Abdominal Fat in Individuals with Overweight Reduced by Consumption of a 1975 Japanese Diet: A Randomized Controlled Trial.

OBJECTIVE: This study aimed to investigate whether the intake of the 1975 Japanese diet (JD) could reduce the amount of abdominal fat in people with overweight. METHODS: Using a single-blind randomized controlled trial, the modern diet (MD) was compared with the 1975-type JD, which is based on the MD but includes five characteristics of the 1975 JD in an enhanced form. Overweight people were randomly assigned to an MD group (n = 30) and a JD group (n = 30). The participants consumed test diets that were provided three times a day for 28 days. Body composition measurements and blood biochemical examinations were performed before and after the test diet intake, and the proportions of change were compared. RESULTS: Those in the JD group had significantly decreased BMI, fat mass, and levels of low-density lipoprotein cholesterol, glycated hemoglobin, and C-reactive protein (P = 0.002, 0.015, 0.014, 0.012, and 0.039, respectively) and significantly increased high-density lipoprotein cholesterol levels compared with those in the MD group (P = 0.020). CONCLUSIONS: The intake of a diet with the characteristics of the 1975 JD may have beneficial effects on lipid metabolism in people with overweight and reduce the onset risk of metabolism-related disorders, such as obesity and diabetes.

Effects of Japanese diet in combination with exercise on visceral fat accumulation.

OBJECTIVES: In our previous study, we showed that among Japanese diets from different time periods, the 1975 Japanese diet has the greatest health benefits and is the most effective to prevent obesity. In addition, exercise is also effective to reduce obesity. Therefore, we conducted a human clinical trial combining the 1975 Japanese diet and exercise and, as a result, found a reduction in body weight, visceral fat, and serum lipids. However, the mechanism of this phenomenon was not determined. Therefore, in this study, we examined this mechanism in mice using a diet that was similar to that used in the human trial. METHODS: The modern and 1975 Japanese diets were cooked, lyophilized, powdered, and fed freely to 5 wk old male C57 BL/6 J mice for 8 wk. In addition, the mice exercised on a treadmill. RESULTS: Total white adipose tissue weight decreased significantly due to the interaction between the 1975 Japanese diet and exercise. A histologic examination revealed that the hypertrophy of adipocytes was suppressed. To clarify this mechanism, the mRNA levels for lipid metabolism-related genes in epididymal adipose tissue were measured, and the mRNA level of hormone sensitive lipase (Hsl), which is related to lipolysis, was found to be significantly increased after intake of the 1975 Japanese diet combined with exercise. In the gut microbiota analysis, the Bacteroidetes to Firmicutes ratio, which is decreased in obese people, was increased by the 1975 Japanese diet and exercise. At the genus level, there was an increase in butyrate-producing bacteria as a result of the 1975 Japanese diet intake and exercise. CONCLUSIONS: A combination of the 1975 Japanese diet and exercise increased lipolysis in white adipose tissue and increased butyrate-producing bacteria in gut microbiota, and thereby suppressed fat accumulation.

Effects of the 1975 Japanese diet on the gut microbiota in younger adults.

Japan is known for its longevity worldwide; the Japanese diet is thought to contribute to this longevity. However, the Japanese diet has become westernized over the past years, with a parallel increase in the incidence of lifestyle diseases. Thus, whether the modern Japanese diet is still healthy requires investigation. A diet with characteristics of the 1975 Japanese diet (JD) was previously shown to have beneficial effects on mice and humans. In this study, we examined whether intestinal bacteria are involved in the health benefits of this diet by analyzing changes in the composition of the fecal microbiota between humans who ingested the JD and those consuming a modern Japanese diet (MD). We also examined correlations between intestinal bacteria and biological parameters. A randomized controlled trial was performed to determine the effects of the 1975 JD compared to those of the MD. Subjects aged 20-29 years were randomly assigned to the JD (n=11) and MD (n=10) groups. Each subject consumed their respective diet three times per day for 28 days, and changes in intestinal bacteria before to after this period were evaluated. Four genera (unclassified Lachnospiraceae, Parabacteroides, Sutterella and unclassified Rikenellaceae) were significantly changed upon intake of the JD. Based on correlation analysis, relationships were found between changes in these genera and decreases in fat%; fat mass; and levels of blood glutamic oxaloacetic transaminase, blood triacylglycerols and hemoglobin A1c. These results suggest that changes in intestinal bacteria are involved in the health benefits of the JD.

The effect of dietary lipid on gut microbiota in a senescence-accelerated prone mouse model (SAMP8).

