In the news: Flavonoids Quercetin & Catechins Associated with Better Anti-VEGF Outcomes in Wet AMD

Intake of Certain Flavonoids Linked to Better anti-VEGF Treatment Outcomes Over Time

Flavonoids, a group of vasoactive phytochemicals found in fruits, vegetables, grains, tea, and wine, have been shown to display a range of antioxidant and anti-inflammatory activity in ocular tissues. But aside from a Blue Mountain Eye Study report linking higher total intake of flavonoids and several flavonoid classes with a lower risk of AMD(1), research on the relationship between these nutrients and AMD has been scarce.

Australian vision researchers from the Universities of Sydney and Perth sought to assess whether dietary intake of phytochemicals from the six major classes of bioflavonoids would be associated with treatment outcomes among patients with neovascular age-related macular degeneration (nAMD) receiving anti-vascular endothelial growth factor (anti-VEGF) therapy.

The recently published study found an association between three flavonoids – quercetin, epigallocatechin (EGC), and epigallocatechin 3-gallate (EGCG) – and better treatment outcomes.

Design & Methods

In this longitudinal study(2), 547 participants with a recent diagnosis of neovascular AMD (nAMD) were recruited and 494 were followed-up after receiving 12 months of anti-VEGF therapy. Dietary intake of total and specific flavonoids over the 12 months prior to the baseline data was obtained using a validated food frequency questionnaire. Intake of flavonoids was divided into three equal groups (tertiles).

At follow-up, presence of intra-retinal and sub-retinal fluid, retinal pigment epithelium detachment and central macular thickness were assessed by OCT scans. Visual acuity was documented using LogMAR charts.

Results

At follow-up, participants in the first or lowest tertile of quercetin, EG and EGCG intake had significantly worse vision than those in the highest or third tertile of intake. (Multivariable-adjusted LS mean of visual acuity: 14.68 vs. 19.53 [p = 0.04]; 14.06 vs. 18.89 [p = 0.0 4]; 13.86 vs. 18.86 [p = 0.03], respectively).

Those in the first vs. third tertile for the flavan-3-ol class of bioflavonoids, EG, and ECGC intake all had a two-fold higher risk of intra-retinal fluid. (Multi-variable-adjusted p trend of 0.03, 0.01, and 0.02, respectively).

The first vs. the third tertile of tea intake had significantly worse vision (LS mean visual acuity: 13.49 vs. 19.04, p = 0.02), increased risk of intra-retinal fluid (OR 2.13), and greater mean central macular thickness (279.59 μm vs. 256.52 μm, p = 0.04).

Tea is a common source of EGC and EGCG while quercetin is abundant in a variety of fruits and vegetables as well as tea.

Comments

This longitudinal cohort study found an independent association between higher intake of select bioflavonoids and treatment outcomes at 12 months.

There is evidence that quercetin (from the flavanol class of bioflavonoids and catechin (from the flavan-3-ol class) exert anti-angiogenic activity. So, in addition to acting as antioxidants and anti-inflam-matory nutrients they may also act in slowing the growth of abnormal new blood vessels from the choroid under the macula – a hallmark of wet AMD.

Intervention studies are warranted to confirm these associations and, perhaps, identify a promising new adjunct for standard neovascular AMD therapy.

References

1. Gopinath B, et al. Dietary flavonoids and the prevalence and 15-year incidence of age-related macular degeneration. Am J Clin Nutr. 108:381-87, 2018.
2. Detaram HD, et al. Dietary flavonoids are associated with longitudinal treatment outcomes in neovascular age-related macular degeneration. Eur J Nutr. Epub May 19, 2021.