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.

Influence of Japanese diet consumption during pregnancy and lactation on lipid metabolism in offspring.

OBJECTIVE: Previous studies have demonstrated that obesity is rare among those who consume the Japanese diet because of its lower caloric content compared with the American diet. Meanwhile, it has been reported that maternal caloric restriction, which induces antiobesity effects, during pregnancy and lactation increases the likelihood of a low birthweight infant, which increases the risks for obesity and diabetes later in life. The aim of this study was to examine the influence of maternal consumption of the Japanese diet during pregnancy and lactation on the risk for obesity and diabetes in the offspring later in life. METHODS: Pregnant mice were divided into three groups and fed either a control diet, Western diet, or Japanese diet, and their offspring were raised until 7 wk old. RESULTS: Examinations of 18-d-old and 7-wk-old offspring showed no effect of consistently eating a Japanese diet during pregnancy and lactation on the health conditions of 18-d-old offspring, but 7-wk-old offspring showed a decrease in visceral fat and liver triacylglycerol levels. In addition, 7-wk-old offspring from mothers who consumed the Japanese diet during pregnancy and lactation showed a decrease in the homeostatic model assessment of insulin resistance and a reduced risk for developing diabetes. This tendency was also confirmed in 18-d-old offspring. Evaluation of the mechanism revealed that fatty acid synthesis in the liver of the offspring was suppressed by the mother's consumption of the Japanese diet. CONCLUSION: From these results, maternal consumption of the Japanese diet during pregnancy and lactation did not adversely affect the offspring, and continual intake of this diet reduced the risk for developing obesity and diabetes in the offspring later in life.

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 a moderate-fat diet that is enriched with fish oil on intestinal lipid absorption in a senescence-accelerated prone mouse model.

OBJECTIVES: We examined a moderate-fat (MF) diet that is enriched with fish oil (FO) and assessed whether lipid absorption was inhibited in senescence-accelerated prone mice (SAM-P8). METHODS: All mice (N = 70) were fed a normal diet that contained 4 g soybean oil/100 g of diet for 6 mo and then divided the mice into four groups (n = 10 or 20/group). Mice in the baseline group were euthanized at 6 mo old, those in the control group continued on a normal diet until 15 mo of age, those in the MF diet group switched to an MF diet (8 g soybean oil/100 g of diet) until 15 mo of age, and those in the MF + FO group switched to an MF diet that was enriched with FO (6.4 g soybean oil + 1.6 g FO/100 g of diet) until 15 mo of age. RESULTS: The area under the curve for lipid absorption decreased with age but lipid absorption tended to be less attenuated with an MF diet that contained FO. Messenger RNA (mRNA) levels of apolipoprotein B, fatty acid transport protein 4, and microsomal triacylglycerol transfer protein in the small intestine decreased with age but tended to be maintained with an MF diet with or without FO. A histologic analysis of the small intestine showed that villi degenerated with age but the decline was less in mice in the MF + FO group. CONCLUSIONS: The results of this study suggest that MF + FO diets can inhibit the attenuation of lipid absorption commensurate with aging in SAM-P8 via a delay of the natural degeneration that occurs in small intestinal villi over time.

The 1975 Japanese diet has a stress reduction effect in mice: search for physiological effects using metabolome analysis.

We aimed to find new physiological effects of the Japanese diet. First, to determine the key components in serum from mice fed the 1975 diet, serum from mice fed the 1960, 1975, 1990 or 2005 Japanese diet was analyzed using CE-TOFMS and LC-TOFMS. Based on these results, the key components were determined by principal component analysis. Among the identified compounds, GABA was included. Therefore, a stress reduction effect was inferred as a novel physiological effect of this diet. Next, we tested whether the 1975 diet had an actual stress reduction effect in mice. Mice were given the 1975 diet or a control diet for 4 weeks, after which they were divided into restraint stress and non-stress groups. Mice fed the 1975 diet had significantly decreased stress parameters compared with those fed the control diet. These results provide the first evidence that the 1975 Japanese diet has a stress reduction effect.

Effect of the Japanese diet during pregnancy and lactation or post-weaning on the risk of metabolic syndrome in offspring.

We examined the effects on offspring of ingestion of the 1975 Japanese diet during pregnancy and lactation and after weaning in mice. Pregnant dams were divided into groups that were fed the Japanese diet or a control diet and raised until offspring were weaned. The offspring after weaning were further divided into groups that were raised on the Japanese diet or the control diet. Ingestion of the Japanese diet after weaning suppressed accumulation of visceral fat in offspring, and reduced the amount of lipids in serum and liver. This effect was weakened if the Japanese diet was only ingested during pregnancy and lactation. Therefore, it was suggested that ingestion of the Japanese diet of mothers during pregnancy and lactation weakens the lipid accumulation inhibitory effect of the Japanese diet in children.

Standardisation of the Japanese diet for use in animal experiments.

