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Gouty arthritis is a common metabolic disease. Most patients have recurrent joint swelling and pain, and most patients can achieve long-term relief after continuous uric acid reduction [1-2]. The prevalence of hyperuricemia and gout is increasing worldwide, especially in high-income and economically developing countries. Available analyses suggest that the prevalence of hyperuricemia in adults is approximately 20 percent, the prevalence of hyperuricemia in adolescents is 14 percent, and the prevalence of gout is 2.6 percent [3-4]. This means that almost one in five people have high uric acid levels.
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More than drugs can lower uric acid
Intra-articular urate crystals usually take a year to completely dissolve, and tophi takes longer, usually several years. The key to preventing the recurrence of gouty arthritis is to keep the blood uric acid level up to the standard, but not all gout patients need to be treated with uric acid-lowering drugs, and national guidelines do not recommend starting uric acid-lowering therapy for patients with a first attack, because the drug benefit-risk ratio is not high. .
Since its discovery in 1932 by Hungarian biochemist Albert Szent-Gy rgyi, its role in regulating various biological processes has been extensively studied. Vitamin C is a water-soluble vitamin with many physiological functions, such as antioxidant, promotion of collagen synthesis, improvement of immunity, alleviation of toxicity, prevention of atherosclerosis, etc. It plays an important physiological function in the body.
In the 1980s, it was clinically discovered that Vitamin C has the effect of lowering uric acid and reducing the incidence of gout in the general population, which is economical and has no toxic side effects.
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Research proves vitamin C can lower uric acid!
It turns out that vitamin C can also reduce uric acid? Do not believe? Let’s see what studies confirm this.
A randomized controlled trial [5] of 184 non-smoking patients with hyperuricemia compared vitamin C with placebo, and the results showed that the vitamin C group received oral vitamin C 500mg/d , after 2 months of treatment, the blood uric acid level decreased by 0.5mg/L, and the blood uric acid level in the placebo group decreased by 0.09mg/L. The uric acid-lowering effect of vitamin C was significantly better than that of the placebo group. In addition, vitamin C can also increase the patient’s glomerular filtration rate. No significant side effects of vitamin C have been reported.
Ma Ling et al[6] found that the serum vitamin C level in patients with hyperuricemia was significantly reduced, and the reduction of vitamin C may be related to its role as an antioxidant, which is consumed in the process of scavenging excessive free radicals Related, vitamin C plays an important antioxidant effect in the prevention or reduction of diseases caused by oxygen and nitro free radicals. Vitamin C promotes uric acid excretion, increases fractional uric acid excretion, reduces oxidative stress-induced cell damage, and indirectly reduces blood uric acid levels.
Jia Shaodan et al[7] also showed that oxidative stress also exists in hyperuricemia. Vitamin C plays an important antioxidant effect in the prevention or reduction of diseases caused by oxygen and nitro free radicals.
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Why does vitamin C reduce uric acid?
The mechanism by which vitamin C lowers blood uric acid levels is not fully understood and may include the following mechanisms:
1. Vitamin C can reduce blood uric acid levels mainly because it can promote uric acid excretion, which may compete with it to inhibit the anion transporter of proximal convoluted tubules Related [8], at the tip of the proximal convoluted tubule brush border, vitamin C can specifically bind to the uric acid reabsorption site of urate transporter 1 and sodium-dependent anion cotransporter SLC5A8/A12.
2. Vitamin C is also known as L-ascorbic acid, which can enhance the ability of dissolving uric acid accumulated in tissues and facilitate the excretion of uric acid. Vitamin C may also increase glomerular filtration rate and increase uric acid excretion by reducing glomerular capillary ischemia and dilating glomerular afferent arteries.
3. In addition, vitamin C is a powerful antioxidant, which can reduce the damage of free radicals to cells, thereby reducing the formation of uric acid and reducing 24h uric acid [9].
4. Recent studies have also shown that ascorbic acid plays an important role in reducing uric acid-induced inflammation by inhibiting the activation of the NLRP3 inflammasome [10-11].
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What fruit can I eat to supplement vitamin C?
In general, most people can get enough vitamin C from their daily diet without taking extra vitamin C supplements. Which foods are rich in vitamin C? The following fruits may be tried.
No. 1: Sour Dates. The vitamin C contained in the jujube is available in the human body as high as 86.3%, which is the best among all fruits. Therefore, the jujube has become the first place in the vitamin C fruit list.
2nd place: Blackcurrant. The vitamin C content in the same amount of blackcurrants is 4 times that of oranges.
3rd place: Strawberry. Strawberries are rich in malic acid, citric acid, carotene and trace elements, among which, the vitamin content is 7-10 times higher than that of apples and grapes.
No. 4: Kiwi. Kiwi fruit is rich in kiwi alkaloid, proteolytic enzymes, various trace elements and 17 kinds of amino acids required by the human body. Kiwi fruit contains a very high content of vitamin C. A kiwi fruit can provide a person Vitamin content for a day.
