High-intensity exercise impairs intestinal barrier function by generating oxidative stress.

The intestine functions as a barrier preventing the entry of extrinsic factors into the body. This barrier function is disrupted by oxidative damage along with an impaired mucosal layer. Excessive exercise can generate oxidative stress in the intestinal tissue; however, the effect of exercise-induced oxidative stress on intestinal permeability is unclear. In this study, we examined the involvement of oxidative stress in barrier function of the ileum of mice following high-intensity exercise. Male ICR mice (12-week-old) were divided into sedentary and exercise groups. Mice in the exercise group underwent a single bout of treadmill running, and the ileum was collected for histological and biochemical analyses. Plasma fluorescence intensity level after oral administration of fluorescein isothiocyanate-dextran gradually increased until 30 min after exercise in response to intensity of exercise. Relatively high levels of oxidative proteins and low level of claudin-1, a tight-junction protein, were observed in the exercise group. Treatment with a xanthine oxidase inhibitor suppressed exercise-induced increases in intestinal permeability. Moreover, excessive exercise training for two weeks led to relatively high intestinal permeability at rest. These results suggest that high-intensity exercise increases intestinal permeability and tight junction damage, which may be mediated by oxidative stress.

Current Nutritional and Pharmacological Approaches for Attenuating Sarcopenia.

Sarcopenia is characterized by a gradual slowing of movement due to loss of muscle mass and quality, decreased power and strength, increased risk of injury from falls, and often weakness. This review will focus on recent research trends in nutritional and pharmacological approaches to controlling sarcopenia. Because nutritional studies in humans are fairly limited, this paper includes many results from nutritional studies in mammals. The combination of resistance training with supplements containing amino acids is the gold standard for preventing sarcopenia. Amino acid (HMB) supplementation alone has no significant effect on muscle strength or muscle mass in sarcopenia, but the combination of HMB and exercise (whole body vibration stimulation) is likely to be effective. Tea catechins, soy isoflavones, and ursolic acid are interesting candidates for reducing sarcopenia, but both more detailed basic research on this treatment and clinical studies in humans are needed. Vitamin D supplementation has been shown not to improve sarcopenia in elderly individuals who are not vitamin D-deficient. Myostatin inhibitory drugs have been tried in many neuromuscular diseases, but increases in muscle mass and strength are less likely to be expected. Validation of myostatin inhibitory antibodies in patients with sarcopenia has been positive, but excessive expectations are not warranted.

Matcha green tea beverage moderates fatigue and supports resistance training-induced adaptation.

BACKGROUND: Resistance training adaptively increases muscle strength and mass, contributing to athletic performance and health promotion. Dietary intervention with natural foods provides nutrients that help accelerate muscle adaptation to training. Matcha green tea contains several bioactive factors such as antioxidants, amino acids, and dietary fibers; however, its effect on muscle adaptation is unclear. In this study, we aimed to investigate the effects of matcha beverage intake on muscle adaptation to resistance training. METHODS: Healthy, untrained men were randomized into placebo and matcha groups. Participants consumed either a matcha beverage containing 1.5 g of matcha green tea powder or a placebo beverage twice a day and engaged in resistance training programs for 8 (trial 1) or 12 weeks (trial 2). RESULTS: In trial 1, maximum leg strength after training tended to increase more in the matcha group than that in the placebo group. In the matcha group, subjective fatigue after exercise at 1 week of training was lower than that in the placebo group. Gut microbe analysis showed that the abundance of five genera changed after matcha intake. The change in Ruminococcus, Butyricimonas, and Oscillospira compositions positively correlated with the change in maximum strength. In trial 2, the change in skeletal muscle mass in response to training was larger in the matcha group. In addition, the salivary cortisol level was lower in the matcha group than that in the placebo group. CONCLUSION: Daily intake of matcha green tea beverages may help in muscle adaptation to training, with modulations in stress and fatigue responses and microbiota composition.

