The Study
Chronic dietary exposure to branched chain amino acids impairs glucose disposal in vegans but not in omnivores
This study watched what happened when 16 people took extra amino acid pills for three months. It saw that vegans' bodies handled sugar differently afterward, but omnivores didn't change. That doesn't mean the pills caused the change — it just means they happened together in this small group.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Vegans naturally have better blood sugar control than meat-eaters. When they took big BCAA supplements for 3 months, their blood sugar control got worse. Meat-eaters didn’t get worse — their bodies just stored more fat instead.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 551 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — a 1.64 drop in insulin sensitivity is clinically meaningful and could increase diabetes risk over time, especially in people eating plant-based diets who aren’t used to high amino acid intake.
- 2Vegans: insulin sensitivity dropped by 1.64 mg/kg/min.
- 3Meat-eaters: no drop in insulin sensitivity, but fat-storage genes went up.
- 4Both groups: muscles worked harder.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
European Journal of Clinical Nutrition
Year
2017
Authors
J. Gojda, L. Rossmeislová, R. Straková, J. Tumova, M. Elkalaf, M. Jaček, P. Tůma, J. Potočková, E. Krauzová, P. Waldauf, J. Trnka, V. Štich, M. Andel
Related Content
Claims (6)
Skeletal muscle controls how the body removes glucose from the blood and helps maintain normal insulin sensitivity.
In people who eat meat and dairy, long-term supplementation with branched-chain amino acids increases the activity of genes that promote fat storage in under-the-skin fat tissue, and this is associated with reduced emphasis on glucose metabolism improvements.
In healthy vegans, taking 15–20 grams of branched-chain amino acids daily for three months lowers insulin sensitivity by about 1.64 mg/kg/min, as measured by glucose infusion rate during a clamp test. This reduction does not occur in omnivores with similar baseline traits, indicating that prior dietary patterns influence how the body responds to amino acid supplementation.
People who follow a vegan diet and those who eat animal products respond differently to branched-chain amino acid supplements: vegans show lower insulin sensitivity, and omnivores show higher fat production in adipose tissue, reflecting differences shaped by long-term dietary patterns.
People who follow a long-term plant-based diet show higher insulin sensitivity than people who eat animal products, as measured by how efficiently their bodies use glucose during a controlled metabolic test.
Long-term supplementation with branched-chain amino acids increases the activity of the mitochondrial respiratory chain in skeletal muscle, regardless of whether a person follows a vegan or omnivorous diet.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.