By Dr. Frank Sabatino

In the early part of the 19th century, protein was recognized as a primary building block of life and given a name derived from the Greek word proteios meaning “of the first rank or importance”. And in 1902, it was proposed that proteins are composed of building blocks, amino acids, bonded and connected to each other like beads on a string. 

There are thousands of proteins in the human body that are important for a variety of life-supporting functions, including growth and repair of cells and organs, and the production of hormones and enzymes.  All proteins in the human body are constructed from 20 basic amino acids, including nine essential amino acids that can’t be made by the body, and must be provided by a diverse diet. The additional  eleven non-essential amino acids can either be provided by the protein intake of your diet or made by the body itself. When dietary proteins are digested, their component amino acids are organized  under the direction of your DNA into the panorama of proteins you need.

Therefore, protein is a significant and crucial macronutrient of any healthy diet, and it is crucial to realize that whole plant foods are fundamentally the most important and traditionally overlooked source of this nutrient. The element nitrogen is essential for the synthesis of all amino acids. While the air you breathe is 78% nitrogen, nitrogen in the atmosphere is inert and unavailable for protein production by all animals, including humans.  Only plants, in combination with certain bacteria in the soil, can capture atmospheric nitrogen and convert it into a usable form that is available for all animals. Therefore, all amino acids and all proteins are initially made by plants, and all animal protein is actually just recycled plant protein.  So contrary to the uncertainty, misunderstanding and faulty nutritional bias that have been instilled in us about ensuring adequate protein intake from plant sources,  there is no doubt that consuming a variety of whole plant foods provides all the protein you will ever need, including all the essential amino acids that you are incapable of making yourself.

Unfortunately, because of the importance of protein, you have all been sold the unconscionable idea that for you to be healthy, build strong muscle mass,  and even control your weight, it is necessary to eat huge amounts of protein, especially from animal sources. Not only is this a glaring lie with no scientific validity, but it is a dangerous myth that defies the basic science that plants are the fundamental source of all protein, that humans are not carnivores by nature and evolution, and that by eating animal foods you participate in unnecessary rituals and industries of wanton violence and killing that lay the insidious dietary foundation for heart disease, type 2 diabetes, and cancer as well as devastating climate change and environmental destruction. 

And this devastation has once again been instigated and reinforced by the recent governmental dietary guidelines emphasizing red meat and full fat dairy products as primary protein sources. Keep in mind that the strongest, largest mammals, with the largest muscle mass (elephants, rhinos, hippos, giraffes etc.)  are all strict plant eaters. If the adult male elephant can maintain a body weight of 10-15,000 pounds, with huge muscle mass on plant  protein, you certainly can maintain strong powerful muscles and satisfy your protein needs in a body of 100-200+ pounds with the protein in plants. Also, our closest powerful non-human primate relatives , chimps, bonobos, and gorillas, with similar anatomy and DNA, obtain their protein on a diet that is predominately fruit, greens, roots and shoots. 

Not only can a diversified whole plant diet provide all your protein needs, but it also eliminates the exaggerations and excesses of certain amino acids and nutrients that are linked with a variety of devastating chronic conditions, including cancer, heart disease, and brain damage. This  clearly rejects a common notion that many people have about nutrition, that if something is good, more must be better, and a lot more must be a lot better. Actually, all too often in nutrition, more can be dangerous and a lot more can be toxic. 

Some of these excesses include oxidized cholesterol (oxysterols), saturated, trans, and oxidized fat, the essential amino acid methionine and heme iron. Compared to plants, methionine is extremely high in meat, fish and eggs. This excess can promote free radical damage (oxidative stress) in the energy factories (mitochondria ) of cells to foster premature aging. (1) Cancer cells have a strong dependency on methionine (methionine addiction), and excessive methionine promotes the growth and spread of cancer referred to as the Hoffman effect. (2) Exaggerated methionine can also increase the excessive production of the vascular toxin homocysteine that can promote cardiovascular disease, cognitive dementia , and Alzheimer’s disease. (3)

