Hormesis is a theoretical phenomena of dose response relationships, whereby low doses of toxins produce beneficial effects. Dietary phytochemicals, are considered important hormetic messengers, given they contain noxious properties that play a crucial role in dissuading insects from eating plants, yet at the relatively small doses consumed by humans induce mild cellular stress responses (prepare cells to resist severe episodes of stress). In a recent study, researchers from the Bioanalytical Science Department at the Nestec Research Institute examined the role that phytochemicals play in improving human health (Holst & Williamson, 2008). In this study, it was found that many phytochemicals activate specific or generalised adapative cellular response pathways to oxidative stress and environmental toxic exposure. This being so, phytochemicals may exert at least part of their beneficial effects by acting as low dose stressors or pro-oxidants that can prepare cells to resist severe episodes of stress.
Holst, B. & Williamson, G. Nutrients and phytochemicals: from bioavailability to bioefficacy beyond antioxidants. Current opinions in Biotechnology, 19, 2, 73-82.