Association of skeletal muscle mass and risk of hypertension in Korean adults: secondary analysis of data from the community-based prospective cohort study.

Background: Cross-sectional studies have revealed a link between low muscle mass and hypertension. However, whether the degree of muscle mass predicts hypertension risk has not been confirmed. This study aimed to verify an association between skeletal muscle mass and incident hypertension in a longitudinal follow-up of middle-aged Korean adults. Methods: The community-based prospective Korean Genome and Epidemiology Study (KoGES) data from 2,669 participants who were free of hypertension at baseline were prospectively assessed at 2-year intervals for 16 years. The participants were divided into tertiles T1-T3 of relative skeletal muscle mass (RSM) according to their baseline whole-body skeletal muscle mass measured as bioelectrical impedance. Incident hypertension was estimated using multivariate logistic regression with the Cox proportional hazard regression model. Results: Over the 16-year follow-up, the rates of incident hypertension at RSM T1, T2, and T3 were 18.7, 17.1, and 13.4% in men (P for trend = 0.0002) and 18.8, 14.7, and 12.9% in women (P for trend = 0.0007), respectively. The multivariate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for the incidence of hypertension for men and women in T1 and T2 were 1.36 (1.11-1.67) and 1.59 (1.31-1.94), and 1.20 (0.99-1.46) and 1.70 (1.41-2.04), respectively, compared with T3 as the reference. Conclusion: A low skeletal muscle mass in middle-aged Korean men and women was significantly associated with incident hypertension in later life. Further investigation is needed to comprehend the mechanisms of this relationship and validate the findings in a large cohort.

Effects of Omega-3 Fatty Acid Supplementation on Skeletal Muscle Mass and Strength in Adults: A Systematic Review.

Previous studies have suggested that omega-3 polyunsaturated fatty acids, predominantly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have several health benefits. However, their effect on changes in skeletal muscle mass and strength has not been established, owing to differences in study designs. This systematic review aimed to investigate the recent evidence regarding the role of dietary EPA and DHA in muscle mass changes and their association with muscle strength. Databases including PubMed and Google Scholar were searched for randomized controlled trials and single-arm interventions that investigated the effects of omega-3 fatty acids on skeletal muscle mass, strength, and body composition in adults aged 18 years and older. A total of 18,521 studies were retrieved from the databases and manual searches; 21 studies were quality assessed, and the findings were summarized. Studies were categorized into 3 main categories according to the type of omega-3 fatty acid supplementation: pure compounds such as oil tablets, formulated forms with protein, leucine, and vitamin D, and ingredients added to enteral nutrition support products. Overall, the majority of the study results appeared to indicate that omega-3 fatty acids are beneficial for muscle health. However, meta-analysis was not conducted because of the heterogeneity of the study participants, evaluation method of muscle indices, and intervention periods among the studies. High-quality studies are required to validate our conclusions. However, this systematic review of the effects of EPA and DHA on skeletal muscle and body composition provides evidence that can be applied in both clinical and industrial settings.

The ability of the geriatric nutritional risk index to predict the risk of heart diseases in Korean adults: a Korean Genome and Epidemiology Study cohort.

Introduction: The predictive ability of nutritional risk index on cardiovascular outcomes in middle-aged and non-hospitalized adults has not yet been reported. This study investigated whether the Geriatric Nutritional Risk Index (GNRI), an index for assessing the risk of developing malnutrition, could predict heart disease in middle-aged Korean adults. Methods: The cohort used in this study consisted of 3,783 participants selected from 10,030 Korean adults who participated in the Ansan-Ansung cohort study as part of the Korean Genome and Epidemiology Study. The GNRI was determined based on serum albumin level, proportion of current weight, and ideal body weight. Participants were then divided into two groups: GNRI ≤98 and > 98, which corresponded to the risk of malnutrition and normal, respectively. The major outcome of this study was coronary artery disease (CAD) or congestive heart failure (CHF) during a 15-year-follow period. Results: During the follow-up period spanning 2004-2018, 136 events of heart disease occurred. Using a Kaplan-Meier analysis, event-free rates were found to be associated with 90.5% on a GNRI ≤98 and 96.6% on a GNRI >98 (p < 0.0009). GNRI ≤98 showed a 3.2-fold (hazard ratio, 3.22; 95% credit interval, 1.49-6.96; p = 0.0029) increase in the incidence of heart disease, including CAD or CHF, compared with GNRI >98, after controlling for potential confounders. Conclusion: Malnutrition risk confers a significantly increased risk for heart disease in middle-aged Koreans. Further studies with larger cohorts are needed to verify the efficacy of the GNRI in predicting disease risk in adults with pre-disease.

