Paldama (Gynura bicolor ) leaves (PL) are a local green vegetable cultivated on the Miyake Island of Okinawa Prefecture. The main components of the leaves were carbohydrates, a large fraction of which was dietary fiber (DF), composed of 75% insoluble fiber. The DF was a viscous, water soluble fiber. PL also contained considerable amounts of nutrients, such as calcium, magnesium, ferrous and carotene. The effect of the water soluble DF (SDF) on blood glucose control action was examined in vitro and in vivo . The glucose diffusion rate across a 7mm water layer and the permeation rate of glucose in cultured Caco-2 cells were both significantly reduced by the addition of appropriate amounts of viscous SDF. Furthermore, an elevation in postprandial blood glucose levels in rats given an oral dose of 5.0ml of 20% glucose solution containing 2% PL-SDF was significantly suppressed compared with control rats given 20 % glucose solution only. It is suggested that Paldama leaves are a useful food material.
Key words: Paldama leaves, Gynura bicolor , viscous substance, soluble dietary fiber, Caco-2 cells, blood glucose.