Low Amino Acid Score of Breakfast is Associated with the Incidence of Cognitive Impairment in Older Japanese Adults: A Community-Based Longitudinal Study.

BACKGROUND: The protein digestibility-corrected amino acid score (PDCAAS) represents the degree of utilizable dietary protein, namely the protein quality. The PDCAAS of a diet is required to be evaluated on a meal-by-meal basis, as food digestion and absorption occur with each meal intake. Although a positive association between protein intake and cognitive function has been reported, no study has investigated the association between PDCAAS of a diet and cognitive function. OBJECTIVES: To investigate the relationship between PDCAAS of a diet and cognitive impairment in older adults. DESIGN: Longitudinal epidemiological study. SETTING: Community-based setting. PARTICIPANTS: We analyzed 541 community-dwellers who participated in both baseline and follow-up survey. They were 60-83 years of age without cognitive impairment at baseline. MEASUREMENTS: Cognitive impairment was defined as a Mini-Mental State Examination (MMSE) score ≤27. Individual PDCAASs were calculated for each of three regular meals from the 3-day dietary records at baseline. Participants were classified into two groups according to the sex-specific tertiles (T1-T3) of the PDCAAS for each meal (i.e., T1 as the low score group and T2-T3 as the medium and high score group). The dependent variable was cognitive impairment observed after 4 years, and the explanatory variables were the PDCAAS groups for each meal (the medium and high group as the reference) and covariates (sex, age, body mass index, education, depressive symptoms, medical history, protein intake at each meal, and the MMSE score at baseline). Multivariable logistic regression analysis was performed to evaluate the low PDCAAS group for cognitive impairment after 4 years. RESULTS: A significant association was observed only between a low PDCAAS of breakfast and the incidence of cognitive impairment (the adjusted odds ratios [95% confidence intervals] of low PDCAAS for cognitive impairment for breakfast, lunch, and dinner were 1.58 [1.00-2.50], 0.85 [0.54-1.34], and 1.08 [0.71-1.65], respectively). CONCLUSION: A lower PDCAAS of breakfast, i.e., a diet with poor quality of protein, was associated with the incidence of cognitive impairment in older adults of the community.

Weight loss is associated with plasma free amino acid alterations in subjects with metabolic syndrome.

OBJECTIVES: The prevalence of metabolic syndrome is increasing worldwide, especially in Asian populations. Early detection and effective intervention are vital. Plasma free amino acid profile is a potential biomarker for the early detection for lifestyle-related diseases. However, little is known about whether the altered plasma free amino acid profiles in subjects with metabolic syndrome are related to the effectiveness of dietary and exercise interventions. METHODS: Eighty-five Japanese subjects who fulfilled the Japanese diagnostic criteria for metabolic syndrome were enrolled in a 3-month diet and exercise intervention. The plasma free amino acid concentrations and metabolic variables were measured, and the relationships between plasma free amino acid profiles, metabolic variables and the extent of body weight reduction were investigated. Those who lost more than 3% of body weight were compared with those who lost less than 3%. RESULTS: Baseline levels of most amino acids in the subset that went on to lose <3% body weight were markedly lower compared with the counterpart, although both groups showed similar proportional pattern of plasma amino acid profiles. The weight loss induced by the diet and exercise intervention normalized plasma free amino acid profiles. For those with a high degree of weight loss, those changes were also associated with improvement in blood pressure, triglyceride and hemoglobin A1c levels. CONCLUSIONS: These data suggest that among Japanese adults meeting the criteria for metabolic syndrome, baseline plasma free amino acid profiles may differ in ways that predict who will be more vs less beneficially responsive to a standard diet and exercise program. Plasma free amino acid profiles may also be useful as markers for monitoring the risks of developing lifestyle-related diseases and measuring improvement in physiological states.

Plasma amino acid profiles are associated with insulin, C-peptide and adiponectin levels in type 2 diabetic patients.

OBJECTIVES: Plasma-free amino acid (PFAA) profiles have been associated with a future risk of developing diabetes or cardiovascular disease in nondiabetic subjects. These PFAA alterations might predominantly result from the metabolic shift caused by insulin resistance and visceral fat deposition. The variety of PFAA profiles within diabetic subjects is not well researched. In this study, we focused on type 2 diabetic subjects and examined the association between PFAA profiles and insulin- and glucose-related variables. METHODS: Fifty-one Japanese subjects diagnosed with type 2 diabetes were recruited from an outpatient clinic. The plasma concentrations of 21 amino acids; glucose-related markers including glucose, hemoglobin A1c (HbA1c), glycoalbumin and 1,5-anhydroglucitol; insulin-related markers including insulin, C-peptide, and the homeostasis model assessment of insulin resistance; and adipocytokines including adiponectin and leptin were determined. The association of PFAA and other metabolic profiles were analyzed, and stratified analyses of the PFAAs and clinical characteristics were performed according to the fasting plasma insulin and HbA1c levels. In addition, the PFAA indices that correlate to visceral fat obesity were evaluated. RESULTS: Although strong correlations between PFAAs and glucose-related markers were not observed, several amino acids (branched-chain amino acids, tryptophan, alanine, tyrosine, glutamate and proline) and PFAA indices that evaluate visceral obesity were highly correlated with insulin-related markers and adiponectin (P<0.001). In the group of diabetic patients with hyperinsulinemia, the amino acid levels were significantly increased, which generally demonstrated good concordance with insulin-related markers and adiponectin levels. CONCLUSIONS: The PFAA profiles in diabetic patients were strongly associated with hyperinsulinemia and hypoadiponectinemia, which might become risk evaluation factors for the development of cardiovascular diseases.