Role of Dgat2 in Glucose Uptake and Fatty Acid Metabolism in C2C12 Skeletal Myotubes.

Acyl-coenzyme A (CoA):diacylglycerol acyltransferase 2 (DGAT2) catalyzes the last stage of triacylglycerol (TAG) synthesis, a process that forms ester bonds with diacylglycerols (DAG) and fatty acyl-CoA substrates. The enzymatic role of Dgat2 has been studied in various biological species. Still, the full description of how Dgat2 channels fatty acids in skeletal myocytes and the consequence thereof in glucose uptake have yet to be well established. Therefore, this study explored the mediating role of Dgat2 in glucose uptake and fatty acid partitioning under short interfering ribonucleic acid (siRNA)-mediated Dgat2 knockdown conditions. Cells transfected with Dgat2 siRNA downregulated glucose transporter type 4 (Glut4) messenger RNA (mRNA) expression and decreased the cellular uptake of [1-14C]-labeled 2-deoxyglucose up to 24.3% (p < 0.05). Suppression of Dgat2 deteriorated insulininduced Akt phosphorylation. Dgat2 siRNA reduced [1-14C]-labeled oleic acid incorporation into TAG, but increased the level of [1-14C]-labeled free fatty acids at 3 h after initial fatty acid loading. In an experiment of chasing radioisotope-labeled fatty acids, Dgat2 suppression augmented the level of cellular free fatty acids. It decreased the level of re-esterification of free fatty acids to TAG by 67.6% during the chase period, and the remaining pulses of phospholipids and cholesteryl esters were decreased by 34.5% and 61%, respectively. Incorporating labeled fatty acids into beta-oxidation products increased in Dgat2 siRNA transfected cells without gene expression involving fatty acid oxidation. These results indicate that Dgat2 has regulatory function in glucose uptake, possibly through the reaction of TAG with endogenously released or recycled fatty acids.

Perspectives on the systematic review for the 2020 Dietary Reference Intakes for Koreans for calcium.

An accurate assessment of the recommended calcium (Ca) intake may contribute to reducing the risk of fractures and chronic diseases, ultimately improving quality of life. This review was performed to summarize key findings of Ca studies, investigate the effect of Ca intake on health outcomes, and determine the adequacy of evidence to revise the 2015 Dietary Reference Intakes for Koreans (KDRIs) for Ca in 2020. Databases were searched for intervention studies that assessed health outcomes by providing Ca in diets or as supplements. The framework of the systematic review comprised conducting literature searches, data extraction, quality assessment of the literature, and summarizing key findings relevant to set the Estimated Average Requirement (EAR) and Tolerable Upper Intake Level (UL) for Ca for the 2020 KDRI. The final search was performed in June 2019. A total of 13,309 studies were identified through databases and manual search. Sixtyfive studies were included in the final quality assessment and were summarized according to health indicators. As bone health was used as an indicator of the EAR for Ca, literature reports on bone health were further categorized by the life-cycle stage of the participants. This systematic review did not find new evidence that could be applied to the general Korean adult population, including postmenopausal women, for defining a new EAR for Ca in the 2020 KDRIs. Evidence in most of the reviewed literature was considered weak; however, some evidence was found that could improve the criteria on how the EAR for Ca was determined in children and adolescents. A review of the literature for the 2020 KDRIs for Ca did not find strong evidence in order to change the recommended values of the 2015 KDRIs. More clinical interventions are required among Koreans to strengthen the body of evidence to warrant the revision of the KDRIs.

Effect of the Timing of Nutritional Support Team Intervention on Nutritional Status on Patients Receiving Enteral Nutrition.

