Herbal medicines sold online frequently contain 'dangerous levels of toxic metals'

A fifth of Ayurvedic treatments - a traditional Indian medicine - contained doses of toxic metals and chemicals up to 10,000 times higher than acceptable limits, researchers found.

The scientists said products with such high levels of dangerous metals should be banned from sale.

Toxic remedy: The findings could put people off buying herbal medicines online

Ayurveda has been practised in India for thousands of years and is used by 80 per cent of the country's population.

It combines herbal medicine with oils, massage, yoga and meditation and is increasingly popular as an alternative to western medicines for a huge range of illnesses.

Fans include Madonna, Naomi Campbell and Cherie Blair. The study, led by Dr Robert Saper from the Boston University School of Medicine, looked at 193 Ayurvedic products bought from 25 websites.

They were made by 37 manufacturers in India and the U.S.

These were analysed for metal traces using a technique called X-ray fluorescence spectroscopy, reported the Journal of the American Medical Association.

The highest levels of toxic metals were found in medicines used in a branch of Ayurveda called rasa shastra, which is used to treat serious illnesses including paralysis. It combines herbs with lead, iron and zinc, as well as minerals such as mica and gems such as pearls.

In total, around a fifth of the products contained lead, mercury or arsenic. The scientists said all exceeded 'one or more standards for acceptable daily metal intake'.

Lead was the most commonly found toxin, followed by mercury and arsenic.

Rasa shastra medicines were more than twice as likely as herbal-only medicines to contain the toxins, and had higher levels of lead and mercury.

Many rasa shastra medicines were elaborately prepared with various forms of metals including 'cinnabar' (mercuric sulphide), 'galena' (lead sulphide), 'realgar' (arsenic sulphide) and 'white arsenic' (arsenic trioxide).

Since 1978, more than 80 cases of lead poisoning have been linked to Ayurvedic medicines.

Dr Saper said the findings highlighted the need for proper regulation of dietary supplements.

'Our first priority must be the safety of the public,' he added.

'Herbs and supplements with high levels of lead, mercury and arsenic should not be available for sale on the internet or elsewhere.'

The report's co-author Professor Venkatesh Thuppil, from St John's Medical College in India, said: 'The medicines which are supposed to cure sickness should not promote another illness due to the presence of toxic materials such as lead.'