Protein is a vital macronutrient that makes up every cell of your body. Proteins build muscle and regulate all chemical reactions to preserve life. Of the twenty amino acids that the body needs to create protein, nine are essential amino acids (EAAs) which can not be synthesised by the body and need to be regularly supplemented in foods to meet protein requirements. The nine EAAs are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Most plant proteins present in smaller quantities and lack one or several essential amino acids. It is therefore important that we eat a wide variety of plant-based foods to deliver all EAAs for our bodily needs. The few plants that contain a complete protein include soybean, chia, quinoa and buckwheat.
Many vegetarian and vegan Internet resources will talk about protein combining, which means that you need to eat specific protein sources together to create a complete protein (all 20 amino acids), such as brown rice with chickpeas or barley with lentils. However, protein combining is old science and sourcing your proteins should not be a complex task in food preparation. The body has ample protein and amino acid stores to support any immediate dietary amino acid insufficiencies. It is, however, vital that you maintain an optimal amino acid pool in your body by maintaining a broad dietary intake of plant-based foods.
We also need to keep in mind that not all proteins are equal in digestibility and bioavailability.
Animal proteins have the better bioavailability because they contain a complete protein (contain all 20 amino acids). Of all the animal proteins eggs, milk and whey powder have the highest digestibility and bioavailability.
All plants contain antinutrient factors such as phytates, glucosinolates, tannins, isothiocyanates and digestive enzyme inhibitors. Antinutrient factors bind with proteins or inhibit enzymes to assimilate proteins.
Considerable amounts of antinutrient factors are present in seeds, cereals, nuts, pulses and legumes. The good news is that many of these inhibitors can be diminished with either heat (as in cooking or baking), soaking, sprouting and fermenting. With proper preparation plant protein, availability is approximately 50-80%. You can also supplement your protein from vegetable protein powders which mostly come in a concentrated form with a digestibility of more than 95%.
If you are one of these people that needs some extra protein you can always supplement your diet with some dairy or plant-based protein powder. Supplementation can also include calcium, iron, B12 and zinc and will be discussed under each nutrient section.
The symptoms of insufficient protein or specific essential amino acids may show as muscle wasting or difficulty in gaining muscle mass and underweight. Also, mood changes including depression and anxiety, loss of menstrual cycle, anorexia, anaemia, muscle weakness, fatigue, malabsorption and digestive issues, reduced liver function, brittle nails, dull hair, frequent infections, pale or pasty complexion and lack of appetite.
(Many of these symptoms are not exclusive to protein deficiency and it is recommended to seek professional advice if you experience any of these symptoms)