Many hospitalized patients usually have a high risk of malnutrition, which delays the therapy process and can lead to severe complications. Despite of the potential benefits, the effects of timely intervention by nutrition support team (NST) on the nutritional status of admitted patients are not well established. This study aimed to compare the nutritional status between patients with early and delayed NST supports and to assess the effect of the timing of NST support initiation on the nutritional status of enteral nutrition patients. In a simple comparison between the two groups, the early NST intervention group had shorter hospital stays and fewer tube feeding periods than the delayed NST intervention group. The increase in the amount of energy intake from first to last NST intervention was 182.3 kcal in patients in the early NST intervention group, higher than that in patients in the delayed intervention group (p = 0.042). The extent of reduction in serum albumin and hemoglobin levels between the initial and last NST intervention tended to be lower in the early NST intervention group than in the delayed NST intervention group. The mean odds ratio for the patients who were severely malnourished in the early NST intervention group was 0.142 (95% confidence interval, 0.045-0.450) after adjusting for hospital stay and age. The results of this study indicate that early NST intervention can improve patients' overall nutritional status.

All-Cause Mortality and Cardiovascular Death between Statins and Omega-3 Supplementation: A Meta-Analysis and Network Meta-Analysis from 55 Randomized Controlled Trials.

Statins and omega-3 supplementation have shown potential benefits in preventing cardiovascular disease (CVD), but their comparative effects on mortality outcomes, in addition to primary and secondary prevention and mixed population, have not been investigated. This study aimed to examine the effect of statins and omega-3 supplementation and indirectly compare the effects of statin use and omega-3 fatty acids on all-cause mortality and CVD death. We included randomized controlled trials (RCTs) from meta-analyses published until December 2019. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated to indirectly compare the effect of statin use versus omega-3 supplementation in a frequentist network meta-analysis. In total, 55 RCTs were included in the final analysis. Compared with placebo, statins were significantly associated with a decreased the risk of all-cause mortality (RR = 0.90, 95% CI = 0.86-0.94) and CVD death (RR = 0.86, 95% CI = 0.80-0.92), while omega-3 supplementation showed a borderline effect on all-cause mortality (RR = 0.97, 95% CI = 0.94-1.01) but were significantly associated with a reduced risk of CVD death (RR = 0.92, 95% CI = 0.87-0.98) in the meta-analysis. The network meta-analysis found that all-cause mortality was significantly different between statin use and omega-3 supplementation for overall population (RR = 0.91, 95% CI = 0.85-0.98), but borderline for primary prevention and mixed population and nonsignificant for secondary prevention. Furthermore, there were borderline differences between statin use and omega-3 supplementation in CVD death in the total population (RR = 0.92, 95% CI = 0.82-1.04) and primary prevention (RR = 0.85, 95% CI = 0.68-1.05), but nonsignificant differences in secondary prevention (RR = 0.97, 95% CI = 0.66-1.43) and mixed population (RR = 0.92, 95% CI = 0.75-1.14). To summarize, statin use might be associated with a lower risk of all-cause mortality than omega-3 supplementation. Future direct comparisons between statin use and omega-3 supplementation are required to confirm the findings.

Associations of Dietary Intake with Cardiovascular Disease, Blood Pressure, and Lipid Profile in the Korean Population: a Systematic Review and Meta-Analysis.

OBJECTIVE: Previous studies have separately reported the contributions of dietary factors to the risk of cardiovascular disease (CVD) and its markers, including blood pressure (BP) and lipid profile. This study systematically reviewed the current evidence on this issue in the Korean population. METHODS: Sixty-two studies from PubMed and Embase were included in this meta-analysis. We performed a random-effects model to analyze pooled odds ratios (ORs) and hazard ratios (HRs) and their 95% confidence intervals (CIs) for the consumption of 14 food items, three macro- and eight micro-nutrients, two dietary patterns, and three dietary indices. RESULTS: An analysis of pooled effect sizes from at least four individual study populations showed significant associations between coffee consumption and CVD (OR/HR, 0.71; 95% CI, 0.52-0.97) and elevated/high triglycerides (TG) (OR, 0.84; 95% CI, 0.78-0.90), sugar-sweetened beverage intake and elevated BP (OR/HR, 1.20; 95% CI, 1.09-1.33), and milk and dairy intake and elevated/high TG and low high-density lipoprotein cholesterol (HDL-C) (OR/HR, 0.82; 95% CI, 0.76-0.89 for both). Carbohydrate consumption and the low-carbohydrate-diet score were consistently related to an approximately 25% risk reduction for elevated TG and low HDL-C. A lower risk of elevated total cholesterol, but not low-density lipoprotein, was additionally observed for those with a higher low-carbohydrate-diet score. A healthy dietary pattern was only associated with a reduced risk of elevated TG in the Korea National Cancer Screenee Cohort (OR, 0.81; 95% CI, 0.67-0.98). CONCLUSION: This study showed that milk and dairy and coffee had protective effects for CVD and its risk factors, such as BP and lipid profile, while sugar-sweetened beverages exerted harmful effects.