Gut microbiota change with aging and diet. In a previous study, it was shown that a moderate-fat diet enriched with fish oil had beneficial effects for elderly patients, so we examined the effect of this diet on aging-related changes in gut microbiota in this study. We used 3-month-old male senescence-accelerated prone mice (SAMP8). The mice were fed a normal diet containing 4 g soybean oil/100 g of diet for 6 months and then divided into 4 groups: (1) the Baseline group, ended breeding at 6 months old; (2) the Control group, continued on a normal diet until 15 months old; (3) the MF group, switched to a moderate-fat diet until 15 months old; and (4) the MF + FO group, switched to a moderate-fat diet enriched with fish oil until 15 months old. When mice were 6 or 15 months old, fecal samples were collected and gut microbiota analysis was performed. Gut microbiota analysis at the genus level showed that bacteria known to increase in association with fatty liver and intestinal inflammation increased with aging. However, this alteration was largely inhibited by the moderate-fat diet enriched with fish oil. On the other hand, there was a decrease with aging in the bacteria that play a role in energy consumption, but this alteration was inhibited by the moderate-fat diet enriched with fish oil. These results suggest that a moderate-fat diet enriched with fish oil has beneficial effects on gut microbiota in aging.

Fermented Soybean Suppresses Visceral Fat Accumulation in Mice.

SCOPE: Mice are fed a soybean diet before or after fermentation in the present work to allow direct comparison of the antiobesity effect of fermentation. METHODS: C57BL6J mice were fed high-fat diets containing boiled soybeans (prefermentation) or Natto (postfermentation) for 4 weeks. Prefermented cooked soybeans or Natto was added at levels of 2.5 and 5%, which are the amounts that can be ingested in a normal diet once and twice a day. In addition, mice gut microbiota from fecal samples were analyzed to explore the mechanisms of effects caused by fermentation. RESULTS: Natto intake significantly reduced visceral fat in a dose-dependent manner, inhibited hypertrophy of adipocytes, improved carbohydrate metabolism, and reduced oxidative stress. These effects were seen in mice fed soybeans before fermentation, but were stronger in mice fed Natto. Therefore, soybean intake has beneficial effects and fermentation of soybeans enhances these effects. Natto was found to suppress fatty acid synthesis and promote fatty acid catabolism in the liver. These effects were also stronger with Natto compared with soybeans before fermentation. In addition, Natto had more potent beneficial effects on gut microbiota compared to soybeans. CONCLUSIONS: These results suggest that Natto intake supports maintenance of health.

The 1975 Type Japanese Diet Improves Lipid Metabolic Parameters in Younger Adults: A Randomized Controlled Trial.

In our previous study, the health benefits of the 1975 Japanese diet were shown to be the highest, since the diet suppressed visceral and liver fat accumulation, and hyperglycemia. In addition, the 1975 Japanese diet promoted maintenance of learning memory ability and a lengthened life span. However, the effect of the 1975 Japanese diet has not been ascertained in humans. In the current study, a diet with the characteristics of the 1975 Japanese diet was prepared to examine if this diet is beneficial for human health. The purpose of this randomized controlled trial was to determine effects of the 1975 Japanese diet (JD) in comparison with a modern Japanese diet (MD). Subjects aged 20~29 years old were randomly assigned to the MD (n=16) and JD (n=16) groups. Each subject consumed the diet three times a day for 28 days. Changes in physical conditions, including body composition and blood biochemistry, from before to after the study period were evaluated. As a result, body weight (p < 0.05), body fat percentage (p < 0.05), body fat mass (p < 0.05), serum triglyceride level (p < 0.05), and serum low-density lipoprotein cholesterol level (p < 0.05) were significantly decreased and serum high-density lipoprotein cholesterol (p < 0.05) and serum magnesium levels (p < 0.05) were significantly increased in JD group. These results showed that a diet with the characteristics of the 1975 Japanese diet has a beneficial effect on lipid metabolic parameters.

Effects of Dietary Intake of Japanese Mushrooms on Visceral Fat Accumulation and Gut Microbiota in Mice.

A lot of Japanese people are generally known for having a healthy diet, and consume a variety of mushrooms daily. Many studies have reported anti-obesity effects of mushrooms, but few have investigated the effects of consuming a variety of edible mushroom types together in realistic quantities. In this study, we investigated whether supplementation with a variety of mushroom types affects visceral fat accumulation and gut microbiota in mice. The most popular mushroom varieties in Japan were lyophilized and mixed according to their local production ratios. C57BL/6J mice were fed a normal diet, high-fat (HF) diet, HF with 0.5% mushroom mixture (equivalent to 100 g mushrooms/day in humans) or HF with 3% mushroom mixture (equivalent to 600 g mushrooms/day in humans) for 4 weeks. The mice were then sacrificed, and blood samples, tissue samples and feces were collected. Our results show that mushroom intake suppressed visceral fat accumulation and increased the relative abundance of some short chain fatty acid- and lactic acid-producing gut bacteria. These findings suggest that mushroom intake is an effective strategy for obesity prevention.