‘Spiking’ (not Replacing) Suboptimal Amounts of #Whey With #EAAs Yields Increase in Net Protein Balance, Yet not(!) Protein Synthesis in Muscle – Acute Response Study

'Spiking' (not Replacing) Suboptimal Amounts of #Whey With #EAAs Yields Increase in Net Protein Balance, Yet not(!) Protein Synthesis in Muscle - Acute Response Study
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You will probably have read about the results of this recent study from the University of Arkansas for Medical Sciences elsewhere already – hopefully in an article that applied the same rigorous scrutiny as this one.

“Wait: EAAs are better than whey?” If that’s your overgeneralized and essentially wrong (there was no comparison of EAA vs. Whey, but one of EAA+whey vs. whey 😎) take-home message from the abstract of a recent study in the Journal of the International Society of Sports Nutrition you may have recently read about on Facebook, you better read the rest of today’s SuppVersity article on Park’s paper, of which I would like to point out that the authors come to a very different, accurate, and more nuanced conclusion, that reads as follows:

“that a composition of a balanced EAA formulation combined with whey protein is highly anabolic as compared to a whey protein-based recovery product, and that the response is dose-dependent” (Park 2020).

Ok, that’s correct and nuanced, but we should be more specific with respect to the real-world implications, and more nuanced when it comes to describing and reflecting on the methodology. A classic SuppVersity ‘On the Other Hand’ (Carl Lanoreif you will; and an article that may help you answer the question: “Do I have to add EAAs to every meal?”
As you may already have learned from the abstract, the scientists have “determined the acute response of protein kinetics to one or two servings (6.3 g and 12.6 g) of a proprietary composition containing free-form essential amino acids (EAA) (3.2 g EAA per serving) and whey protein (2.4 g per serving), as well as the response to consumption of a popular whey-based protein supplement (Gatorade Recover) (17 g; 12.6 g protein)” (Park 2020).

We’re talking about an overall low(ish) if not clearly insufficient amount of protein

Those < 13g of protein are insufficient – at least, if maximal skeletal muscle protein synthesis is the goal which has been shown to saturate (#ceilingEffect | see 1st infobox) at >20-25g in healthy, young (early to mid-twenties) male and female subjects as they participated in the study at hand.

Figure 1: Previous studies such as Churward-Venne et al (2014) show that extra leucine (low: 2.25g; high: 4.25g) can boost the protein synthetic effects of insufficiently low amounts of whey (6g) dose-dependently to what you’d see w/ 25g of whey (required addition of 4.25g of leucine). Moreover, 15g of EAA administered to elderly subjects were found to surpass the anabolic effects of 15g of whey in an often-cited study by Paddon Jones, et al. (2006).

In this regards, the study at hand is neither the only nor the first study to suggest that ‘spiking’ a suboptimal amount of whey protein with BCAAs (especially leucine) or EAAs can further promote the postprandial increase in post-prandial (=after a meal) protein synthesis. In that, the studies by Churchward-Venne where 6g of whey +4.25g of leucine mirrored the effects of 25g of whey (see Figure 1, left) and Paddon Jones’ study which directly compared 15g of EAAs to whey (see Figure 1, right) are yet only the most positive examples of an overall rather heterogenous research (e.g. no leucine effect in Tipton 2009), which suggests that any benefits of EAAs and/or additional leucine begin to vanish when the amount of whey that’s used as a comparison passes the 20-25g threshold (in the elderly 30-40g may be necessary).

What’s a ceiling effect? At lower protein intakes, there’s a clear “more helps more”-effect for each additional gram of protein. When the serving size increases beyond 20-30g (sex-, age-, exercise-, weight-, type-, […], and diet-dependent), however, ‘more does no longer help more’, the measurable fractional protein synthesis rates max out and the superfluous protein is used as an energy substrate, instead of being incorporated into the muscle cells. Learn more about the protein requirements of athletes in the ISSN Position Stand (free full-text!).