Suppression of long chain acyl-CoA synthetase blocks intracellular fatty acid flux and glucose uptake in skeletal myotubes.

Alterations in fatty acid metabolism are associated with impaired glucose uptake in skeletal muscle. Long-chain acyl-CoA synthetase (Acsl) 6 is the one of the Acsl isoforms expressed in skeletal muscle although its role in muscle energy metabolism has not been studied. Thus, the aims of this study were to investigate the role of Acsl6 in fatty acid partitioning and glucose uptake in differentiated skeletal myotubes using a siRNA-mediated knockdown approach. Compared with cells transfected with control siRNA, cells transfected with Acsl6 siRNA exhibited reduced intracellular triacylglycerol (TAG) accumulation. The initial rate of [1­14C]­oleic acid uptake was not altered while the incorporation of [1­14C]­acetic acids into total cellular lipids decreased under Acsl6 knockdown (p < 0.05). In a metabolic labeling study, Acsl6 suppression decreased the incorporation of [1­14C]­oleic acids and [1­14C]­acetic acids into TAG and diacylglycerol (DAG) (p < 0.05). During the chase period of a pulse-chase experiment, Acsl6 suppression increased the intracellular free fatty acids and decreased the fatty acid channeling toward the reacylation of TAG (p < 0.05). The incorporation of the labeled fatty acids into acid-soluble metabolites, ß-oxidation product, was not changed under Acsl6 knockdown. Acsl6 siRNA decreased the insulin-induced uptake of [1­14C]­2­deoxyglucose (p < 0.05) but did not change the glucose uptake in the presence of acipimox, inhibitor of lipolysis. Suppression of Acsl6 deteriorated Akt phosphorylation and Glut4 mRNA expression in response to insulin. These results suggest that Acsl6 activates and channels fatty acids toward anabolic pathways and has a role in glucose and fatty acid cycling through the re-esterification of fatty acids in skeletal muscle.

Erratum: A Vegetable and Fish Dietary Pattern Is Positively Associated with Skeletal Muscle Mass in Korean Men.

[This corrects the article on p. 1 in vol. 8, PMID: 30746343.].

Erratum: Total energy intake according to the level of skeletal muscle mass in Korean adults aged 30 years and older: an analysis of the Korean National Health and Nutrition Examination Surveys (KNHANES) 2008-2011.

[This corrects the article on p. 222 in vol. 12, PMID: 29854328.].

A Vegetable and Fish Dietary Pattern Is Positively Associated with Skeletal Muscle Mass in Korean Men.

Isolating the effects of a single nutrient or food in relation to health outcomes including increased skeletal muscle mass is a challenging task because dietary constituents are highly correlated and synergistic. Hence, diet pattern analysis may be used to investigate the role of certain diets in health outcomes. The present study investigated the dietary patterns and their relationship to skeletal muscle mass in Korean adults. Data were extracted from the 2008-2011 Korea National Health and Nutrition Examination Surveys. To explore the dietary patterns of the study subjects, factor analysis was performed using data obtained from a 24-hour recall. The skeletal muscle index according to dietary pattern scores was then investigated to estimate the changes in skeletal muscle mass. Three patterns were initially identified from the factor analysis. Of these vegetables and fish (VF) pattern was the primary factor with high reliability and was a common factor in sex-separated analyses. The VF pattern scores were positively associated with increased skeletal muscle mass in both men and women. Further analysis according to quartile levels of VF pattern scores showed a positive association between skeletal muscle mass and VF pattern in men but not in women. These results suggest that dietary patterns focused on vegetables and seafoods may contribute to increased skeletal muscle mass in Korean men but that sex difference should be considered in nutrition care for skeletal muscle health.

