Subchronic 4-month oral toxicity study of dried Smallanthus sonchifolius (yacon) roots as a diet supplement in rats

Yacon roots are a rich source of fructooligosaccharides (FOS) and have a long use tradition as food in the Andean region. However, there are no published reports regarding their toxicology and use safety. The aim of this study was to analyze the effects of subchronic (4-months) oral consumption of dried yacon root flour as a diet supplement using normal Wistar rats. Two daily intake levels were used, equivalent to 340 mg and 6800 mg FOS/body weight, respectively. Yacon administered as a diet supplement was well tolerated and did not produce any negative response, toxicity or adverse nutritional effect at both intake levels used. Yacon root consumption showed no hypoglycemic activity in normal rats and resulted in significantly reduced post-prandial serum triacylglycerol levels in both doses assayed. Conversely, serum cholesterol reduction was not statistically significant. Cecal hypertrophy was observed in rats fed only the high dose. Our results indicating lack of toxicity and a certain beneficial metabolic activity in normal rats warrant further experiments with normal subjects and patients suffering metabolic disorders. They should also be considered when establishing the regulatory framework of this natural product by national health authorities and international trade agencies. (c) 2005 Elsevier Ltd. All rights reserved.