By Jonathan Cerna
Among the myriad of controversies surrounding plant-based diets, protein is central. Canada’s dietary guidelines, for instance, have gone out of their way to recommend plant-based proteins over animal-derived ones. However, most people are still getting a mixed message regarding their effectiveness. Recently, an online debate between a documentary-producer, James Wilks, and a functional medicine practitioner, Chris Kresser, spun this debate into another confusion carousel. This debate brought up a key issue that is worth pondering on: Can plant-proteins be as effective as animal-based sources? Fortunately, a really well conducted study provided some insights.
What benefits are we talking about?
You might be asking, “What do you consider effective?”. What kind of superiority are plant-based proteins supposedly able to match? Longevity outcomes? Better blood lipids? Although many of these outcomes, among others, have been explored, this study aimed to explore the question of protein quality. In other words, if I ingest the exact same macronutrient through different sources, will I get the same results?
The Importance of Assessing Quality Appropriately
A quick search on your browser of choice will quickly prove that this question of protein sources has been looked at before. What makes this study unique? Unfortunately, grabbing an accurate scale and weighing two foods to the same weight will not yield the same results. Protein consumed in plant foods is mixed with carbs, and occasionally fat. A step further, isolating protein from plants and conducting a study based on it would still not yield an accurate answer because not all plant proteins contain all essential amino acids. Interestingly, even the frequently touted suggestion to mix plant sources to make a complete protein can leave you confused as to why one wouldn’t see the same results after putting all of these pieces together. As a matter of fact, leucine, an essential amino acid, is primarily responsible for stimulating muscle protein synthesis, and matching its content is paramount. Lastly, plants have several anti-nutrients that can reduce their bioavailability and the actual protein content that is available for utilization needs to be matched. Impressively, the research team that conducted this study accounted for every one of these variables. They equated the amount of available protein, their leucine content, and even the amount of essential amino acids.
18 young (~25 years of age), and healthy weight (~24 BMI) participants were randomized to take one of three plant-based blends, or a control (whey protein, the gold-standard of protein quality), and later cycle through each option. This is called a double-blind (neither participants nor researchers knew which option they would take) randomized (option received was sorted randomly) cross-over study (participants had to drink all beverages at some point during the study), which is the gold standard for randomized controlled studies.
Interestingly, all blends resulted in less amino acids found in the blood with no differences between any of the blends. Should we conclude that these results seem to clearly state that protein quality of plant-based protein blends are inferior? Translating results into meaningful takeaways is always challenging.
Yes, the response seemed superior for whey protein, but this doesn’t necessarily translate into “protein-blends are inferior, and animal-based sources are always superior”. This study matched critical variables for protein digestibility, and amino acid content, and then measured the response in blood. It does not tell us if people will accumulate more muscle mass. All beverages could have maximized the benefits, but that cannot be necessarily derived from amino acids rising in blood. From this study, we can absolutely tell that plant sources of protein don’t result in a massive increase of amino acids like dairy sources (specifically, whey protein), but they definitely do raise them substantially. As to whether all possible advantages for sports performance and muscle mass accretion are maximized is a question that has yet to be answered.
Peer-edited by Raj Trikha