L-leucine
What is L-leucine and where does it come from?
L-leucine (C6H13NO2) is an essential branched-chain amino acid (BCAA) that is broken down into fat structures. The other two essential BCAAs are L-valine and L-isoleucine. L-leucine cannot be produced by the body itself and must therefore be supplied through food. This amino acid is found in nuts, brown rice and whole wheat products, among other things.
What does L-leucine do? And which scientific studies prove this?
L-leucine makes up around eight percent of the total amount of amino acids in the body's protein structures and is the amino acid with the fourth highest concentration in skeletal muscle.
As one of the three BCAAs, L-leucine is essential for general health. L-leucine has numerous medical and sporting applications. L-leucine has numerous positive effects on athletic performance. It helps maintain muscle tissue (1), provides the body with energy during heavy exertion (e.g. during intense exercise) (2), maintains muscle glycogen levels (glucose stored in the muscle to provide energy for muscle contractions), maintains a positive nitrogen balance and improves the ability to concentrate, which can decrease when the intensity of physical activity increases (3). L-leucine also supports the healing of bones, skin and muscle tissue. In addition to this, L-leucine may increase the release of growth hormone - a hormone that can lead to healthier joints, a slowing (and possibly even a reversal) of the aging process, a reduction in body fat and an increase in strength and muscle mass. The effects of L-leucine in the diet are profound. As the "strongest" of the three BCAAs, L-leucine is known as a "limiting nutrient," meaning that you must have enough L-leucine relative to other amino acids in order for your body to use what you eat. Simply put, this means the following: If you're L-leucine deficient, your body won't be able to use the rest of the protein you eat, regardless of how much protein you consume. And as long as you don't have enough L-leucine, the money you spend on high-quality food and supplements is wasted. To get the most out of what you eat, you need two parts L-leucine and two parts L-valine for every part L-isoleucine you consume. If you do not maintain this exact ratio, you will not achieve optimal results. In the medical field, L-leucine has several applications, including the treatment of amyothrophic lateral sclerosis - also known as Lou Gehrig's syndrome. This is a neuromuscular disorder that affects more than 30,000 people in America and is newly diagnosed 5,000 times each year.
Why is it called Lou Gehrig's syndrome?
In the United States, ALS is often referred to as Lou Gehrig's syndrome because New York Yankees star Lou Gehrig was diagnosed with ALS in the 1930s. Lou Gehrig's syndrome stands for a disease called amyotrophic lateral sclerosis or ALS for short. The official name is made up of the following Greek words:
- "a" for without
- "myo" for muscle
- "trophic" for nutrient supply
- "lateral" for side (of the spine)
- "sclerosis" for hardening or scarring
L-leucine has shown promise as an adjunct to conventional ALS therapy, as it can increase muscle strength in ALS patients by working together with the other BCAAs to activate glutamate dehydrogenase (4). People suffering from liver or kidney problems may benefit from L-leucine supplementation as it can increase the rate of liver protein synthesis and improve breathing quality and sleep quality in people with kidney dysfunction (5). Finally, L-leucine may be able to lower blood glucose levels and normalize and control insulin secretion and insulin function. For this reason, L-leucine can provide helpful support for diabetics.
Who needs L-leucine? And what are the symptoms of a deficiency?
L-leucine is an essential amino acid. For this reason, everyone needs L-leucine to maintain general health. L-leucine deficiency can result in muscle wasting, depression, low energy levels, muscle weakness and blood sugar irregularities such as hypoglycemia.
Leucine Update
Leucine has the unique ability to stimulate muscle protein synthesis independently of insulin. Leucine's anabolic actions work through the mTor pathway, which promotes cell growth (mTor stands for mammalian Target of Rapamycin). Scientists have discovered that leucine is the most important amino acid for protein synthesis.