Exercise-acclimated microbiota improves skeletal muscle metabolism via circulating bile acid deconjugation.

Habitual exercise alters the intestinal microbiota composition, which may mediate its systemic benefits. We examined whether transplanting fecal microbiota from trained mice improved skeletal muscle metabolism in high-fat diet (HFD)-fed mice. Fecal samples from sedentary and exercise-trained mice were gavage-fed to germ-free mice. After receiving fecal samples from trained donor mice for 1 week, recipient mice had elevated levels of AMP-activated protein kinase (AMPK) and insulin growth factor-1 in skeletal muscle. In plasma, bile acid (BA) deconjugation was found to be promoted in recipients transplanted with feces from trained donor mice; free-form BAs also induced more AMPK signaling and glucose uptake than tauro-conjugated BAs. The transplantation of exercise-acclimated fecal microbiota improved glucose tolerance after 8 weeks of HFD administration. Intestinal microbiota may mediate exercise-induced metabolic improvements in mice by modifying circulating BAs. Our findings provide insights into the prevention and treatment of metabolic diseases.

Mumefural prevents insulin resistance and amyloid-beta accumulation in the brain by improving lowered interstitial fluid pH in type 2 diabetes mellitus.

The present study tried to clarify if mumefural would prevent hyperglycemia, one of the typical symptoms of type 2 diabetes mellitus (T2DM), since mumefural is an extract from Japanese apricots preventing hyperglycemia. To clarify if mumefural would prevent T2DM pathogenesis, we used Otsuka Long-Evans Tokushima fatty (OLETF) rats, T2DM model. Mumefural diminished hyperglycemia, HOMA-IR and plasma triglyceride concentration in OLETF rats under fasting conditions. In addition, mumefural elevated protein expression of sodium-coupled monocarboxylate transporter 1 (SMCT1) in the distal colon participating in absorption of weak organic acids, which behave as bases but not acids after absorption into the body. Mumefural also increased the interstitial fluid pH around the brain hippocampus lowered in OLETF rats compared with non-T2DM LETO rats used as control for OLETF rats. Amyloid-beta accumulation in the brain decreased in accordance with the pH elevation. On the one hand, mumefural didn't affect plasma concentrations of glucagon, GLP-1, GIP or PYY under fasting conditions. Taken together, these observations indicate that: 1) mumefural would be a useful functional food improving hyperglycemia, insulin resistance and the lowered interstitial fluid pH in T2DM; 2) the interstitial fluid pH would be one of key factors influencing the accumulation of amyloid-beta.

Household Income Is Related to Dietary Fiber Intake and Dietary Acid Load in People with Type 2 Diabetes: A Cross-Sectional Study.

Household income was related to habitual dietary intake in general Japanese people. This cross-sectional study investigated the relationship between household income and habitual dietary intake in people with type 2 diabetes mellitus (T2DM). Household income was evaluated using a self-reported questionnaire and categorized into high and low household income. Nutritional status was assessed using a brief-type self-administered diet history questionnaire. Among 128 men and 73 women, the proportions of participants with low household income were 67.2% (n = 86/128) in men and 83.6% (n = 61/73) in women. Dietary fiber intake (11.3 ± 4.2 vs. 13.8 ± 6.0 g/day, p = 0.006) was lower, and dietary acid load, net endogenous aid production score (NEAP) (51.7 ± 10.5 vs. 46.8 ± 10.4 mEq/day, p = 0.014) and potential renal acid load score (PRAL) (9.5 ± 10.7 vs. 3.7 ± 14.1 mEq/day, p = 0.011) were higher in men with low household income than in those without. Multivariable linear regression analyses demonstrated that log (dietary fiber intake) in men with low household income was lower than that in those with high household income after adjusting for covariates (2.35 [2.26−2.44] vs. 2.52 [2.41−2.62], p = 0.010). Furthermore, NEAP (54.6 [51.7−57.4] vs. 45.8 [42.5−49.2], p <0.001) in men with low household income were higher than in those with high household income after adjusting for covariates. Contrastingly, household income was not related to diet quality in women. This study showed that household income was related to dietary fiber intake and dietary acid load in men but not in women.

