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Top1. Introduction
Mercury (Hg) is a toxic, global pollutant biomagnified through the food chain (UNEP, 2002). Humans are exposed to organic forms of mercury like methyl mercury (CH3Hg+) - produced through biomethylation of the inorganic mercury present in aquatic organisms - through consumption of contaminated food and water (Klaassen, 1996); and ethyl mercury (CH3CH2Hg+) through vaccines, (Fitzgerald & Clarkson, 1991; Clackson et al., 2003).
Mercurous and mercuric ions impart their toxicological effects mainly through molecular interactions with sulfhydryl groups on various molecules like GSH, metallothionein and albumin (McGoldrick et al, 2003; Yoshida et al., 2006); or induction of stress proteins like heat shock proteins (HSPs) and glucose regulated proteins - GRPs (Goering et al., 2000; Papaconstantinou et al., 2003), leading to oxidative stress and cellular damage. Health effects of these exposures include reduced growth and development, cancer, organ damage, kidney damage, nervous system damage, development of autoimmunity and in extreme cases, death (Houston, 2007; Yoshida et al., 2006).
The management and treatment of metal poisoning has been with the use of chelators which mobilize and enhance excretion of these metals from the body and sometimes form stable complex with the metal, thus shielding the biological targets from it. The use of these chelators has been reported to reduce the tissue metal burden in many cases (Anderson, 1999; Nwokocha et al., 2011; 2012). However, various side effects of the chelators, their high toxicity, their chemistry with regards to mercury toxicokinetics and toxicodynamics, and the fact that they are not able to reverse damages already done, makes them not very effective for use (Cory-Slechta et al., 1987; Flora et al., 2008).
Growing awareness of the use of nutritional and medicinal plants to maintain optimum health emphasizes the relevance of considering the way that nutritional factors may affect metal toxicity (Zorn & Smith, 1990; Nwokocha et al., 2011a, b). There are reports that nutrients interact with the metabolism of heavy metals at the physiologic level (Nwokocha et al., 2012a, b). Medicinal plants and nutrients can affect bioavailability, toxico-dynamics, and transport to target organs, and influence the immunologic, biochemical, or cytologic functional responses.