Strength training slows down the absorption of leucine and BCAAs
Many bodybuilders know that consuming a mixture of BCAAs or leucine before weight training enhances the anabolic effect of training, but new research suggests that weight training may slow the absorption of BCAAs and leucine. Scientists measured the maximum concentration of amino acids (BCAA, leucine and glutamine) at rest and before intense resistance training. Subjects consumed 50 mg of leucine (4 grams total), BCAAs (4 grams of leucine, 1 gram of isoleucine, 1 gram of valine) or glutamine (4 grams) per kilogram of body weight immediately before performing a standardized training session with weights to stimulate muscle hypertrophy. Consuming 4 grams of leucine is roughly equivalent to eating 230 grams of beef. Here are the results:
Maximum peak blood concentrations: - Leucine: o At rest: 67 minutes o Before resistance training: 90 minutes o 23 minutes delay
- BCAA o Resting state: 72 minutes o Before resistance training: 78 minutes o 6 minutes delay
- Glutamine o Resting state: 60 minutes o Before resistance training: 57 minutes
The scientists speculated that the delay in the maximum peak concentration of leucine and BCAAs was related to delayed gastric emptying, as blood flow is diverted from the stomach to the exercised muscles, slowing down the digestion process. The scientists were puzzled by the fact that this delay was not also observed with glutamine. They speculated that glutamine is metabolized in a different way and resistance training does not slow down the kinetics of absorption. The bottom line from this is that leucine should be taken at least 90 minutes before exercise so that maximum leucine concentrations are already present in the blood when you arrive at the gym. (Mero A, Leikas A, Knuutinen J, Hulmi JJ, Kovanen V. Effect of strength-training session on plasma amino acid concentration following oral ingestion of leucine, BCAAs or glutamine in men. Eur J Appl Physiol. October 21, 2008)
Leucine could be the perfect supplement for low-carbohydrate diets
Previous research has shown that leucine stimulates insulin secretion, but it is not known how much this affects fat metabolism. The effect of leucine on protein synthesis is based on insulin-independent mechanisms, although a certain level of insulin is important for maximum effect. The way in which leucine develops its metabolic effects has not yet been fully researched. Scientists compared the insulin and glucose response to leucine (7 grams) and leucine (7 grams) & glucose (25 grams) in a study. The leucine dosage used corresponds approximately to the amount of leucine contained in a 350 gram steak. The scientists found that leucine on its own resulted in a moderate increase in insulin levels, although the increase was small compared to the combined administration of leucine and glucose. The combination of leucine and glucose resulted in a higher increase in insulin levels than was the case with glucose alone. The insulin response to the combined administration of leucine and glucose was 72 percent stronger than the insulin response to the administration of glucose without leucine. The administration of leucine alone resulted in a strong increase in glucagon concentration, but did not result in changes in blood glucose levels. The key point is that for bodybuilders on a low carbohydrate diet, leucine may be an excellent way to maintain anabolism in a caloric deficit environment while also maintaining a state of ketosis, as leucine administration does not raise blood glucose levels, the insulin response to leucine is only moderate, glucagon levels rise and the concentration of leucine in the blood rises sharply. Another interesting result of the studies was that leucine tends to induce a stronger feeling of satiety! (Kalogeropoulou D, Lafave L, Schweim K, Gannon MC, Nuttall FQ. Leucine, when ingested with glucose, synergistically stimulates insulin secretion and lowers blood glucose. Metabolism. December 2008:57(12):1747-52.)
Leucine the ultimate anti-catabolic supplement
Leucine could be the perfect competition supplement as it has strong anti-catabolic effects. Leucine is an essential amino acid capable of exerting anabolic effects in muscle tissue, with high doses of leucine also capable of promoting important anti-catabolic actions. Leucine has been shown to reduce muscle catabolism during weight loss, promote muscle healing and improve skeletal muscle protein turnover in the elderly. In a recent article published in the Journal of Nutrition and Metabolism, scientists described the anti-catabolic actions of leucine in humans.
In human studies, leucine supplementation clearly inhibits proteolysis in skeletal muscle (anti-catabolic effects) and there are several studies suggesting that the leucine concentration capable of preventing protein breakdown may be greater than the leucine concentration capable of maximally stimulating protein synthesis. This appears to be particularly the case in a catabolic environment. Under catabolic conditions, the muscle tends to become leucine resistant. However, leucine still prevents the breakdown of muscle tissue. (Zanchi NE, Nicastro H, Lancha AH Jr. Potential antiproteolytic effects of L-leucine: observation of in vitro and in vivo studies. Nutr Metab (Lond), July 17, 2008;5:20)