Module 2: Protein – Animal & Plant Sources


Proteins are biochemicals made up 20 amino acids that can be combined trillions of ways.

Amino acids are like the pieces of an erector set. We can assemble them into proteins.

In turn, protein is the primary building block of most life on Earth. Protein is the bricks forming our cells and bodies. Amino acids comprise the enzymes, hormones and other parts of our bodies.

We need proteins to function. It makes up about 20% of our bodies.

Therefore, we need adequate amounts of all 20 of the amino acids.

If one is short of any of the amino acids, then their body can’t make all the proteins, and they may come up short somewhere.

Because so much of our bodies are made up of proteins, proteins and amino acids are necessary for “building” — growth and repair.

Growing children need lots of protein.

So do athletes building muscle mass.

And people recovering from injuries and surgery.

We all need some.

But, unless we are still a growing child, a competitive athlete or recovering from a major physical trauma, not too much.1

In fact, most Americans eat far more protein than they need. Nutritional science now says to get around 0.8 or 0.9 of a gram per “healthy” kilogram of body weight.

That means to use the ideal weight, not the actual weight.

Multiply the ideal weight (in pounds) by four.

Divide by 10.

That’s how many grams of protein we need every day.

Though, it is affected by our physical activity level. If we sit in a chair all day, we don’t need that much. If we’re an athlete in heavy training, we need more.2, 3, 4

Animal vs. Plant Proteins

Structurally, amino acids are the same regardless of their source. Lysine is lysine whether it comes from meat or a vegetable.

The difference comes from the amino acid profiles of various sources. There are 20 amino acids. How many of each does a source contain? And in what proportions?

And what else are we consuming along with the protein?

For example, animal protein sources contain no fiber. Plant sources do.

Fiber has nothing to do with protein, but it is itself important in our diet. We need to consume plenty of it to excrete toxins from our body.


That stands for mechanistic (or mammal) target of rapamycin.

It’s a signaling pathway in our body. It tells cells to grow, grow, grow.

Therefore, it’s no surprise that protein helps to trigger this pathway.

Eating lots of protein, especially the amino acid leucine, is like a big truckload of bricks showing up at a construction site. The on-site supervisor (mTOR) tells the crew to get to work using those bricks to build the body.

To the extent our body needs to repair damage from our daily activities, that’s good.

Beyond that, however, it’s bad.

Again, assuming one is a mature adult who’s not still competing in bodybuilding competitions, they would want to repair, but not keep growing.

Excess growth is a sign of cancer.

Increased mTOR is associated with cancer. Remember, unregulated growth is the major attribute of cancer. That’s what makes it dangerous.

Increasing mTOR drives cancer cells to keep growing. And it supports angiogenesis, which is the body making new blood vessels to supply the tumor with glucose and oxygen.

And mTOR decreases autophagy. That’s the process our body uses to clean up old and damaged cells. Thorough autophagy cleans cancer cells out of our body.

Therefore, we want to limit mTOR.

Therefore, we need to consume just enough protein.5, 6

Methionine and IGF-1

Methionine is one of the eight essential amino acids we must consume to remain in good health.

However, it’s also closely associated with growth. It’s considered an anabolic stimulant. It stimulates our body into growing more.

It’s needed for cells to grow and multiply, to make protein and synthesize RNA.

It’s also correlated with Insulin Growth Factor – 1 (IGF-1), a hormone that signals our body’s cells to keep growing and multiplying.

The more IGF-1 in our blood, the higher our risk for cancer. 7

Most malignant tumors are covered with IGF-1 receptors. But if there’s not enough IGF-1 available, that limits their growth.

In one major study, researchers followed 6,000 men and women over the age of 50 for 18 years.

Those who were under the age of 65 who ate high amounts of protein had four times the risk of dying from cancer. That’s comparable to the risk caused by smoking.

However, this association held true only for animal protein, not plant protein. 8, 9, 10, 11

Although methionine is labeled “essential,” (meaning we need to consume it), it’s the only essential amino acid which we can live for a long time without consuming.

That’s because we can recycle it in our bodies through two separate methylation pathways.

However, most cancer cells cannot recycle methionine, so they need it directly.

In this respect, methionine is similar to glucose. Our healthy cells can live just fine without glucose by switching to burning fatty acids. Cancer cannot.

Our healthy cells can live without consuming methionine. Cancer cells cannot. It needs methionine to keep growing.

In test tubes, many types of cancer cells die without methionine.12, 13

Scientists believe methionine has a pro-oxidant effect on our bodies. That means it increases the production of free radicals, which damage and age our cells. And our mitochondria and DNA, leading to cancer.

Therefore, some believe restricting the consumption of methionine leads to less production of free radicals, which leads to less risk of cancer (and of many other diseases including aging in general).14, 15, 16, 17, 18, 19

Protein > Animal Sources

For the last hundreds of thousands of years, people have hunted, caught and eaten a huge variety of creatures.

But in modern, 21st century America, the vast majority of animal protein comes from just three animals: cows, pigs and chickens — and their byproducts.

From cows, we get milk, and all the dairy products from that: butter, cheese, cream, cottage cheese, and yogurt.

From chickens we get eggs.

Proteins are made up of amino acids, but not all proteins contain the same amino acids. That varies by the source of the protein.

