Leucine is an essential amino acid that plays a vital role in muscle protein synthesis (MPS), making it an important nutrient for athletes, bodybuilders, and weekend warriors alike. But which foods are rich in leucine, and how much do you need to consume? Here, we’ll explore the answers to these questions and more, including the benefits of leucine, the risks of deficiency, and foods rich in leucine.
Overview of Amino Acids
Amino acids are the building blocks of proteins. There are 20 amino acids1, and they are divided into two categories: essential amino acids and non-essential amino acids.
Essential amino acids, including branched-chain amino acids (BCAAs) (leucine, isoleucine, and valine), are not produced in sufficient quantities and must be obtained through the diet. On the contrary, non-essential amino acids can be synthesized by the body.
Essential amino acids are involved in the production of protein, which is an essential nutrient for optimal health and multiple bodily functions. Protein synthesis is the process by which the body builds and repairs tissues, including muscles, organs, and cells. In addition, protein plays a vital role in maintaining and building muscle mass after exercise. When protein synthesis is activated, all 20 amino acids are needed to support this process.
BCAAs are receiving special attention in the fitness industry for their role in MPS and post-workout recovery. Leucine is a branched-chain amino acid that is particularly important for enhancing muscle growth and recovery.
What Is Leucine? Why Is It Important?
Leucine is an important amino acid that is important for MPS and overall health. After a protein-rich meal, the amount of leucine in the blood increases, and so does the level of leucine. Leucine triggers a signaling system in the muscles called mTOR, which then stimulates mechanisms involved in protein synthesis.
So, how much leucine should you consume per day to support muscle growth and repair? For best results, Layman recommends consuming about 2 to 3 grams of leucine per meal. For example, one large egg contains about 0.6 grams of leucine, making it a convenient and affordable source.
While leucine is essential for muscle growth and repair, some research suggests that consuming excessive amounts of leucine alone may not provide additional benefits. For this reason, Lyman says it’s wise to start with breakfast and stagger your leucine intake throughout the day, rather than trying to cram all of your leucine into one meal.
According to an older 2008 study, a diet deficient in leucine may hinder the activation of mTOR and hinder MPS, which can adversely affect muscle growth and repair. In addition, insufficient leucine intake can lead to muscle atrophy and a decline in muscle strength over time. That’s why eating leucine-rich foods is essential to ensure you’re meeting your recommended daily intake and supporting muscle health.
While leucine is important, other amino acids are also important. Therefore, consuming a variety of high-protein foods is ultimately the best way to support your muscle-building goals and overall health.
What if You’re Vegan?
Plant proteins typically contain lower levels of leucine compared to animal proteins. For example, grains like wheat and quinoa have leucine levels of less than 7%, while legumes like soybeans or peas have leucine levels of around 8%. On the other hand, chicken breast has a leucine content of about 12%.
However, with a careful diet plan, vegetarians and vegans can get enough leucine to support muscle growth and overall health.
Because plant-based protein may not provide optimal amounts of leucine alone, plant-based dieters can ensure adequate leucine intake by combining different plant-based protein sources. For example, eating legumes, grains, nuts, and seeds can produce a complete protein profile that provides all essential amino acids, including leucine.
Additionally, prioritizing leucine-rich plant foods such as tofu, tempeh, edamame, pumpkin seeds, and certain legumes can further increase leucine intake.
For vegetarians, it’s simple to get enough leucine by consuming dairy products and eggs. Vegetarians need to consider supplementing with protein sources, such as corn, soybeans, and rice. However, modern commercially available protein isolates and essential amino acid supplements, often from vegetarian sources, tend to be higher in leucine.
Leucine Benefits:
1. It can reduce age-related muscle loss.
A study published in the International Journal of Sports Nutrition and Exercise Metabolism found that leucine supplementation significantly increased MPS in older adults, suggesting a potential role in fighting sarcopenia, an age-related type of muscle loss.
Another review found that leucine supplementation significantly improved sarcopenia, which included improvements in lean muscle mass. The benefits in terms of muscle strength have shown mixed results.
2. Combined with resistance training, it promotes muscle growth and recovery.
Research published in the Journal of Sports Medicine and Physical Health has shown that leucine supplements, combined with resistance training, significantly increase muscle mass and strength more than placebo. This suggests that leucine has the potential to promote muscle growth and recovery. More research is needed to further support these benefits.
3. It can enhance bone health.
A study published in the Journal of Bone and Mineral Research investigated the relationship between dietary leucine intake and bone mineral density in postmenopausal women. The results of the study showed a positive correlation between leucine intake and bone mineral density, suggesting a potential role for leucine in promoting bone health.
Another study found that when participants took a whey supplement rich in vitamin D, calcium, and leucine, there was a small positive increase in bone mineral density.
Leucine-rich foods:
- Soybeans: 3.3 grams per 100 grams
- Pumpkin seeds: 2.4 grams per 100 grams
- Chicken: 2.3g/100g
- Hemp seeds: 2.2g/100g
- Tuna: 1.9g/100g
- Lentils: 1.8 grams per 100 grams
- Black beans: 1.7 grams per 100 grams
- Peanuts: 1.7 grams per 100 grams
- Salmon: 1.6 grams per 100 grams
- Almonds: 1.5 grams per 100 grams
- Chickpeas: 1.5g/100g
- Beef: 1.3 grams per 100 grams
- Cottage cheese: 1.1 grams per 100 grams
- Eggs: 1.1 grams per 100 grams
- Oats: 1.0 grams per 100 grams
Example of a Leucine Meal Plan
To help you meet your daily leucine and protein needs, here’s a sample three-day meal plan that includes a variety of delicious and leucine-rich options.
Day 1:
Breakfast: Greek yogurt, topped with mixed berries and pumpkin seeds.
Lunch: Grilled chicken breast salad with mixed vegetables, cherry tomatoes and almond slices.
Dinner: Grilled salmon with quinoa and steamed broccoli.
Snack: boiled eggs and a handful of pistachios.
Day 2:
Breakfast: Oatmeal cooked in almond milk and topped with banana slices and chia seeds.
Lunch: lentil soup with spinach salad and avocado slices.
Dinner: Grilled tofu stir-fried with a variety of colorful vegetables and brown rice.
Snack: Greek yogurt with peach slices and a small handful of pumpkin seeds.
Day 3:
Breakfast: Scrambled eggs with spinach and feta cheese.
Lunch: Quinoa salad with chickpeas, diced cucumbers, cherry tomatoes and lemon vinaigrette.
Dinner: Grilled lean steak with roasted sweet potatoes and sautéed asparagus.
Snack: cottage cheese with pineapple chunks and a handful of almonds.