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Randomized Controlled Trial
. 2021 May 11;151(5):1190-1196.
doi: 10.1093/jn/nxaa401.

Metabolic Evaluation of the Dietary Guidelines' Ounce Equivalents of Protein Food Sources in Young Adults: A Randomized Controlled Trial

Sanghee Park  1   2 , David D Church  1 , Scott E Schutzler  1 , Gohar Azhar  1 , Il-Young Kim  2 , Arny A Ferrando  1 , Robert R Wolfe  1
Affiliations
Randomized Controlled Trial

Metabolic Evaluation of the Dietary Guidelines' Ounce Equivalents of Protein Food Sources in Young Adults: A Randomized Controlled Trial

Sanghee Park et al. J Nutr. .

Abstract

Background: The Dietary Guidelines for Americans (DGAs) published an "ounce equivalents" recommendation to help consumers meet protein requirements with a variety of protein food sources. However, the metabolic equivalency of these varied protein food sources has not been established.

Objective: We have investigated the hypothesis that the anabolic responses to consumption of ounce equivalents of protein food sources would be directly related to the essential amino acid (EAA) content of the protein food source.

Methods: Following 3 d of dietary control, a total of 56 healthy young adults underwent an 8.5-h metabolic study using stable isotope tracer methodology. The changes from baseline following consumption of 1 of 7 different protein food sources were compared with the baseline value for that individual (n = 8 per group).

Results: Consumption of ounce equivalents of animal-based protein food sources (beef sirloin, pork loin, eggs) resulted in a greater gain in whole-body net protein balance above baseline than the ounce equivalents of plant-based protein food sources (tofu, kidney beans, peanut butter, mixed nuts; P < 0.01). The improvement in whole-body net protein balance was due to an increase in protein synthesis (P < 0.05) with all the animal protein sources, whereas the egg and pork groups also suppressed protein breakdown compared with the plant protein sources (P < 0.01). The magnitude of the whole-body net balance (anabolic) response was correlated with the EAA content of the protein food source (P < 0.001).

Conclusion: The "ounce equivalents" of protein food sources as expressed in the DGAs are not metabolically equivalent in young healthy individuals. The magnitude of anabolic response to dietary proteins should be considered as the DGAs develop approaches to establish healthy eating patterns.

Keywords: anabolic response; essential amino acids; net protein balance; ounce equivalent; stable isotope tracers.

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Figures

FIGURE 1
FIGURE 1
Experimental protocol.
FIGURE 2
FIGURE 2
Changes in whole-body protein kinetics [net protein balance (NB), protein synthesis (PS), and protein breakdown (PB)] over postabsorptive values following protein meal consumption. One-factor repeated-measures ANOVA indicated a main effect of ounce-equivalent food source for NB, PS, and PB (P < 0.001). Groups not sharing the same letter are significantly different. Values (n = 8 per ounce-equivalent food source) are expressed as means ± SEMs.
FIGURE 3
FIGURE 3
Whole-body net protein balance normalized by caloric intake. One-factor repeated-measures ANOVA indicated a main treatment effect in net balance normalized by caloric intake (P < 0.05). Groups not sharing the same letter are significantly different. Values (n = 8 per ounce-equivalent food source) are expressed as means ± SEMs.
FIGURE 4
FIGURE 4
Plasma essential amino acid (EAA) temporal and AUC responses following protein meal intake. A factor-way ANOVA indicated a significant difference in the plasma EAA AUC response following ounce-equivalent food source ingestion (P < 0.01). Groups not sharing the same letter are significantly different. Values (n = 8 per ounce-equivalent food source) are expressed as means ± SEMs.
FIGURE 5
FIGURE 5
Relations between total essential amino acids (EAAs) per serving and the change in whole-body net balance (left panel) and between plasma EAA AUC over fasting value (right panel). Partial correlation coefficient analysis controlled for source (plant compared with animal) revealed significant associations between total EAA serving and changes in whole-body net balance (r = 0.44, P = 0.001) and plasma EAA AUC (r = 0.51. P < 0.001). n= 8 per ounce-equivalent food source.
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References

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