Certain compounds found in green tea and apples reduce risk of heart diseases and cancer by blocking a molecule that triggers those illnesses.
Scientists from the Institute of Food Research (IFR) have found evidence for the mechanism showing how people who eat the largest amounts of fruit and vegetables stay healthy.
Polyphenols in green tea and apples block a signalling molecule called VEGF, which in the body can trigger atherosclerosis and is a target for some anti-cancer drugs.
The molecule VEGF is a main driver of the process called angiogenesis that triggers cancer progression and development of atherosclerotic plaques and plaque rupture leading to heart attacks and stroke.
Even low concentrations of the polyphenol epigallocatechin gallate (EGCG) from green tea and procyanidin from apples were enough to stop a crucial signalling function of VEGF in cells taken from human blood.
This study is the first to establish the direct interaction between polyphenols and VEGF.
"If this effect happens in the body as well, it provides very strong evidence for a mechanism that links dietary polyphenols and beneficial health effects," said Dr Paul Kroon, research leader at IFR.
The polyphenols also set off another mechanism that generates nitric oxide in the blood, which helps widen the blood vessels and prevent damage.
It was known that VEGF itself stimulates nitric oxide, which is why some anti-cancer drugs that block VEGF cut nitric oxide in the process and lead to an increased risk of hypertension in some users.
High levels of polyphenols are found in berries, plums, olive oil and cereals. Cocoa powder, dark chocolate, coffee, tea, and flaxseed meal are also high in the beneficial compound.
The polyphenol epigallocatechin-3-gallate or EGCG has been shown in earlier studies to trigger a process in the mitochondria that leads to oral cancer cell death.
Green tea made from unfermented leaves is believed to contain the highest concentration of powerful antioxidants called polyphenols. Antioxidants fight free radicals — compounds in the body that change cells, damage DNA, and cause cell death.
Green tea contains six polyphenol compounds of which EGCG is one.
Clinical studies indicate that the antioxidant properties of green tea may help prevent atherosclerosis, lower total cholesterol and raise HDL, protect against cancer and kill cancerous cells and stop them from growing.