Genetically Mediated Lipid Metabolism and Risk of Insulin Resistance: Insights from Mendelian Randomization Studies.

Dysregulated lipid metabolism, characterized by higher levels of circulating triglycerides, higher levels of small, low density lipoprotein, and accumulation of intracellular lipids, is linked to insulin resistance and related complications such as type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD). Considering that various metabolic, genetic, and environmental factors are involved in the development of T2DM and CVD, the causalities of these diseases are often confounded. In recent years, Mendelian randomization (MR) studies coupling genetic data in population studies have revealed new insights into the risk factors influencing the development of CVD and T2DM. This review briefly conceptualizes MR and summarizes the genetic traits related to lipid metabolism by evaluating their effects on the indicators of insulin resistance based on the results of recent MR studies. The data from the MR study cases referred to in this review indicate that the causal associations between lipid status and insulin resistance in MR studies are not conclusive. Furthermore, available data on Asian ethnicities, including Korean, are very limited. More genome-wide association studies and MR studies on Asian populations should be conducted to identify Asian- or Korean-specific lipid traits in the development of insulin resistance and T2DM. The present review discusses certain studies that investigated genetic variants related to nutrient intake that can modify lipid metabolism outcomes. Up-to-date inferences on the causal association between lipids and insulin resistance using MR should be interpreted with caution because of several limitations, including pleiotropic effects and lack of information on genotype and ethnicity.

Total energy intake according to the level of skeletal muscle mass in Korean adults aged 30 years and older: an analysis of the Korean National Health and Nutrition Examination Surveys (KNHANES) 2008-2011.

BACKGROUND/OBJECTIVES: Since gain or loss of skeletal muscle mass is a gradual event and occurs due to a combination of lifestyle factors, assessment of dietary factors related to skeletal muscle is complicated. The aim of this study was to investigate the changes in total energy intake according to the level of skeletal muscle mass. SUBJECTS/METHODS: A total of 8,165 subjects ≥ 30 years of age from the Korean National Health and Nutrition Examination Surveys (KNHANES) 2008-2011 were included in the analysis, and multivariate-adjusted regression analyses were performed to analyze the association of the quartiles of sarcopenia index (SI) with energy intake of the study population after adjusting for age and metabolic parameters. RESULTS: The increase in SI quartile was in proportion to the gradual decrease in systemic lipids and the anthropometric measurement of fat accumulation (P < 0.001). Subjects in higher SI quartiles tended to consume more total energy and energy-producing nutrients than those in lower quartiles (P < 0.001). After age, body weight, alcohol consumption, and metabolic parameters were adjusted in the analysis, total energy intake gradually increased according to the increase in SI quartile, and the association between total energy intake and SI was more pronounced in men. However, the risk (odd ratio) of having a low SI was not affected by any single macronutrient intake. CONCLUSIONS: In this study, total energy intake was positively associated with SI and relative skeletal mass in both men and women. However, no significant association or a weak association was observed between any single macronutrient intake and skeletal muscle mass. The data indicated that acquiring more energy intake within the normal range of energy consumption may help to maintain skeletal muscle mass.

Nutritional Status of Korean Children and Adolescents with Attention Deficit Hyperactivity Disorder (ADHD).

