Effect of Rice-shaped Glucomannan Diet on Prevention and Improvement of Metabolic Syndromes in the Noto District of Ishikawa Prefecture in Japan

Abstract

Noto Peninsula is located the north of the central part of Japan. Approximately 40% of the population is aged over 65 years. In this area, there is known to be a high consumption of rice. A total of 11 males and females with waist circumference of >= 80 cm were enrolled, and instructed to add rice-shaped glucomannan into their usual boiled rice at least two times a day for 3 or 6 months (33% calorie-off). Glucomannan is from Amorphophallus konjac and is a barely digestible polysaccharide. Body weight, %fat and waist circumference significantly decreased after the glucomannan diet for 3 months. Serum low-density lipoprotein cholesterol was significantly decreased, and high-density lipoprotein cholesterol and triglyceride tended to decrease. It is thought that a composition from glucide to triglyceride decreased in the abdominal adipose tissue and that dietary fiber with the glucomannan diet suppressed absorption of fat derived from meal. These results suggest that a glucomannan diet might be effective for prevention and improvement of metabolic syndrome without changing the quantity of meals.