Lactococcus cremoris subsp. cremoris FC-fermented milk activates protein synthesis and increases skeletal muscle mass in middle-aged mice.

Age-related muscle atrophy is associated with decreased protein anabolic capacity. Dietary intervention is an important strategy for the treatment of age-related muscle atrophy. This study examined the effect of Lactococcus cremoris subsp. cremoris FC-fermented milk on muscle mass and protein anabolic signaling in middle-aged mice. Male C57BL/6J mice (18-month-old) were divided into the control and Lactococcus cremoris subsp. cremoris FC-fermented milk supplementation groups. Mice were administered unfermented or fermented milk (300 µL/day) by gavage every alternate day for 8 weeks; thereafter, muscle weight, protein metabolic signaling factors, and inflammatory factors were investigated. Soleus muscle weight was higher in the fermented milk group than in the control group. Expression of insulin growth factor-1, a typical anabolic factor, and phosphorylation levels of anabolic signaling factors (mTOR and p70S6K) were higher after fermented milk supplementation. Levels of tumor necrosis factor-α, an inhibitor of protein anabolism, were lower in the fermented milk group. These data suggest that the daily intake of Lactococcus cremoris subsp. cremoris FC-fermented milk increased skeletal muscle mass as well as protein synthesis in the middle-aged mice, which may be mediated by reduction in the levels of inflammatory factors. Therefore, accelerated protein synthesis, induced by the consumption of fermented milk, has a potential role in counteracting muscle atrophy.

A nutritional intervention that promotes increased vegetable intake in Japanese with non-alcoholic fatty liver disease: a six-month trial.

The aim of this study was to investigate whether a nutritional intervention motivating increased vegetable consumption would be an effective treatment and diet therapy for patients with non-alcoholic fatty liver disease. We examined 15 patients with this disease (5 men and 10 women). During the 6-month intervention period, all participants received a small amount of vegetables twice a month as a nutritional education tool aimed at increasing vegetable consumption. They also received nutritional counseling and underwent ultrasound and blood biochemical examinations at baseline and 3 and 6 months after initiation of the intervention. Moreover, they were requested to submit dietary records for any 2 days. Green, white, and total vegetable intakes were significantly higher at 3 and 6 months than at baseline in 8 patients. These patients had significantly lower alanine amino-transferase and triglyceride concentrations than those whose vegetable intake did not increase. Additionally, green vegetable intake significantly negatively correlated with weight at 3 and 6 months (r = -0.617, p = 0.032 and r = -0.848, p = 0.008, respectively). These results suggest that our nutritional approach effectively increased vegetable consumption in at least some patients with non-alcoholic fatty liver disease, consequently improving their condition.

Roles of Skeletal Muscle-Derived Exosomes in Organ Metabolic and Immunological Communication.

Skeletal muscles secrete various factors, such as proteins/peptides, nucleotides, and metabolites, which are referred to as myokines. Many of these factors are transported into extracellular bodily fluids in a free or protein-bound form. Furthermore, several secretory factors have been shown to be wrapped up by small vesicles, particularly exosomes, secreted into circulation, and subsequently regulate recipient cells. Thus, exosome contents can be recognized as myokines. In recipient cells, proteins, microRNAs, and metabolites in exosomes can regulate the expression and activity of target proteins associated with nutrient metabolism and immune function. The levels of circulating exosomes and their contents are altered in muscle disorders and metabolic-related states, such as metabolic dysfunction, sarcopenia, and physical fitness. Therefore, such circulating factors could mediate various interactions between skeletal muscle and other organs and may be useful as biomarkers reflecting physiological and pathological states associated with muscular function. Here, this review summarizes secretory regulation of muscle-derived exosomes. Their metabolic and immunological roles and the significance of their circulating levels are also discussed.

