BACKGROUND/OBJECTIVES: To identify modifiable risk factors for type 2 diabetes mellitus and explore the relationship between diet sodium intake and blood glucose levels. MATERIALS/METHODS: Based on inclusion and exclusion criteria, we extracted, analyzed, and assessed the available crossover studies of dietary salt intake restriction and insulin resistance in PubMed, Web of Science, MEDLINE, Embase, Wanfang, and CNKI databases. RESULTS: We included 6 studies with 8 sets of data, covering 485 subjects. I² statistics results showed insignificant heterogeneity among all data (I² = 39.2% < 50%). Thus, a fixed-effect model was adopted for the final pooled effect size. Weighted mean difference and its 95% confidence interval (CI) value was 0.193 (95% CI, 0.129-0.257), and the test of the overall effect showed P < 0.001. The results revealed that the blood glucose levels in the subjects in the low-salt intake group were significantly higher than those in the normal or high-salt intake groups. We also found no significant change occurred after the removal of any study through sensitivity analysis, which confirmed that the outcome we calculated was prudent and credible. The quantitative Egger's test (P = 0.109 > 0.05) indicated that insignificant publication bias existed. CONCLUSION: This meta-analysis highlights the relationship between dietary sodium intake and blood glucose levels. Our findings show that higher blood glucose levels might be expected in hypertensive or normal people with low-salt consumption compared to those with normal or high-salt consumption, although these differences were not clinically significant.

BACKGROUND/OBJECTIVES: Curcumin is a well-known phytochemical with anti-inflammatory effects. Heat shock protein (HSP) 70, an intracellular chaperone, inhibits proinflammatory signaling activation. Although curcumin has been shown to induce HSP70 expression in various cell types, whether HSP70 mediates the anti-inflammatory effects of curcumin in mature adipocytes remains unclear. MATERIALS/METHODS: To assess the role of HSP70 in regulating the anti-inflammatory response to curcumin in adipocytes, fully differentiated 3T3-L1 adipocytes were treated with curcumin, lipopolysaccharide (LPS), and/or the HSP70 inhibitor pifithrin-µ (PFT-µ). The expression levels of HSP70 and proinflammatory cytokines were then measured. RESULTS: Curcumin upregulated HSP70 expression at both protein and mRNA levels and attenuated LPS-induced Il6, Ptx3, and Ccl2 mRNA upregulation. PFT-µ tended to exacerbate the LPS-induced upregulation of Il6, Ptx3, Ccl2, and Tnfa mRNA expression. However, on curcumin pretreatment, the tendency of PFT-µ to upregulate LPS-induced proinflammatory cytokine expression decreased or disappeared. CONCLUSION: These results indicate that HSP70 is involved in the regulation of inflammatory responses but may not be crucial for the anti-inflammatory effects of curcumin in 3T3-L1 adipocytes.

BACKGROUND/OBJECTIVES: Hizikia fusiformis (HF) is a class of brown seaweeds whose active ingredients exert central nervous system protective effects, such as neuroprotection; however, the underlying mechanisms remain unknown. Given that dopamine (DA) and serotonin (5HT) are two major neurotransmitters involved in various psychiatric disorders and neuronal growth in early neurodevelopmental processes, we investigated whether HF extract could modulate the molecular expression associated with DA and 5HT transmission as well as the structural formation of neurons. MATERIALS/METHODS: In vitro cell cultures were prepared from cerebral cortical neurons obtained from CD-1 mice on embryonic day 14. Cultured cells were treated with 0.1, 1.0, or 10.0 ㎍/mL of HT extract for 24 h, followed by fluorescence immunostaining for DA and 5HT-related receptors and transporters and some neuronal structural formation-associated molecules. RESULTS: HF extract dose-dependently upregulated the expression levels of selective DA and 5HT receptors, and downregulated the levels of DA and 5HT transporters. Moreover, HF extract increased the neurofilament light chain expression. CONCLUSION: These results suggest that HF may modulate DA and 5HT transmission, thereby affecting neurodevelopment.

