A review of recent evidence of dietary protein intake and health

The Korea National Health and Nutrition Examination Survey of 2013 to 2017 reported that the average protein consumption of the Korean population is above the current recommended nutrient intake of protein proposed by the Dietary Reference Intakes for Koreans. Some health professionals and the media often advise consuming diets high in protein for promoting metabolic regulation, weight control, and muscle synthesis. However, due to lack of scientific evidence, the validity and safety of high protein consumption are yet to be fully ascertained. The present review assesses recent evidence published in 2014–2020 from human studies, focusing on adequate protein intake and protein sources for the prevention of chronic diseases, particularly metabolic disorders and sarcopenia.

2020 Korean Dietary Reference Intakes for Protein: Estimation of protein requirements and the status of dietary protein intake in the Korean population / 한국영양학회지

This article evaluated levels of Estimated Average Requirements (EARs), Reference Nutrient Intakes (RNIs), and Acceptable Macronutrient Distribution Ranges (AMDRs) of protein using the recently revised Dietary Reference Intakes (DRIs) for Koreans (2020). Dietary protein requirements are based on amounts sufficient to satisfy physiological demands to accomplish nitrogen equilibrium. The same principle was applied to estimate EARs and RNIs, for adults in DRIs conducted in 2015 and 2020 in Koreans. EAR was estimated to be 0.73 g/kg body weight/day, according to data (0.66 g/kg body weight/day) obtained using the nitrogen balance method and adjusted by efficiency of protein use (90%). RNI was calculated as EAR increased by an amount equal to twice the standard deviation of an age group so as to cover 97.5% of the group and was found to be 0.91 g/kg body weight/day. For weaned infants, children, and adolescents, growth requirement was added to estimate EAR. In particular, growth requirement was adjusted by efficiency of protein use in the revised EAR, which led to higher EARs for weaned infants, children, and adolescents of both genders as compared with 2015 DRIs. The AMDR for protein was set at 7%–20% of energy intake, which was the same as 2015 DRIs. Current, average protein intake by the Korean population is almost twice times the EAR, which suggests it might be better to increase the minimal margin for AMDR.However, it was not adjusted in this revision due to lack of evidence.

Free fatty acid-induced histone acetyltransferase activity accelerates lipid accumulation in HepG2 cells

BACKGROUND/OBJECTIVES: Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disease triggered by epigenetic alterations, including lysine acetylation at histone or non-histone proteins, affecting the stability or transcription of lipogenic genes. Although various natural dietary compounds have anti-lipogenic effects, their effects on the acetylation status and lipid metabolism in the liver have not been thoroughly investigated. MATERIALS/METHODS: Following oleic-palmitic acid (OPA)-induced lipid accumulation in HepG2 cells, the acetylation status of histone and non-histone proteins, HAT activity, and mRNA expression of representative lipogenic genes, including PPARγ, SREBP-1c, ACLY, and FASN, were evaluated. Furthermore, correlations between lipid accumulation and HAT activity for 22 representative natural food extracts (NExs) were evaluated. RESULTS: Non-histone protein acetylation increased following OPA treatment and the acetylation of histones H3K9, H4K8, and H4K16 was accelerated, accompanied by an increase in HAT activity. OPA-induced increases in the mRNA expression of lipogenic genes were down-regulated by C-646, a p300/CBP-specific inhibitor. Finally, we detected a positive correlation between HAT activity and lipid accumulation (Pearson's correlation coefficient = 0.604) using 22 NExs. CONCLUSIONS: Our results suggest that NExs have novel applications as nutraceutical agents with HAT inhibitor activity for the prevention and treatment of NAFLD.

Ethanol extract of Allium fistulosum inhibits development of non-alcoholic fatty liver disease

BACKGROUND/OBJECTIVES: Non-alcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease and is closely associated with metabolic syndrome. In the present study, we observed the effect of ethanol extract of Allium fistulosum (EAF) on NAFLD and have suggested the possibility of using EAF as a natural product for application in the development of a treatment for NAFLD. MATERIALS/METHODS: The preventive effect on hepatic lipid accumulation was estimated by using an oleic acid (OA)-induced NAFLD model in vitro and a Western diet (high-fat high-sucrose; WD)-induced obese mouse model. Animals were divided into three groups (n = 7): normal diet group (ND), WD group, and WD plus 1% EAF group. RESULTS: EAF reduced OA-stimulated lipid accumulation in HepG2 cells in the absence of cellular cytotoxicity and significantly blocked transcriptional activation of sterol regulatory element-binding protein 1 and fatty acid synthase genes. Subsequently, we investigated these effects in vivo in mice fed either ND or WD in the presence or absence of EAF supplementation. In comparison to the ND controls, the WD-fed mice exhibited increases in body weight, liver weight, epididymal fat weight, and accumulation of fat in hepatocytes, and these effects were significantly attenuated by EAF supplementation. CONCLUSIONS: Allium fistulosum attenuates the development of NAFLD, and EAF elicits anti-lipogenic activity in liver. Therefore, EAF represents a promising candidate for use in the development of novel therapeutic drugs or drug combinations for the prevention and treatment of NAFLD.

