Taking apples daily is one way of keeping risks linked with cardio health at bay. Catherine Bondonno, doctoral student in pharmacology at the University of Western Australia, researched the effect of apples on nitric oxide (NO) production and endothelial function, which affect cardiovascular health. "The endothelium is a single layer of cells lining blood vessels and produces nitric oxide," says Bondonno. Flavonoids, collectively known as Vitamin P and cirtrin, concentrate in the skin of apples, which also give fruits their distinctive flavours. "Nitric oxide signals the surrounding muscles to relax, which causes the blood vessel to dilate increasing blood flow through the vessel," a Western Australia statement quoted her as saying. Bondonno selected a group of healthy volunteers, who after undergoing a battery of tests, were randomly assigned to consume either the apple with skin first followed by the flesh only, or vice versa. On the study day, an apple was eaten with breakfast and again with lunch to account for the varying times the flavonoids peak in the blood stream. Results indicated that flavonoid rich apples improve nitric oxide status and endothelial functions, factors affecting cardiovascular health.