Question

How is limiting amino acid concern for vegetarian athlete

Answer 1

Athletes have higher demands for energy and hence, proteins are used for meeting these energy demands. Plant based diets have less amounts of Branched Chain Amino Acids (BCAA) as compared to animal based diets. BCAA amino acids are leucine, isoleucine and valine. They also lack important essential amino acids. These EAAs and BCAA (a part of EAA) will be therefore limiting nutrients in vegetarian diet.

Common limiting nutrients present in plant based diets are lysine, methionine, isoleucine, threonine and tryptophan. Limiting amino acids will lead to inadequate protein synthesis. Lysine is mostly absent in cereal grains, although beans and legumes are rich in them. Lysine is required for production of carnitine too, which is involved in breakdown of fatty acids for energy. It also reduces cholesterol levels and is involved in production of collagen for bone, cartilage and skin. Limiting amino acids are mostly essential amino acids that are required for MPS. Proteins which are rich in essential amino acids are known to reduce protein breakdown. Hence, increased EAA will help the athlete to add muscle mass. Myofibrillar-MPS following resistance exercise is only stimulated when all EAA are provided to the athlete.

Leucine is a BCAA that is required for muscle protein synthesis (MPS) as a trigger. MPS is required by athletes for recovery and adaptation from exercise. There is less hypertrophy of muscles when plant based diets are consumed by vegetarian athletes. Plants proteins are also less digested than animal proteins. BCAA maximize the anabolic state by stimulating MPS. BCAA reduce fatigue as they prevent muscle breakdown. Recovery from exercise, adaptation and anabolism requires a positive net protein balance, which is balance between protein synthesis and breakdown in muscles. Lean mass has to be preserved by athletes via increase protein intake and the diet should promote satiety.