Eating animal protein following training can improve recovery, study finds

The type of protein you eat after intense physical training can significantly impact recovery, according to new research from Texas A&M University’s Department of Kinesiology and Sport Management.

The study, led by Dr. Richard Kreider, a researcher with over 30 years of experience studying creatine and sports nutrition, examined how different protein sources in military-style meals ready-to-eat (MREs) affected recovery in members of Texas A&M’s Corps of Cadets after completing the Army Combat Fitness Test.

Creatine — a compound stored in muscle and essential for cellular energy production and recovery — is most abundant in animal-based protein like meat and fish. While the recommended daily intake ranges from 2 to 4 grams, depending on muscle mass and activity level, most individuals fall short, especially those following vegetarian or vegan diets. Combined with a lack of essential amino acids, this can make recovery after intense training difficult for vegetarians and vegans. 

The 2023 MRE meal plan includes nine plant-based options and 14 animal-based menus, with only one featuring pork as the primary protein. Because pork is particularly rich in both creatine and essential amino acids, researchers compared recovery outcomes between pork-based and plant-based MREs to determine whether protein source influences recovery.

“Our concern was that if we’re expecting our military to perform at their best and they’re consuming plant-based MREs, we have to make sure those meals provide enough essential amino acids and creatine to meet daily needs,” Kreider said.

Researchers from the Exercise & Sport Nutrition Laboratory tracked members of the Corps of Cadets — the largest uniformed student body in the nation outside of the military academies — who consumed pork-based or plant-based protein after completing the Army Combat Fitness Test, a rigorous battery of sprints, drag pulls, weightlifting and other exercises designed to assess combat readiness. In a tightly controlled four-day protocol, participants were fed a pre-exercise meal before completing the fitness test. They then consumed standardized MREs — either pork-based or plant-based — three times daily for the next three days. 

Researchers monitored blood and urine biomarkers, muscle soreness and cognitive performance throughout the recovery period. On the third day, cadets repeated the fitness test to assess recovery outcomes. 

Despite consuming the same amount of protein, the cadets who ate pork-based MREs showed less muscle soreness, reduced nitrogen excretion (a marker of muscle breakdown) and lower levels of inflammation than those who were fed the plant-based protein. Hormonal responses also improved, with better testosterone-to-cortisol ratios observed in the pork group.

Kreider said the findings suggest that individuals who follow a plant-based diet may not recover as well from intense military-style activities as those who consume animal-based protein. 

Each MRE is standardized to contain 45 grams of protein, he said, but the difference is that plant-based proteins contain 30% to 40% fewer essential amino acids than animal protein and only trace amounts of creatine.

The study, published in the journal Nutrients, recommends that plant-based MREs be fortified with 6 to 10 grams of essential amino acids and 2 to 3 grams of creatine monohydrate to help maintain optimal recovery and performance for military personnel following a vegetarian diet.

“The long-term health implication is that people who have low creatine and low-quality protein in their diet may not be able to recover and may not be able to perform when military tasks are needed,” Kreider said. “It applies to sports, and it even applies to aging. We used to think simply having enough protein is all you need, but the type of protein does matter.”

This study was funded by the National Pork Board/U.S. Department of Agriculture as part of a subaward from the U.S. Department of Defense.