Phenolic acids are a diverse group of plant compounds found abundantly in fruits, vegetables, coffee, and whole grains. They are well-known for their antioxidant and anti-inflammatory properties, and their potential role in supporting vascular health, including the capillary system, has been explored in a range of scientific studies. Research indicates that phenolic acids, such as ferulic acid, caffeic acid, and chlorogenic acid, can help protect endothelial cells (which line the interior surface of blood vessels) from oxidative stress and inflammation. These actions are important because capillaries, the smallest blood vessels in the body, are particularly susceptible to oxidative damage and increased permeability in various disease states (such as diabetes and hypertension).

Several preclinical studies have shown that phenolic acids can reduce capillary fragility and permeability in animal models. Human studies, though more limited, suggest that diets rich in phenolic acids may improve microvascular function and reduce markers of vascular inflammation. However, most clinical evidence is indirect, based on the consumption of phenolic acid–rich foods rather than isolated compounds. As such, while the biological plausibility is strong and animal studies are promising, more targeted clinical trials are needed to confirm direct effects.

In summary, the use of phenolic acids to support capillary health is grounded in scientific evidence, particularly from basic and animal research, and is rated as moderate (3 out of 5) due to limited direct human data.