Fishing for Better Wheys to Improve Your Physique and Overall Health? 6g/d Cod Protein Could Help You Cut Body Fat & Build Muscle Without Having to Change Your Diet

Image 1: This can of tuna (140g) would contains exactly 7 servings of muscle building fat burning fish protein... well, sort of. At least it contains as much protein as the subjects in the Vikøren study consumed in the form of capped cod protein isolate in the 2nd half, the "high-dose" phase of the 8-week intervention (Vikøren. 2012)
Protein days at the SuppVersity! Well, sort of... after yesterday's news on the pro-insulinogenic effects of whey protein and its not so significant negative impacts on your body composition in the absence of profoundly increased energy consumption (i.e. whey, ah... I mean "way" beyond the ~20% max. increase I suggest for a clean bulk). We will take a look at another, hitherto largely overlooked protein source: Fish! Yeah, I know, you all eat your serving of fish once or twice a week - fatty fish to be precise to derive the alleged health benefits of the latter, but did you ever remotely consider supplementing with fish protein? As a regular you may in fact have done that after reading about the superiority of cod over casein and pea as far as muscle repair are concerned, here at the SuppVersity, and if you have not the data from a recently published study from the Institute of Medicine and the Department of Heart Disease at the University of Bergen in Norway (Vikøren. 2012) could not just be an incentive for you to do so, it could in fact promote the production of fish protein isolates, which has not really kicked off before the 2011 when a Peruvian company hit the market with fat-free, membrane-refined fish protein and fish peptide products at prices of $5/kg and thus at least 38% cheaper than whey or egg protein isolates (Daniells. 2011).

Fish protein supplementation: A little goes a long way

What is so particularly stunning about the data from the 8-week double-blinded cod protein supplementation trial Linn A. Vikøren and her colleagues conducted were not so much the results,
  • a decrease in postprandial blood glucose AUC,
  • more pronounced, yet less sustained insulin responses (sign of increases insulin sensitivity),
  • a decrease in C-reactive peptide (CRP) levels, and
  • reduced LDL cholesterol, as well as
  • increases in lean muscle mass, and
  • decreases in fat mass,
but rather the amount of supplemental fish protein which elicited those changes: 3g/day for the first 4 weeks and 6g/day for the last 4 weeks - not much, if you relate that to the average protein intake (70-90g) of the overweight, yet healthy middle-aged study participants, right?

The whole is mostly way more than just the sum of its parts

If we go simply by the protein content that previous studies, such as , even the large dose, i.e. the 6g of cod protein isolate per day, the subjects received in the 2nd month of the intervention period, equals no more than
*Please keep in mind that Pilon et al. observed differences with respect to the physiological effects of fish proteins from different sources. In their rodent study, only salmon, yet not bonito, herring or mackerel protein had ameliorative effects on body weight and visceral body fat gain in rodents on a high-fat diet (Pilon. 2011)
  • 20g of tuna
  • 21g anchovies
  • 22g salmon or halibut
  • 23g snapper or tilapia
Now, feeding them fish, was however not a viable option. After all, it is pretty easy to distinguish a can of tuna such as the one in image 1 from a similar can with chicken, let alone "fillers and sweeteners", the sole ingredients of the placebo tablets. So in as much as you may decry the use of supplemental, instead of real fish protein, it is hardly debatable that the use of 500mg fish protein (cod) caps was necessary to effectively double-blind the study.
Figure 1: Comparison of amino acid concentration  (g/kg) of fish and whey protein (data for fish and whey from Vikøren. 2012 and Engelen. 2012, respectively)
If we take a look at the actual amino acid content (which is yet, as you should know, only one of the potential reasons we would see differences to other protein sources), it is evident that cod has a similarly high essential amino acids content as whey, but contains significantly less proline, much more arginine, glutamine and taurine.
Reminder: Just in case you have forgotten about the SuppVersity news from Friday, May 4th, 2012, I suggest you briefly go back and read up on how "Cod Protein Promotes Muscle Repair After Injury More than Casein or Peanut Protein"

What is it about fish protein that makes it so potent - arginine, taurine, or synergistic effects?