BACKGROUND/OBJECTIVES: Chronic or intermittent hyperglycemia is associated with the development of diabetic complications. Oxidative stress and inflammation can be altered by hyperglycemia in diverse tissues, including kidneys and eyes, and play a pivotal role in diabetic complications. Our previous studies showed that the water-insoluble 5,7-dihydroxyflvone chrysin effectively combats diabetic damages incurred in diabetic kidneys and retinas. The current study employed the newly-synthesized 5.7-di-O-acetylchrysin, having higher solubility than chrysin, to compare the effects on diabetes-associated renal fibrosis and abnormal retinal neovascularization. MATERIALS/METHODS: In the in vivo study, db/db mice as animal models of type 2 diabetes were orally administrated 10 mg/kg BW diacetylchrysin, daily for 10 weeks. RESULTS: Unlike chrysin, oral administration of 10 mg/kg diacetylchrysin did not lower the blood glucose level and 24 h urine volume in db/db mice. Nevertheless, the urinary albumin excretion was markedly reduced. The administration of diacetylchrysin also diminished the deposition of collagen fibers in diabetic glomeruli and tubules by suppressing the induction of connective tissue growth factor and collagen IV in diabetic kidneys. Supplying diacetylchrysin enhanced the membrane type-1 matrix metalloproteinase (MMP) expression reduced in diabetic kidneys, while the tissue inhibitor of MMP-2 induction was attenuated in diacetylchrysin-challenged diabetic kidneys. In addition, supplementing diacetylchrysin to diabetic mice ameliorated renal injury due to glomerulosclerosis and tubular interstitial fibrosis. Furthermore, the reduced retinal inductions of Zonula occludens-1 and vascular endothelial cadherin in db/db mice were elevated in the retinal tissues of diacetylchrysin-treated animals. Oral administration of diacetylchrysin curtailed the induction of vascular endothelial growth factor (VEGF) and VEGF receptor 2 in db/db mice, ultimately retarding diabetes-associated retinal neovascularization. Additionally, the retinal formation of acellular capillaries with leaky vessels was reduced in diacetylchrysin-treated db/db mice. CONCLUSION: Diacetylchrysin may act as a potent pro-health agent for treating renal fibrosis-associated diabetic nephropathy and retinal neovascularization-associated diabetic retinopathy.

BACKGROUND/OBJECTIVES: Limited studies reported that quercetin inhibited adipogenesis and neovascularization by inhibiting matrix metalloproteinases (MMPs) activity, but such mechanisms have not been elucidated in animal experiments. In this study, we investigated the inhibitory effects of quercetin on weight gain and adipose tissue growth through the regulation of mRNA expressions of adipogenic transcription factors and MMPs in mice fed a high-fat diet (HFD). MATERIALS/METHODS: Five-wk-old C57BL/6J mice were fed a normal diet (ND), HFD, HFD containing 0.05% of quercetin (HFQ0.05), or HFD containing 0.15% of quercetin (HFQ0.15) for 16 wks. Glycerol-3-phosphate dehydrogenase (GPDH) activity was measured using a commercial kit. The mRNA expressions of transcription factors related to adipocyte differentiation were determined by real-time polymerase chain reaction (PCR). The mRNA expressions of MMPs and concentrations of MMPs were measured by real-time PCR and enzyme-linked immunosorbent assay kit, respectively. RESULTS: Quercetin intake reduced body weight gain and epididymal adipose tissue weights (P < 0.05). GPDH activity was higher in the HFD group than in the ND group but lower in the quercetin groups (P < 0.05). The mRNA expressions of CCAAT/enhancer binding protein β (C/EBPβ), C/EBPα, peroxisome proliferator-activated receptor γ, and fatty acid-binding protein 4 were lower in the quercetin groups than in the HFD group (P < 0.05). Similarly, the mRNA expression and concentrations of MMP-2 and MMP-9 were significantly lower in the quercetin groups than in the HFD group (P < 0.05). CONCLUSION: The study confirms that quercetin suppresses body weight gain and adipogenesis by inhibiting transcription factors related to adipocyte differentiation and MMPs (MMP-2 and MMP-9), in mice fed a HFD.