The protein we get from animal sources contain more of the 20 amino acids we need. The amino acids include methionine, tryptophan, lycine, and isoleucine.

Essentially, because animals are biologically closer to us than plants are, animal proteins are closer to the amino acid ratios in our bodies.

Therefore, animal protein is easier for our bodies to digest and put to use.

However, that ease of digestion is a double-edged sword. Because protein is for growth and proliferation, consuming more than we need to repair and replace stimulates the IGF-1 hormone, which is closely associated with cancer risk.20, 21, 22, 23

Animal proteins contain a lot more methionine, and that puts us at a higher risk of cancer.24, 25, 26

Heme Iron

In 2012, two major studies documented the close association between eating red meat and cancer. Those studies were the Nurses’ Health Study and the NIH-AARP study.

But what about eating red meat causes cancer?

One theory is that red meat contains heme iron which is found in blood and muscle.

We need some iron in our body, or we may suffer from anemia.

But too much iron is a pro-oxidant. It raises levels of free radicals.27

And experts have previously said iron is more dangerous than we realize.28

If true, that seems to explain why women live longer than men. And why women of menstruating age rarely suffer heart attacks.

And why donating blood may reduce the risk of cancer. 29

And it’s much easier for our body to absorb the heme iron in red meat than the iron in plant foods.30

Therefore minimizing consumption of red meat makes sense to help prevent cancer.

And donating blood two to three times a year may also lower our risk.

Unless, of course, a young woman is at risk for having low iron: anemia.

Factory Farmed Animal Protein

The vast majority of the animal protein eaten in the developed world — and a fast-growing percentage in the developing world — comes from factory farms. Or, more technically, Confined Animal Feeding Operations (CAFO).

These animals are raised totally to maximize financial efficiency.

The industry knows the exact cost of feeding each cow and how much they get.

The cost of the antibiotics, the growth hormones, the feed and everything else is calculated precisely.

Because if a farmer requires 5 cents more per pound to make a profit than the market price, they will go eventually go out of business. To compete, they must keep costs to the minimum.

The animal’s optimal nutritional needs are not usually considered unless it affects the farmer’s costs versus return.

Our optimal nutritional needs are not considered AT ALL.

So long as the vast majority of supermarket and restaurant consumers continue to buy and eat these foods, the industry will not change.

These animals contain disease bacteria that can be transmitted to us. They’re fed chemical additives that will make them fatter.

They are fed the cheapest possible food. That includes grains they would not encounter if naturally grazing in a pasture. And it includes the ground-up remains of slaughtered animals.

Because animals are kept in extremely cramped conditions, they are under chronic stress. This produces chemicals in their bodies that we the consumers ultimately eat.

Factory farm chicken contains arsenic, a poison, and known carcinogen.

CAFO animals live and die in extremely inhumane conditions.

Those conditions produce incredible amounts of pollution that damage the soil, air, and water supply of the surrounding environment.

Most of us discount, tolerate or simply ignore those two issues to gain the benefit of cheap and abundant animal foods.

However, the meat, fish, poultry, dairy, and eggs we eat contains significant amounts of substances that cannot be good for our health.

Substances like antibiotics used on the animal that we ingest disrupting our gut microbiome health and, therefore, our immune systems. And which may breed disease bacteria that are resistant to those same antibiotics.

Substances like growth hormones that disrupt our hormonal balance and which encourage the unregulated growth of our cells: cancer.

And substances like microbes that can infect us with diseases.

Meat that is high in inflammatory Omega-6 fats and low in anti-inflammatory Omega-3 fats.


Avoid or minimize animal foods.

Meat/dairy/eggs should be a part of our meals, not the main course.

Avoid commercial animal products from average supermarkets and restaurants.

Eat animal foods grown organically with their natural diet.

That sounds convoluted. But, under federal law, beef can be labeled “organic” if the cow was fed with organic corn.

But corn is not good food for cows. So, one must make sure to buy only “grass-fed” beef (and dairy).

And only eggs laid by free range chickens that.

The following article explains a lot how to do this.31

We should look for organic, grass-fed cattle ranchers closer to us.

Or search for online suppliers.

Protein > Plant Sources

Plants are not as rich in amino acids as animals are, but they still contain them. Everything that was once alive must have some protein.

And the real issue of asking plant or animal? Is not the quality of the amino acids. They remain the same.

The importance of the source lies in what we’re consuming or not consuming along with the protein.

Of plant sources, fruits, grains, and vegetables contain protein, but not so much.

However, beans, nuts, soy, and seeds contain significant amounts of protein.

Still, we have to eat more plant foods to get the same amount of protein as we get from animal sources. But plant food sources do contain all the amino acids, although not in the same high proportions.

Therefore, animal sources are considered to be of higher “quality.” We can get the same amount of protein from eating less animal food.

Therefore, with plant foods, we can eat more — filling ourselves up — without raising our risk of cancer.

In the 1970s people believed that, because plant proteins were incomplete, we needed to eat complementary plant foods together at the same meal to get enough protein. Rice and beans were one such combination.

That does make a good dish, but the myth that plant foods are incomplete has been refuted.32, 33, 34


Eating a large quantity and variety of plant foods, will give us all the protein we need.