Proteins were first described by the Dutch chemist Gerardus Johannes Mulder and named by the Swedish chemist Jöns Jacob Berzelius in 1838. It was said to be the most sacred nutrient. The term "protein" to describe these molecules was proposed by Mulder's associate Berzelius; protein is derived from the Greek word πρώτειος (proteios), meaning "primary", "in the lead", or "standing in front".
Early nutritional scientists such as the German Carl von Voit believed that protein was the most important nutrient for maintaining the structure of the body, because it was generally believed that "flesh makes flesh". Protein was synonymous with meat, and this connection has stayed with us for well over 100 years. We have been taught that protein is the core element of animal based foods.
Carl Voit found out that man needed only 48.5g of protein per day, but nonetheless he recommended a whopping 118g a day, because of the cultural bias of the time. It was considered you can't have too much of a good thing.
Voit had been mentor for several well-known nutrition researches of that time, including Max Rubner(1854-1932) and W. O. Atwater(1844-1907). Both students followed the advice for their teacher and this is how it snow-balled. Rubner stated, that protein intake, meaning meat, was a symbol of civilization itself: "A large protein allowance is the right of civilized man." Atwater went on to organize the first nutrition laboratory at the United States Department of Agriculture (USDA). He recommended 125g of protein per day! It's like cattle herder recommending to eat as much of his beef as possible.
Rich people ate meat and poor ate mostly plant foods such as potatoes and bread. The lower classes were considered lazy and inept as a result of not eating enough meat.
Proteins function as enzymes, hormones, structural tissue and transport molecules, all of which makes life possible. They are constructed as long chains of amino acids. They wear out in the body on a regular basis and must be replaced by consuming foods that contain protein. When digested, these proteins replace the worn out amino acids in the body.
About 8 amino acids that are needed for making our tissue proteins must be provided by food we eat. They are called "essential" amino acids, because our bodies cannot make them on their own. If our food lacks one of the eight essential amino acids, then the synthesis of new proteins will be slowed down or stopped.
Food proteins that are considered as "quality" proteins are those that provide us with right amounts and right kinds of amino acids needed to synthesize our new tissue proteins. The proteins of other animals are very similar to our proteins because they mostly have the right amount of each of the needed amino acids. This is the only reason animal based protein is considered high quality proteins.
While "low quality" plant based proteins are lacking one or more of essential amino acids, as a group, they do contain all of them. The concept of quality really means the efficiency how these proteins promote growth. It has nothing to do with being healthy or not. There are hundreds of researches done showing that low quality plant protein, which allows for slow but steady synthesis of new proteins, is the healthiest type of protein.
The focus on efficiency of body growth, as if it were good health, encourages the consumption of protein with the highest quality.
Even if it is known that plants have protein, there is still concern about its perceived poor quality. This has led people to believe that they must combine proteins from different plant sources during each meal to compensate the deficit of amino acids, which is not the case.
It is known that through enormously complex metabolic systems, the human body can derive all the essential amino acids from the natural variety of plant proteins that we counter every day. It doesn't require eating higher quantities of plant protein or to vigorously plan every meal.
Consumption of animal protein leads to changes in the concentration of certain chemicals in our blood. These chemicals are called biomarkers. As example, blood cholesterol is a biomarker for heart disease. It has been measured that six blood biomarkers are present with animal protein intake. Every single of these blood biomarkers are associated with cancer.
Animal based protein rises the blood cholesterol and having blood cholesterol levels above 150mg/dL, increases your chance of all kinds of cardiovascular diseases and heart diseases including stroke as well as heart attack. Liver cancer has strong association with high blood cholesterol. Read also: High blood cholesterol?
Diabetes is strongly associated with the over consumption of animal based foods and animal protein in particular. Diabetes brings increase in nervous system diseases, dental diseases and many other illnesses.
Consuming animal protein 21 g/day or more is closely correlated with kidney stones. When enough animal protein containing foods are consumed, the concentrations of calcium and oxalate in the urine increase sharply, usually within hours. The kidney is under constant, long term assault from increased calcium and oxalate which may result in kidney stones.
The critically important activation of the vitamin D in the body can be inhibited by acid-producing animal proteins.
Animal protein, unlike plant protein, increases the acid load in the body. Increased acid load means that our blood and tissues become more acidic. The body starts to fight the acidity. In order to neutralize the acid, the body uses calcium. Calcium is pulled from the bones which weakens them, putting them at a greater risk of fractures.
The animal protein consumed by many of people on daily basis is capable of causing substantial increases in urinary calcium. Doubling protein intake from animal based foods from 35 - 78g/day causes 50% increase in urinary calcium, which leads to greater increase in calcium loss hence bone fractures.
The more animal protein in the diet, the more acid in the body which leads into less vitamin D absorption. And being deficient in vitamin D can cause many serious health issues.
According to the recommended daily allowance(RDA) for protein consumption, we should get about 10% of our energy from protein, which means 50-60g per day. This is considerably more than the actual amount required. Only 5-6% of total calorie intake as protein is required to replace the amino acids. RDA recommends it like this to surely cover the 5-6% of proteins humans need. 9-10% can already be too much!
This goes regarding to animal based protein. Eating 10% of total calorie intake as plant based protein has no adverse effects.
If animal protein, which is found, of course, in all animal products, is causing us so much harm to our health, then are we really supposed to eat meat, dairy or eggs?!
*Information in this article is mostly from the book China Study by T. Colin Campbell. Buy from here: The China Study
Campbell has become known for his advocacy of a low-fat, whole foods, plant-based diet. He is the author of over 300 research papers and three books, The China Study (2005, co-authored with his son, Thomas M. Campbell II, which became one of America’s best-selling books about nutrition), Whole (2013) and The Low-Carb Fraud (2014). Campbell featured in the 2011 American documentary Forks Over Knives.
Campbell was one of the lead scientists of the China–Cornell–Oxford Project on diet and disease, set up in 1983 by Cornell University, the University of Oxford, and the Chinese Academy of Preventive Medicine to explore the relationship between nutrition and cancer, heart, and metabolic diseases. The study was described by The New York Times as “the Grand Prix of epidemiology“.