BACKGROUND/OBJECTIVES: The purpose of this study was to establish a database (DB) of foods containing vitamin D that were investigated in the Korea National Health and Nutrition Examination Survey (KNHANES), to estimate the dietary vitamin D intake, to evaluate the dietary adequacy of this intake, and to identify the major food sources of Koreans that contain vitamin D. SUBJECTS/METHODS: This study used data from the KNHANES 2016-2019. Individuals aged ≥ 1 year who participated in the nutrition survey (n = 28,418) were included. The dietary intake was assessed by the 24-h dietary recall method and individual dietary vitamin D intake was estimated using a newly established vitamin D DB. Dietary adequacy was evaluated by comparing the dietary intake of the participants with adequate intake (AI) as defined by Dietary Reference Intakes for Koreans (KDRIs) 2020. RESULTS: The average dietary vitamin D intake for all the subjects was 3.13 ㎍/d, which was 33.1% of AI. Dietary vitamin D intake was lower in rural residents, the elderly, and those with low income. The major food groups that contributed to the total dietary vitamin D intake were fish and shellfish (61.59%), eggs (17.75%), meat (8.03%), milk (4.25%), legumes (3.93%), and grains (3.84%). The top 10 individual food items that contributed to the total vitamin D intake were eggs (17.44%), squid (8.5%), eels (7.44%), salmon (5.35%), mackerel (5.27%), anchovies (4.65%), yellow croakers (4.58%), pork meat (4.47%), soymilk (4.46%), and skipjack tuna (3.80%). CONCLUSION: These results show that the mean dietary vitamin D intake of Koreans is lower than the reference AI level. Nutritional policies need to be put in place to increase the vitamin D intake of Koreans in the future. In addition, comprehensive research on all the sources of vitamin D, including intake of supplements and biosynthesis in the skin, is required.

BACKGROUND/OBJECTIVES: Estimation of energy demand using resting energy expenditure (REE) is a reasonable approach for optimizing glycemic control and weight management in patients with type 2 diabetes mellitus (T2DM). This study aimed to compare REE predictions and objective measurements in patients with T2DM in Korea. SUBJECTS/METHODS: This study enrolled 36 participants with T2DM (age range, 20-60 years). Anthropometric variables including height, weight, waist-hip ratio, blood pressure, body fat, body fat percentage, and total body weight were measured using bioimpedance. REE was evaluated using indirect calorimetry. The measured REE values were compared to values estimated using five predictive equations: the Harris-Benedict, Mifflin, Owen, Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO), and Schofield equations. This study evaluated the associations between measured REE values and anthropometric/clinical data, including height, weight, and age, using multivariate linear regression. RESULTS: The mean measured REE value was 1891.79 ± 288.03 kcal/day (male), 1,502.00 ± 202.96 kcal/day (female). REE estimates generated from the Mifflin equation showed the largest differences from measured REE values, whereas estimates derived from the FAO/WHO equation were the closest to the measured REE values. This study also identified associations between measured REE values and various anthropometric/clinical variables. CONCLUSION: The accuracy of REE prediction equations is critically important in promoting the efficacy of dietary counseling and the effective treatment of diabetes. Our results indicate the need for additional studies informing more suitable methods for determining the energy requirements of Korean patients with T2DM.

BACKGROUND/OBJECTIVES: This study aimed to evaluate the effect of preoperative immunonutrition on the composition of fecal microbiota following a colon cancer surgery. MATERIALS/METHODS: This study was a secondary analysis of a randomized controlled trial assessing the impact of preoperative immunonutrition on the postoperative outcomes of colon cancer surgery. Patients with primary colon cancer were enrolled and randomly assigned to receive additional preoperative immunonutrition or a normal diet alone. Oral nutritional supplementation (400 mL/day) with arginine and ω-3 fatty acids were administered to patients in the immunonutrition group for 7 days prior to surgery. Thirty-two fecal samples were collected from 16 patients in each group, and the composition of fecal microbiota was compared between the 2 groups. RESULTS: At the phylum level, no significant difference was observed in the composition of microbiota between the 2 groups (Firmicutes, 69.1% vs. 67.5%, P = 0.624; Bacteroidetes, 19.3% vs. 18.1%, P = 0.663; Actinobacteria, 6.7% vs. 10.6%, P = 0.080). The Firmicutes/Bacteroidetes ratio (4.43 ± 2.32 vs. 4.55 ± 2.51, P = 0.897) was also similar between the 2 groups. At the genus level, the proportions of beneficial bacteria such as Faecalibacterium spp. (8.1% vs. 6.4%, P = 0.328) and Prevotella spp. (6.9% vs. 4.8%, P = 0.331) were higher, while that of Clostridium spp. was lower (0.5% vs. 1.2%, P = 0.121) in the immunonutrition group, but the difference was not significant. CONCLUSIONS: Immunonutrition showed no significant association with the composition of fecal microbiota. The relationship between immunonutrition and the fecal microbiota should be investigated further in large-scale studies.

