Frailty is a common clinical syndrome in older adults that increases the risk for poor health outcomes including falls, disability, hospitalization, and mortality. Previous research showed increased protein needs and reduced anabolic response to meals in older adults, indicating the need for proteins with a high anabolic capacity to prevent and attenuate physical and cognitive health decline throughout the frailty cycle. Recently, more people have chosen to eliminate animal (i.e., beef) products from their diets which is concerning because of beef's anabolic properties due to high essential amino acid (EAA) levels and many other positive health effects. The Researchers' recently developed stable isotope amino acid pulse method enables measurement of the true intracellular anabolic response to a meal and bioavailability of food-derived amino acids. The research objective is to examine differences in the anabolic response and bioavailability of individual EAA and non-essential amino acids (NEAA) in beef as compared to plant protein in older adults with and without (pre-)frailty.
Age 65-95 years old
Ability to walk, sit down, and stand up (independently or with walking assistance device)
No recent use (< 4 weeks prior to start of the study) of dietary supplements and medication influencing protein and amino acid metabolism (e.g., antibiotics, oral corticosteroids)
Willingness to lay supine in bed for up to 6 hours
Presence of malnutrition (BMI < 17 kg/m2), 2). BMI >35 kg/m2 to avoid weight-related metabolic disturbances,
Established diagnosis and active treatment of chronic disease: Insulin-dependent diabetes mellitus, active malignancy, heart disease, kidney disease, liver disease, HIV/AIDS, Asthma (moderate to severe), Hep (A, B, or C)
History of untreated metabolic disease including hepatic or renal disorder
Presence of fever within the last 3 days
Crossover
Beef
Other interventionBeef, ground, 93% lean meat / 7% fat, patty, cooked, broiled: 100g = 26.2 g protein
Tofu
Other interventionFried tofu: 100g = 18.8 g protein
Placebo
Other interventionwater (to correct the anabolic data obtained after intake of the proteins for baseline (postabsorptive) values
Protein and amino acid synthesis capacity of beef and soy protein in older adults measured by the use of stable isotope tracers
A novel stable isotope technique will be used to assess simultaneously the anabolic response and whole body production rates of a variety of amino acids to intake of both dietary proteins in sarcopenic older participants. The samples will be stored in laboratory freezers and the amino acid isotope enrichments and concentrations analyzed by Liquid Chromatography with tandem mass spectrometry (LC-MS/MS). The researchers will then conduct LC-MS/MS analysis, peak integration, calculation of amino acid concentrations and whole body productions from raw data.
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