Food ingestion in an upright sitting position increases postprandial amino acid availability when compared with food ingestion in a lying down position.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 28212491 · doi:10.1139/apnm-2016-0522
What was done
In a crossover trial, 8 young males (age 26 ± 1 years; BMI 24.0 ± 0.9 kg·m⁻²) ingested 20 g of intrinsically L-[1-¹³C]-phenylalanine-labeled milk protein combined with 1.5 g paracetamol while in an upright sitting position or a supine lying position. Blood samples were collected over a 5-hour postprandial period to assess gastric emptying rates (plasma paracetamol) and dietary protein digestion and amino acid absorption kinetics (plasma amino acid concentrations and L-[1-¹³C]-phenylalanine enrichments).
What was found
- Peak plasma leucine concentrations were significantly higher when sitting upright compared to lying supine: 213 ± 15 vs 193 ± 12 μmol·L⁻¹ (P < 0.05). - Overall leucine response showed a trend toward an increase in the sitting position: 13,989 ± 720 vs 11,875 ± 1073 AU (P = 0.05). - Peak plasma paracetamol concentrations were higher in the sitting versus lying position: 11.6 ± 0.5 vs 9.3 ± 0.6 mg·L⁻¹ (P < 0.05).
Why it matters
Body position during feeding modulates digestion and absorption kinetics, showing that an upright posture accelerates gastric emptying and increases systemic amino acid availability. This has implications for nutritional support strategies in hospitalized or bedridden individuals.
Limits
The study had a very small sample size (n = 8) and was restricted entirely to young, healthy males. Muscle protein synthesis was not directly measured, and the study evaluated only a single dose of liquid milk protein.
Cited by
- partial Consuming food while sitting upright stimulates gastric emptying, leading to faster circulating amino acid release and greater muscle protein synthesis stimulation compared to eating while lying down.