One thing that Park et al. rightly highlight in the introduction of their paper is the fact that the putative effects of (extra) EAAs cannot be equated to the amount of leucine in the added free-form amino acids. The previously cited study by Churchward-Wenne, for example, administered leucine alongside the two other BCAAs, isoleucine and valine, and combined them with the non-essential amino acids alanine and glycine (note: the content of the NEAAs is relatively low in regular whey protein).

And in fact, the Churward-Wenne study is one of several examples that would support the notion that you want to spike a specific (low) amount of protein with amino acids (especially the EAAs) this type of protein is naturally low in. Accordingly, Park et al. formulate a hypothesis in their paper that focuses, on the putative benefits of ‘#EAA-spiking’:

Table 1: Test product composition (Park 2020). As you can see it’s not the higher leucine content that could possibly make a difference (wih 20% vs. 24% it’s even lower in the EAA supplement), but what differs profundly is the histidin content of the treatments, which is more than 3x higher in the added EAAs trial compared to the Gatorade (whey) trial.

“The EAA with the lowest concentration relative to demand will limit the anabolic response, regardless of the extent of excess of the other EAA, including leucine. Consequently, maintaining a balance of EAA that is roughly proportionate to the demand for each EAA is important. For this reason, the idea of combining a balanced formulation of all of the EAA with an intact protein is appealing. A combination of a balanced formulation of EAA and a high-quality intact protein should provide the beneficial effect of a rapid and large increase in leucine concentration to activate the protein synthesis at a molecular level, while also providing sufficient other EAA to maintain a prolonged availability of all the necessary precursors for protein synthesis” (Park 2020).

That EAAs in general and more specifically the mTOR-activator leucine is not the key to unlock limitless protein synthetic potential has also been confirmed in a recent study by researchers from Brazil and Canada (de Andrade 2020) who fed twenty-five, resistance-trained men (27 ± 5 y; 78.4 ± 11.6 kg; 24.8 ± 3.0 kg/m²) 1.8 ± 0.4 g protein·kg/d plus either 2 x 5 g/d of either free leucine (LEU n=12) or alanine (PLA n= 13), while undergoing a supervised 12-week, twice-weekly lower-limb RT program. Their results were not what supplement producers would like to hear: there was no effect of extra leucine ingested on top of an already high protein diet (the regular diet provided 11g of leucine, alone) – That’s the ceiling effect in (real-world vs. lab) action!

Figure 2: Not what the #snakeOil… ah, amino acid vendors wanted to see – If the baseline protein intake is high (in th study at hand that was 1.8g/kg; with 11g leucine in it), additional free-form leucine doesn’t add to the size gains in 12-week study with twenty-five, young, resistance-trained men (de Andrade 2020).

When we’re evaluating the significance of the results of the study at hand we do thus have to look at the subjects baseline protein intake and the amount of nitrogen the subjects consumed while keeping in mind that as a single acute response study Park’s latest investigation can tell us very little about the practical relevance of the results in terms of #gainz over weeks and months. So, let’s see…

Acute effects, fasted subjects, no training, low(ish) amount of whey… no way this study will deliver definitive answers about the usefulness/superiority of EAA > whey.

To validate their EAA hypothesis, Park et al. used a randomized, two-period, stable isotope infusion protocol that compared the net protein balance in a 4.5 h basal fasted period to the 4 h post-meal period (total 8.5 h) after the ingestion of either…

  • two doses of the proprietary free-form EAA/protein study supplement (6.3 g and 12.6 g | containing a total of 4.284 g leucine), or
  • 17.6 g of a product (Gatorade Recover) containing 12.6 g of whey protein, of which 24%, i.e. 3,024 g were leucine

…with a >1 week washout period in-between the two isotope infusions and in the absence of exercise (needless to say that the latter could have had significant effects on the results).

Figure 3: This figure from the FT suggests a huge effect… an effect that was however measured in response to a single meal, in the absence of training, with suboptimal amounts of whey and in a fasting context where any ceiling effects would disappear (Park 2020)… judge for yourself how large the real-world relevance of this experimental set-up is 🙄.

