Flavans, a subclass of flavonoids found in various fruits, vegetables, tea, and cocoa, have been studied for their antioxidant, anti-inflammatory, and vasoprotective properties. Scientific interest in their use for diabetic retinopathy arises from preclinical and limited clinical studies suggesting that flavans can mitigate oxidative stress and inflammation—key contributors to the progression of diabetic retinopathy. Experimental models demonstrate that flavans such as epicatechin and catechin can protect retinal cells from hyperglycemia-induced damage, improve capillary function, and reduce vascular leakage.

Some small-scale clinical trials and observational studies have shown improved retinal microcirculation and reduced markers of oxidative damage in diabetic patients consuming flavan-rich foods or supplements. However, the quality of clinical evidence remains moderate, with most studies being short-term, involving small sample sizes, or using surrogate outcomes rather than direct measures of retinopathy progression. Notably, meta-analyses of flavonoid supplementation in diabetes have found modest improvements in biomarkers of vascular health, but data specific to diabetic retinopathy are still emerging.

In summary, there is scientific rationale and preliminary evidence supporting the use of flavans to help manage or slow the progression of diabetic retinopathy, primarily due to their antioxidative and vascular protective effects. However, large, well-controlled clinical trials are needed to confirm efficacy and establish standardized dosing protocols.