In reviewing the previous two articles, proteins contain 20 amino acids. Humans make 11 and must consume the remaining nine essential amino acids (EAAs) dietarily. Proteins vary in their biological availability/usability depending on the ratio of these nine EAAs.  

The degree of usable protein foods has, varies. Fruits have the lowest quantity of protein and have substantially different EAA ratios than a fully complete protein like egg-whites. Other vegetation such as vegetables, grains, greens, lentils, mushrooms, and beans, have higher quantities of proteins. Regardless, their EAA ratio differs substantially from the ideal. Notwithstanding, if sufficient calories are consumed, a healthy sedentary individual is unlikely to become protein deficient (Messina & Mangels, 2001). However, others, like an athlete engaged in heavy resistance training, may have an interest in consuming higher quantities of total, biologically available protein. 

This article explains the practicality of combining various plant sources to increase protein completeness, the circumstances in which protein supplementation is advisable, and individual amino acids that may increase performance.  

Combining Foods 

Specific foods will help illustrate how the quantities and completeness of proteins in foods matter. For example, 100 Calories of egg whites contains 21g of protein. It also has the ideal EAA ratio making all 21g usable. However, 100 Calories of broccoli only contains 2.5g of protein and only about half of this is biologically available. The limited methionine in broccoli prevents assembly of many of its other amino acids into proteins. Another example is millet, with 3g of protein per 100 Calories. Lysine is its limiting amino acid (LAA) making its protein also only about half complete.  

Generally, methionine is the LAA in most plant foods and never excessively abundant. Nevertheless, some plant foods, such as millet, with an LAA of lysine, have higher levels of methionine. So, when consumed with broccoli, which has excessive lysine and low methionine, the complementary EAA ratios increase protein usability.  

Further improving usability, amino acids not used to form proteins from one meal are not immediately degraded. They can form proteins with amino acids from subsequent meals. So, amino acids from oatmeal at breakfast can combine with the amino acids from legumes at dinner to increase protein usability. 

Protein Supplementation 

Athletes and those recovering from injury need more protein and may benefit from supplementation. Many may tolerate animal sources such as whey and casein. Peas, soy, and rice, may be adequate vegetable sources. Given the complexity of EAAs, if stakes are high, consulting a registered dietitian familiar with EAAs and sports medicine may be worthwhile. 

Supplementing with particular amino acids may benefit athletes. For example, the branched chain amino acids leucine, isoleucine, and valine are more abundant in muscle tissue. Consuming these with sufficient protein may improve muscle repair. Further, evidence supports that isoleucine and valine help regulate energy levels and protein synthesis. Creatine has also been shown to increase muscle growth after resistance training. Additionally, arginine and citrulline can boost nitric oxide levels improving blood flow during exercise. 

Conclusion 

A healthy sedentary individual, consuming adequate Calories, even if on a vegan diet, is likely not protein deficient. However, an athlete wishing to build and retain muscle, may benefit from consuming protein toward the upper range of the 0.8g/kg to 2.2g/kg body mass recommendation. For those recovering from surgery, this can increase to 2.5g/kg. Strategically combining plant sources can improve the EAA ratio and protein usability. But athletes not consuming many animal sources may benefit from supplementation. Supplementing with specific amino acids may additionally optimize performance.  

Patrick Traynor, PHD, MPH, RD, CPT is a registered dietitian with an insurance-based practice, MNT Scientific in South Lake Tahoe, Sacramento, Minden, and does telehealth. Inquiries can be directed to Dr. Traynor at (530)429-7363 or info@MNTScientific.com.