Study finds that the source and quantity of protein consumed significantly affect muscle building in older men

Writing in The American Journal of Clinical Nutrition, researchers led by Stuart Philips of the Exercise Metabolism Research Group at McMaster University compared the effects of additional whey, pea, and collagen protein supplementation on muscle protein synthesis (MPS) in a group of 30 men between the ages of 65 and 80.

“We aimed to determine the impact of consuming higher- versus lower-quality protein supplements above the recommended dietary allowance (RDA) on integrated MPS rates,” they wrote. “We hypothesized that increasing total protein intake above the RDA, regardless of the source, would support higher integrated rates of myofibrillar protein synthesis.”

The study was supported by a research contract from French food company Roquette Frères.

Skeletal muscle mass is determined predominantly by feeding- and activity-induced fluctuations in muscle protein synthesis (MPS), the study noted. Older adults have a lower MPS response to protein ingestion (age-related anabolic resistance) that contributes to the progression of age-related muscle loss (sarcopenia), which increases the risk of mobility issues, falls, fractures, hospitalization, and frailty.

“The United States–Canadian dietary guidelines recommended dietary allowance (RDA) for protein intake remains the same for all adults (0.8 g/kg/d), regardless of age, with little reference to source or pattern of intake,” the researchers wrote. “Several factors have been proposed to affect older adults’ MPS response, including quantity (per-meal protein ‘dose’), quality, and distribution of protein intake.”

Noting that protein intake in older adults is typically skewed towards dinner in the United States and Canada, they pointed to evidence supporting the lean muscle mass preserving benefits of consuming extra protein at breakfast and lunch.

The double-blind, randomized controlled trial recruited 45 healthy older males. During the control phase, they consumed a controlled diet with protein intake set at RDA before being randomly assigned to either consume 25 g of whey (Sureprotein WPC450, NZMP), pea (Nutralys S85 Plus N, Roquette) or collagen (Bodybalance, Gelita) protein twice a day, at breakfast and at lunch, for a week.

Fourteen individuals were lost to follow up, leaving 10 participants in both the whey and collagen groups and 11 in the pea group.

Deuterated water ingestion and muscle biopsies assessed integrated MPS and acute anabolic signaling. Postprandial blood samples were collected to determine feeding-induced aminoacidemia (presence of amino acids in the blood).

Findings indicated that whey and pea supplementation increased integrated-MPS compared to RDA but remained unchanged with collagen and that supplemental protein was sufficient to overcome anabolic signaling deficits (mTORC1 and rpS6), corroborating the greater postprandial aminoacidemia.

“Manipulating dietary protein to increase daily consumption of higher-quality—whey and pea but not collagen—proteins by targeting the lowest protein-containing meals offers a viable strategy to enhance integrated MPS in older adults,” the researchers concluded. “Consuming protein much closer to expert group consensus recommendations may help to increase integrated MPS, preserve skeletal muscle mass with advancing age, and extend healthspan—compressing the years of disease and disability commonly experienced by older individuals closer to the end of life.”

Dr. Philipps told NutraIngredients-USA that RDAs “absolutely” need to be updated as the current recommendation is insufficient to support optimal rates of muscle protein synthesis in older adults. He also previewed upcoming research including a study in older women and a longer-term trial to show that effects extend to periods longer than two weeks.

Source: The American Journal of Clinical Nutrition
doi: 10.1016/j.ajcnut.2024.05.009
“The effects of whey, pea, and collagen protein supplementation beyond the recommended dietary allowance on integrated myofibrillar protein synthetic rates in older males: a randomized controlled trial”
Authors: McKendry et al.