Cells in humans are constantly exposed to a variety of oxidizing agents. These agents may be present in air, food and water, or they may be produced by metabolic activities within cells. The key factor is to maintain a balance between oxidants and antioxidants to sustain optimal physiologic conditions in the body. Overproduction of oxidants can cause an imbalance, leading to oxidative stress, especially in chronic bacterial, viral and parasitic infections (Liu & Hotchkiss, 1995). Moreover, oxidative stress can cause oxidative damage to large biomolecules such as proteins, DNA and lipids, resulting in an increased risk of cancer and cardiovascular disease (Ames and Gold, 1991 and Ames et al., 1993). To prevent or slow down the oxidative stress induced by free radicals, sufficient amounts of antioxidants need to be consumed. Fruits and vegetables contain a wide variety of phytochemicals compounds, such as phenolics and carotenoids, that may help to protect the cellular systems from oxidative damage and to decrease the risk of chronic diseases (Liu, 2003).