The aim of this study was to develop a database to identify dietary amino acid intake levels, and to determine whether any amino acid groups were independently correlated with skeletal muscle mass index (SMI). We used data from the Korea National Health and Nutrition Examination Survey 2008–2011, and a total of 3292 participants aged 50–64 years were included in the analysis. Dietary data were obtained using the 24 h recall method. Data regarding dietary amino acid intake was assessed using the computer-aided nutritional analysis program 4.0 published by the Korean Nutrition Society. Multivariate linear regression analysis was used to identify independent correlates of SMI. The major food group that contributed the highest essential amino acid intake was grain and grain products (histidine 25.5%, isoleucine 43.9%, leucine 44.2%, methionine 31.0%, phenylalanine 44.8%, tryptophan 26.4%, and valine 50.8%). Higher SMI was independently associated with sex (men), lower age and body mass index, higher levels of physical activity, and a higher intake of energy and branched-chain amino acids. These results are expected to be used as a basis for developing dietary amino acid intake guidelines for Koreans.

Sarcopenia is a disease of old age characterized by decreased muscle mass and strength. Branched-chain amino acids (BCAAs) promote muscle mass synthesis and increase muscle strength. We aimed to develop a dietary amino acid database and to examine the association between BCAA intake and handgrip strength in Korean older adults. Data from the Korea National Health and Nutrition Examination Survey 2014–2018 were used. Overall, 4852 participants aged ≥65 years were included in the study. Demographic, lifestyle, and health data were obtained through interviews and questionnaires. The 24-h recall method was used to assess dietary intake. An amino acid database was established using the 9th revision of the Korean Standard Food Composition Table. The mean handgrip strength was estimated from triplicate measurements obtained using the dominant hand. Multivariable linear regression analysis was performed to assess the association between BCAA intake and handgrip strength. Grains greatly contributed to amino acid intake; however, a significant negative association was observed between handgrip strength and increased BCAA intake through grains. In the fully adjusted model, leucine intake and handgrip strength showed a positive association. Thus, consuming BCAAs (especially leucine) via a variety of food sources can help maintain muscle health in older people.

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BACKGROUND/OBJECTIVES The branched-chain amino acids (BCAA), including isoleucine, leucine, and valine, promote muscle protein synthesis. However, obesity may interfere with protein synthesis by dysregulating mitochondrial function in the muscles. This study aimed to examine the association between dietary intake levels of BCAA and skeletal muscle mass index (SMI) in middle-aged participants, and the effect of obesity/abdominal obesity on this association. SUBJECTS/METHODS The data of 3,966 men and women aged 50–64 years who participated in the 2008–2011 Korea National Health and Nutrition Examination Survey were analyzed. Intake levels of energy-adjusted dietary amino acids were obtained using a 24-hour dietary recall. SMI was calculated by dividing the appendicular skeletal muscle mass by body weight (kg) and multiplying the result by 100%. Multivariable general linear models were used to analyze the association of dietary BCAA intake levels with SMI. RESULTS The beneficial effects of energy-adjusted dietary BCAA intakes on SMI were greater in the non-obesity/non-abdominal obesity groups; however, no significant associations were observed in the obesity/abdominal obesity groups ( P > 0.05). CONCLUSIONS Healthy weight and sufficient intake of dietary BCAA are recommended to maintain muscle mass.

BACKGROUND/OBJECTIVES This study aimed to analyze the association between dietary omega-3 fatty acid intake and depression in postmenopausal women using data from the Korea National Health and Nutrition Examination Survey (KNHANES) VI. SUBJECTS/METHODS The KNHANES is a cross-sectional nationwide health and nutrition survey. Dietary data, including omega-3 fatty acids, were assessed using the 24-h recall method. Depression was evaluated using a survey questionnaire. The association between dietary omega-3 fatty acids and depression was evaluated using multivariate logistic regression analysis. Depression, according to the dietary omega-3 fatty acid intake, was expressed as the odds ratio (OR) with a 95% confidence interval (CI). A total of 4,150 postmenopausal women were included in the analysis. RESULTS In the fully-adjusted model, the group with the highest dietary omega-3 fatty acid intake significantly showed lower prevalence of depression than the group with the lowest intake (OR, 0.52; 95% CI, 0.33–0.83); a significant linear trend was detected ( P for trend = 0.04). According to the dose-response analysis using cubic restricted spline regression, this association was linear and monotonic ( P for non-linearity = 0.32). CONCLUSIONS In this study, the dietary omega-3 fatty acid intake in postmenopausal women was inversely proportional to depression in a dose-response manner. Large cohort studies are needed to verify the causality between omega-3 fatty acids and depression in Korean postmenopausal women.