Debunking the Myth: The Completeness of Plant Protein


Aug 31, 2024

 by Rob Bratcher
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There has been a persistent myth that plant protein is incomplete, meaning it lacks all the essential amino acids required by the human body. This misconception has led many to believe that a plant-based diet cannot provide adequate protein for optimal health. In this blog, we’ll explore the origin of this myth, the science that debunks it, and why plant protein is, in fact, complete and sufficient for human needs.

1. Origin of the Myth

The idea that plant proteins are incomplete stems from research conducted in the early 20th century. In 1914, a study by Dr. Thomas Osborne and Dr. Lafayette Mendel examined the protein content of various foods. Their findings suggested that animal proteins were superior because they contained all nine essential amino acids in proportions that better matched human needs. This led to the widespread belief that only animal-based proteins were complete, while plant proteins were inherently inferior.

2. Misinterpretation and Spread

Over time, the findings of Osborne and Mendel were misinterpreted and exaggerated. The study did not state that plant proteins were incomplete, only that some plant foods might have lower proportions of certain amino acids compared to animal products. This nuance was lost as the research was popularized, leading to the broad and incorrect generalization that all plant proteins were incomplete.

3. Why the Myth is Wrong

Modern nutritional science has debunked the notion that plant proteins are incomplete. Here’s why:

  • Complete Proteins in Plants: Many plant foods, such as quinoa, soy, buckwheat, and hemp seeds, are complete proteins, containing all nine essential amino acids in sufficient quantities.
  • Protein Combining is Unnecessary: It was once thought that plant-based eaters needed to combine different plant foods at each meal to get a complete amino acid profile. However, the American Dietetic Association clarified that as long as a variety of plant foods are consumed throughout the day, the body will obtain all the essential amino acids it needs.
  • Adequate Amino Acid Intake: Studies have shown that diets rich in a variety of plant foods provide all the essential amino acids required for human health. A well-planned plant-based diet can meet or exceed the protein requirements for all stages of life.

4. Scientific Evidence

Several studies have supported the completeness of plant protein:

  • Campbell, T. Colin (2006). The China Study: This extensive research study showed that populations consuming primarily plant-based diets had lower rates of chronic diseases and met their protein needs effectively.
  • Young VR, Pellett PL. (1994). Plant proteins in relation to human protein and amino acid nutrition: This review highlights that when a variety of plant proteins are consumed, all essential amino acids are provided in sufficient amounts.

5. Quotes from Experts

Dr. Michael Greger, a prominent lifestyle medicine advocate and author of How Not to Die, states:

“The concept of ‘incomplete’ plant proteins is a myth that should have been buried long ago. With the variety and richness of plant-based foods, it’s easy to get all the essential amino acids the body needs without ever worrying about ‘protein combining’ at meals.”

6. Conclusion

The myth that plant proteins are incomplete is rooted in outdated and misunderstood research. Modern science affirms that plant-based diets provide all the essential amino acids necessary for health when a variety of foods are consumed. By embracing plant proteins, we can support our health and well-being while also benefiting the environment and promoting sustainability.

It's time to put the myth to rest and enjoy the full benefits of plant-based proteins