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Scientists are calling for greater control and research into herbal and plant-based remedies following studies showing that apparently beneficial herbal antioxidants may cause cancer or other illnesses in some people.
It was found that quercetin and ferulic acid, antioxidants taken to prevent cancer, when fed to diabetic laboratory rats, actually aggravated and possibly even caused kidney cancer.
Another paper published in the Journal of Forensic Science in the US revealed that many supposedly safe, plant-derived remedies contained potentially lethal concentrations of arsenic, mercury and lead. In one case, a five-year-old boy who had been administered 63g of “Tibetan herbal vitamins” over a four-year period was diagnosed with lead poisoning.
In 2007 a causative link was established in a disease known as endemic (Balkan) nephropathy, which occurs in rural areas of the Balkans. The disease progresses rapidly to chronic renal failure and upper urinary tract cancer (UUC), through damage to renal DNA by aristolochic acid. The toxin derives from the European birthwort (Aristolochia clematitis), which grows in wheat fields in the Balkan region. Seeds of the plant were found to be contaminating grain, entering the food chain and causing toxicity.
The researchers turned their attention to south-east Asia, where several Aristolochia species have long been used in herbal remedies. A study in Taiwan discovered that about one third of patients taking prescription medicines consume herbs likely to contain aristolochic acid.
In a DNA study of UUC patients, 83 per cent were found to contain metabolites of aristolochic acid bound to DNA within the renal cortex, suggesting aristolochia use.
It is hoped that these findings will provide a solid foundation for health officials to develop education strategies designed to reduce aristolochia use and related UUC.