Wednesday, June 14, 2017

Pre-Bed Protein Supplementation Revisited: No Increased Protein Synthesis W/ 30g | Time to Give up Pre-Bed Casein?

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I've written about the possible net protein gains you can make by consuming a large bolus (20g) of slow-digesting casein before - for the first time in 2012 in my article "3.2kg of Lean Mass Over Night W/ 40g of Slow Digesting Protein 30min Before Bed!?" (read it), then again in 2015 addressing a study that used significantly less protein "12-Week Study: 25g Bed-Time Protein Almost Doubles Size & Increases Strength Gains - Where's the Catch?" (read it), and roughly a year ago in "40g Casein Build Lean Muscle Overnight: 27% Elevated MPS Even W/Out Training (30% W/ Ex) - And That in 70-Y+ Olds!" (read more).

The reason I want to address the topic again is the publication of a new paper which suggests that the significance of the increase in protein synthesis you would see with the consumption of a pre-bed protein may be (a) generally overrated or (b) require very high doses of protein.
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More specifically, Jan Trommelen's study tested the scientists' hypothesis that "pre-sleep ingestion of 30 g dietary protein increases post-exercise overnight muscle protein synthesis rates and provides amino acids that are incorporated into myofibrillar protein during overnight sleep" (Trommelen 2017) and investigate whether these obviously beneficial effects would be augmented/modified by the co-supplementation of an additional 2 g of crystalline leucine.
"In the present study, we tested our hypotheses by selecting 36 healthy young subjects who ingested 30 g casein protein with (PRO+leu) or without (PRO) an additional 2 g of crystalline leucine, or a placebo (PLA) before going to sleep. By combining contemporary stable isotope methodology with the ingestion of intrinsically L-[1-13C]- phenylalanine and L-[1-13C]-leucine labeled protein we were able to assess i) the postprandial release of dietary protein-derived amino acids into the circulation, ii) their impact on overnight whole-body protein kinetics, iii) myofibrillar muscle protein synthesis rates, and iv) the incorporation of dietary protein-derived amino acids into muscle protein during overnight sleep" (Trommelen 2017).
In contrast to the previously cited 2016 study, Trommelen et al. used 36 healthy, recreationally active, young men (age: 23±1 y; BMI: 22.6±0.3 kg/m², participating in exercise other than structured resistance-type exercise training, for 1-3 d/wk for ≥ 12 months) were selected to participate in this study. Subjects were randomly assigned to ingest ...
  • a placebo (PLA), 
  • 30 g micellar casein protein (PRO), or 
  • 30 g micellar casein protein plus 2 g of crystalline leucine (PRO+leu) 
before going to sleep (note: the FT doesn't say explicitly that the researchers used micellar, not sodium or calcium caseinate - I specifically asked the authors about that).
Do not buy sodium or calcium caseinate: Irrespective of the fact that the study at hand seems to refute or at least belittle the benefits of pre-bed micellar casein supplementation, buying the cheaper sodium or calcium caseinate will further reduce your chances of seeing overnight gains, 'cause they're digested at a similar speed as whey protein - the prolonged hyperaminoacidemia the scientists' hoped (and previously observed) would trigger a sign. increase in overnight muscle protein synthesis would thus not occur with either of the formerly mentioned fast digesting proteins (including whey protein); it should, and  I want to highlight that, though, occur with slow-digesting dietary proteins like micellar casein from dairy products and/or slow digesting meat proteins, or, as a study by Snijder et al. from 2015 suggests a combination of fast and slow digesting proteins.
The extra casein protein was added on top of the already high protein content of the standardized diet all subjects received on the experimental day - a diet that contained 0.16 MJ/kg, providing 62 energy percentage (En%) carbohydrate, 13 En% protein, and 22 En% fat and thus approximately ~1.2±0.01 g protein per kg bodyweight; and a diet that was supplemented with an extra 20g milk protein shake that was consumed by all participants right after their PM workout at 20:45h.
Figure 1: Graphical overview of the experimental protocol/schedule (Trommelen 2017).
As the detailed outline of the schedule in Figure 1 tells you, the scientists took blood samples to analyze the disappearance of the protein/amino acids repeatedly during the night.
Do not assume that more helps more if the corresponding evidence isn't there, yet. While Trommelen et al. rightly point out that the most straightforward explanation for the lack of increase in MPS may be the comparatively lower amount of protein, you will soon notice that consuming 80-100g of casein before bed is going to have such a profoundly negative effect on your sleep that I bet you end up more catabolic than you would if you ate nothing before bed. Personally, I believe that it rather depends on the 24h protein intake which was relatively high in the study at hand (1.2g from food + 20g from supplements even in the placebo group) and may thus have made the extra 30g of pre-bed casein the scientists used in the study at hand obsolete.
In conjunction with the comparison of the pre- vs. post-muscle biopsies the analyses of the corresponding data revealed a significant increase in the net protein balance (see Figure 2) of the subjects in both, the protein only and the protein + leucine group.
Figure 2: Net protein synthesis, protein breakdown, and protein oxidation as well as resulting net protein balance (left) in the 7.5h after the ingestion of the pre-bed protein and corresponding fractional myofibrillar synthesis rates (right) measured using phenylalanine (A) and leucine (B) as a tracer (Trommelen 2017).
The hoped for increase in myofibrillar protein synthesis, however, was not observed for either phenylalanine or leucine - an observation Trommelen et al. interpret as follows:
"The present study shows that ingestion of 30 g casein protein with or without additional free leucine prior to sleep is not sufficient to stimulate overnight muscle protein synthesis during post-exercise overnight recovery" (Trommelen 2017)
The authors do yet also point out that the protein is not wasted. After all, their study indicates that "casein protein ingested prior to sleep provides amino acids that are incorporated into myofibrillar protein and improves overnight whole-body protein net balance during sleep" (Trommelen 2017).

