Lead extraction with green tea: AAS reveals efficacious lead detox

Brewing up lead treatment

Atomic absorption spectroscopy and other techniques have been used to study the effects of green tea extract on reducing lead toxicity in laboratory rats. Green tea is tea brewed with the unprocessed leaves of Camellia sinensis. Green tea originates from China and has become associated with many cultures in Asia from Japan and South Korea to the Middle East. Black tea by contrast is more familiar in the West and is made from the "oxidised" leaves, which gives it a stronger flavour.

There have been various medical claims made for all forms of tea, but green tea extract has come to the fore as having unproven health benefits, such as helping with weight control, lowering the risk of cardiovascular disease and cancer. The presence of antioxidants including polyphenols and the presence of the stimulant caffeine are all considered in the general assessment of tea's physiological effects. Green tea extracts are herbal derivatives from green tea leaves that contain antioxidants, mainly green tea catechin polyphenols (GTC).

Green tea extract has been linked to lower cholesterol levels in animal studies and in humans GTE apparently increases the rate of fat oxidation in the body while modulating insulin activity. Obtaining proof of such benefits is fraught with epidemiological hazards. However, atomic absorption spectroscopy can demonstrate quantitative changes in levels of metal contaminants in a sample that would indicate benefits in some contexts. For instance, if GTE were able to chelate toxic lead ions in the body and allow them to be flushed out by the kidneys then that health effect could be demonstrated in a relatively straightforward way.

Lead toxicity

Green tea is tea made solely with the leaves of Camellia sinensis that have undergone minimal oxidation during processing. Green tea originates from China and has become associated with many cultures in Asia from Japan and South Korea to the Middle East.

Now, writing in the journal Atomic Experimental and Toxicologic Pathology, an international team based in Egypt and India, report on a study into lead toxicity amelerioration with GTE in male Sprague-Dawley rats. Lead is a common cause of chronic health problems in humans and poisoning of domestic animals throughout the world. The early stages of inorganic lead exposure are manifested by loss of appetite, weight loss, constipation, irritability, fatigue, occasional vomiting, lead line of gums and anaemia. Health risks associated with lead exposure from industrial and environmental sources are now well recognized and it is known that the metal interferes with many biochemical and physiological functions.

E.E. Mehana of the Department of Pathology, College of Veterinary Medicine, Alexandria University, M.A. Meki of the Department of Biochemistry, College of Medicine, Assiut University, in Egypt, and Khalid Majid Fazili of the Department of Biotechnology, University of Kashmir, Srinagar, J&K, in India, studied four groups of rats. They gave the animals lead and GTE orally with drinking water for 8 weeks. "Lead concentration in the digested tissues of liver was detected using atomic absorption spectroscopy," the team explains, and "the activities of glutathione-S-transferase (GST) and superoxide dismutase (SOD) were used as markers to evaluate the antioxidant status of tissues."

They found that exposure to lead alone reduced the antioxidant capacity of the liver. However, this was reversed to some degree by ingestion of green tea extract. The team explains that the levels of liver enzymes ALT, AST and ALP and serum protein determinations showed that GTE has a protective effect on liver function in the face of lead. "Histopathological studies of liver revealed that supplementation of green tea extract resulted in mild degeneration and congestion of the blood vessels and an enhanced regenerative capacity," the team adds."