Attention deficit hyperactivity disorder (ADHD) has been associated with an elevated risk for obesity but this seems to be paradoxical to the fact that many youths with ADHD have symptoms of hyperactivity. People diagnosed with ADHD tend to have a high risk of developing undesirable diet habits and consequently have health related problems. However, less attention has been paid to obesity in ADHD while many efforts have been devoted to the prevention of childhood obesity in mentally normal people. Hence the purpose of this study was to explore the nutritional status and life habits of children and adolescents with ADHD (n = 76) based on degree of obesity by utilizing the Korean National Health and Nutrition Examination Survey (KNHANES) data from 2005-2013. As results the levels of blood pressure, total triglycerides and the fat intake relative to total energy intake in overweight ADHD group were higher than those in normal weight group. Interestingly, overweight ADHD subjects consumed significantly less amount of iron compared to normal weight ADHD subjects and the level of serum ferritin was lower in the overweight ADHD group (59.0 ng/mL) than in the normal weight ADHD group (47.9 ng/mL). After adjusting total energy intake, total vegetable consumption was 14.3% lower in overweight group compared to the consumption in normal weight group. These results indicate a plausible relationship of iron status and obesity in ADHD subjects but this relationship may not be specific to ADHD. A future study with case-control design is necessary to investigate the association of obesity, nutrient intake, and cognitive/mental status of ADHD.

The Level of Serum Cholesterol is Negatively Associated with Lean Body Mass in Korean non-Diabetic Cancer Patients.

Due to poor nutrition and abnormal energy metabolism, cancer patients typically experience the loss of muscle mass. Although the diabetic conditions or dyslipidemia have been reported as a causal link of cancer but the consequence of such conditions in relation to gain or loss of skeletal muscle mass in cancer patients has not been well documented. The purpose of this study was to investigate the relationship of lean body mass and systemic parameters related to lipid metabolism in non-diabetic cancer patients using data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008-2011. As results the level of serum total cholesterol (total-C) was negatively associated with both total lean body mass and appendicular lean body mass in cancer patients after adjustment for sex, physical activity, energy intake and comorbidity. The associations between consumption of dietary factors (energy, carbohydrate, protein and fat) and lean body mass were disappeared after adjusting comorbidities of cancer patients. Multivariate-adjusted linear regression analysis by quartiles of serum total-C showed that higher quartile group of total-C had significantly lower percent of lean body mass than reference group in cancer patients. The data indicate that serum lipid status can be the potential estimate of loss of skeletal muscle mass in cancer patients and be referenced in nutrition care of cancer patients under the onset of cachexia or parenteral/enteral nutrition. This data need to be confirmed with large pool of subjects and should be specified by stage of cancer or the site of cancer in future studies.

Integrated Regulation of Hepatic Lipid and Glucose Metabolism by Adipose Triacylglycerol Lipase and FoxO Proteins.

Metabolism is a highly integrated process that is coordinately regulated between tissues and within individual cells. FoxO proteins are major targets of insulin action and contribute to the regulation of gluconeogenesis, glycolysis, and lipogenesis in the liver. However, the mechanisms by which FoxO proteins exert these diverse effects in an integrated fashion remain poorly understood. We report that FoxO proteins also exert important effects on intrahepatic lipolysis and fatty acid oxidation via the regulation of adipose triacylglycerol lipase (ATGL), which mediates the first step in lipolysis, and its inhibitor, the G0/S1 switch 2 gene (G0S2). We also find that ATGL-dependent lipolysis plays a critical role in mediating diverse effects of FoxO proteins in the liver, including effects on gluconeogenic, glycolytic, and lipogenic gene expression and metabolism. These results indicate that intrahepatic lipolysis plays a critical role in mediating and integrating the regulation of glucose and lipid metabolism downstream of FoxO proteins.

Effect of Silicon Supplementation on Bone Status in Ovariectomized Rats Under Calcium-Replete Condition.

Previous studies have suggested that silicon (Si) had positive effects on bone, but such benefits from Si may be dependent on calcium status. Also, several biochemical roles of Si in osteoblastic mineralization, the regulation of gene expression related to bone matrix synthesis, and the decrease in reactive oxygen species and pro-inflammatory mediators were reported, but these effects were mostly shown in cell culture studies. Hence, we tested the effect of Si supplementation on bone status and the gene expression related to bone metabolism and inflammatory mediators in young estrogen-deficient rats under calcium-replete condition (0.5 % diet). Results showed that 15-week supplementation of both high and very high doses of Si (0.025 and 0.075 % diet, respectively) could not restore the ovariectomy (OVX)-induced decrease of bone mineral density (BMD) of vertebrae, femur, and tibia. Also, several bone biochemical markers (ALP, osteocalcin, CTx) and mRNA expression of COL-I, RANKL, IL-6, and TNF-α in femur metaphysis were not significantly changed by Si in OVX rats. However, a very high dose (0.075 %) of Si supplementation significantly increased OPG expression and decreased the ratio of RANKL/OPG in mRNA expression comparable to that of sham-control animals. Taken together, Si supplementation did not increase BMD under calcium-replete condition but the decrease in the ratio of RANKL/OPG expression to the normal level suggests the possibility of a bone health benefit of Si in estrogen deficiency-induced bone loss.

