The problem of heavy metals in herbal medicines

On the one hand herbal medicine is great, it tends to be more gentle, to not have withdrawals, allows synergistic combinations of herbs to create complex actions, and often is much milder in side effects. Tonic herbalism as taught by some practitioners of Indian and Chinese medicine emphasises taking specific herbs like ashwagandha or panax ginseng, long term as supportive agents for overall health and longevity. As long as the herbs suit the individual and there are no contra indications, this does not seem like an unreasonable idea. However, there is a danger in this, and that comes in the form of contamination, and is especially an issue using imported herbs from countries like China and India.

Contamination in herbs can be due to the presence of herbicides or pestidicides, but some of the greatest concern at the moment is the presence of heavy metals that may have accumulated in the plant whilst growing in polluted conditions (Ernst, 2002). This is particuarly true for countries with poor standards of environmental control and with terrible pollution problems. One such country is China, I was struck when travelling China some ten years ago by railway, how built up and polluted the city, countryside, and air was. It was not until we reached the Himalayan mountains far in the West until this dissapeared. It is important when practising herbalism that the user of herbs is aware of potential contamination issues in widely available supplements from abroad. It is sensible especially when dealing with herbs that come from countries, such as China and India, to ask for a certificate of analysis to determine whether the material has contamination with heavy metals. The company should be able to provide lab results.

Edzard Ernst writes in his review article, on the subject of contamination in herbal medicine, that, “…Woo reported the detection of toxic heavy metals that exceeded Singapore’s legal limits in 42 Chinese proprietary medicines. They collected 2080 samples of such medicines in Singapore and tested them for heavy metal content. Forty-two different medicines were found to contain metals in amounts exceeding the legal limits. Mercury was found in 28 products, lead in eight, arsenic in six and copper in one. One product contained both mercury and lead and another product contained both mercury and arsenic.” (Ernst, 2002).

Heavy metals can accumulate in the human body and may cause serious damage thus completely going against the point of tonic herbalism. It is best to seek out suppliers who do reliable transparent testing or grow far away from polluted areas. For example, Na’vi Organics provides lab results on request, this is from their website (

“In 2015, we were very fortunate to find a wonderful producer to work with in China. They have a very strict sourcing policy and a passionate in-depth knowledge of Traditional Chinese Medicine. After sampling their products and getting to know them, we were satisfied by their dedication to clean sourcing, high quality, and attention to detail during the processing involved. With this new partnership, we began to offer a select range of tonic herbs.

Since making a choice to stock some products that are produced in China, we understandably began to receive emails from customers expressing their concern regarding potential environmental pollutants. In response to this, all our products produced in China have Certificates of Analysis available on request”.

I can recommend reading Edzard Ernt’s review article listed below.

A simple way of avoiding heavy metal contamination is just to source from countries where herbs are grown in areas of low pollution, a reputable company in the U.S.A will already do this. So the problems of getting herbs from India and China are eliminated.


Ernst, Edzard. “Toxic heavy metals and undeclared drugs in Asian herbal medicines.” Trends in pharmacological sciences 23.3 (2002): 136-139.