning of the study. In the 20 year follow-up period the authors documented 1,317 new cases of gout (incident gout).
The follow-up data suggested an inverse relationship between total vitamin C intake (dietary & supplemental) and the risk of developing gout. In other words, the risk of gout reduced as vitamin C intake increased.
In terms of actual numbers, results from statistical analysis showed that the risk of gout decreased by 17% for every 500 mg increase in vitamin C and by 45% when participants took more than 1,500 mg of vitamin C a day.
The study authors concluded that:
Higher vitamin C intake is independently associated with a lower risk of gout. Supplemental vitamin C intake may be beneficial in the prevention of gout.
‘Effect of oral vitamin C supplementation on serum uric acid: A meta‐analysis of randomized controlled trials’ — by Stephen Juraschek et al, was first published in June 2011, and pooled the findings from 13 randomized controlled trials (RCTs) conducted between 1990 and 2009, including Huang’s 2005 RCT above.
The objective was to use meta‐analysis across an aggregate of small-scale trials (13) to help establish a ‘more stable estimate’ of the effectiveness of vitamin C supplementation on blood uric acid.
The total number of participants across all RCTs was 556 whilst the individual trial sizes ranged from 8–184 participants. Pretrial blood uric acid levels ranged from 2.9-7.0 mg/dl. The median study duration was 30 days and the median dosage was 500 mg / day.
The conclusion from this meta‐analysis approach was:
In aggregate, vitamin C supplementation significantly lowered SUA. Future trials are needed to determine whether vitamin C supplementation can reduce hyperuricemia or prevent incident and recurrent gout.
However, this study — “Clinically Insignificant Effect of Supplemental Vitamin C on Serum Urate in Patients With Gout: A Pilot Randomized Controlled Trial” — of 40 actual gout patients over an 8 week period, by Lisa K Stamp et al., and published in 2013 in Arthritis & Rheumatism, concluded that:
A modest dosage of vitamin C (500 mg/day) for 8 weeks had no clinically significant urate-lowering effects in patients with gout, despite the fact that plasma ascorbate levels increased. These results differ from previous findings in healthy control subjects with hyperuricemia. The uricosuric effect of modest-dose vitamin C appears to be small in patients with gout, when administered as monotherapy or in combination with allopurinol.
What can we take from these studies?
Although Stamp’s 2013 study found “no clinically significant urate-lowering effects in patients with gout,” the other studies were more positive.
And Choi’s 2009 study of nearly 47,000 participants absolutely dwarfed Stamp’s study of only 40 patients. Even Huang’s 2005 study had 184 participants and Juraschek‘s meta‐analysis of 13 RTC trials encompassed 556 participants (including Huang’s 184 of course).
However, it has to be pointed out that Stamp’s study was the only one I could find whose participants were all actual gout patients. The other studies were largely based on patients with no previous history of gout or a mixture of both — although some had (previously undiagnosed) high uric acid levels when entering the trials.
So, taking the studies together, we could conclude that vitamin C may help to prevent incident (first time) gout but may not be effective for recurrent gout (in already diagnosed patients).
It’s also important to to note that the 2013 study did not say that moderate vitamin C supplementation did not lower uric acid, just that it had ‘no clinically significant urate-lowering effects in patients with gout.’ But what does that really mean?
Personally speaking, I like to think that ANY reduction in blood uric acid is relevant for gout. Here I’m thinking along the lines of continuous ‘micro improvements’ from various sources — vitamin C being just one — that compound into real, measurable improvements over time.
On balance, then, I’ve taken the view that vitamin C can help me to manage my uric acid levels. But, of course, not on its own. It has to be part of a wider approach that includes a low-purine diet with more plant-based foods and some lifestyle changes.
So, if vitamin C can reduce uric acid, how does it work?
It’s believed that vitamin C’s uricosuric effect increases the rate of urate excretion through the kidneys. This reduces the amount of uric acid being reabsorbed back into the bloodstream, which then lowers the concentration of uric acid circulating in the bloodstream and which, in turn, helps to lower the risk of gout.
But, notwithstanding the possible link between vitamin C and a lower risk of gout, there are important health benefits for ensuring you get enough daily vitamin C…
Health Benefits of Vitamin C
Studies suggest that vitamin C may help to:
- strengthen your body’s immune system.
- lower blood pressure.
- reduce the risk of heart disease and stroke.
- improve iron absorption and so prevent iron deficiency.
- limit cold and flu symptoms and reduce the risk of further complications.
- improve skin health.
- reduce the risk of some cancers.
- protect your body’s cells against free-radical damage.
So insufficient vitamin C can negatively affect your health. But your body doesn’t produce or store water-soluble vitamin C, so you need to get it every day from your diet…
Best dietary sources of vitamin C.
Fruits & berries such as guavas, mangoes, papayas, kiwis, cantaloupe, pineapple, blackcurrants, lychees, strawberries, oranges, lemons, grapefruit, and other citrus fruits are rich in vitamin C.
Vegetables like potatoes, tomatoes (technically a fruit), green chili peppers, red and green bell peppers, Brussels sprouts, cauliflower, kale, broccoli, and dark green leafy vegetables in general, are also excellent sources, as are herbs such as thyme, parsley and mustard spinach.
So there’s plenty of choice and no real reason not to get your recommended daily allowance from your diet.
How much vitamin C do I need?
According to the National Institutes of Health (U.S. Department. of Health & Human Services) the recommended daily amount of vitamin C is 90 mg and 75 mg for adult men and women respectively.
And, if you smoke, “add 35 mg to the above values to calculate your total daily recommended amount…” because “…smoke increases the amount of vitamin C that the body needs to repair damage caused by free radicals.”
You can easily get your daily recommended amount through a balanced diet containing a wide variety of foods. For example, 1 large orange has 97.5 mg vitamin C, 1 large potato contains 72.7 mg, while a cup of broccoli contains 81.2 mg. Source.
How much vitamin C to reduce the risk of gout?
Those studies linking vitamin C with a reduced gout risk, used 250, 500, and 1,000+ mg doses, way more than the recommended daily amount.
So you would have to consume 3x times the recommended daily amount, at the very least. Even if you are following a healthy gout diet with lots of plant-based foods it may be difficult to reach that intake on a daily basis without some supplementation.
Just be aware that too much vitamin C can cause things like diarrhea and nausea, although a tolerable upper level of 2,000 mg for vitamin C in adults has been established by the Food and Nutrition Board, Institute of Medicine, in the U.S.
However, there is some evidence of a potential link between mega-doses of vitamin C (over 2,000 mg) and kidney stones.
So, if you are considering vitamin C supplements, you first need to consult with your doctor to be on the safe side.
Personally, I reckon I get plenty vitamin C (more than the recommended daily amount) from my gout diet which contains lots of vegetables and fruit.
