Animal vs. Vegetarian Protein Sources
One concept always brought up when debating animal versus plant protein is the completeness of the protein. Animal proteins offer a complete array of the amino acids our body needs, and has always been set as the golden standard of protein completeness. Vegetable proteins, on the other hand, are derided as being “incomplete”, or lacking in certain essential amino acids. This is true, but in a limited sense.
In reality, the only commonly lacking amino acid in plant-based protein sources is lysine, and plant-based proteins are only lower in it, not completely devoid of it. The amount of lysine considered necessary is a highly debated topic. Low estimates put it at 12 mg/kg, or 870 mg a day for a 160lb. adult, whereas high “safe level” estimates place it at 60 mg/kg, or 4350 mg a day. The estimated amount of lysine the average American consumes in a day is 7600 mg, which is 175% more than the amount even the highest recommendations place.
Different vegetables have different amounts of lysine, with some being close to or even above what animal products contain as a percentage of total protein. A few examples of high-lysine vegetables are all the legumes, spinach, quinoa and amaranth, pistachios, pumpkin seeds, apples, potatoes, and pineapples. Many more are close enough as to be considered good sources. As long as your diet consists of a variety of plant-based foods, it is unlikely you will consume too little lysine, or any other essential amino acid.
It is also not necessary to combine proteins in one meal, as was once taught. As long as your diet is diverse throughout the week, your body will be able to use the amino acids as they come.