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Protein: The Bioavailability of Plant-Based versus Animal-Based Proteins

Updated: Jun 23, 2022

The building blocks of the human body, from skeletal muscle all the way down to the double helix of the DNA strand, are constructed of proteins. Proteins, and by extension, amino acids, are the foundation of life and its subsequent growth. Despite an abundance of proteins in our Earthly environment, the dietary requirements and even more so, bioavailability of protein as a component of overall health, remains a topic of debate with context that all too often gets lost in translation. To make matters more polarizing, there are many common misconceptions in regards to protein sources and their true amino acid makeup.

Presently, there is a large argument taking place in regards to animal-based proteins vs plant-based proteins. The opinions on both can be clouded, manipulated, and create disturbances in the true nature of what our bodies need to thrive. The reality of it all is that science is clear-cut in the understanding of amino acids as well as the bioavailability of proteins. (Merriam Webster defines bioavailability as the degree and rate at which a substance is absorbed into a living system or is made available at the site of physiological activity.)

The human body needs 20 amino acids to properly function. Incredibly, the human body produces 11 of those amino acids naturally. The other nine, though, are essential for functionality and must be consumed through whole food sources. It is important to note that not all proteins are created equal and not all protein sources contain all nine essential amino acids (EAAs).

Animal proteins are complete, meaning they contain all nine essential amino acids. Animal proteins are typically lower in calories and carbohydrates as well making it an incredibly bioavailable source of amino acids for the human body. Choosing lean sources of meat also lowers the fat content as well.

Plant proteins unfortunately, are incomplete proteins. In order to consume all nine essential amino acids in plant-based proteins, one must mix two sources such as pea protein (a legume) and rice protein (a grain). The problem lies in the amount required of each source to match the bioavailability of an animal protein - so much so that you may need to consume 20-50% more plant based protein as you would animal based protein sources in order to absorb equal amounts of amino acids . (Dietary Protein) Because of this, consuming plant proteins also means consuming a much higher calorie and carbohydrate amount than animal protein when a desired protein intake is the goal. In all actuality, plant proteins do not absorb in the body as efficiently as animal based proteins.

Although possible, the caloric intake of plant proteins in regards to proper protein absorption may not be beneficial, particularly for a fat loss goal. For example all of the following food sources contain 25 grams of protein, but their caloric numbers vary based off of the source of protein they are:

Quinoa 666 calories

Peanut Butter 587 calories

Black Beans 385 calories

Edamame 251 calories

*Beef 210 calories

If we take note of these numbers, we will realize the astronomical number of calories in relation to the grams of protein each source equally contains. Additionally, *beef is the only source on this list with a complete protein complex. (Dr. Bret Scher, MD)

In this regard, plant-based protein can have detrimental impacts on caloric intake and protein consumption/absorption in regards to muscle maintenance, muscle gain, and/or fat loss if not meticulously planned for.

Protein, as you probably already know, plays a major role in muscle maintenance and functionality. Our skeletal muscle also plays a key role in our metabolism both when we are resting as well as active. To be deficient in amino acids can create a survival state in the human body resulting in bodily breakdown from muscles to tendons, ligaments and bones, to organ functionality, brain cognition, and all five human senses working properly. This is known as catabolism, or a catabolic state, and places our body in survival mode.

Maintaining an anabolic state, or the building and maintenance of our bodily structure, allows the human body to maintain homeostasis and focus on building and repairing rather than destruction and breakdown. Anabolic states are also known for lower levels of mental health issues such as anxiety and depression which are triggered when in survival mode. On average, per gram animal proteins have higher muscle-building effects when compared to their plant protein counterparts. Animal protein sources are also higher in Vitamin B12, Vitamin D, Omega-3 fatty acids, heme-iron, zinc, and Vitamin K. All which play a role in vitality, bodily functions, and regeneration in the human body.

Plant-based proteins are typically higher in Vitamin C, fiber, and flavonoids which are beneficial for immune health. If one is partaking in plant-based protein consumption, supplementing with the vitamins and minerals listed in animal proteins is recommended and highly beneficial. Conversely, eating more vegetables rich in vitamins and minerals that are otherwise lacking in meat is recommended for a balanced diet.

While it is great to get proteins from both animal and plant protein sources, the evidence in regards to overall anabolically beneficial outcomes for the human body clearly point to a more animal-based diet. The saving grace for individuals on plant based diets that are looking to tone up, maintain, or develop muscle mass is plant-based protein supplements. Vega protein powder for example, offers a complete protein and amino acid profile derived from peas, pumpkin seeds, and alfalfa. Companies like Vega, use proprietary processes to extract protein from these sources in order to obtain and separate the low calorie good stuff from the high calorie fattening stuff. Plant-based protein powders may be the only viable way for calorie conscious individuals to properly supplement their diets with adequate proteins while also sticking to a plant-based diet.

All in all, making the choice of what protein approach you choose to take is entirely up to your lifestyle as well as your previous life experiences. Should you choose one over the other, prioritizing the goal of getting in all EAAs with each protein sitting as well as aiming for 1g of protein per pound of lean body mass (unless otherwise determined by a dietician or physician) can result in exponentially higher results in your physical fitness and bodily functions.



Dr. Bret Scher, MD. “Plant Protein vs. Animal Protein: Which One Is Healthier for You?â€Â Diet Doctor, Diet Doctor, 17 June 2022, https://www.dietdoctor.com/high-protein/plant-vs-animal-protein.Â

Dietary Protein Quality Evaluation in Human Nutrition. https://www.fao.org/3/i3124e/i3124e.pdf.Â


Van Vliet, Stephan, et al. “The Skeletal Muscle Anabolic Response to Plant- versus Animal-Based Protein Consumption.â€Â

The Journal of Nutrition, vol. 145, no. 9, 2015, pp. 1981–1991., https://doi.org/10.3945/jn.114.204305.Â


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