No.5: Loquat. Ripe loquat contains various fructose, various vitamins and trace elements, among which the content of carotene ranks third among various fruits. The pulp of loquat also has the functions of moistening the lungs, relieving cough and quenching thirst. The vitamin C content in loquat can whiten the skin and lighten the spots.
No. 6: Oranges. The specific weight of an orange cannot be measured. According to the composition analysis, every 100g of orange contains 28 mg of vitamin C, but the vitamin C content in orange is lower than that of loquat.
No. 7: Orange. It contains a variety of organic acids and vitamins that can help the human body regulate metabolism in the human body, and vitamin C can also have a certain anti-cancer effect.
No. 8: Cherry. Compared with vitamin C, cherries actually contain more iron, and the content of vitamin A and carotene is many times that of grapes, apples and oranges.
No. 9: Lemon. Lemons are rich in citric acid and vitamin C, which can treat bronchitis, whooping cough, loss of appetite, vitamin deficiency, heatstroke and polydipsia. The vitamin C contained in lemons makes lemons the nemesis of scurvy.
No. 10: Lychee. Lychee is rich in glucose, sucrose, protein, fat and various vitamins A, B and C, which are very beneficial to the human body.
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Summary
Vitamin C has a positive effect on purine metabolism, which can help reduce uric acid levels, thereby reducing the risk of monosodium urate crystal deposition in joint structures and soft tissues. However, these studies are limited due to the short observation time. Long-term follow-up of more patients and long-term intervention studies are needed to draw final conclusions. And excessive intake of vitamin C is harmful to the blood system, nervous system, kidney system, digestive system, etc. Therefore, it is recommended that you consume adequate amounts of vitamin C.
Currently, the most reasonable way to treat gout is to recommend a balanced diet with more vegetables, fruits and grains and less meat and meat products. In addition, it is necessary to maintain an appropriate body weight and physical activity, while smoking cessation is also very important.
References:
[1]Chen Yuhang, Zhuang Yu, Wang Zhiwen, et al. Clinical observation of a new method for lowering uric acid in the treatment of acute gouty arthritis [J]. Qingdao Medical and Health, 2017 49 (5): 321 -323.
[2]Gonzalez EB.An update on the pathology and c1inicaI management of gouty arthritis[J].Clin Rheumatol, 2012, 31 (1): 13-21.
[3]Li L, Zhang Y, Zeng C. Update on the epidemiology , genetics, and therapeutic options of hyperuricemia. Am J T ransl. Res, 2020, 12, 3167-3181.< /p>
[4]oman YM,Daniel K.Inouye College of Pharmacy Scripts: Perspectives on the Epidemiology of Gout and Hyperuricemia.Hawaii J. Med. Public Health,2019, 78, 71C76.
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[5]Juraschek SP,Miller ER, Gelber AC.Effect of oral vitamin C supplementation on serum uric acid: a meta-analysis of randomized controIled trials[J].Artbritis Care Res (Hoboken ), 2011 , 63 (9) : 1295-1306.
[6] Ma Ling, Wang Li, Zhou Yong, etc. Correlation between serum vitamin A, C, E levels and uric acid levels [J] Chinese Journal of Gerontology, 2013, 33(12): 2742-2744.
[7] Jia Shaodan, Wang Yangang, et al. Study on the relationship between different uric acid concentrations and oxidative stress and endothelial injury indicators [J]. Chinese Journal of Internal Medicine, 2008, 47(8): 38-41.
[8] Ma Qiaolan, Jiang Zhuoqin, Deng Liang. A case-control study on the relationship between lifestyle and dietary factors and hyperuricemia [J]. Public Health and Preventive Medicine, 2012, 34 (2 ) : 29-32.
[9] Jia Ruijie, Zhang Qiang, Ru Jifeng, et al. Kinetic model analysis of biological antioxidants detected by photo-induced reactive oxygen species destruction method [J]. Analytical Chemistry, 2016, 44 (8 ) : 1257-1262.
[10]Kim SK,Choe JY,Park KY. TXNIP-mediated nuclear factor-κB signaling pathway and intracellular shifting of TXNIP in uric acid-induced NLRP3 inflammasome. Biochem. Biophys. Res. Commun. 2019, 511, 725-731.
[11]Choe JY, Kim SK. Quercetin and Ascorbic Acid Suppress Fructose-Induced NLRP3 Inflammasome Activation by Blocking Intracellular Shuttling of TXNIP in Human Macrophage Cell Lines. Inflammation 2017, 40,980-994.
This article was first published: Rheumatism and Nephrology Channel of the Medical Community
This article was written by: Fu Er
Review of this article: Chen Xinpeng, Deputy Chief Physician
Editor in charge: Yuan Xueqing, Zhang Li
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