Supplementation of Seaweeds Extracts Suppresses Azoxymethane-induced Aberrant DNA Methylation in Colon and Liver of ICR Mice.

BACKGROUND: Seamustard and seatangle are commonly consumed seaweeds in Korea and rich sources of non-digestible polysaccharides which possess biological activities. However anti-mutagenic and anti-cancer activities of these seaweeds under physiological condition have not been clarified yet. The objective of this study was to investigate the effect of seaweeds consumption on azoxymethane (AOM) -induced DNA methylation at N(7) and O(6) position of guanine base, an indicator of DNA damage related to cancer initiation. METHODS: THIRTY ICR MICE WERE DIVIDED INTO FIVE GROUPS AND FED ONE OF THE FOLLOWING DIETS FOR TWO WEEKS: control diet, diet containing 10% water-soluble or water-insoluble fraction of seamustard or seatangle. After two weeks of experimental diet AOM was injected at 6 hours before sacrifice and N(7)-methylguanine (N(7)-meG) and O(6)-methylguanine (O(6)-meG) from the colon and liver DNA were quantified using a gas chromatography-mass spectroscopy. RESULTS: Water-soluble fractions of both seamustard and seatangle significantly reduced AOM-induced production of N(7)-meG guanine in colon and liver. Also water-soluble fractions of these seaweeds suppressed the level of methylation at O(6)-guanine of colon and liver directly responsible for tumorigenesis. While water-insoluble fraction of seamustard suppressed the production of N(7)-meG in liver this seaweed fraction decreased O(6)-meG and the ratio of O(6)/N(7)-meG in liver. Water insoluble fraction of seatangle decreased both O(6)- and N(7)-meG in colon and liver. Supplementation of all seaweeds extracts increased fecal weight of animals and the increase of fecal weight by water-insoluble fraction of seaweeds were higher than that by water-soluble fraction. CONCLUSION: Seamustard and seatangle intake may effectively prevent colon and liver carcinogenesis by decreasing DNA damage and the mechanism of inhibiting carcinogenesis by seaweeds in a long term study are warranted.

Chemopreventive effects of curcumin on chemically induced mouse skin carcinogenesis in BK5.insulin-like growth factor-1 transgenic mice.

The insulin-like growth factor-1 (IGF-1) signaling pathway is strongly associated with the risk of various cancers, and its inhibition has emerged as a potent anticancer strategy. Accumulating evidence from in vitro studies has shown that curcumin is a potent inhibitor of the IGF-1 signaling pathway. However, direct evidence that curcumin modulates IGF-1-induced tumorigenesis in a physiological system has not been reported. Therefore, in this study, we assessed the anticarcinogenic activity of curcumin on skin cancer by using BK5.IGF-1 transgenic (Tg) mice that overexpress IGF-1 in the skin epidermis. In 7,12-dimethylbenz(a)anthracene (DMBA)-tetradecanoyl phorbol-13-acetate (TPA) two-stage skin carcinogenesis, a curcumin diet (0.02% wt/wt) fed for 14 wk remarkably reduced mouse skin tumor multiplicity by 53%, epidermal hyperplasia and proliferation compared to the control diet group. TPA-induced phosphorylation of Akt, S6 kinase (S6K), and eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) in mouse skin was lower in the curcumin group than in the control group. Curcumin treatment inhibited IGF-1-induced phosphorylation of the IGF-1 receptor, insulin receptor substrate-1, Akt, S6K, and 4EBP1 in the mouse keratinocyte cell line, C50 in a dose-dependent manner. Taken together, these data suggest that curcumin exerts significant anticarcinogenic activity in skin cancer through the inhibition of IGF-1 signaling.