Walnut oil is supported by scientific evidence for its potential benefits to the arteries and cardiovascular system. Walnut oil is rich in polyunsaturated fatty acids, particularly alpha-linolenic acid (ALA), an omega-3 fatty acid. Studies have shown that regular consumption of walnuts or walnut oil can improve endothelial function (the ability of blood vessels to relax and contract), reduce LDL ("bad") cholesterol, and lower markers of inflammation, all of which are associated with improved arterial health and reduced risk of cardiovascular disease.

For example, a 2010 randomized controlled trial published in the journal Circulation found that a walnut-enriched diet improved endothelial function in overweight adults, compared to a control diet. Another review in Nutrients (2019) summarized that walnut consumption, including walnut oil, is linked to favorable changes in lipid profiles and vascular health markers. However, most studies have focused on whole walnuts, with fewer specifically examining walnut oil, though the fatty acid profile is similar.

While promising, the evidence is not as robust as for some other oils (such as olive oil) and is not entirely conclusive, resulting in a moderate rating. The use of walnut oil for artery support is thus scientifically plausible and has some human clinical backing, but more targeted research on walnut oil itself would be beneficial.