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| Dairy or eggs? Why not just dairy and eggs - Protein mix exerts most promising effects on signalling proteins related to increased muscle mass and fat loss, analysis of the results of a study shows. |
Well, despite the fact that this is a rodent study and irrespective of the questionable link between acute markers of protein synthesis and long-term gains, this is imho the first study to compare the effects whey and egg proteins have on skeletal muscle, adipose tissue and hypothalamic satiety-related markers at the same time.
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| Figure 1: Expression of protein synthesis and selected signalling proteins in skeletal muscle (PGC-1a, AMPK) and brain (POMC) in response to the different protein supplements (Mobley, 2015). |
- WPC and 70 W/30E increased muscle protein synthesis (MPS) 104% and 74% 180 min post-treatment, respectively (p < 0.05), and
- 70 W/30E increased p-AMPKα (Thr172) 90 and 180-min post-treatment as well as PGC-1α mRNA 90 min post-treatment.
A closer analysis of the protein responses in the subcutaneous (SQ) and omental fat (OMAT) depots of the rodents showed that
- 70 W/30 W increased SQ fat phosphorylated hormone-sensitive lipase [p-HSL (Ser563)] 3.1-fold versus CTL and a 1.9–4.4-fold change versus all other test proteins 180 min post-treatment (p < 0.05); and
- WPC, 70 W/30E and 50 W/50E increased OMAT p-HSL 3.8–6.5-fold 180 min post-treatment versus CTL (p < 0.05).
Lastly, the 70 W/30E and 30 W/70E increased hypothalamic POMC mRNA 90 min post-treatment versus CTL, an effect that suggests that an increased satiety response may have occurred in the former groups. An effect that was not counter by a compensatory increase in orexigenic (=appetite increasing) AGRP mRNA in the 70 W/30E group 90 min post-treatment versus and compensated by increases in orexigenic NPY mRNA in the 30 W/70E group 90 min post-treatment.
Why egg? Widespread interest has also surrounded the positive health benefits of dietary egg protein due to its high es sential amino acid (EAA) content and high digestibility (Buford. 2007). Similar to whey protein, egg protein feeding in rats has been found to significantly increase postprandial MPS (Norton. 2012). Likewise, one report suggests that bioactives isolated from egg protein down-regulate serum myostatin (MSTN | Colker. 2009 | this effect was not observed in the study at hand(!)); an effect which may enhance skeletal muscle hypertrophy with chronic supplementation. However, unlike the aforementioned whey protein re search, there is a paucity of data regarding the physio logical effects of dietary egg protein on other tissues (i.e., adipose tissue and the hypothalamus).
Practically speaking, the data would suggest that (1) the pure whey protein supplement had the most pronounced pro-anabolic effects on the muscle, while (2) the egg protein supplements had hardly any effect (this is different to studies, where egg supplements were given after workouts). (3) as far as the oxidative prowess of the muscles is concerned, the mix of whey + egg protein (70:30) was yet the only protein supplement to elicit significant changes in the "fat burning" protein AMPK and the mitochondrial builder PGC-1a.Similarly, (4) with respect to the effects on the adipose tissue, the protein mix containing whey and egg protein at a ratio of 70:30 showed superior effects on the libid mobilizer HSL in both subcutaneous and omental fat depots, while (5) the 50:50 mix affected the release of fat from the adipocytes only in the belly (omental) fat. If we also take into account that (6) only the 70:30 mix increased the level of satiety related proteins in the brain without corresponding increases in satiety triggering hormones, the results of the study at hand would suggest that the pure whey protein may have the pro-anabolic edge, the addition of egg protein, however, appears to make the mix more suitable for body recomposition goals, because it will simultaneously increase the level of key proteins that could trigger an increase in fat oxidation and a decrease in energy intake. What reamains to be seen, though, is whether these effects translate into corresponding changes in body composition in longer-term human studies with an exercise component, though | Comment on Facebook!
- Buford, Thomas W., et al. "Journal of the International Society of Sports Nutrition." Journal of the International Society of Sports Nutrition 4.6 (2007): 6.
- Colker, C. "Effect on serum myostatin levels of high-grade handled fertile egg yolk powder" (Conference abstract). J Am Coll Nutr. 28.3 (2009).
- Mitchell, Cameron J., et al. "Last Word on Viewpoint: What is the relationship between the acute muscle protein synthetic response and changes in muscle mass?." Journal of Applied Physiology 118.4 (2015): 503-503.
- Mobley, Christopher Brooks, et al. "Effects of protein type and composition on postprandial markers of skeletal muscle anabolism, adipose tissue lipolysis, and hypothalamic gene expression." Journal of the International Society of Sports Nutrition 12.1 (2015): 14.
- Norton, Layne E., et al. "Leucine content of dietary proteins is a determinant of postprandial skeletal muscle protein synthesis in adult rats." Cellulose (Fiber) 53.53.7 (2012): 53-7.