All these fruit are sources of vitamin C. (Photos.com)
Gout quite often affects the ball of the foot (the major joint of the big toe), but the condition can affect any joint. Conventional medical treatment is centered on painkillers for attacks of gout, as well as drugs that can lower uric acid levels by speeding its elimination from the body through the kidneys (known as having a uricosuric effect).
Conventional drugs are apparently not the only agents that have a uricosuric effect. Previous studies have found that vitamin C also does this [1-4]. Recently, we saw the publication of a study that assessed the relationship between vitamin C intake and risk of gout in almost 47,000 men [5]. All the men had no history of gout when they entered the study. Their intakes of vitamin C (via diet and supplements) were assessed every 4 years over a 20-year period.
Risk of gout was found to be lower in individuals with higher vitamin C intake. Compared to individuals with a total vitamin C intake of less than 250 mg per day, those with total intakes of 500–999 mg per day had a 17 percent reduced risk of gout. For intakes of 1,000–1,499 mg and 1,500 mg or more per day, the risk of getting gout was down by 34 and 45 percent, respectively.
The authors of this study also looked at the relationship between amounts of vitamin C ingested in supplement form only and risk of gout. Here again, higher supplemental levels were associated with a reduced risk of gout. Compared to those who did not supplement with vitamin C, those supplementing with 1,000–1,499 mg and 1,500 mg or more of vitamin C per day were found to be at 34 and 45 percent reduced risk of gout, respectively.
These results suggest that vitamin C, either from diet or supplements, is associated with a reduced risk of gout. This study is epidemiological in nature and cannot be used to conclude that vitamin C reduced the risk of gout. However, the fact that vitamin C is known to be uricosuric does make a genuine protective effect likely.
Another piece of research, which provides supporting evidence for this, is a randomized controlled trial in which individuals were treated with 500 mg of uric acid or placebo over a two-month period [6]. Vitamin C, compared to placebo, led to a statistically significant reduction in uric acid levels (the average fall in uric acid levels in this study was 0.5 mg/dL, which is equivalent to about 30 micromoles/liter).
These results suggest that vitamin C has real potential to help prevent gout. My tendency in practice is to use doses of about 2,000 mg per day (as 1,000 mg taken twice a day).
Individuals who should consult their doctors before supplementing with vitamin C include those with the condition glucose-6-phosphate dehydrogenase deficiency, those suffering from conditions in which iron levels are elevated in the body, such as hemosiderosis or hemochromatosis (vitamin C enhances iron absorption), and those with a history of kidney stones or kidney failure.
References:
1. Stein HB, et al Ascorbic acid-induced uricosuria: a consequence of megavitamin therapy. Annals of Internal Medicine 1976; 84:385–8
2. Sutton JL, et al Effect of large doses of ascorbic acid in man on some nitrogenous components of urine. Human Nutrition–Applied Nutrition 1983; 37:136–40
3. Berger L, et al. The effect of ascorbic acid on uric acid excretion with a commentary on the renal handling of ascorbic acid. American Journal of Medicine 1977; 62:71–6
4. Mitch WE, et al. Effect of large oral doses of ascorbic acid on uric acid excretion by normal subjects. Clinical Pharmacology & Therapeutics 1981; 29:318–21
5. Choi HK, et al. Vitamin C intake and the risk of gout in men: a prospective study. Archives of Internal Medicine 2009; 169(5): 502–7
6. Huang HY, et al. The effects of vitamin C supplementation on serum concentrations of uric acid: results of a randomized controlled trial. Arthritis & Rheumatism 2005; 52(6): 1843–7
Dr. John Briffa is a London-based physician and health writer with an interest in nutrition and natural medicine. His Web site is drbriffa.com
