Can You Get All the Protein You Need from Plant Foods?

Nutrition experts have been telling us for over 100 years that protein is more important than carbohydrates in a healthy diet. Every cell in the body needs the essential amino acids digested from protein every day.  

These are nutrients our bodies can't make and can't store, at least for much more than about 24 hours. When the body starts to reassemble its own proteins from amino acids, it has to have the right amino acids in the right order, or it will tear down non-essential tissues, like muscle and immune cells, to release them.

An entire diet industry has developed around the incorrect idea that we have to consume complete protein every three hours to stay alive, begging the question of why people don't die in their sleep unless the sleepwalk to the refrigerator to make salami sandwiches. The simple fact is, however, we don't need as much protein as the diet food vendors and protein powder makers would like us to believe, and we don't need to get protein from meat, fish, eggs, or dairy, with the right planning.

Meat and Protein

Any nutritional expert who claims that eating animal foods is essential for health makes an argument that animal foods are superior for protein because they contain "complete" protein. A complete protein contains all the amino acids needed to make human proteins, in the right proportions.

Amino acids are like Lego blocks

They snap together in the right order to make proteins. If a single amino acid is missing, or replaced with another amino acid, or put in the wrong order, the protein will not do its work or fit in a tissue. Proteins contain from 2 to 27,000 amino acids in a precise order coded by genes. The 24 amino acids the human body uses can be joined into chains to make over 50,000 different proteins.

A child or adult has to get histidine, isoleucine, leucine, lysine, methionine, phenylalanine, taurine, threonine, tryptophan, tyrosine, and valine each and every day (although not at each and every meal). Babies also have to get arginine and carnitine from food or breast milk. Humans at any stage of life can  make alanine, aspartic acid, cysteine, GABA, glutamic acid, glutamine, glycine, homocysteine (which is actually essential to regulating certain neurochemicals), hydroxyproline, and proline from other amino acids, if the other amino acids are available in sufficient amounts.

Our bodies are "meat," and other animal flesh is also "meat," containing the same amino acids. The idea that if we just meat all our protein needs are taken care of, however, is not necessarily so. Here is why:

• Adults need a bare minimum of about 30 grams of complete protein (containing all the essential amino acids and enough total protein to make the non-essential amino acids) every day to keep tissues from breaking down.
• Most vegetarian or vegan diets contain 80 to 100 grams of total protein daily.
• We "recycle" another approximately 100 grams of complete protein every day in the form of saliva and digestive juices, in effect digesting non-essential parts of our own bodies to keep protein in balance.
• The human body cannot store amino acids indefinitely, but various buffers keep them available for approximately 24 hours before breaking them down into sugar and ammonia.

Is Meat Essential?

It is hard to become protein-deficient even on a vegan diet, although some people manage to do this (and some meat eaters also develop protein deficiencies). When vegans become deficient in amino acids, there are usually certain predictable problems:

• Eating extremely high-carbohydrate or high-sugar foods with low protein levels for several days deprives the lining of the intestine of the glutamic acid it needs to regenerate its lining. The lining of the intestine has to get this amino acid to be able to absorb the other amino acids.
• Whole grains and leafy vegetables contain a compound called phytate, which binds calcium, iron, magnesium, manganese, and zinc. When zinc is deficient, appetite increases. If this results in eating even more whole grains and leafy vegetables, zinc can continue to be deficient and appetite increased even more.
• Vegan diets are often deficient in the amino acid cysteine.

These predictable problems can be prevented with the help of five vegan and vegetarian high-protein food groups.