Using the amino acid leucine as a supplement also boosts the muscle building effect of slow proteins such as casein, according to a human study published by researchers at the University of Maastricht, Netherlands, in Clinical Nutrition. This means that leucine probably also enhances the anabolic effect of an ordinary well-balanced meal.
Using the amino acid leucine as a supplement also boosts the muscle building effect of slow proteins such as casein, according to a human study published by researchers at the University of Maastricht, Netherlands, in Clinical Nutrition. This means that leucine probably also enhances the anabolic effect of an ordinary well-balanced meal.
Using the amino acid leucine as a supplement also boosts the muscle building effect of slow proteins such as casein, according to a human study published by researchers at the University of Maastricht, Netherlands, in Clinical Nutrition. This means that leucine probably also enhances the anabolic effect of an ordinary well-balanced meal.
Leucine is an extremely interesting amino acid for athletes. About 3 g of the stuff will increase the impact of the proteins in your diet on your muscles. Muscle cells ‘see’ leucine and, depending on the amount of leucine they ‘see’, they decide how hard their anabolic machinery needs to work. It’s hardly surprising that masses of natural bodybuilders swear by leucine, and add it regularly to their protein shakes.
Some sports nutritionists have wondered whether leucine boosts the anabolic stimulus of all sorts of protein. For one thing, amino acids enter the blood quickly. Even if you take them in combination with proteins that are digested slowly, the concentration of amino acids in the blood increases within an hour.
This is not the case for amino acids that you ingest in the form of protein. If you consume ‘fast’ whey protein, the amino acids in the whey make their way relatively quickly to your blood stream – not as fast as consuming separate amino acids, but faster than many other protein types, such as casein. Soya protein is a bit slower than whey, but faster than casein. The protein in beef, boiled and fried eggs is slower than casein.
So does leucine work when combined with a slow protein? Can muscle cells do anything with the anabolic stimulus from leucine if the amino acids in a slow protein still haven’t managed to find their way to the muscle tissue?
The Dutch researchers answered this question in their study. They gave 12 men, average age 74, a shake containing 20 g casein [PRO], and 12 other men a shake containing 20 g casein and 2.5 g leucine [PRO+LEU].
The amino acid phenylalanine in the casein was labelled so that the researchers could see whether it was absorbed by the muscle tissue. The researchers took cells samples out of the men’s leg muscles just before intake, after 2 hours and after 6 hours, and measured the amount of labelled amino acid from the casein had been absorbed by the muscle cells. Supplementation with leucine had increased the amino acid uptake.
Leucine co-ingestion improves post-prandial muscle protein accretion in elderly men.
Wall BT, Hamer HM, de Lange A, Kiskini A, Groen BB, Senden JM, Gijsen AP, Verdijk LB, van Loon LJ.
Source
Department of Human Movement Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, PO Box 616, Maastricht, 6200 MD, The Netherlands.
Abstract
BACKGROUND & AIMS:
It has been speculated that the amount of leucine in a meal largely determines the post-prandial muscle protein synthetic response to food intake. The present study investigates the impact of leucine co-ingestion on subsequent post-prandial muscle protein accretion following the ingestion of a single bolus of dietary protein in elderly males.
METHODS:
Twenty-four elderly men (74.3±1.0 y) were randomly assigned to ingest 20 g intrinsically L-[1-(13)C]phenylalanine-labeled casein protein with (PRO+LEU) or without (PRO) 2.5 g crystalline leucine. Ingestion of specifically produced intrinsically labeled protein allowed us to create a plasma phenylalanine enrichment pattern similar to the absorption pattern of phenylalanine from the ingested protein and assess the subsequent post-prandial incorporation of L-[1-(13)C] phenylalanine into muscle protein.
RESULTS:
Plasma amino acid concentrations increased rapidly following protein ingestion in both groups, with higher leucine concentrations observed in the PRO+LEU compared with the PRO group (P<0.01). Plasma L-[1-(13)C]phenylalanine enrichments increased rapidly and to a similar extent in both groups following protein ingestion. Muscle protein-bound L-[1-(13)C]phenylalanine enrichments were significantly greater after PRO+LEU when compared with PRO at 2 h (72%; 0.0078±0.0010 vs. 0.0046±0.00100 MPE, respectively; P<0.05) and 6 h (25%; 0.0232±0.0015 vs. 0.0185±0.0010 MPE, respectively; P<0.05) following protein ingestion. The latter translated into a greater muscle protein synthetic rate following PRO+LEU compared with PRO over the entire 6 h post-prandial period (22%; 0.049±0.003 vs. 0.040±0.003% h(-1), respectively; P<0.05).
CONCLUSION:
Leucine co-ingestion with a bolus of pure dietary protein further stimulates post-prandial muscle protein synthesis rates in elderly men.
Copyright © 2012 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.
PMID: 23043721 [PubMed – in process]
