Amino acids are the crucial regulators of protein synthesis. Leucine is one of the three branched-chain amino acids (BCAAs) and one of the nine essential amino acids (EAAs). Leucine comprises approximately 40% of the free essential amino acids in blood plasma, along with valine and isoleucine. Although several isolated amino acids can stimulate protein synthesis, leucine has a potent effect. Leucine can also regulate cellular processes such as protein synthesis, tissue regeneration, and metabolism. Therefore, leucine supplementation has been studied in various conditions such as ageing, muscle loss, protein or energy deprivation, obesity, and diabetes mellitus.
Being an essential amino acid, our body can not synthesize it; hence has to be supplied externally. Some leucine-rich foods include beans, cottage cheese, sesame seeds, eggs, lentils, peanuts, spirulina, hemp and pumpkin seeds.
Here is the leucine content of some foods per 100 g, as given by ICMR.
- Jowar: 12 g
- Cow’s Milk: 10.6 g
- Whole Egg: 7.9 g
- Sardine: 8.2 g
- Dry Maize: 12.2 g
- Ragi: 8.9 g
- Soybean: 8.1 g
- Black Chana: 8.8 g
- Spinach: 8.7 g
- Chicken breast: 7.9 g
In addition to dietary sources, some studies claim that leucine supplementation also improves nutritional status, muscle function, and physical performance.
Let’s discuss in detail how leucine benefits our body.
- Promote muscle growth: Leucine is fondly called an anabolic amino acid due to its potential to promote muscle growth and act as an ergogenic agent. Leucine supplementation during exercise is responsible for muscle growth, strength and performance. To examine the same, a study was conducted in 2019. Researchers observed that three grams of leucine supplementation per day for 45 days significantly enhanced gym goers’ muscle growth and strength performance.
- Prevent muscle breakdown: There could be some days when you are off training due to many reasons like taking a rest or a break, injury or illness. During these recovery periods, no one would prefer losing the muscle mass that took months of hard work to build. Fortunately, leucine could help us out here. Nutritional research suggests that leucine can prevent muscle breakdown. In another study mentioned in the British Medical Journal, leucine amino acid was given for 12 weeks to the elderly in combination with moderate training. At the end of the study, investigators found that leucine counteracted the negative effects of eccentric exercise and reduced exercise-induced strength loss.
- Provide strength and endurance: Branched-chain amino acids (BCAAs), particularly leucine, undergo increased oxidation during prolonged endurance exercises like running a marathon, indicating that raising the levels of leucine in the blood through supplementation could benefit endurance performance and skeletal muscle protein synthesis. For these reasons, one can not overlook the potential of BCAA supplementation to enhance both endurance and strength exercise performance.
- Support immune health: T-cells play a critical part in providing immunity against foreign substances. Evidence suggests that leucine is vital for the immune response as it plays a role in T-cell activation.
- Improve blood sugar levels: Leucine supplementation might also help people with diabetes manage their blood glucose levels. It supports glucose metabolism by exerting acute and chronic effects on pancreatic β-cells, releasing insulin hormone.
To sum up, we can say that leucine is an essential component of our daily protein requirements for general health. Although there is no recommended dosage of leucine as per the health authorities, studies suggest that 10 g leucine per day may offer performance-enhancing properties and support overall health. It is advisable not to take leucine in excess, say more than 30 g per day, to avoid side effects like gastro-intestinal disturbances, a negative nitrogen balance and low sugar levels.