Scientists from the Institute of Food Research have found evidence for a mechanism by which certain food compounds could help protect our health.
Dietary studies have shown that people who eat the largest amounts of fruit and vegetables have a reduced risk of developing chronic conditions, such as heart disease and cancer. There could be several reasons for this. Some fruit and vegetables naturally contain high amounts of compounds called polyphenols, which could provide protective health benefits.
In this study, Dr Paul Kroon and his team at IFR have shown that 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.
In the body, VEGF is a main driver of blood vessel formation in these cell types via a process called angiogenesis. Angiogenesis is crucial in cancer progression, as well as in the development of atherosclerotic plaques and plaque rupture which can cause heart attacks and stroke.
Using cells derived from human blood vessels, the researchers found that low concentrations of the polyphenols epigallocatechin gallate (EGCG) from green tea and procyanidin from apples stopped a crucial signalling function of VEGF.
Inhibition of VEGF signalling by dietary polyphenols has previously been implicated in other studies, but this study provides the first evidence that polyphenols can directly interact with VEGF to block its signals, at the levels you would see in the blood stream after eating polyphenol rich foods.
Polyphenols are a group of vegetable chemical substances, characterized by the presence of more than one phenolic group. Their phenolic reactions produce gelatines, alkaloids and other proteins. The polyphenols are responsible for the coloring of some plants. Polyphenols have been shown to be strong antioxidants with potential health benefits.
“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 activated another enzyme signalling system that generates nitric oxide in the blood, which helps widen the blood vessels and prevent damage. This was unexpected, as VEGF itself stimulates nitric oxide, and anti-cancer drugs that block VEGF also reduce nitric oxide, leading to an increased risk of hypertension in some users.
Uncovering the links between food and health is a key part of the mission of the Institute of Food Research. This research was funded by the Biotechnology and Biological Sciences Research Council (BBSRC), a Marie Curie Intra European Fellowship, Correscence Ltd, and the European Union through the BACCHUS project. BACCHUS is a collaborative project under the 7th Framework Program of the European Commission, led by IFR, focusing on the action of bioactive substances found in foods that are common in European diets.
Green tea is a product made from the Camellia sinensis plant. It can be prepared as a beverage, which can have some health effects. Or an “extract” can be made from the leaves to use as medicine.
Green tea is used to improve mental alertness and thinking.
It is also used for weight loss and to treat stomach disorders, vomiting, diarrhea, headaches, bone loss (osteoporosis), and solid tumor cancers.
Some people use green tea to prevent various cancers, including breast cancer, prostate cancer, colon cancer, gastric cancer, lung cancer, solid tumor cancers and skin cancer related to exposure to sunlight. Some women use green tea to fight human papilloma virus (HPV), which can cause genital warts, the growth of abnormal cells in the cervix (Cervical dysplasia), and cervical cancer.
Green tea is also used for Crohn’s disease, Parkinson’s disease, diseases of the heart and blood vessels, diabetes, low blood pressure, chronic fatigue syndrome (CFS), dental cavities (caries), kidney stones, and skin damage.
Instead of drinking green tea, some people apply green tea bags to their skin to soothe sunburn and prevent skin cancer due to sun exposure. Green tea bags are also used to decrease puffiness under the eyes, as a compress for tired eyes or headache, and to stop gums from bleeding after a tooth is pulled.
Now scientists have documented how a catechin (a polyphenol plant compound) in green tea known as epigallocatechin-3-gallate (EGCG) may protect people with high-glucose conditions such as diabetes and the pre-diabetic metabolic syndrome from heart disease and other medical ills.
Polyphenols, including EGCG, comprise around 30% of the dry leaf weight of green tea and researchers think EGCG is one of the most beneficial types of all the natural phytochemicals. In fact, recent studies have shown EGCG has a positive impact on arthritis, mental health problems, oral health, heart disease and even weight loss.
Researchers have also noted a link between consuming green tea and the risk of developing diabetes. In a new study just published in the journal Food Chemistry, a team of researchers from the Department of Food Science and Biotechnology at National Chung-Hsing University and the National Institute of Cancer Research in Taiwan have determined that under high-glucose conditions, EGCG may trigger beneficial processes in the body. This suggests the green tea component can protect diabetics and those with pre-diabetic conditions from serious complications.
Reference: Potent inhibition of VEGFR-2 activation by tight binding of green tea epigallocatechin gallate and apple procyanidins to VEGF: Relevance to angiogenesis, Christina W. A. Moyle et al, Molecular Nutrition and Food Research, 59(3) 401-412 doi: 10.1002/mnfr.201400478
Norwich BioScience Institutes
Molecular Nutrition and Food Research