Sulphur-Free Shan Yao

Sulphur is often used to make herbs appear brighter, more attractive, to extend shelf-life and to kill any insects. However, this greatly changes the chemical composition of the herb. Studies have shown that sulphur reacts with the herb to create new and unwanted chemicals, whilst reducing the level of active ingredients used for treatment. Unfortunately, the herbal market is saturated with sulphur treated herbs and herbalists are rarely taught how to distinguish them from natural forms

Shan Yao

Shan Yao is also known as East Asian mountain yam, Chinese yam or Japanese yam and is often used to make soba noodles. It is the rhizome of a Dioscorea japonica perennial climbing vine, native to mountain slopes and rivers in the Henan province and is usually harvested in winter. The rhizomes are washed and peeled before the roots are removed. The herb is then sliced and dried. 

Shan Yao is favoured for its ability to tonify Qi, especially in the Spleen, Lung Qi and Kidney Yin. It is often used to treat diarrhoea, fatigue, chronic cough and urine and menstrual problems. As this herb moistens and is neither hot nor cold, it benefits both the Yin and Yang of the Lungs and Kidneys.

Sulphur-Free Shan Yao

As we are against the use of sulphur, our current batches of Shan Yao have small amounts of the common ‘Biscuit Beetle’, which is a harmless insect that is often found in food storage or retailing premises. Unfortunately, as we do not use sulphur or pesticides, this is an unavoidable issue. Shan Yao is a carbohydrate and nutrient-dense herb and naturally attracts these insects, however, they are harmless and the herb can be used as normal if washed. 

Please be aware that other sources of Shan Yao may be sulphur treated; the texture of the herb will be smooth rather than slightly rough and the colour will be unnaturally very white.

Sulphur-Treated Shan Yao

Sulphur-treated Shan Yao is made from large straight cylindrical pieces, which are sun-dried and whitened using sulphur, before being polished. This species is known as Guang Shan Yao or ‘Polished Yam’. 

Guang Shan Yao’s effectiveness may be significantly reduced compared to the authentic species. The new chemical components in sulphur treated herbs are not intended to be in the herb, therefore an unwanted risk of adverse reaction can be created. There have been an increasing amount of studies on the effects of sulphur treated herbs on health and it is deemed an unacceptable method of processing. 

At Phoenix Medical, we do not condone the sale of sulphur treated herbs and we are proud to be the leading organisation in the UK to supply a 100% non-sulphur treated herbal product range.

To find out more regarding sulphur and how it can affect herbs, please visit our quality assurance page. If you have any queries regarding sulphur-use, please contact us at

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