Abstract
Since the Japanese are known for their long life span, it has been theorized that a Japanese-style diet has potential for health promotion. To identify the health effects of components of the Japanese diet that have changed over the last five decades, we conducted a study to examine their influence on obesity in mice. Based on National Nutrition Survey data, one-week menus of Japanese foods representative of those that used to be consumed in 2005, 1990, 1975 and 1960 were prepared, cooked, and powderized. Each of these diets was given to ICR mice for four weeks. It was found that Japanese food representative of 1975 suppressed lipid accumulation in white adipose tissue and expansion of adipocytes. To examine the underlying mechanisms responsible, we conducted DNA microarray analysis of the liver, which is responsible for lipid energy metabolism, and found that Japanese food representative of 1975 promoted the expression of genes related to high-energy expenditure. We then prepared purified diets mimicking Japanese foods from each period based on their energy balance of protein, fat and carbohydrate, and fed them to mice for four weeks. No significant differences in white adipose tissue weight were evident among the four groups. Overall, our findings suggested that Japanese foods typical of the period around 1975 are more effective than modern Japanese foods for preventing obesity, and that this effect is not dependent on energy balance.