Cystine supplementation sustains plasma mercaptalbumin levels in rats fed low-protein diets more effectively than methionine.

We recently reported that dietary cystine maintained plasma mercaptalbumin levels in rats fed low-protein diets. The present study aimed to compare the influence of low-protein diets supplemented with cystine and methionine, which is another sulfur amino acid, on plasma mercaptalbumin levels in rats. Male Sprague-Dawley rats were fed a 20% soy protein isolate diet (control group), 5% soy protein isolate diet (low-protein group) or 5% soy protein isolate diet supplemented with either methionine (low-protein + Met group) or cystine (low-protein + Cyss group) for 1 week. The percentage of mercaptalbumin within total plasma albumin of the low-protein + Met group was significantly lower than that of the control and low-protein + Cyss groups. No significant differences in the mRNA levels of tumor necrosis factor-α, interleukin-6, interleukin-1ß, and cyclooxygenase 2 in blood cells were observed between the low-protein + Met and low-protein + Cyss groups. Treatment with buthionine-(S,R)-sulfoximine, an inhibitor of glutathione synthesis, did not influence the percentage of mercaptalbumin within total plasma albumin in rats fed the low-protein diet supplemented with cystine. These results suggest that supplementation with cystine may be more effective than that with methionine to maintain plasma mercaptalbumin levels in rats with protein malnutrition. Cystine might regulate plasma mercaptalbumin levels via the glutathione-independent pathway.

Metabolic functions of flavonoids: From human epidemiology to molecular mechanism.

Dietary flavonoid intake is associated with the regulation of nutrient metabolism in the living body. Observational and cohort studies have reported a negative association between flavonoid intake and the risk of metabolic and cardiovascular diseases. Several intervention trials in humans have also supported the benefits of dietary flavonoids. In experimental studies using animal models, a daily diet rich in typical flavonoids such as catechins, anthocyanin, isoflavone, and quercetin was shown to improve whole-body energy expenditure, mitochondrial activity, and glucose tolerance. For some flavonoids, molecular targets for the metabolic modulations have been suggested. Although the effect of flavonoids on neurons has been unclear, several flavonoids have been shown to regulate thermogenesis and feeding behavior through modulating autonomic and central nervous systems. Based on epidemiological and experimental studies, this review summarizes the evidence on the metabolic benefits of flavonoids and their potential mechanism of action in metabolic regulation.

Intensive, prolonged exercise seemingly causes gut dysbiosis in female endurance runners.

Intensive, prolonged exercise is known to induce gastrointestinal disorders such as diarrhea, with gut dysbiosis suggested as being one of the causatives. In the present study, we wanted to investigate the relationship between intensive exercise and the gut microbiota status. To that end, the microbiota, the moisture content and the bacterial metabolites (e.g., organic acids) of female endurance runners (n = 15) and those of non-athletic but healthy, age-matching female controls (n = 14) were compared. The analysis of the gut microbiota analysis showed that, unlike control subjects, female endurance runners had distinct microbiotas, with some bacteria found in higher abundances likely being involved in gut inflammation. The concentration of succinate, a gut bacterial metabolite regarded as undesirable when accumulated in the lumen, was significantly (p<0.05) higher in the female endurance runners. Faecalibacterium, that was significantly (p<0.05) abundant in female endurance runners, can produce succinate in certain environments and hence may contribute to succinate accumulation, at least partly. The present work suggested that the gut microbiotas of female endurance runners are seemingly dysbiotic when compared with those of control subjects. Further investigation of the mechanism by which intensive, prolonged exercise affects the gut microbiota is recommended.

Therapeutic Potential of Astaxanthin in Diabetic Kidney Disease.

