Evaluation of Quercetin as a Countermeasure to Exercise-Induced Physiological Stress

Excerpt

Polyphenols are a large class of colourful, plant-based, phenolic organic compounds (USDA 2007). They are enriched in certain vegetables, fruits, seeds and beverages (e.g. tea and wine) and are regarded as semi-essential nutrients in humans.

Flavonoids, a polyphenolic subgroup, provide many of the colours in fruits and vegetables (Nieman et al. 2010a). As a natural antioxidant, flavonoids constitute significant components of the human diet and exhibit a diverse array of biological effects (Kandaswami and Middleton 1994, Korkina and Afanas’ev 1997, Li et al. 2000, Middleton et al. 2000).

Flavonoids compromise a large group of plant metabolites, 6000 of which have been identified to date (Erdman et al. 2007) and can then be divided into six subgroups. One of these six groups is flavonols, which it contains the abundant and diffuse flavonoid quercetin (Nieman et al. 2010a). Food-based sources of quercetin include tea, onions, apples, peppers, blueberries and dark green vegetables (Chun et al. 2007, USDA 2007).

The intake of these compounds improves an individual’s health and decreases their risk of cardiovascular disease (Korkina and Afanas’ev 1997, Kim et al. 2004, Scalbert et al. 2005).