This should remind you of the data in Figure 2 (left) showing an increase in whole-body protein synthesis that must obviously have occurred in tissues other than muscle, i.e. splanchnic tissues. As the authors highlight, it is not news that "feeding has been shown to improve gut tissue protein net balance" what is not known, however, is "if a more positive protein net balance in splanchnic tissues results in organ growth and whether this has any functional relevance" (Trommelen 2017).
Qumoradriceps muscle CSA before and after 12 wk of resistance-type exercise training (A) and changes during the 12 wk (B) in healthy young men who did or did not receive protein supplementation. Values are means ± SEMs, n = 19 (placebo) or 20 (protein). NS, P ≤ 0.05; *Different from before the intervention, P < 0.001; **Different from PLA group, P < 0.05. CSA, cross-sectional area; PLA, placebo supplemented (Snijder 2012).
So what does this all mean? Well, there are three take-home messages to remember: (1) Ingesting "only" 30g of slow digesting 150 minutes after a workout (+ protein shake) and right before going to bed will not promote the expected increase in overnight protein synthesis in the muscle. (2) The protein is not wasted, though, as it contributes to increases in whole body protein synthesis, of which we (3) do not know exactly where they are taking place and whether they are relevant for your health or physical performance.

That the latter could be relevant, however, would be supported by a previously discussed 2015 study on the effects of consuming 30 g casein protein prior to sleep on the muscle mass and strength gains of young men during a 3-months resistance-type exercise training study (Snijders 2015) - a study with a similar workout and supplementation timing (20:00-22:00h), but lower post-workout protein intake (10g vs. 20g in the study at hand) and a mix of fast- and slow-digesting protein before bed.

For you, Snijder's 2012 study provides the evidence the new study, due to its acute supplementation design, lacks: adding a significant amount of slow-digesting pre-bed protein to a rather low(ish) - in BB-terms - protein diet can augment your training results (strength- and sizewise).

If this "extra serving" should supply 40g instead of 30g or slow-digesting protein and whether it may be a smart move to combine, as Snijders et al. did it in 2015, fast- and slow-digesting proteins to see even more pronounced effects, is yet, with the publication of Trommelen's excellently designed study, still in the open. I guess, future studies will answer these questions and the SuppVersity is the place you're going to read about the answers | Comment!
  • Snijders, Tim, et al. "Protein ingestion before sleep increases muscle mass and strength gains during prolonged resistance-type exercise training in healthy young men." The Journal of Nutrition 145.6 (2015): 1178-1184.
  • Trommelen, Jorn, et al. "Pre-sleep dietary protein-derived amino acids are incorporated in myofibrillar protein during post-exercise overnight recovery." American Journal of Physiology-Endocrinology and Metabolism (2017): ajpendo-00273.