L-Leucine (C6H13NO2) is an essential branched-chain amino acid (BCAA) that's broken down in fat structures. The other two essential BCAA's are L-Valine and L-Isoleucine.
L-Leucine can not be made by the body, and must be acquired through food or dietary supplements.
It can be found in nuts, brown rice and whole wheat bread products.
L-Leucine comprises about eight percent of the total amino acid count in your body's protein structures; it is the forth most concentrated amino acid in skeletal muscle tissue.
As one of the three BCAA's, L-Leucine is essential to your basic health. It has athletic applications.
L-Leucine has many beneficial effects on sports performance. It helps preserve lean muscle tissue, it supplies the body with energy when under stress (i.e. when engaging in athletic activity), it preserves muscle glycogen (glucose stored in muscle tissue used to power muscular contraction), it maintains nitrogen balance, and it enhances thinking abilities that can decline as physical activity becomes more intense.
The effects of L-Leucine in the diet are profound. As the strongest of the BCAA's, L-Leucine is what's known as a "limiting nutrient" - meaning that you must have enough L-Leucine in proportion to other amino acids in order for your body to make use of what you eat. Simply: If you suffer from an L-Leucine deficiency, your body will not be able to make use of the protein that you give it - no matter how much protein you consume. And, unless you have enough L-Luecine, the money you spend on quality food and dietary supplements will be wasted.
To make the most of what you eat, you need two parts L-Leucine and two parts L-Valine for every one part of L-Isoleucine. You'll fail to get optimal results if you fall short of meeting this exact ratio.
That means that no matter how little or how much protein you ingested, its muscle-building effects (or lack thereof) were almost entirely controlled by the amount of one specific amino acid you had in your bloodstream.
And the name of that specific amino acid?
Leucine.
It seems clear now that Leucine stimulates protein synthesis and translation initiation and is likely the major amino acid responsible for the anabolic effects of a meal.(1)(2)
"At this point, it seems clear that most of the effects of amino acids on protein synthesis are mediated by Leucine."
— Martha Stipanuk, PhD, Cornell University
Just adding a few grams of Leucine to a meal, high protein or not-so-high protein, increases muscle protein synthesis by 50-70 percent in humans (3)(4) and increases protein turnover by over 500 percent!(5)
Apparently, orally administered Leucine stimulates muscle-protein synthesis by itself, independent of the insulin surge you get from a meal. However, it does seem that the role of insulin is permissive in that some rise in insulin is necessary to allow Leucine to do its work. (6)
The message is that Leucine is best used with a meal, rather than taken in-between meals by itself.
Additionally, adding Leucine to a 100% carbohydrate meal isn't the best idea, either. It seems the effects of Leucine are rate-limited if other amino acids aren't present.(6) That means that Leucine, while anabolic all on its own, won't do its best work unless there are at least some other amino acids present.
In short, a protein meal is good, but adding Leucine to it makes it much, much better.
Furthermore, it seems the change in Leucine concentration in the blood may be more important than the actual amount of Leucine in the blood, so you don't want to take Leucine non-stop.(1) It's better to take a scoop of it (about 5 grams) with a meal, let blood levels drop, and then take another scoop about 4 hours later.
"Supplemental Leucine allows for the muscle to achieve maximum protein synthesis and anabolic recovery."
Just add one 5-gram scoop to water, a protein shake, your workout drink, or just sprinkle it over your food. Just don't exceed four scoops (20 grams) per day.
L-Leucine is simple, it's economical, and by increasing the anabolic quality of food by 70%, it's oh-so effective.