As a regular, here at the SuppVersity, you will also know that there exists a fairly decent amount of research on potential and scientifically established health effects of arginine and taurine. Whether those two individual amino acids or rather synergistic effects due to the specific protein / peptide structure of cod proteins are able to explain any of the observed health benefits (see bullet points 1-4) or the changes in body composition (see bullet points 5-6 and figure 2, below) remains yet to be elucidated.
Figure 2: Macronutrient composition of the diets at baseline, after 4 weeks and 8 weeks and changes in body composition compared to baseline (Vikøre. 2012)
Whatever the exact reasons may be, the -1.6% drop in body fat percentage (this is different from body fat mass!) is certainly astonishing given the fact that it occurred in the absence of significant changes in either the macronutrient composition or total energy content of the subjects' diets.

So what? Are fish protein isolates, the better whey?

Now without knowing the exact physiological mechanism behind the the observed effects on glucose and lipid metabolism and body composition of the 16 male and 19 female study participants, which could, as Vikoren et al. rightly point be a result of either the
  • specific amino acid profile,
  • the presence or formation of specific peptides (protein bonds), or 
  • as of yet unknown bioactive components of fish/cod protein,
it would certainly be premature for most of you to make a switch from whey to cod, before scientific data from human trials confirms not just the efficacy, but also the supremacy of high(er) dose cod supplements over whey and other dairy proteins as the go-to muscle builders for physical culturists.

In view of the results of previous studies by by Zhang etl al. (1993), Shukla et al. (2006), and specifically van Post-Skagagard et al. (2006) on the health effects of supplemental cod protein, it may yet be prudent to make another switch in your dietary / supplement regimen, namely one from fish oils to whole fish, which has already been shown to produce superior weight-loss and health effects than supplemental fish oil (e.g. Gunnarsdotti. 2008) - results of which we know by know that they well be mediated by the synergistic effects of oil and protein from whole fish.

  1. Daniells S. Low-cost, fat-free fish protein facility gets go ahead. May, 27 2011. < >
  2. Engelen MP, Rutten EP, De Castro CL, Wouters EF, Schols AM, Deutz NE. Casein protein results in higher prandial and exercise induced whole body protein anabolism than whey protein in Chronic Obstructive Pulmonary Disease. Metabolism. 2012 Apr 16.  
  3. Gunnarsdottir I, Tomasson H, Kiely M, Martinéz JA, Bandarra NM, Morais MG, Thorsdottir I. Inclusion of fish or fish oil in weight-loss diets for young adults: effects on blood lipids. Int J Obes (Lond). 2008 Jul;32(7):1105-12. Epub 2008 May 20.
  4. Lavigne C, Tremblay F, Asselin G, Jacques H, Marette A. Prevention of skeletal muscle insulin resistance by dietary cod protein in high fat-fed rats. Am J Physiol Endocrinol Metab. 2001 Jul;281(1):E62-71.
  5. Pilon G, Ruzzin J, Rioux LE, Lavigne C, White PJ, Frøyland L, Jacques H, Bryl P, Beaulieu L, Marette A. Differential effects of various fish proteins in altering body weight, adiposity, inflammatory status, and insulin sensitivity in high-fat-fed rats. Metabolism. 2011 Aug;60(8):1122-30.
  6. von Post-Skagegård M, Vessby B, Karlström B. Glucose and insulin responses in healthy women after intake of composite meals containing cod-, milk-, and soy protein. Eur J Clin Nutr. 2006 Aug;60(8):949-54.
  7. Shukla A, Bettzieche A, Hirche F, Brandsch C, Stangl GI, Eder K. Dietary fish  protein alters blood lipid concentrations and hepatic genes involved in cholesterol homeostasis in the rat model. Br J Nutr. 2006 Oct;96(4):674-82.
  8. Vikøren LA, Nygård OK, Lied E, Rostrup E, Gudbrandsen OA. A randomised study on the effects of fish protein supplement on glucose tolerance, lipids and body composition in overweight adults. Br J Nutr. 2012 May 31:1-10.
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