UB Researcher Urges Exploration of Flavonoids' Health-Promoting Properties

Elliott Middleton, Jr., M.D., professor of medicine at the University at Buffalo, thinks the answer is yes. He has been investigating the function of these low-molecular-weight, organic plant compounds for 16 years, and has published a number of papers on the subject.

Middleton was invited to review his findings and summarize other flavonoid research today (April 12) at the annual meeting of the Federation of American Societies of Experimental Biology.

"Flavonoids have existed in nature for one billion years, so clearly they are doing something very important for plants," Middleton says. "It may be that they are important for humans too, but they haven't been studied sufficiently.

"At present, flavonoids -- found in fruits, vegetables, nuts, seeds, stems, bark, flowers, tea and wine -- are considered to be secondary, non-essential dietary factors. However, this position may need to be modified in view of their potentially health-promoting activities that have come to be appreciated, at least in experimental settings. They display a remarkable array of biochemical and pharmacological actions, some of which suggest that certain members of this group of compounds may significantly affect the function of many human cells and tissues."

Flavonoids, of which more than 4,000 exist in nature, are responsible for the red, yellow and orange of flowers, vegetables and fruit, and for the hues of autumn leaves. They are involved in plant growth, sex determination, nitrogen fixation, respiration and photosynthesis. They also protect plants from insects and act as antioxidants and sunscreens.

Given this broad range of action in plants, it is reasonable to think they are important micro-nutrients for humans as well, Middleton asserts.

€ Enzymatic effects: Flavonoids have been shown to influence enzyme systems associated with cell processes that result in specific activities, e.g. secretion, cell division and differentiation, and motility.

€ Anti-allergy activities: They can inhibit the degranulation of mast cells and basophils, which in turn inhibits the release of histamine.

€ Anti-inflammatory activities: They can inhibit the activation and degranulation of neutrophils, preventing the production of free radicals that damage cells.

€ Anti-viral activities: They have been shown to inhibit the activity of a number of viruses, including polio, herpes, RSV and parainfluenza, and to inhibit some enzyme functions essential for the life of the HIV virus.

€ Anti-cancer activities: They have been shown to interfere with the growth of tumor cells, causing them, in some cases, to mature into a nonmalignant state. They also have been shown to inhibit the development of mammary cancer in rats.

€ Anti-thrombosis activities: Flavonoids are thought to be the active agent in red wine responsible for the so-called French paradox. The polyphenols in red wine, also found in red grape juice, are credited with causing a lower heart-disease rate among the French, despite a diet high in saturated fat and cholesterol.

Middleton is preparing the first literature review of studies dealing with the effects of flavonoids on gene function, and is continuing his own flavonoid research.

"We are going to be hearing a lot more about these compounds in the next five years," he states.