Astaxanthin is a carotenoid that has potent protective effects on diabetic kidney disease (DKD) in diabetic mice models. DNA microarray study clearly demonstrated the involvement of mitochondrial oxidative phosphorylation pathway in the renal glomerular cells of diabetic mice and also showed that the expression of upregulated genes associated with this pathway was decreased by the treatment with astaxanthin. Proteomic analysis confirmed that the increases of 4-hydroxy-2-nonenal (HNE)- and Nε-(hexanonyl)lysine (HEL)-modified proteins were inhibited by the treatment with astaxanthin. These results demonstrated that astaxanthin exerts a protective effect against hyperglycemia-induced DKD by attenuating mitochondrial oxidative stress and subsequent cellular dysfunction.

Changes in iron metabolism centered on hepcidin due to high-intensity exercise under restricted food intake.

OBJECTIVES: The purpose of this study was to observe changes in iron metabolism of rats due to high-intensity exercise during reduced food intake. METHODS: Thirty-six, 4-wk-old male Wistar rats were divided into six groups after being acclimated to running: rested control, intense exercise, 80% feeding and rested, 80% feeding and intense exercise, 70% feeding diet and rested, and 70% feeding and intense exercise groups. Only three intense exercise groups underwent acute running sessions for 30 min (30 m/min) once a day for 7 d. RESULTS: Rats did not develop anemia with exercise and food intake restriction. Serum iron levels, transferrin saturation, hepcidin-25, and hepatic iron levels in the exercise groups were lower than those in the respective resting groups. However, these values in the 70% diet groups were slightly higher than those in the 80% diet groups. Serum erythropoietin levels decreased as food intake decreased, but the serum erythropoietin level in the 70% feeding and intense exercise group was similar to that in the rested control group. Serum interleukin-6 levels were significantly lower in the groups with restricted food intake than in the free-fed group, and exercise had no effect. CONCLUSIONS: High-intensity exercise under restricted food intake may significantly alter the iron metabolism to maintain blood cell levels due to the strong promotion of metabolic iron utilization in response to dietary iron depletion, increased iron demand, and excretion.

Validation of computer software to estimate dietary intake among patients with type 2 diabetes.

Tailored nutritional guidance by a registered dietitian is necessary for feasible, practical application of nutrition therapy. In order to reduce the requirement for estimation by a dietitian and to increase the time available for practical advice, we developed and validated computer software for estimating dietary intake among patients with type 2 diabetes. The study enrolled 46 patients with type 2 diabetes, recruited from an outpatient clinic in 2015. We used the computer software "Syokuseikatsu Shindan System" (SSS; Nissha, Kyoto, Japan). SSS allows the user to choose pictures of dishes and the portions he/she has consumed for each meal. The one-day dietary intake estimations for SSS were validated against a reference estimation of 24-h dietary recall by a registered dietitian. The mean carbohydrate intake as assessed by SSS and 24-h recall was 210.6 ± 55.1 and 215.5 ± 52.9 g/day, with a positive correlation (r = 0.53, p<0.001). Bland-Altman analysis showed that limits of agreement in carbohydrates between the methods were -107.4 to 97.5 g/day. Even though the limits of agreement were wide and non-negligible at the individual level for clinical use, SSS appears to have potential as a dietary estimation tool under registered dietitian supervision.

Astaxanthin-, ß-Carotene-, and Resveratrol-Rich Foods Support Resistance Training-Induced Adaptation.

