Plasma Amino Acid Appearance and Status of Appetite Following a Single Meal of Red Meat or a Plant-Based Meat Analog: A Randomized Crossover Clinical Trial

Abstract

Background: Red meat is a nutrient-dense food and a dietary staple. A new generation of plant-based meat analogs (PBMAs) have been designed to mimic the experience of eating meat, but there is limited evidence about their digestive efficacy and nutritional quality.

Objectives: We compared the postprandial digestive response of a single meal containing meat commercially raised in New Zealand, including lamb, on-farm pasture-raised beef (Pasture), or grain-finished beef (Grain) with a PBMA (Beyond Burger; Beyond Meat) sold through consumer retail. The primary outcome was the appearance of amino acids in plasma. Secondary outcomes included glucose and insulin, appetite assessment, and anthropometry.

Methods: Thirty healthy men (20-34 y) participated in a double-blinded randomized crossover trial. Each consumed 1 of the 4 test meals on 4 occasions separated by a washout period of at least 1 wk, following an overnight fast. The meal was a burrito-style wrap containing meat or PBMAs, vegetables, salsa, and seasonings in a flour tortilla. The amount of Pasture, Grain, Lamb, or BB was 220 g raw (∼160 g cooked). Venous blood samples were collected over 4 h. Appetite and hunger status was scored with visual analog scales.

Results: Pre-meal amino acid concentrations in plasma did not differ by group (P > 0.9), although several nonessential amino acids differed strongly according to participant BMI. Postprandial amino acids peaked at 2-3 h in all groups. The BB meal produced significantly lower plasma concentrations of total, essential, branched-chain, and non-proteogenic amino acids than the Lamb, Pasture, or Grain meals, based on AUC. There were no significant differences between meal groups in scores for hunger, fullness, or cravings.

Conclusions: Red meat meals exhibited greater bioavailability of amino acids compared with the PBMA (BB). Pasture versus Grain origins of the beef had little influence on participants' responses. This trial was registered at ClinicalTrials.gov as NCT04545398.

Keywords: amino acid; meat alternative; plant-based meat analog; protein; red meat.

© The Author(s) 2022. Published by Oxford University Press on behalf of the American Society for Nutrition.

Figures

FIGURE 1

Flowchart of the study participant recruitment. The test meal groups contained either pasture-raised beef (Pasture), grain-finished beef (Grain), pasture-raised lamb (Lamb), or Beyond Burger (BB; Beyond Meat).

FIGURE 2

Postprandial plasma concentrations of pooled amino acids. (A) TAAs. (B) BCAAs. (C) EAAs. (D) NEAAs. (E) NPAAs. Markers indicate means ± SEMs (n = 29); note the difference in vertical scales. The test meal groups contained either pasture-raised beef (Pasture), grain-finished beef (Grain), pasture-raised lamb (Lamb), or Beyond Burger (BB; Beyond Meat). A significant effect of time was observed for all pooled classes, and interactions with meal groups occurred for TAAs, BCAAs, EAAs, and NPAAs. Post hoc pairwise comparisons by Tukey's test (P < 0.05) are as follows: aBetween Pasture and Grain, bBetween Pasture and Lamb, cBetween Pasture and BB, dBetween Grain and Lamb, eBetween Grain and BB, fBetween Lamb and BB. BCAA, branched-chain amino acid; EAA, essential amino acid; NEAA, nonessential amino acid; NPAA, non-proteogenic amino acid; TAA, total amino acid.

FIGURE 3

Postprandial plasma concentrations of (A) glucose (mmol/L, n = 29); (B) insulin (µU/mL, n = 29), (C) separating glucose (mmol/L) responses and (D) insulin (µU/mL) according to normal weight [BMI (kg/m2) <25; black lines, n = 19] and overweight (BMI >25; red lines, n = 10) BMI status of participants. The test meal groups contained either pasture-raised beef (Pasture), grain-finished beef (Grain), pasture-raised lamb (Lamb), or Beyond Burger (BB; Beyond Meat). There was no evidence of a group effect in either metabolite, as the group × time interactions were not significant. Markers indicate means ± SEMs.

FIGURE 4

Self-assessed scoring of appetite status anchored at 0 “not at all” and 100 “a lot.” (A) Hungriness score in response to “How hungry do you feel?” (B) Fullness score in response to “How full do you feel?” (C) Satisfaction score in response to “How satisfied do you feel?” (D) Appetite score in response to “How much do you think you can eat?” Markers indicate means ± SEMs (n = 29). The test meal groups contained either pasture-raised beef (Pasture), grain-finished beef (Grain), pasture-raised lamb (Lamb), or Beyond Burger (BB; Beyond Meat). There was an effect of time on all qualities of status, but no group × time interactions.