By Dr Harold Gunatillake Health Writer
Polyphenols have recently been termed "lifespan essentials", and they actively participate in the body to prevent diseases from occurring. Polyphenols are antioxidants from plant foods that work in the body to enhance health in complex ways, and as such they are not simply antioxidants. Their specific health-promoting actions are still being actively researched, and it is generally recognized that they can reduce the risk factors for cardiovascular disease and basically help to protect many body systems from the risks or ravages of many types of chronic disease. Boosting one's intake of antioxidant polyphenols on a daily basis is easy to do, and can be a tasty, gourmet adventure.
They are also antioxidant micronutrients containing poly-phenolic or natural substructure.
There are over 4000 of them and most of them have antioxidant activity in vitreo, meaning studies in the laboratory. They also have the function of signaling from cell to cell, receptor sensitivity and gene regulation.
These polyphenols found in plants are natural metabolites that have antioxidant properties in humans as mentioned before. The U.S. Department of Agriculture has not yet established a recommended daily intake for polyphenols or calculated current average polyphenol consumption in America. Polyphenols are categorized as phenolic acids, flavonoids or tannins, all of which are antioxidants. Only eating a variety of food sources of polyphenol provides access to all three types.
Polyphenols are abundant micronutrients in our diet, and their role in preventing degenerative diseases, including cancer has come to light in recent studies, and their role in the prevention of various diseases associated with oxidative stress, such as cancer, cardio-vascular disease and neurodegenerative diseases.(Scalbert A, Manach C, Morand C, Rémésy C, Jiménez L. Crit Rev Food Sci Nutr, in press).
In addition being functioning as antioxidants these polyphenols have other functions found in medicinal plants, modulate the activity of a wide range of enzymes and cell receptors in this way. In human usage of these polyphenols they may not be absorbed with equal efficacy.They are extensively metabolized by intestinal and hepatic enzymes and by the intestinal microflora. Knowledge of the bioavailability and metabolism of the various polyphenols is necessary to evaluate their biological activity within target tissues.
There are several thousands of phenol molecules having phenolic structure, (i.e. several hydroxyl groups on aromatic rings) have been identified in higher plants, and several hundred are found in edible plants. These molecules are secondary metabolites of plants and are generally involved in defense against ultraviolet radiation or aggression by pathogens.
These polyphenols are flavonoids, stilbenes, isoflavones, proanthocynadins, catechins and anthocyanidins.The many analytic studies of polyphenols in foods that have been conducted to date provide a good indication of polyphenol distribution. Fruit and beverages such as tea, red wine, and coffee constitute the principal sources of polyphenols, but vegetables, leguminous plants, and cereals are also good sources.
Polyphenol concentrations in foods vary according to numerous genetic, environmental, and technologic factors, some of which may be controlled to optimize the polyphenol content of foods. The main tasks ahead are identifying the plant varieties that are the richest in the polyphenols of interest, improving growing methods, and limiting losses during the course of industrial processing and domestic cooking.
Ref: The American Journal of Clinical Nutrition.
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