The Importance of Antioxidant
The leading causes of death in the United States are cardiovascular diseases and cancers. Similarly, in Taiwan, around 27% of deaths are from cancer and 18% of deaths are from cardiovascular and heart diseases (Department of Health Web, 2004). It was estimated by Willet (1994) that roughly 32% (range of 20%–42%) of deaths from cancer could be avoided by dietary modification.
Epidemiological studies have strongly suggested that diet plays an important role in the prevention of chronic diseases (Bauman et al., 2004; Willet, 1995). Polyphenolics, thiols, carotenoids, tocopherols, and glucosinolates commonly found in fruits, vegetables and grains, provide chemoprotective effects to combat oxidative stress in the body and maintain balance between oxidants and antioxidants to improve human health (Adom and Liu, 2002; Dragsted et al., 1993; Jia et al., 1999; Wolfe et al., 2003). An imbalance caused by excess oxidants leads to oxidative stress, resulting in damage to DNA and protein and increased risk of degenerative diseases such as cancer (Farombi et al., 2004).
Consumption of fresh fruits and vegetables, as well as grains, has been associated with reduced risk of coronary heart disease (CHD) (Bazzano et al., 2003; Joshipura et al., 2001; Srinath Reddy and Katan, 2004), stroke (Gillman et al., 1995; Voko et al., 2003), symptoms of chronic obstructive pulmonary disease (Fabricius &
Lange, 2003; Liu et al.,
2004), and different types of cancer, including breast and
ovarian cancer (Duncan et al., 2004) and colon cancer (Frydoonfar et al., 2003). Polyphenolic compounds, widely distributed in higher plants, have been found to have potential health benefits that are believed to arise mainly from their antioxidant activity (Liu, 2003). There is considerable scientific and public interest in the important role that antioxidants may play in health care, such as by acting as cancer chemopreventive and anti-inflammatory agents and by reducing risk of cardiovascular mortality (Cos et al., 2004).