BACKGROUND/OBJECTIVES: Excessive sodium intake, cigarette smoking, and alcohol consumption are risk factors for a wide range of diseases. This study aimed to determine whether smokers and drinkers are more likely to enjoy their food with more salt, and whether the combination of smoking and drinking is associated with salty taste preferences. SUBJECTS/METHODS: This study analyzed the data of over 16 million Koreans from two four-year Korean Community Health Survey cycles (i.e., 2010 to 2013 and 2014 to 2017). The respondents' preferences for salty foods (i.e., their salt intake levels, whether they added salt or soy sauce to foods served on the table, and whether they dipped fried foods in salt or soy sauce), and the odds ratio (OR) of their preference were examined among smokers and drinkers when adjusted for sex, age, body mass index, educational level, household income, marital status, and cigarette smoking or alcohol consumption status. RESULTS: Cigarette smoking and alcohol consumption were correlated with the consumption of salty food. Based on the adjusted model, cigarette smokers and alcohol drinkers preferred adding salt or soy sauce or dipping fried foods in soybean more than non-smokers and nondrinkers. In addition, people who smoked and consumed alcohol reported a more significant stacking effect regarding the salty taste preference. CONCLUSION: This large population-based study found that both cigarette smoking and alcohol consumption were correlated with salty taste preferences, which may cause excessive sodium intake.

BACKGROUND/OBJECTIVES: In the Republic of Korea, "Healthy Restaurant for Sodium Reduction (HRSR)" project have been designated as one of the representative policies for sodium intake reduction. However, as of 2021, only 879 restaurants, less than 0.1% of all restaurants, had been designated. Therefore, to increase the participation of restaurants in this policy, it is necessary to examine the in-depth perception and experience of participants and non-participants in the HRSR. MATERIALS/METHODS: Two focus group discussions were conducted for HRSR project participants and non-participants. RESULTS: A total of 260 semantic units were derived from the 2 groups. The units were further classified into 5 upper categories and 11 subcategories. All the study participants knew the importance of low sodium intake, but they had little information on HRSR project. Various attempts have been made to encourage low sodium practice in restaurants, and the participants reported that the amount of salt used in their restaurants currently is reduced compared to that used in the past. However, they were worried about customers' complaints about the low sodium in their diet and the insignificant beneficent associated with the policy, which makes restaurant owners reluctant to participate in this policy. All the participants agreed on the urgent need for the improvement of public awareness of low-sodium diets and for substantive government support for HRSR. CONCLUSION: This study concluded that strategies such as more active publicity for the practice of sodium reduction in restaurants, identification of approaches to dispel the perception that low-salt diet is not tasty, and development of plans to increase the sale of food in of HRSR, are needed.

