Protein sources – meat, fish, cheese, nuts, beans and greens.

Protein sources in food (© nadianb -

LITTLE ROCK, Ark. — Bad news for vegans looking to get the same nutrition from their meat alternatives. A recent study finds protein coming from meat keeps you leaner and feeling fuller than plant protein. While it is possible to get the same amount of protein from foods like nuts, kidney beans, and tofu in general, researchers in Arkansas say eating meat and eggs may make it easier to maintain a lean muscle mass.

Dietary guidelines have previously published ounce equivalents that allow people to fill protein requirements from different sources other than meat. For example, an ounce of meat is equivalent to a cooked egg or a tablespoon of peanut butter. However, study authors discovered that animal proteins may be of better quality and have a better “protein profile” when it comes to human dietary requirements.

Researchers found that eating animal-based protein results in a greater gain of protein than the ounce equivalents of plant-based protein sources. For the study, 56 young, healthy adult participants either ate two ounces of cooked beef sirloin, two ounces of cooked pork loin, two cooked eggs, half a cup of red kidney beans, two tablespoons of peanut butter, four ounces of tofu, or one ounce of mixed nuts. Prior to the study, the participants followed a three-day diet to reach a baseline value for each individual.

The secret is in meat’s amino acids

The investigators found that animal-based protein food sources produced a stronger response than plant-based protein sources. Whole-body protein balance increased more in the beef, pork, and eggs groups than in all of the groups consuming plant-based protein food sources.

While they may be “ounce equivalents,” the team finds switching out one protein source for another does not replace a certain food’s anabolic response or caloric value.

“Our research illustrates that animal-based protein foods, such as beef, eggs and pork, and plant-based protein foods, such as kidney beans, peanut butter, tofu and mixed nuts, cannot be considered to be equivalent, or a substitute for each other, when developing healthy dietary patterns, given their unique physiological effects,” says Professor Robert Wolfe from the University of Arkansas in a media release.

“While it’s well-established that animal proteins can more readily provide essential amino acids than plant protein foods, our study also indicates that eating animal protein foods such as beef, pork and eggs may lead to increased protein synthesis, which has been shown to have benefits such as improved satiety and lean muscle mass maintenance.”

The findings appear in the Journal of Nutrition.

South West News Service writer Joe Morgan contributed to this report.

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