Of the 20 amino acids the human body needs to function, nine are actually essential. Of those nine, three are branched-chain amino acids (BCAAs). Leucine is both an essential amino acid and a BCAA. All BCAAS are vital for building and repairing muscles, and some researchers say leucine may be the most important of all.
BCAAs got their name from their molecular structure. They are essential because the body can't make them, but they are available in food sources. The other BCAAs besides leucine are valine and isoleucine. Research has been mostly mixed about whether BCAA supplements improve muscle mass or muscle recovery over dietary sources alone.
Recommended Daily Amounts of Essential Amino Acids | |
Amino Acid | Recommended Daily Allowance |
| Histidine | 14 milligrams |
| Isoleucine | 19 milligrams |
| Leucine | 42 milligrams |
| Lysine | 38 milligrams |
| Methionine | 19 milligrams |
| Phenylalanine | 33 milligrams |
| Threonine | 20 milligrams |
| Tryptophan | 5 milligrams |
| Valine | 24 milligrams |
What Are the Benefits of Leucine?
Leucine performs several functions in the body. It helps regulate blood sugar, improves wound healing, and makes growth hormone. But leucine is best known for its role in the muscular system, including these functions:
Muscle building
Scientists know that leucine is vital for muscle building and muscle repair. They aren't sure whether supplementing with leucine and other BCAAs will build or repair muscles faster.
According to the National Institutes of Health, BCAA supplements don't seem to boost endurance but may improve muscle mass when combined with strength training. Also, it's not clear if using supplements is superior to boosting protein in the diet.
Muscle recovery
Leucine may help muscles recover after intense exercise. In one study of highly fit cyclists, taking leucine after a workout increased their speed the next day. They also reported less overall tiredness.
Prevention of muscle loss
Leucine has been shown to improve strength in older adults, especially those with sarcopenia (muscle loss). Exercise may further add to this benefit. In one study, older men increased their synthesis of protein even though they did not lack protein.
Weight control
Leucine seems to play a role in weight control. In animal studies, leucine supplements increased the response to leptin, a hormone that regulates appetite.
Some researchers believe that the success of high-protein diets may be due in part to the role of leucine in regulating blood glucose.
Foods With Leucine
Getting your leucine and other BCAAs from food is safest for most people. The FDA does not regulate supplements, so they may not contain precisely what they say they do. The supplements can have side effects or interact with other medications. Dietary sources are mostly safe, easy to afford, and good in taste.
Nutrition labels for food don't list the individual amino acids, so most people should just be sure they are getting enough protein. Adults need about 7 grams (g) of protein per 20 pounds of body weight, so a person weighing 140 pounds would need 49 grams.
Both plant and animal food can fulfill your protein needs. Once, animal foods were considered superior for protein as they contain all the essential amino acids.
Dietitians now say that it is not necessary to consume all the essential amino acids at one time. Instead, they can be spread over the course of a day, making it much easier for people who are vegan or vegetarian to meet the recommendations for protein.
There are many dietary sources for leucine and other BCAAs. Consider these healthy sources of amino acids:
Salmon
Get your amino acids from salmon, and you'll also get omega-3 fatty acids. There are some health concerns about farmed salmon. Choose wild-caught or limit your servings per month.
Chickpeas
These nutritional superstars contain 7 grams of protein and 6 grams of fiber in just half a cup, and they are high in iron, too. Enjoy them as hummus or add them to soups, stews, curries, and salads.
Brown rice
Try brown rice instead of white. It has a nutty taste and a slightly chewy texture that many people enjoy.
Eggs
Even the American Heart Association says that an egg a day is okay. You'll get 6 grams of protein in one egg.
Soybeans
This versatile legume is available in a variety of forms, including tofu, tempeh, edamame, and roasted soybeans. Today, texturized soy protein is readily available in supermarkets. It can substitute meat in many dishes.
Nuts
Almonds, Brazil nuts, and cashews are good sources of essential amino acids. So are peanuts, although they are technically legumes instead of nuts.
Beef
Beef is one of the best sources of amino acids. To reduce your intake of fats and cholesterol, choose a lean cut or try grass-fed beef.
What Are the Side Effects of Leucine?
Leucine may lower the levels of glucose (or sugar) in your blood, as this amino acid can make your body release more insulin. If you have diabetes or take insulin, don't take leucine supplements without talking to your doctor.
If you take too much leucine, it may cause deficiencies of vitaminsB3 and B6 in your body.
Don't take leucine if you have maple syrup urine disease, as your body can't break down amino acids.
Leucine FAQs
Does Greek yogurt have leucine in it?
Yes, Greek yogurt is an excellent source of leucine.
How many eggs do I need to eat for 3 grams of leucine?
You'd need to eat about six eggs to get 3 grams of leucine.
Is L-leucine worth taking?
Most people usually get enough leucine from their everyday diets and don't need to take a supplement. But certain people, including athletes and the elderly, may benefit from a supplement. Always talk to your doctor before starting any new medications or supplements.