Resistance training adaptively increases the muscle strength associated with protein anabolism. Previously, we showed that the combined intake of astaxanthin, ß-carotene, and resveratrol can accelerate protein anabolism in the skeletal muscle of mice. The purpose of this study was to investigate the effect of anabolic nutrient-rich foods on muscle adaptation induced by resistance training. Twenty-six healthy men were divided into control and intervention groups. All participants underwent a resistance training program twice a week for 10 weeks. Astaxanthin-, ß-carotene-, and resveratrol-rich foods were provided to the intervention group. Body composition, nutrient intake, maximal voluntary contraction of leg extension, oxygen consumption, and serum carbonylated protein level were measured before and after training. The skeletal muscle mass was higher after training than before training in both groups (p < 0.05). Maximal voluntary contraction was increased after training in the intervention group (p < 0.05), but not significantly increased in the control group. Resting oxygen consumption was higher after training in the intervention group only (p < 0.05). As an oxidative stress marker, serum carbonylated protein level tended to be lower immediately after exercise than before exercise in the intervention group only (p = 0.056). Intake of astaxanthin-, ß-carotene-, and resveratrol-rich foods supported resistance training-induced strength and metabolic adaptations.

A milk casein hydrolysate-derived peptide enhances glucose uptake through the AMP-activated protein kinase signalling pathway in skeletal muscle cells.

NEW FINDINGS: What is the central question of this study? How do common active ingredients contained in both Lactobacillus helveticus-fermented milk and milk casein hydrolysate (MCH) enhance glucose metabolism by skeletal muscle? What is the main finding and its importance? MCH enhanced glucose uptake in skeletal muscle cells by stimulating AMP-activated kinase, but not insulin, signalling. Moreover, the MCH-derived specific peptide Ile-Pro-Pro mimicked this effect, suggesting a mechanism for MCH-induced metabolic improvement. ABSTRACT: Improvement of glucose metabolism in the skeletal muscle has a key role in exercise performance and prevention of metabolic diseases. In our previous study, we showed that intake of milk casein hydrolysate improves glucose metabolism in humans, but the mechanism of action was not elucidated. In this study, we aimed to investigate the mechanism of action of milk casein hydrolysate and its derived peptides on glucose uptake and glucose metabolic signalling in cultured skeletal muscle cells. Differentiated C2C12 myotubes were used for the experiments. The differentiated cells were incubated with milk casein hydrolysate, valine-proline-proline and isoleucine-proline-proline. Subsequently, the rate of 2-deoxy-glucose uptake and the phosphorylation levels of insulin-dependent and -independent signalling factors were examined. We found that the rate of 2-deoxy-glucose uptake in both milk casein hydrolysate and isoleucine-proline-proline-treated cells was higher than that in the control cells. Immunoblotting assays showed that the phosphorylation levels of AMP-activated protein kinase, a rate-limiting factor in insulin-independent signalling, and of liver kinase B1, an upstream factor of AMP-activated protein kinase, in both milk casein hydrolysate and isoleucine-proline-proline-treated cells were higher than those in the control cells. Such significant effects were not observed after treatment with valine-proline-proline. Moreover, the insulin-dependent signalling was not significantly affected under the different conditions. The findings of our study suggest that milk casein hydrolysate enhances glucose uptake by activating insulin-independent AMP-activated protein kinase signalling in skeletal muscle cells, which might be mediated by a milk casein hydrolysate-derived peptide, namely, isoleucine-proline-proline.

Polysorbate 80-induced leaky gut impairs skeletal muscle metabolism in mice.

Impaired intestinal permeability can induce systemic inflammation and metabolic disturbance. However, the effect of impaired intestinal permeability on metabolic function in the skeletal muscle is unknown. Dietary polysorbate 80 (PS80), a common emulsifier, has been shown to impair intestinal permeability in mice. Here, we investigated the effect of PS80-induced intestinal permeability on glucose tolerance with metabolic signaling in the skeletal muscle. Male ICR mice were divided into control and PS80 groups. In the PS80 group, PS80 was contained in the drinking water at 1% (w/v). After 4 weeks, plasma fluorescein isothiocyanate (FITC) intensity was measured after orally administering FITC-dextran. Half of the mice in each group underwent running exercises. Metabolic and inflammatory parameters were examined in the blood and skeletal muscle. Plasma FITC and lipopolysaccharide levels were higher in the PS80 group than the control group (p < .01, p = .085). The expression of tumor necrosis factor-α in the skeletal muscle was increased upon PS80 administration (p < .05). Although the homeostasis model assessment ratio was higher in the PS80-fed mice (p < .05), insulin-signaling activity in the muscle did not differ between groups. Muscular pH, mitochondrial cytochrome oxidase activity, and glycogen content after exercise were lower in the PS80 group (p < .05) than the control group. There was a negative correlation between plasma FITC and muscle glycogen levels in the exercised groups (r = -.60, p < .05). These results suggest that daily PS80 intake induces intestinal permeability, leading to glucose intolerance and mitochondrial dysfunction in the skeletal muscle.