The aim of this study was to develop a purified diet that mimics the characteristics of the Japanese diet using readily available materials with a simpler composition and a focus on quality, with the goal of facilitating performance of studies on the Japanese diet worldwide. The utility of the new diet was examined as a mimic of the standard Japanese diet for use in animal experiments. We examined whether a key characteristic of the Japanese diet of being less likely to cause obesity could be reproduced. The mimic diet had a balance of protein, fat and carbohydrate based on the 1975 Japanese diet, which is the least likely to cause obesity, and materials chosen with reference to the National Health and Nutrition Survey (NHNS). To examine similarities of the mimic diet with the model 1975 Japanese diet, we created a menu of the 1975 diet based on the NHNS and prepared the freeze-dried and powdered diet. The mimic diet, the 1975 Japanese diet, a control AIN-93G diet and a Western diet were fed to mice for 4 weeks. As a result, the mimic diet and the 1975 diet resulted in less accumulation of visceral fat and liver fat. Mice given these two diets showed similar effects. This indicates that the mimic diet used in this study has characteristics of the 1975 Japanese diet and could be used as a standard Japanese diet in animal experiments.

Identification of Characteristic Components and Foodstuffs in Healthy Japanese Diet and the Health Effects of a Diet with Increased Use Frequency of these Foodstuffs.

SCOPE: Our recent study showed that the 1975 Japanese diet exhibited strong health benefits. In the current study, we aimed to develop a diet with even higher health benefits. METHODS: First, to determine the characteristic components in the 1975 diet, we used mass spectrometry for analysis of Japanese diets from several years and performed principal component analysis. Next, a diet with an increased use frequency of foodstuffs contained characteristic components (the modified diet) was prepared and fed to mice. RESULTS: Performed principal component analysis revealed that the 1975 diet contained 14 characteristic components that were found in fish, fruits, vegetables, seaweed, soybean foods, soup stock "dashi", and fermented seasoning. Based on these, the modified diet was prepared and fed to mice. The liver total cholesterol and serum LDL cholesterol decreased significantly in mice fed the modified diet and serum total cholesterol showed a downward trend, compared to mice fed the 1975 diet. There was no difference between the modified diet and the control groups. In addition, serum adiponectin level increased in mice fed the modified diet and serum TBARS and IL-6 levels decreased. CONCLUSION: By modifying the 1975 diet, it was possible to make a diet with more benefit.

Intake of mulberry 1-deoxynojirimycin prevents colorectal cancer in mice.

The effect of 1-deoxynojirimycin, a caloric restriction mimetic, was examined in ICR mice with azoxymethane dextran sodium sulfate-induced colorectal cancer. Azoxymethane is a carcinogen (10 mg/kg body weight), and 2% dextran sodium sulfate (w/v) used as a colitis-inducing agent. Mice were separated into 5 groups: a group without colorectal cancer fed a normal diet (CO- group), and groups with colorectal cancer fed a normal diet (CO+ group), a calorie-restricted diet (caloric restriction group), and diets including 0.02% and 0.1% 1-deoxynojirimycin (l-1-deoxynojirimycin and H-1-deoxynojirimycin groups). The tumor incidence and number were reduced significantly in the caloric restriction group compared to the CO+ group, and were also suppressed in a dose-dependent manner by 1-deoxynojirimycin. mRNA for anti-apoptotic Bcl-2 was decreased and that for pro-apoptotic Bax was increased in the carcinoma tissue of CR, l-1-deoxynojirimycin and H-1-deoxynojirimycin groups. These results suggest that caloric restriction and 1-deoxynojirimycin inhibit growth of colorectal cancer by inducing apoptosis in an induced cancer model in mice.

Comparison of the Effects of the 1975 Japanese Diet and the Modern Mediterranean Diet on Lipid Metabolism in Mice.

The Japanese diet and the Mediterranean diet are both known to be good for health, but there had been no direct comparison of their health benefits. In this study, we compared the 1975 Japanese diet, which has been found to have high health benefits, with the 2010 Italian diet, which contributes to the longest life expectancy in Mediterranean countries. Diets were created using one-week menus of the two diets based on FAOSTAT Food Balance Sheets. The diets were prepared, freeze-dried, powdered and fed to mice for 4 weeks to examine their effects on lipid metabolism. In mice fed the Japanese diet, the visceral fat weight was lower, adipocytes were smaller, the liver weight was lower and liver TG tended to be lower than those fed the Italian diet, and little lipid accumulation was observed in hepatocytes of mice fed the Japanese diet. In addition, in mice fed the Japanese diet, the expression levels of genes related to fatty acid synthesis were lower, whereas those of genes related to catabolism of fatty acids and cholesterol were higher than those fed the Italian diet. Therefore, the Japanese diet reduced accumulation of lipids in the white adipose tissue and liver by suppressing fatty acid synthesis and promoting catabolism of fatty acids and cholesterol in the liver, compared to the Italian diet.