science nutrition blog

By Steve Blechman

NEW STUDY!

A groundbreaking Japanese study published on October 18, 2018, in the Journal Nutrients, reveals that taking leucine supplements alone may be more effective for muscle protein synthesis than consuming leucine from food sources. Researchers discovered that blood levels of leucine were higher when pure free leucine was consumed alone compared to the same amount of leucine in a meal. This increase in muscle protein synthesis is heavily dependent on leucine concentration. Research has shown that leucine independently stimulates the anabolic effects on muscle protein (Wilkinson et al J.Physiol.2013). The Nutrients study suggests that the intake of dietary protein from mixed meals may result in a lower maximum plasma leucine concentration compared to 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 immediately after a meal; and 2 grams of leucine, 180 minutes after a meal.

The study concluded that the intake of free leucine alone significantly increased plasma leucine concentration. However, the increase was notably less when leucine was consumed as part of a mixed meal. Moreover, when free leucine was ingested after a mixed meal, the maximum plasma concentration was reduced, although the total leucine content was doubled. These findings highlight the importance of timing when considering when to take leucine, especially in relation to meal intake.

For optimal results as an anabolic trigger, it is recommended to take 5 grams of leucine on an empty stomach 30 minutes before a post-workout meal or protein shake. If you're pondering the best time to take leucine, a meta-analysis (Nutrition, 2017) that combined results from seven studies concluded that BCAA supplements are most effective when taken after exercise, rather than before or during (intra-workout).

Leucine is the key chemical that activates the mTOR pathway, making it more effective and cost-efficient to consume leucine after exercise compared to BCAAs. Understanding the best time to take leucine is crucial, as BCAAs share the same active transport system into cells, and isoleucine and valine can inhibit leucine absorption (Nutrition, 2017; Biochem J, 1966; Int J of Sp Nutr & Exer Metab, 2018). This new study reinforces the recommendation of taking leucine by itself, as found in AML PostWorkout®, on an empty stomach to maximize muscle protein synthesis.

To further expand on the best time to take leucine, consider these points:

• Take leucine supplements on an empty stomach to ensure maximum absorption.
• Utilize leucine as a post-exercise supplement to enhance muscle recovery and protein synthesis.
• Consider the timing of your meals and supplements to optimize leucine's effectiveness.
• Recognize that while leucine is beneficial on its own, the timing of consumption plays a critical role in its efficacy.

References:

Nutrients 2018, 10(10), 1543; https://doi.org/10.3390/nu10101543 Effect of Mixed Meal and Leucine Intake on Plasma Amino Acid Concentrations in Young Men N. Yoshii et 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 https://doi.org/10.1186/s12970-018-0242-y 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.