Contribution of Katsura-uri (Japan's Heirloom Pickling Melon, Cucumis melo var. conomon) at the Completely Ripe Stage to Diabetes Control.

The fruit of Katsura-uri (Japan's heirloom pickling melon, Cucumis melo var. conomon) possesses a fruity aroma and moderate sweetness. The fruit juice has potential to minimize human postprandial blood glucose levels. This study provides information regarding the health benefits of Katsura-uri and its utility in treating diabetes. The study methodology involved measuring the color and firmness of Katsura-uri fruit at five ripening stages, and quantitation of the aroma substances, proximate composition, and sugars. Significant changes were detected in the color, firmness, and level of aroma substances with ripening of Katsura-uri fruit, albeit with no major changes in proximate composition, with the exception of dietary fiber, and sugars. To determine the effects of Katsura-uri juice, the blood glucose levels of ten diabetic volunteers aged 46-75 y were monitored after its consumption, and compared with after consumption of muskmelon juice equivalent to the total weight of Katsura-uri juice. The blood glucose area under the curve level was significantly lower after consumption of Katsura-uri juice (16±5 h • mg/dL) than after consumption of muskmelon juice (55±17 h • mg/dL; p<0.05). The level of the glucose spike was also significantly lower after consumption of Katsura-uri juice (22±5 mg/dL) than after consumption of muskmelon juice (64±6 mg/dL; p<0.05). The completely ripe Katsura-uri fruit provides the best results for diabetic subjects, which is the first case of fruits sweetened with the addition of zero-calorie sweeteners.

Combined intake of astaxanthin, ß-carotene, and resveratrol elevates protein synthesis during muscle hypertrophy in mice.

OBJECTIVE: The antioxidant factors, astaxanthin, ß-carotene, and resveratrol, have a potential effect on protein synthesis in skeletal muscle and a combined intake may have a greater cumulative effect than individual intake. The aim of this study was to investigate the combined effects on skeletal muscle mass and protein metabolic signaling during the hypertrophic process from atrophy in mice. METHODS: Male ICR mice were divided into five dietary groups consisting of seven animals each: normal, astaxanthin, ß-carotene, resveratrol, and all three antioxidants. Equal concentrations (0.06% [w/w]) of the respective antioxidants were included in the diet of each group. In the mixed group, three antioxidants were added in equal proportion. One leg of each mouse was casted for 3 wk to induce muscle atrophy. After removal of the cast, the mice were fed each diet for 2 wk. The muscle tissues were collected, weighed, and examined for protein metabolism signaling and oxidative damage. RESULTS: The weight of the soleus muscle was increased in the astaxanthin, ß-carotene, and resveratrol groups to a greater extent than in the normal group; this was accelerated by intake of the mixed antioxidants (P = 0.007). Phosphorylation levels of mammalian target of rapamycin and p70 S6 K in the muscle were higher in the mixed antioxidant group than in the normal group (P = 0.025; P = 0.020). The carbonylated protein concentration was lower in the mixed antioxidant group than in the normal group (P = 0.021). CONCLUSIONS: These results suggested that a combination of astaxanthin, ß-carotene, and resveratrol, even in small amounts, promoted protein synthesis during the muscle hypertrophic process following atrophy.