Subject Categories: Biotechnology
Published online 14 November 2007
The Chinese yam (Dioscorea opposita) has long been used as a traditional medicine and foodstuff in China, to relieve stomach pain and diarrhoea. Now modern science is revealing that yams have even greater health benefits. Shujun Wang, at Tianjin University, and co-workers have discovered that the starch in yams helps to reduce hyperlipidaemia — high levels of fatty lipid molecules in the bloodstream — which is a major cause of death throughout the world1.
Previous research has established that diet is important in the regulation of cholesterol homeostasis. Therefore, as well as investigating the physicochemical properties of Chinese yam and potato starches, the researchers also studied the effects of the yam starch on the blood lipid levels in hyperlipidaemic rats and compared them with the effects of potato and cereal starches.
They found that the rats that were fed yam starch had significantly decreased levels of cholesterol and triglyceride fats in their blood, but those that were fed potato starch showed a change that was not statistically significant. The researchers believe that yam starch is more resistant than potato starch — it escapes digestion in the small intestine and passes through to the large intestine.
This newly discovered role for starch also implies that uncooked yams with intact starch granules (pictured) are better than cooked yams for lowering blood lipids. In future, the researchers hope to uncover the enzyme and gene mechanisms that work to cause this lipid reduction.
The authors of this work are from:
College of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China; College of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China; Academy of Sciences and Henan Agricultural, Zhenzhou, China; Institute of Tianjin Medicine, Tianjin, China.