While this is a classic protocol and certainly better than measuring mTOR activity, only, the study design suffers from the previously hinted-at short-comings:

    Figure 4: This graph can mislead you to believe that adding EAAs to whey would significantly add to its effect; the “*”, however, denotes a p<0.05 difference to the fasted state – an inter-treatment difference on the fractional synthesis rates was not observed!
  • the study investigates only the 4h post-feeding window; hence, it is an acute phase study that won’t tell us much about the long(er)-term effects of EAA vs. whey on muscle or strength gains;
  • the subjects were fasted, to begin with, and they were not fed anything but the supplement, which eliminates the ceiling effect that people on high(er than RDA | 1.6-1.8g/d) protein diets | see previous remarks on the de Andrade study and the corresponding infobox;
  • the amount of whey was way below the threshold value of 20-30g of which previous studies suggest that it is required to maximize protein synthesis;
  • the subjects did not train! If they had trained, the study may have yielded completely different results;
  • due to its design, the study was unable to account for additional metabolic, anabolic, and health-relevant effects of whey peptides as they have been reported by Saito 2008, Athira 2013, or Tsutsumi 2014 (read this review) have reported – those could become relevant especially in the long-run.
Also worth mentioning: The data in Figure 4, which I grabbed directly from the FT, can easily be misread as ‘EAA + Whey = significantly better than whey, alone,’ when a significant difference in the amount of protein that was actually pumped into the muscle (vs. other organs/tissues) was not observed. Yep, you read that right! The ‘*’ signifies a significant increase over the fasted state, not one between EAA+whey vs whey, alone 😮.

The scientists are right, though, when they conclude: “The principal finding of this study is that a combination of free EAA and whey protein is highly anabolic in healthy young volunteers.”

This is an appropriate (yet hardly comprehensive) conclusion you may find to be in stark contrast to what you’ve probably read in some blogs and on industry-funded websites. Again: there was no increase in muscle protein synthesis with either low or high dose EAA + whey compared to whey and the calculated increase in protein efficiency (increase in protein balance + gram of powder) must not be mistaken as an increase in the amount of protein that went into the muscle.

EAAs are fast: Too fast to sustain muscle growth — Yep, you read that right. As Park et al. admit, they deliberately mixed EAA with whey, instead of using them straight, because the “rapid peak response in plasma EAA”, which “is likely a key reason for [free form EAAs’] effectiveness also limits “the total duration of the response”, because “just as the concentrations of EAA in the blood rise rapidly, they fall rapidly as well”. Hence, “the composition tested in this study contain[ed] protein in addition to the EAA to prolong the anabolic response in the time after consumption” – #hearHear.

The net protein balance leads us to an essential problem: due to its lack of tissue-specificity the reductions in total body protein breakdown and increases in synthesis must not be equated or used as an indicator of muscle gains. Accordingly, the allegedly 3x and 6x greater gains Park et al. calculated based on the net protein balance (not muscular FSR) you may have heard people rave about would probably not have manifested in terms of muscle gains – this is, by the way, in line with the paper by Bukhari et al 2015, which Park et al. claim would have shown that…

“[…t]he stimulation of muscle protein synthesis by consumption of less than 4 g of EAA has been reported to be as great as the response to consumption of 25 g dose of whey protein” (my emphasis in Park 2020).

That’s de facto not correct, as Bukhari et al. found that – I quote – “both WP [whey] and LEAA [EAA] equally stimulated MPS 0–2 h (P 0.05)” (Bukhari 2017). I’ll leave it up to you to decide if this is a random misunderstanding of the Bukhari study or whether it was done with a purpose… anyway, it adds to the previously outlined caveats and the unmistakable reek of bias. In all fairness, it should be added that the scientists explicitly address the limitation in a paragraph of the discussion, where Park et al. admit that their …

“[…] results reflect a pooling of the responses of all proteins in the body, and muscle protein may constitute as little as 25% of the total rate of whole body protein synthesis in some circumstances. Because the majority of whole body protein synthesis occurs elsewhere than the muscle, the rate of whole-body protein synthesis may not directly correspond to muscle protein FSR in some circumstances” (my emphasis in Park 2020).

