Yui Iwagaki

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.

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

Abstract 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. In the current study, we aimed to find new physiological effects of the Japanese diet. As a result, we found that the 1975.

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.

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

Abstract 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. Ingestion of the Japanese diet of mothers during pregnancy and lactation weakens the lipid accumulation inhibitory effect of the Japanese diet in children.

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 mothers 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.

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.

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.

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.