BACKGROUND/OBJECTIVES: The diversity of meal provision places has increased in recent years and sodium intake can vary depending on where meals are eaten, particularly in large cities. In this study, an analysis of the recent trends in sodium intake was performed and a comparison of sodium intake level according to meal provision place among citizens of Seoul was performed. SUBJECTS/METHODS: Data from a 24-h recall dietary intake survey from the 2010-2019 Korea National Health and Nutrition Examination Survey (KNHANES) were used in order to determine the trends in sodium intake among citizens of Seoul, aged 3-74 years old. (n = 11,811). The trend of daily sodium intake was presented in absolute amount and proportion compared to the chronic disease risk reduction intake (CDRR) for each selected characteristic. A comparison of sodium intake level according to meal provision place by sex and age groups as a total amount per meal (mg), density per meal (mg/1,000 kcal), and proportion of the daily sodium intake was performed using the 2016-2019 KNHANES. RESULTS: Sodium intake levels showed a downward trend from 2010-2019. The highest level of sodium intake was observed for subjects aged 30-49, and the level for males aged 30-49 was 202.8% higher than the CDRR. Results of the analysis of sodium intake per meal according to meal provision place showed that the highest sodium intake was in the order of restaurant meal (RM) > institutional foodservice (IF) > home meal (HM) > convenience food (CF). A higher sodium density (mg/1,000 kcal) was observed for IF compared with RM in most adults. Adults aged over 50 years old consumed more than half of the daily sodium in HM. CONCLUSION: Significant variation in the level of sodium intake was observed according to sex and age groups, therefore, different approaches and nutrition policies based on meal provision place are needed.

BACKGROUND/OBJECTIVES: Inflammation is often associated with chronic diseases, and numerous studies suggest that certain foods can modulate inflammatory status. This study aimed to assess the impact of intensive nutrition education on glycemic control and inflammation in patients with diabetes mellitus using the Korean food-based index of dietary inflammatory potential (FBDI). SUBJECTS/METHODS: A total of 120 patients (male: 70, 58.3%) were randomly divided into two groups of 60 each, to be given intensive nutritional education (IE) and basic nutritional education (BE), respectively. As part of the nutrition education intervention, basic diabetes-related nutrition education was provided to both groups initially. In addition, the IE was provided two face-to-face nutrition education sessions based on FBDI over six months, and text transmissions were made at least eight times. We surveyed the anthropometric measurements, biochemical indicators, inflammatory markers, and dietary intake before and after the interventions. We analyzed the effects of the intensive nutrition education using the t-test, χ² test and paired t-test. RESULTS: Of the subjects, 76.7% (46/60) of the IE and 86.7% (52/60) of the BE completed the study. The results of the paired t-test to evaluate the effectiveness of nutrition education using FBDI showed that high density lipoprotein-cholesterol increased significantly from 42.6 mg/dL before intervention to 49.2 mg/dL after intervention (P = 0.009), tumor necrosis factor-α significantly decreased from 1.25 pg/mL before intervention to 1.11 pg/mL after intervention (P =.012) in the IE. Also, glycated hemoglobin decreased from 8.0% to 7.5% in the IE but increased from 7.4% to 7.7% in the BE, and the differences between the groups were significant (P = 0.008). CONCLUSION: These findings suggest that providing intensive FBDI-based education on anti-inflammatory foods positively affected glycemic control and inflammatory status in diabetes patients. Therefore, practical dietary plans using FBDI should be considered for diabetes patients to prevent increased inflammation.

BACKGROUND/OBJECTIVES: This study explores the parental characteristics that affect the eating behaviors of preschool children. The nutrition quotient for preschool children (NQ-P) tool was applied to measure the eating behaviors of preschool children, and the relationship between parents' health beliefs and children's eating behaviors was investigated by applying the health belief model. MATERIALS/METHODS: In August 2018, a self-administered online survey was conducted on a sample of parents of children aged 3 to 5 years living in the Seoul and Gyeonggi area. A total of 248 respondents were analyzed via descriptive statistics, one-way ANOVA, Tukey's multiple comparison test, Pearson correlation analysis, and multiple regression analysis. RESULTS: The eating behaviors of preschool children significantly differed based on parents' education level and monthly income (P < 0.01). Among the factors of the health belief model, "perceived benefit" had the highest score at 4.37 points. The multiple regression analysis confirmed that parents' "self-efficacy" raised the NQ-P scores (β = 0.175, P < 0.05), balance scores (β = 0.204, P < 0.01), and environment scores of preschool children (β = 0.149, P < 0.05). The study results showed that if parents are educated on healthy eating habits and their level of self-efficacy for healthy eating practices increases, the formation of correct eating behaviors for preschool children is more likely. CONCLUSION: This study provides preliminary data to develop an education program for parents to understand proper eating behaviors for their children and may help form healthy eating habits and encourage the healthy growth of preschool children.

