Amino Acid Intake and Conformance With the Dietary Reference Intakes in the United States: Analysis of the National Health and Nutrition Examination Survey, 2001-2018.

BACKGROUND: The lack of complete amino acid composition data in food composition databases has made determining population-wide amino acid intake difficult. OBJECTIVES: This cross-sectional study characterizes habitual intakes of each amino acid and adherence to dietary requirements for each essential amino acid (EAA) in the US population. METHODS: Food and Nutrient Database for Dietary Studies ingredient codes with missing amino acid composition data were matched to similar ingredients with available data so that amino acid composition could be determined for 100% of foods reported in the dietary intake assessment component of NHANES. Amino acid intakes during NHANES 2001-2018 (n = 72,831; ≥2 y) were calculated as relative (mg·kg of ideal body weight-1·d-1) intakes. Data from NHANES 2011-2018 were used to determine the percentage of population consuming less than that recommended by the DRIs for each EAA by age, sex, and race/ethnicity. RESULTS: Relative intakes of EAAs and NEAAs were greatest in those 2-3 y and lowest in older individuals (≥71 y or ≥80 y). In females aged 2-18 y, relative intakes of EAAs were lowest in non-Hispanic White (NHW; histidine, lysine, threonine, methionine, and cysteine) and non-Hispanic Black (NHB; valine, isoleucine, leucine, phenylalanine, tryptophan, and tyrosine) populations and highest in the Asian population. In females aged ≥19 y, relative intakes were lowest in NHW (lysine and methionine only) and NHB populations and highest in the Asian population. In males aged 2-18 y, relative intakes of EAAs were lowest in the NHB population and highest in the Asian population. In males ≥19 y, relative intakes were lowest in NHB and NHW (lysine only) populations and highest in the Hispanic population. Less than 1% of individuals aged ≥19 y did not meet the Estimated Average Requirements for each EAA. CONCLUSIONS: EAA intakes in the US population exceed recommended minimum population requirements. Future studies can use the method described here to quantify amino acid intake and examine relationships with health and disease.

Early time-restricted eating improves markers of cardiometabolic health but has no impact on intestinal nutrient absorption in healthy adults.

Early time-restricted eating (eTRE) improves aspects of cardiometabolic health. Although the circadian system appears to regulate nutrient absorption, little is known about the effects of eTRE on intestinal absorption. In this randomized crossover trial, 16 healthy adults follow a controlled, weight maintenance diet for 9 days, consuming all calories between 0800 and 1400 (eTRE schedule) or 0800 and 2000 (control schedule). We measure the energy content of the diet, stool, and urine with bomb calorimetry and calculate intestinal energy absorption. The eTRE schedule is more effective than the control eating schedule for improving markers of cardiometabolic health, including 24-h mean glucose concentrations and glycemic variability, assessed as the mean amplitude of glycemic excursions. However, eTRE has no effect on intestinal energy and macronutrient absorption, gastrointestinal transit time, colonic hydrogen gas production, or stool microbial composition, suggesting eTRE does not impact gastrointestinal function. This trial is registered (ClinicalTrials.gov: NCT04877262).

Associations between Essential Amino Acid Intake and Functional Health Outcomes in Older Adults: Analysis of the National Health and Nutrition Examination Survey, 2001-2018.

Background: The relationships between habitual essential amino acid (EAA) intake and body composition, muscle strength, and physical function in older US adults are not well defined. Objectives: This cross-sectional study evaluated associations between usual EAA intakes and body composition, muscle strength, and physical function in US adults ≥65 y. Methods: The Food and Nutrient Database for Dietary Studies (FNDDS) 2001-2018 was linked to the US Department of Agriculture Standard Reference database to access existing amino acid composition data for FNDDS ingredients. FNDDS ingredients without existing amino acid composition data were matched to similar ingredient codes with available data. Usual EAA, leucine, lysine, and sulfur-containing amino acid (SAA; methionine + cysteine) intakes (g/d) from National Health and Nutrition Examination Survey 2001-2018 were calculated for individuals ≥65 y (n = 10,843). Dependent variables included muscle strength measured by isometric grip test, body mass index (BMI), waist circumference, dual-energy X-ray absorptiometry-measured appendicular lean mass and whole-body fat mass, and self-reported physical function (that is, tasks of daily living). Regression analyses were used to determine covariate-adjusted relationships between EAA, leucine, lysine, and SAA intake and functional health outcomes. P < 0.0013 was considered significant. Results: EAA, leucine, lysine, and SAA intakes, covaried with physical activity level and usual protein intake, were not associated with muscle strength or self-reported physical function in males or females or with body composition in males. EAA intakes were positively associated with waist circumference in females (ß ± SEM, 2.1 ± 0.6 cm, P = 0.0007). Lysine intakes were positively associated with BMI (3.0 ± 0.7 kg/m2, P < 0.0001) and waist circumference (7.0 ± 1.7 cm, P = 0.0001) in females. Conclusions: Habitual EAA, leucine, lysine, and SAA intakes, covaried with physical activity level and usual protein intake, were not associated with lean mass, muscle strength, or physical function in adults ≥65 y. However, EAA intakes, particularly lysine, were positively associated with measures of adiposity in older females.This trial was registered with the Open Science Framework (https://doi.org/10.17605/OSF.IO/25V63) as osf.io/25v63).