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Human uric acid is the final metabolite of purine, and purine metabolism into uric acid can be divided into endogenous and exogenous. Exogenous purine mainly comes from foods containing purine, but it only accounts for 20% of human uric acid metabolism. Endogenous purines are actually components of DNA and RNA in cells. After cell death, DNA, RNA and ATP in cells will degrade to produce purines (adenine and guanine), so endogenous purines mainly come from metabolically dead cells. Endogenous purine accounts for about 80%.

The direct cause of uric acid is too high: uric acid production >: uric acid is excreted, that is, the speed of uric acid production is greater than that of excretion.

At present, the suggestions to prevent gout and reduce uric acid only suggest reducing the intake of purine-containing foods in the diet, which can only reduce the source of purine by 20%, but more importantly, reduce the production of endogenous purine and the excretion of uric acid. This article is about an important nutrient that can reduce uric acid production and increase uric acid excretion: vitamin C.

Vitamin C, also known as ascorbic acid, is prone to scurvy because of the lack of vitamin C. Therefore, in the recommended intake of RDI, the daily intake of 100mg of vitamin C is based on the premise of preventing scurvy. "Enough" is enough, and more will not help. Vegetables and fruits in the diet are rich in vitamin C, which may indeed be enough to meet the amount of scurvy prevention. However, if vitamin C is needed to improve other health problems, RDI has no reference significance, and everything is subject to research evidence. High uric acid leads to a high risk of gout. This article is about the relationship between vitamin C and reducing uric acid.

Vitamin C is an important antioxidant in human body and a scavenger in blood, which can scavenge free radical ROS, reduce DNA damage and cell death, thus reducing the appearance of endogenous purine and uric acid produced by oxidative stress. Vitamin C can accelerate the excretion of uric acid by affecting the reabsorption rate of uric acid by proximal tubules. [4]

Animal experiments have confirmed that vitamin C can block the production of uric acid [1] and reduce the serum uric acid value [2].

Epidemiological studies also found that vitamin C was inversely related to uric acid. The study [3] published by Qingdao University on 20 18 analyzed the data and eating habits of American 14885 subjects, and found that the more vitamin C intake in the diet, the lower the serum uric acid value.

Clinical intervention research also found that vitamin C helps to reduce uric acid. In 20 12, Johns Hopkins University published a meta-analysis [4], including 13 clinical trials and samples of 556 subjects. The conclusion is that 500mg vitamin C daily can significantly reduce the serum uric acid value, with an average of only 30 days.

There is ample evidence that vitamin C can reduce uric acid, but experts do not quite agree that vitamin C is helpful to gout patients. The latest guide of American Rheumatology Association in 2020 [5] named vitamin C, saying that based on the latest research evidence, vitamin C can no longer be recommended to reduce uric acid in gout patients. I have carefully read the relevant suggestions, in fact, it is the following short paragraph, mentioning that two clinical studies have found that vitamin C has little effect on reducing uric acid in gout patients. According to the relevant literature, I only found one clinical study, and the other was irrelevant. ...

Another related study is a small pilot clinical study published on 20 13. Taking 500 mg of vitamin C every day does not help to improve the condition and reduce uric acid [6]. The researchers concluded that previous studies have confirmed that vitamin C can reduce serum uric acid in people without gout, but it seems to be ineffective for gout patients.

But are the facts really the same as the researchers' conclusions? There is an article about vitamin C in the column of Diet and Peace, which discusses the dosage of vitamin C. The clinical experience of doctors who have used large doses of vitamin C shows that the tolerance of patients to vitamin C dosage is completely different from that of healthy people. That is to say, generally speaking, the dose of vitamin C less than 1g is helpful for patients with high uric acid but not gout, but the same dose may be different for gout patients, so 500mg of vitamin C is not helpful for gout patients to reduce uric acid.

Vitamin C is a safe and cheap nutrient, among which food-borne vitamin C is the best. However, people in China are not used to eating raw salads. Excessive cooking temperature and boiling water will cause a great loss of vitamin C. Some fruits contain more vitamin C. For example, a big orange contains about 80mg- 100mg of vitamin C, but an apple has only one tenth of the vitamin C of an orange. But even if 100mg of vitamin C is enough to prevent scurvy, it may be just a drop in the bucket to achieve anti-oxidation, reduce uric acid production and increase renal excretion rate.

Appropriate daily vitamin C supplementation for people with high uric acid may help to reduce uric acid.

# Health Science Qualifier # # Gout # # Uric acid # # Vitamin C#

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[1] Feigelson P. (1952), Inhibition of trace l- ascorbic acid on xanthine oxidase in vitro. Journal of biochemistry. Possibility; 1952 197(2):843–50.

[2] Barja G et al. (1994), Dietary vitamin C reduces endogenous protein oxidative damage, malondialdehyde and lipid peroxidation, and maintains fatty acid unsaturation in the liver of guinea pigs. Free Radzic Biomedicine. Aug 1994 17(2): 105– 15.

[3] Sun, Yongye & Sun, Jianping & Wang, Jianxun & Gao, Tian Lin & Zhang, Huaqi, Zhang Zhiyong; Horses, people. (20 18). The relationship between vitamin C intake and the risk of hyperuricemia in American adults. Asia-Pacific Journal of Clinical Nutrition. 27. 127 1- 1 276. 10.6 133/apjcn . 20 18 1 1 _ 27(6). 00 14。

[4] Jurascek, Stephen Miller, Edgar Gabe Allen. (20 1 1). Effect of oral vitamin C supplementation on serum uric acid: a meta-analysis of randomized controlled trials. Arthritis care and nursing. Research. 63. 1295-306. 10. 1002/ACR . 205 19。

Fitzgerald, John & Nicolas Darbes; Mikuls, Ted & Brignadro-Peterson, Romina & ampGuyatt, Gordon & Abel, Arie & Gelber Allen Law Firm; Harold, Leslie & Connor, Dines & charles king Law Firm. Gerald levy law firm. Libby, Carlin & Hill, David & Pillinger, Michael & Rosenthal, Ann & Singer Jaswind Company; James & Smith, Benjamin & Wenger, Neil & Nioji, Tuxina. (2020).2020 American Rheumatology Association Gout Management Guide. Arthritis & Rheumatology. 72. 10. 1002/ article No.41247.

[6] Lisa K. Stamper et al. (20 13). The effect of vitamin C supplementation on serum urate in patients with gout has no clinical significance: a randomized controlled trial. Arthritis & rheumatism, 2013; DOI: 10. 1002/art . 37925