Apples lead to healthy heart

LYN WHITE, SCIENCENETWORK WA

Flavonoids are concentrated in the skin of apples. Image: egal/iStockphoto FLAVONOID rich pink lady apples added to the diet may have a positive effect on cardiovascular health according to a recent trial at the UWA. UWA’s School of Medicine and Pharmacology PhD student Ms Catherine Bondonno says cardiovascular disease (CVD) is the leading cause of death in Australia, causing 35 per cent of all deaths. “About 3.7 million Australians have CVD and 1.4 million have a disability associated with the disease impacting on their quality of life,” Ms Bondonno says. Ms Bondonno’s PhD project was to investigate the acute effect of high flavonoid apples on nitric oxide (NO) production and endothelial function, which are factors in cardiovascular health. “The endothelium is a single layer of cells lining blood vessels and produces nitric oxide,” Ms Bondonno says. “Nitric oxide signals surrounding muscles to relax, which causes the blood vessel to dilate increasing blood flow through the vessel.” Ms Bondonno selected thirty healthy volunteers from the general Perth population and conducted preliminary tests of their BMI, blood pressure, cholesterol levels and fasting blood glucose levels to ensure normal health. Flavonoids are concentrated in the skin of apples so the treatment consisted of a high flavonoid apple with skin. The control was given apple flesh only. Participants were randomly assigned to consume either the apple with skin first followed by the flesh only, or vice versa..  The night before the study, all participants consumed the same meal. On the study day, an apple was eaten with breakfast and again with lunch to account for the varying times the flavonoids, epicatechin and quercetin glycosides, peak in the blood stream. Blood pressure, nitrite levels and flow mediated dilatation were measured. Flow mediated dilatation is a measure of the dilation of blood vessels in response to an increase in blood flow. Nitric oxide is highly reactive and is rapidly converted to nitrite and s-nitrisothiol in the blood. “We put a blood pressure cuff around the forearm over the brachial artery and got a picture of the artery on the screen,” Ms Bondonno says. “We increased the pressure to occlude blood flow, then after 5 minutes we released the cuff to get an increase in blood flow. “Then we measured the dilation in response to that increased blood flow.” Results indicated that there was a doubling of s-nitrosothiol in the blood and a 2 per cent increase in flow mediated dilatation after the consumption of the high flavonoid apple. The conclusion was that flavonoid rich apples improve nitric oxide status and endothelial functions which are factors affecting cardiovascular health. Ms Bondonno says this study could translate into a natural, low cost approach to reducing the cardiovascular risk profile of the general population.