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Brian Turner

Posted on October 23 2018

By Steve Blechman



 Wow! A new Japanese study published on October 18, 2018 in the Journal Nutrients found that taking leucine supplements alone may be better for muscle protein synthesis and more anabolic than leucine from food! Japanese researchers found that blood levels of leucine was higher from pure free leucine taken alone compared to the same amount of leucine in a meal. Increase in muscle protein synthesis is dependant on leucine concentration. Research has shown that leucine stimulates the anabolic effect of muscle protein on its own (Wilkinson et al J.Physiol.2013.) The Nutrients study showed that, “based on these findings, it is presumed that compared to the intake of protein alone or free amino acids alone, the intake of dietary protein from mixed meals may result in a lower maximum plasma leucine concentration. However, no study to date has investigated the changes in amino acid concentrations after the ingestion of mixed meals in comparison to those after the intake of a similar amount of free amino acids.”

 In a randomized crossover study ten healthy, young Japanese men underwent tests under different conditions. 2 grams of leucine alone, a mixed meal with 2.15 grams of leucine without any additional leucine supplementation; 2 grams of leucine right after a meal; and the final serving consisted of 2 grams of leucine, 180 minutes after a meal.

 According to the study, the conclusion was, “based on the aforementioned discussions, the intake of free leucine alone markedly increased the plasma leucine concentration. However, the increase in leucine concentration after the intake of a mixed meal containing the same amount of leucine was significantly less than that of free leucine intake alone. Moreover, when free leucine was ingested after a mixed meal with the purpose of increasing the plasma leucine concentration, the maximum plasma concentration was attenuated when it was ingested immediately after the mixed meal, despite the fact that the total leucine content was doubled. These results suggest that when free amino acids ingested with the purpose of increasing plasma amino acid concentrations, the timing in relation to the mixed meal intake needs to be considered.”

 As per my last article, for best results to use as an anabolic trigger, take 5 grams of leucine (on an empty stomach) 30 minutes before a post-workout meal, or   protein shake. A meta-analysis (Nutrition, 2017) that combined the results of seven studies showed that BCAA supplements are best taken after exercise, not before, or during exercise (intra-workout).

 Leucine, not branched-chain amino acids (BCAAs), is the most important chemical that turns on the mTOR pathway, so it is likely that consuming leucine after exercise would be more effective (and cheaper) than consuming BCAAs. The BCAAs share the same active transport system into cells and muscle cells. Indeed, isoleucine and valine have been shown to inhibit absorption of leucine (Nutrition, 2017; Biochem J, 1966; Int J of Sp Nutr & Exer Metab, 2018). This new study further confirms my position on taking leucine by itself (found in AML PostWorkout®) on an empty stomach for maximizing muscle protein synthesis!



Nutrients 2018, 10(10), 1543; Effect of Mixed Meal and Leucine Intake on Plasma Amino Acid Concentrations in Young Men N. Yoshii at al

Rahimi MH, Shab-Bidar S et al. Branched-chain amino acid supplementation and exercise-induced muscle damage in exercise recovery: A meta-analysis of randomized clinical trials. Nutrition 2017.

ISSN exercise & sports nutrition review update: research & recommendations. Chad M. Kerksick Colin D. Wilborn, Michael D.

Roberts, et al. Journal of the International Society of Sports Nutrition 2018 15:38 1 June 2018

Szmelcman S, Guggenheim K. Interference between leucine, isoleucine and valine during intestinal absorption. Biochemical Journal 1966;100(1):7-11.

Wilkinson, D.J et al. Effects of leucine and its metabolite beta-hydroxy-beta-methylbutyrateonhumanskeletalmuscleproteinmetabolism.J.Physiol.2013,591,2911–2923.