Dietary sugar intake and dietary behaviors in Korea: a pooled study of 2,599 children and adolescents aged 9-14 years

BACKGROUND/OBJECTIVES: Dietary sugar intake, particularly added sugar and sugar-sweetened beverages, has received worldwide attention recently. Investigation of dietary behaviors may facilitate understanding of dietary sugar intakes of children and adolescents. However, the relationship between dietary sugar intake and dietary behaviors in the Korean population has not been investigated. Thus, this study aimed to estimate dietary sugar intake and food sources according to sex as well as examine the relationship of dietary sugar intake with frequent snacking and dietary patterns among Korean children and adolescents. SUBJECTS/METHODS: We pooled data from five studies involving Korean children and adolescents conducted from 2002 to 2011. A total of 2,599 subjects aged 9-14 years were included in this study. Each subject completed more than 3 days of dietary records. RESULTS: Mean daily total sugar intake was 46.6 g for boys and 54.3 g for girls. Compared with boys, girls showed higher sugar intakes from fruits (7.5 g for boys and 8.8 g for girls; P = 0.0081) and processed foods (27.9 g for boys and 34.9 g for girls; P < 0.0001). On average, 95.4% of boys and 98.8% of girls consumed snacks during the study period, and total sugar intake showed a significantly increasing trend with increasing energy intake from snacks (P < 0.0001 for both sexes). Two dietary patterns were identified by cluster analysis: Traditional and Westernized patterns. Total sugar intake was higher in the Westernized pattern (56.2 g for boys and 57.2 g for girls) than in the Traditional pattern (46.5 g for boys and 46.3 g for girls). CONCLUSIONS: These results suggest that multilateral and practical development of a nutrition education and intervention program that considers dietary behaviors as well as absolute sugar intake is required to prevent excessive sugar intake in Korean children and adolescents.

Developing and testing the reliability of a measurement tool for an urban area food environment in Korea: Focusing on food stores / 한국영양학회지

PURPOSE: The aim of this study was to develop a reliable measurement tool to assess the urban food environment, particularly focusing on food stores in Korea. METHODS: The items for the measurement tool were selected through systematic literature reviews and adjusted to the Korean food environment. A total of 25 food stores in an urban area were recruited for the pilot test to evaluate the time required for completion of the survey, ease of response, willingness to participate, difficulties in conducting the survey, and appropriateness, and 34 food stores were recruited for assessment of the reliability of the tool using percent agreement and kappa value. RESULTS: The measurement tool is composed of questions regarding food store characteristics, accessibility, and food availability. On average, 26 minutes was required to survey a single food store, and the subjects and interviewers answered that the process was not difficult for the survey. The percent agreement for the inter-rater and test-retest reliability ranged from 93.9~98.8% and 91.9~97.9, respectively. The kappa values ranged from 0.78 to 0.97, which was very high. Percent agreement and kappa value of food with healthy option were lower than those of the general food in the inter-rater reliability (p = 0.0027, p = 0.0095 respectively) as well as in the test-retest reliability (p = 0.0081, p = 0.0290, respectively), although they were still high enough (86.4~98.0% for percent agreement, 0.64~0.96 for kappa value). CONCLUSION: The newly developed measurement tool for assessment of food store environment appears to be feasible and reliable; therefore, it can be applied to research on the association between food environment and dietary behaviors as well as health outcomes.

Nicolau Syndrome following Diclofenac Injection in an Emergency Department

Nicolau syndrome is a rare adverse reaction at the site of an intramuscular injection, and is characterized by severe pain immediately after the injection and rapid development of distinct skin lesions. As this syndrome is rare, it may be overlooked at the early clinical phase and subsequently, clinical outcomes may be worse due to delay in treatment. We report on a female who developed Nicolau syndrome following intramuscular diclofenac injection, which required surgical reconstruction. Understanding the characteristics of Nicolau syndrome and careful surveillance for relevant clinical features may help physicians to more quickly diagnose and treat this condition.