Heme iron in meat protein causes a rapid, excessive absorption of iron from the small intestine that can cause dangerous iron overload in the heart and other vital organs. To protect you,  the liver produces a compound called hepcidin that blocks iron transport, and slows down absorption from the small intestine into the blood. Iron can then build up in the intestine, provoking oxidation, DNA and cell damage, and increasing the risk of colon cancer by more than 30%. (4)

The recommended dietary allowance for protein is 0.36 grams per pound of body weight. However, based on certain contingencies of aging and performance, including the loss of muscle mass, problems with the digestion, absorption and utilization of protein, body building resistance training etc., increasing protein intake to 0.45 grams or more per pound of body weight may be necessary. Increasing protein intake as you get older may lower disease risk and help decrease risky visceral belly fat and weight. (5) Therefore, consuming 36-90 grams of protein for people between 100-200 pounds can satisfy protein needs, and can be maintained comfortably on a whole food plant diet.

It is a common mistake to think that protein only exists in protein dense foods like beans, nuts, seeds, soybean products, meat, eggs, and dairy products. In fact, nature doesn’t make a piece of fruit or a leaf of lettuce without some protein content. So any diverse whole-food plant diet will also contribute meaningful protein content from the increased consumption  of low protein fruits and vegetables. The following examples illustrate how a diversity of whole plant foods contain all the protein you need, while in most cases also providing low calorie density to support decreased weight and body fat. 

Beans/lentils (14-18 grams protein/cup, 180 calories)

Nuts and seeds (4-12 grams protein / ounce, 160 calories)

Oatmeal and quinoa (8 grams/cup, 300 calories)

Broccoli (5 grams protein/8 ounces, 79 calories)

Kale (4 grams/8 ounces, 64 calories)

Spinach (6 grams protein/8 ounces, 52 calories)

So if you ate a cup of oatmeal for breakfast with some fruit or berries, and 1-2 tablespoons of ground flax and hemp seeds, a couple of pounds of green vegetables in salads and steamed vegetables throughout the day and evening dinner, 1-2 ounces of nuts, , a baked sweet potato with your salad for lunch, and a cup of beans with a cup of quinoa for dinner, you would consume 70-80+ grams of protein, satisfying your protein need while providing your daily requirements of fiber, micronutrients and essential fatty acids. 

Another benefit with proteins from legumes is their low calorie density compared to animal protein. Both legumes and animal protein (meat and fish) provide more than 25-30% of their calories from protein, but animal foods provide 50-75% of their calories from fat., especially risky saturated fat, compared to legumes that are  only 3-5% fat, and mostly healthier unsaturated fats. Since fat is the most calorie dense macronutrient,  animal proteins have much higher calorie density that can  promote problems of increased weight and body fat. 

in addition, while a variety of plant foods, including quinoa, soybeans, chia seeds, buckwheat , broccoli, and kale provide complete protein containing all the essential amino acids, many plant foods are incomplete. But nutritional science has conclusively  shown that it is not necessary to eat complete proteins at every meal.  By eating a variety and diversity of whole plant foods throughout the day you will consume all the amino acids you need and provide a pool of amino acids that promotes healthy protein production and satisfies your protein requirements. 

Eating a diverse and exclusive diet of whole plant foods is the best way to satisfy your protein needs throughout your lifetime and eliminates any concerns or fears about protein deficiency and getting the protein you need to support life and health.

References

1. Sanz A, et al. Mitochondrial restriction decrease oxygen radical generation and leak as well as oxidative damage to mitochondrial DNA and proteins. FASEB J. 2006 Jun;20(8):1064-1073.

2. Kaiser P. Methionine dependence of cancer. Biomolecules 2020 Apr 8;10(4):568.

3. Ungvari A, et al. The role of methionine-rich diet in unhealthy cerebrovascular and brain aging: mechanisms for cognitive impairment. Nutrients 2023;15(21):4682.

4. Bastide NM, et al. Heme iron from meat and risk of colorectal cancer: a meta-analysis and a review of the mechanisms involved. Cancer Prev Res. 2011 Feb;4(2):177.

5. Pasiakos SM, et al. Higher-protein diets are associated with higher HDL cholesterol and lower BMI and waist circumference in US adults. L Nutr. 2015;145(3):605-614.