Long-chain omega-3 fatty acids regulate bovine whole-body protein metabolism by promoting muscle insulin signalling to the Akt-mTOR-S6K1 pathway and insulin sensitivity.
Level 5 - mechanism / opinion, no new human data
Animal experimental study (bovine model)
PubMed 17158167 · doi:10.1113/jphysiol.2006.121079
What was done
Researchers evaluated the effect of long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) on protein metabolism and insulin signaling in growing steers. The study used a switchback design consisting of three 5-week experimental periods in six steers comparing continuous abomasal infusion of LCn-3PUFA-rich menhaden oil to an iso-energetic control oil mixture. Hyperinsulinemic clamp and muscle insulin-signaling measurements were supplemented with data from a second cohort of six steers (total n = 12).
What was found
Enteral LCn-3PUFA significantly increased insulin-stimulated whole-body amino acid disposal from 152 to 308 µmol kg⁻¹ h⁻¹ (P = 0.006). Chronic adaptation to LCn-3PUFA in the fed steady-state increased activation of the muscle Akt-mTOR-S6K1 signaling pathway (P < 0.05). In addition, whole-body total phenylalanine flux decreased from 87 to 67 µmol kg⁻¹ h⁻¹ (P = 0.04), and oxidative metabolism was reduced (P = 0.05).
Why it matters
This study provides mechanistic evidence in a large animal model that omega-3 fatty acids can directly enhance muscle insulin sensitivity and stimulate downstream anabolic signaling to improve protein utilization.
Limits
The study was conducted exclusively in young, growing cattle using direct abomasal infusion rather than standard oral ingestion, limiting direct translation to human clinical contexts. The sample size was small (total n = 12 across two cohorts), and long-term functional outcomes on muscle mass preservation were not evaluated.
Cited by
- supports A study out of Laval demonstrated that infusing growing steers with omega-3 fatty acids altered whole-body protein balance.
- supports In animal and cell studies, as well as Bettina Mittendorfer's human studies, omega-3 potentiation of muscle protein synthesis is associated with activation of the mTOR-p70S6K signaling pathway.