Quercetin, Rutin, Vitamin C (2002, 2015, 2017) Flavonoids & Cataracts
Like other nutrient combinations, the combination of quercetin and vitamin C or rutin and vitamin C are effective in reducing the risk of developing cataracts. Quercetin and vitamin C are an especially effective combination.
Diabetics are at greater risk of developing cataracts than other populations. Researchers evaluating the mechanics of cataract development in diabetics have noted a number of mechanisms (maillard reaction, enhanced polyol pathway, and oxidative insults, epithelial mesenchymal transition) by which this is true. The latter mechanism, epithelial mesenchymal transition, refers to epithelial cells losing their polarity and ability to adhere to neighboring cells resulting in migration and invasion in other parts of the body. In this case the process takes place in the lens.
The researchers found that the flavonoids rutin, and especially quercetin, in combination with vitamin C had a potent and beneficial effect in reducing these malefic processes.
Cornish, K.M., Williamson, G., Sanderson, J. (2002). Quercetin metabolism in the lens: role in inhibition of hydrogen peroxide induced cataract. Free Radic Biol Med, Jul 1;33(1):63-70.
Du, L., Hao, M., Li, C., Wu, W., Wang, W., et al. (2017). Quercetin inhibited epithelial mesenchymal transition in diabetic rats, high-glucose-cultured lens, and SRA01/04 cells through transforming growth factor-β2/phosphoinositide 3-kinase/Akt pathway. Mol Cell Endocrinol, Sep 5;452:44-56.
Another study notes that the quercetin is one of the main flavonoids in green tea - and that consumption of green tea is associated with reduced risk of cataract.
Sheng, Y., He, F., Lin, J.F., Shen, W., Qiu, Y.W. (2015). Tea and Risk of Age-Related Cataracts: A Cross-Sectional Study in Zhejiang Province, China. J Epidemiol, 26(11): 587–592.