Fishing for Muscle: Cod Protein Promotes Muscle Repair After Injury More than Casein or Peanut Protein
|Image 1: There are obviously more nutritionally valuable parts to cod than just its liver.
COD - Canned or dried? Probably doesn't matter as long as you eat it.
In a recently published paper on yet another rodent protein feeding trial (Dort. 2012), Junio Dort and his colleagues from the Laval University and the Research Center of CHUQ, CHUL in Quebec, Canada, report that the artificially injured tibialis muscle of rodents that were kept on cod-protein based diets for 21-days healed significantly faster than the skeletal muscle of the peanut or casein protein control groups.
|Figure 1: Amino acid profile of casein, peanut and cod protein source on which the otherwise identical rodent diets were based (based on Dort. 2012)
118 neutrophils and still counting: Cod protein (not oil, in this case) tames the inflammation
In order to assess how peanut, casein and cod-based diets would modulate the rodents' response to muscular injury the animals were treated with bupivacaine, a substance that is myotoxic ("kills" muscle cells, but - and this is a specialty of bupicacaine - not satellite cells) at higher doses (here 100µL). The drug was injected into one of the animals' tibialis muscles, while the contra-lateral side was sham-injected (saline injection) to serve as a control. At days 3, 14, and 24 post-injury, both the injured and sham-injected tibialis muscles were "collected" (8 animals per dietary group) and the neutrophil count, and macrophage infiltration - both measures of ongoing inflammation and thusly incomplete healing subsequent to prior muscle damage - were assessed.
|Figure 2: Neutrophil count and EDI+ macrophage count in bupivacaine injected tibialis muscle 3 and 14 days and 14 and 24 days after the injection; data expressed relative to sham control (data calculated based on Dort. 2012)
The anti-inflammatory effects of cod protein reach beyond skeletal muscle
Though muscle is, as my friend Carl Lanore likes to say, "metabolic currency" and it's protection and repair should be on everyone's, man and women top list of health priorities, the benefits of cod protein extend beyond skeletal muscle. A brief review of the literature revealed among others ...
- increases in HDL, decreasse in VLDL with cod over casein and soy (Jacques. 1995)
- restoration of GLUT-4 activity in skeletal muscle of HFD obese rodents (Trembley. 2003)
- lower hepatic triglyceride production vs. beef or casein (Demonti. 2003)
- lowest insulin / glucose ratio (vs. soy or casein), when given as part of complex test meal (Post-Skagegard. 2006)
- improvements in insulin sensitivity and reductions in C-reactive protein vs. diet containing beef, pork, veil, eggs and dairy in insulin resistant men and women (Ouellet. 2007; Ouellet. 2008)
[...] an impairment of insulin-stimulated glucose uptake and a reduction of protein synthesis, combined with an increase of muscle protein degradation, are the main adverse metabolic changes induced by injuries in skeletal muscle.In previous studies, the researchers were also able to show that the profound impairment of the AKT /PKB pathway, which is one of the key mechanisms behind the nutrient induced increase of protein synthesis, is protected from the impairments of "high fat diets" (the researcher variety, which is more akin to the standard American than to "low carb" diet), if the latter contains cod, instead of soy- or casein-protein (Tremblay. 2003).
Arginine for repair, EAA for growth: It may be of interest that Dort et al. attribute the muscle building and muscle repairing effects of cod protein to different amino acid in the cod protein. While they believe that its high arginine content suffices as NO precursor to drive and accelerate the repair process, they hold the high essential amino acid (EAA) content responsible for its pro-anabolic effects which are comparable to those of casein (and probably even whey) proteins.
|Image 2: Fish is not for you? Maybe you just don't know how to prepare it properly? It's not really difficult to grill a fillet, trust me - even I can do that.