And the ‘trends’ (statistical significance not established) the authors highlight for FSR, i.e. the proxy of the amount of protein that actually ended up in skeletal muscle, may point into the right direction but they are not statistically significant differences that would warrant the conclusion that a relevant part of “the gain in net protein balance occurred in the muscle” (Park 2020).

Figure 5: Relative contribution of individual amino acids (in %) to total EAA content of the powders used in the study (my illustration of Table 2. Take a look at phenylalanine and histidine, of which whey has comparatively low concentrations the differences are not discussed in the paper, but they should be if your theory is that the magic lies in the contribution of non-leucine EAAs as authors of the study at hand claim, both in the introduction and discussion section of their paper.

Ok, enough of that… one last thing, though: Maybe you too have asked yourself why one would mention the brand name of the placebo but avoid naming the producer and product name of the “proprietary free-form EAA/protein study supplement” the authors repeatedly call “a balanced formulation of free EAA” or “a composition of exact proportions of EAA” (no idea whatever “balanced” is supposed to mean in this context and there’s no mention of potential implications of most striking difference in EAA make-up, i.e. histidine and phenylalanine, see Figure 5). Ha? I don’t know the answer either.

Article from the archive addresses question: “Would it be advisable to switch from the large scoop with protein (red) to the small one with (EAAs) or take both?” | read it

Don’t be fooled: No study will ever be able to ‘prove’ the superiority of one supplement over another, once and for all. This is particularly true when the study cannot measure the two actually relevant outcomes: here, muscle and strength gains because it was an acute response study, an acute response study with rather low amounts (probably too low) of protein that was conducted in a fasted state that precludes ceiling effects as they’ve been observed when doses were escalated (to 20-30g in young and 30-40g in older people) or the baseline protein intake was high (~2x the RDA or more | note: in the study at hand, the intake was ZERO – at least for the relevant time window).

In view of the previously discussed caveats, the only thing you can conclude with some confidence is that the provision of a relatively small quantity of “balanced” (again, no idea what that’s supposed to mean) proprietary blend of extra EAAs on top of an insufficient amount of whey protein to fasted non-trained subjects can lead to short-lived improvements in the subjects’ net protein balance, which are driven largely by a reduction in protein breakdown all over the body and not by a significantly increased protein synthesis in skeletal muscle 😑 | Comment on Facebook!


  • Athira S, Mann B, Sharma R, Kumar R. “Ameliorative potential of whey protein hydrolysate against paracetamol-induced oxidative stress.” J Dairy Sci. 96.3 (2013).
  • Churchward-Venne, Tyler A., et al. “Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial.” The American journal of clinical nutrition 99.2 (2014): 276-286.
  • de Andrade, et al. “Leucine Supplementation Has No Further Effect on Training-induced Muscle Adaptation” Medicine & Science in Sports & Exercise: February 19, 2020 – Volume Publish Ahead of Print
  • Jäger, Ralf, et al. “”International society of sports nutrition position stand: protein and exercise.” Journal of the International Society of Sports Nutrition 14.1 (2017): 1-25.
  • Paddon-Jones, Douglas, et al. “Differential stimulation of muscle protein synthesis in elderly humans following isocaloric ingestion of amino acids or whey protein.” Experimental gerontology 41.2 (2006): 215-219.
  • Park, Sanghee, et al. “Anabolic response to essential amino acid plus whey protein composition is greater than whey protein alone in young healthy adults.” Journal of the International Society of Sports Nutrition 17.1 (2020): 9.
  • Saito T. “Antihypertensive peptides derived from bovine casein and whey proteins.” Adv Exp Med Biol. 606:295 (2008).
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  • Tsutsumi R, Tsutsumi YM. “Peptides and proteins in whey and their benefits for human health.” Austin J Nutri Food Sci. 1:1 (2014).

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