BACKGROUND/OBJECTIVES: A meal companion is an important social determinant of eating behaviors and is related to what and how much a person will eat within the social context. This study examined the difference in diet quality according to the type of dining companion. SUBJECTS/METHODS: This study included 15,074 adults (6,180 men and 8,894 women, ≥ 19 years) who participated in the 6th (2013-2015) Korea National Health and Nutrition Examination Survey. Korean Healthy Eating Index (KHEI) scores were calculated using the food frequency questionnaire data. Survey multivariate linear regression analysis was used to assess the association of dining companions (ordinary type, eating with family members, eating alone, and eating with others) and the total and component scores of KHEI. RESULTS: People who exclusively ate with someone other than family or exclusively ate alone had lower total KHEI scores in both men (57.23 ± 0.67, 58.56 ± 0.73 vs. 62.71 ± 0.26) and women (57.6 3±0.97, 63.89±0.58 vs. 65.79±0.22) compared to people with the ordinary type (all P < 0.05). Both men and women who ate exclusively with someone other than family had lower KHEI component scores for breakfast, whole grains, and fruit, excluding juice, compared to the ordinary type and family eating group. Compared to the eating alone group, the component scores for breakfast and whole grains were lower in the eating with others group. CONCLUSION: The diet quality differed according to the meal companion type. People who always ate with someone other than family members and men who ate alone showed lower diet quality scores than the ordinary type. More research will be needed to improve their adherence to dietary recommendations.

BACKGROUND/OBJECTIVES: With the outbreak of infectious diseases, such as coronavirus disease 2019 (COVID-19), public interest in health and safety has increased, and consequently, interests in food safety have been heightened too. The purpose of this study was to compare and analyze the involvement of various categories of consumers in food safety, the subjective evaluation of food safety in Korea, and the willingness of the consumers to pay extra for safe food according to their demographic and socioeconomic characteristics. MATERIALS/METHODS: This study used data from the 2020 Consumer Behavior Survey for Food provided by the Korea Rural Economic Institute (KREI). The subjects were 6,355 adult household members aged 19 to 75 years old. The survey was conducted from June 10th to August 21st, 2020. The data for the study were subjected to statistical analyses, including descriptive statistics, complex sample general linear model, k-means cluster, and multiple regression analyses. RESULTS: The factors affecting the willingness to pay extra for safe food were education level, occupation, monthly household income, presence of a young (teenager) household member, and the subjects' involvement in food safety. the significant factors affecting the willingness to pay extra for safe food were sex, age, and income level for the group exhibiting a low level of involvement in food safety, while education level and presence of a young household member were the statistically significant factors for the group exhibiting a high level of involvement in food safety. CONCLUSION: This study verified the differences in the factors associated with the willingness to pay extra for safe food according to the demographic and socioeconomic characteristics, involvement in food safety, subjective evaluation of food safety. This study offers practical implications to the industry and government that would help in directing strategies to strengthen safe food management.

BACKGROUND/OBJECTIVES: Despite the rapid growth of the online food delivery service market since the outbreak of coronavirus disease 2019, little research has focused on how consumers are using food delivery service and what they are concerned about when using food delivery service. Moreover, previous studies have not paid adequate attention to how these concerns are related to consumers' intention to use food delivery service. Therefore, our study examines behaviors and concerns regarding food delivery service and identifies the key factors in consumers' intention to use food delivery service. SUBJECTS/METHODS: Using data collected from 549 Korean consumers, we conducted descriptive analysis, exploratory factor analysis, and multiple regressions. RESULTS: We found that using food delivery service is not only for main meals at home or the office but also to meet a variety of dietary needs and occasions. The findings indicated that Korean consumers are most concerned about the sustainability of food delivery service, followed by health, hygiene, hedonic, and usability aspects of the service. Hygiene concerns and a hedonic aspect of the service were negatively associated with consumers' intention to use food delivery service among users, while health concerns decreased the intention of non-users. CONCLUSION: The findings have implications for practitioners and policy makers in food delivery service. To further propel market growth, they should help reduce health concerns of non-users, as well as hygiene and hedonic concerns of existing users.