Flavonoids accomplish this by several mechanisms. They increase blood supply to the heart muscle and decrease blood vessel resistance thereby reducing the heart's workload. The end result is better oxygenation of the heart tissue and the rest of the body, as well. Some of the flavonoids work like digitalis to stabilize the heart's rhythm. Hawthorn can also have a calming effect on the nervous system which can also improve cardiac function.
Some flavonoids work like calcium channel blockers to regulate intracellular calcium levels.
OPC's have potent anti - oxidant activity and are probably responsible for the fact that in people if a heart attack does occur, the damage to the heart muscle is much less in those who use hawthorne. Hawthorn berries are also high in B - vitamins and other important nutrients. Hawthorne contains substances that protect heart cells. Medical studies have established that when hawthorne is present the heart muscle can survive on less blood and oxygen. The flavonoids in Hawthorn work to increase oxygen utilization by the heart.