Researchers at Purdue University have discovered that protein derived from animal-based foods provides better bioavailability of essential amino acids (EAA) compared to protein from plant-based sources. The quality of a food’s protein content, indicated by its EAA content, significantly impacts how amino acids are utilized for muscle and overall protein synthesis.
Bioavailability of essential amino acids refers to the extent to which these fundamental building blocks of proteins can be efficiently absorbed and utilized by the body from ingested foods. It reflects the capacity of a dietary protein source to provide the necessary amino acids that the body requires for processes like muscle growth, tissue repair, and overall protein synthesis, impacting overall health and physiological functions.
Higher bioavailability implies that a protein source offers a greater proportion of essential amino acids that can be effectively absorbed and used by the body to support various vital functions.
The Importance of Essential Amino Acids
Essential amino acids are important for individuals of all age groups and stages of life. It holds particular significance for individuals with higher protein needs, such as athletes and those engaged in physical training, as well as for individuals recovering from injuries or surgeries.
Additionally, it is crucial for populations with specific nutritional requirements, like growing children and adolescents, pregnant and lactating women, and older adults who may experience reduced muscle mass and protein metabolism with age.
Athletes can particularly benefit from considering the bioavailability of essential amino acids in their diets. During intense physical training, the body undergoes increased protein turnover and tissue repair, making sufficient protein intake essential for muscle recovery and growth.
Amino acids are the building blocks of proteins, and essential amino acids cannot be synthesized by the body, so they must be obtained through the diet. Protein sources with high bioavailability of essential amino acids ensure that the body has the necessary components to repair and build muscle tissue effectively.
The Dietary Guidelines for Americans (DGAs) emphasize the consumption of diverse protein sources based on equivalent ounce portions with similar nutritional profiles. One ounce-equivalent (oz-eq) is equivalent to one ounce of meat, a whole egg, 0.25 cups of beans, or 0.5 ounces of nuts.
Dr. Wayne Campbell, lead researcher from Purdue University’s Department of Nutrition Science, points out that the rationale behind considering these protein sources “equivalent” and nutritionally similar remains unclear.
Dr. Campbell highlights the differences in energy, nutrients, and protein quantity and quality among protein foods. Moreover, there is a limited understanding of how consuming oz-eq portions of protein from various sources within a mixed meal affects protein digestion and utilization, particularly in populations with restricted protein options, like younger and older adults.
With these factors in mind, the research aimed to investigate whether consuming two oz-eq portions of animal-based and plant-based protein foods as part of a mixed whole foods meal influences EAA bioavailability for protein synthesis in these population groups.
The study involved two crossover randomized controlled trials conducted on 30 young adults and 25 older adults. Each participant underwent four separate 300-minute trials, with a minimum three-day gap between trials. The order of protein food assignments remained undisclosed to the researchers until testing concluded.
During the trials, participants consumed standardized meals containing two oz-eq of either animal-based protein foods (such as lean pork loin and scrambled eggs) or plant-based protein foods (like black beans and raw sliced almonds). Blood samples were collected at intervals to assess EAA bioavailability, blood sugar, and insulin levels.
The study confirmed the hypothesis that meals with two oz-eq of animal-based protein foods yielded higher EAA levels in the bloodstream compared to plant-based protein foods for both young and older adults. This has implications for body protein and muscle synthesis, contributing to overall health and physical function across the lifespan.
Noteworthy findings include the higher EAA bioavailability of lean pork compared to eggs, with no differences between black beans and almonds. Furthermore, the study found no age-related differences in EAA bioavailability.
Further Research is Needed
The study has some limitations, such as the potentially unrealistic portion sizes of protein foods compared to actual consumption habits. Additionally, the study lacked direct measures of changes in muscle protein synthesis or whole-body protein balance in response to different protein foods.
Further research is necessary to comprehensively understand how animal-based and plant-based protein foods influence muscle and overall health across different age groups to encourage healthy aging.
In terms of public health nutrition implications, the study authors suggest that the findings could influence future dietary guidelines. The equivalence of various protein sources in the protein foods group based on oz-eq may need reevaluation.
Dr. Campbell adds that these results are pertinent to the recommendation to incorporate more plant-based foods while stressing the significance of nutrient-rich animal-based protein foods in dietary guidance.
Important Note to Readers
Please take into consideration that the research on this topic was financially supported by the Pork Checkoff and the American Egg Board’s Egg Nutrition Center. While these organizations undoubtedly have an interest in promoting the consumption of pork and eggs, one must approach the findings with a cautious perspective.
The potential for bias or influence on the research outcomes does exist, as funding from industry-related sources could lead to unintentional or subtle favoring of results that align with their interests.
Nonetheless, numerous independent studies and research have established that animal-based proteins, due to their amino acid composition and digestibility, tend to provide a more comprehensive profile of essential amino acids that the body can readily absorb and utilize for various physiological functions.
This broader consensus lends some credence to the research findings, but as with any scientific inquiry, maintaining a critical and balanced perspective is essential.