Protein-based products and benefit claims have proliferated, as has protein-related research, particularly in the sports science arena. Research findings provide valuable evidence-based guidance that product developers and marketers can use to formulate efficacious products and create benefit claims that are truthful and not misleading. Bob Murray, PH.D., FACSM, Managing Principal, Sports Science Insights, LLC, and Co-founder and former Director, Gatorade Sports Science Institute, gave insights into proteins’ role in muscle synthesis when formulating products during Global Food Forums’ 2022 Protein Trends & Technologies Seminar.
In his presentation “The Science of Muscle Protein Synthesis: Practical Takeaways for Product Developers,” Murray noted that the science of protein metabolism can quickly become complex and arcane. Still, important practical learnings about the amounts, types, and timing of protein intake and other considerations can inform product development decisions. This presentation will highlight those key practical findings.
Key Findings on the Role of Proteins’ in Muscle Protein Synthesis
Murray’s delved into research on the role of protein in muscle protein synthesis (MPS). Examples of 13 product benefit claims ranged from “supports workout recovery” to “repair-, rebuild- and/or maintain lean muscle and body tissue.” “There is robust evidence that protein intake with training enhances MPS, lean body mass (LBM), strength and performance,” he noted, “with the one exception being ‘energizing protein to fuel your day.’”
Protein is not a nutrient that our cells preferentially use for energy. Instead, carbohydrates and fats are used, said Murray. Results from 49 studies with 1,863 participants showed that dietary protein supplementation increased prolonged resistance exercise training (RET)-induced gains in muscle mass and strength. Gains in LBM were reported to be more effective in resistance-trained individuals.
Protein supplementation beyond the total intake of 1.6g/kg/day resulted in no further RET-induced gains (Morton, RW, et al. Brit J Sports Med. 2018). Strength training and eating a meal rich in essential amino acids (EAA) increase protein synthesis. This cellular mechanism is dependent on a cascade of protein kinases, along with the activation of the mammalian target of rapamycin (mTOR). When training and protein intake are combined, the effects add up and result in a more significant impact on MPS than either strength training or eating alone.
Proteins that result in a rapid and prolonged (~1 hour) increase in the EAA leucine in the blood maximize the activation of mTOR and the increase in MPS and strength (Baar K., Sports Sci Exchange. 2014).
“It seems intuitively reasonable that increasing strength will increase performance. This relationship isn’t clear-cut, as it is difficult to study and depends on the performance metric being measured. However, this benefit claim is unlikely to be challenged,” explained Murray.
Protein Metabolism Science Guides Product Development
The science of protein metabolism can inform product development. Muscle protein basics tell us that, for a 70kg body weight, there is about 12kg of total body protein with 250g total free AA and 120g AA pool within muscles. But muscle is only ~30% of whole-body protein synthesis—a relatively small amount, recognizing that muscle represents only 20% of resting metabolic rate.
“Muscle contractile proteins turn over slowly at ~1g/kg/d,” revealed Murray, “and only about 10% of ingested AA are used by muscle.” The elderly may require more than 20-25g of protein in a single serving to optimize MPS because of resistance to the anabolic effects of AAs that occur with age. Large athletes may need more as well.
The type of protein affects MPS, with research showing EAA in plasma are highest and appear most rapidly with supplementation of whey hydrolysate, followed by soy protein isolate and then casein. Similar results were noted for the appearance of leucine (Tang, JE, et al. J App Physiol. 2009).
Murray also provided information on animal vs. plant proteins. Plant proteins typically have a limiting EAA profile, which can be overcome by combining plant sources. Both plant and animal sources contain leucine and other branched-chain amino acids (BCAAs), and their contents can be increased using concentrates and isolates. There are a variety of plant and animal foods and ingredients that contain similar amounts of BCAAs.
Males and females appear to respond similarly to dietary proteins. Plant and animal proteins, protein blends and hydrolysates, and AA mixtures (e.g., EAAs, BCAAs) can effectively increase MPS. There is more rapid absorption with liquid vs. solid protein supplementation. “MPS will be enhanced with the presence of all EAA, as well leucine (2-4g/serving appears optimal), but any leucine is better than none. Suppose a product has a sub-optimal amount and/or type of protein. In that case, MPS can be improved by including carbohydrates, beta-alanine, vitamin C, creatine, collagen, carnitine and omega-3 fats,” explained Murray.
Murray summarized his talk with the following takeaways:
- Most current structure-function claims for protein foods formulated for athletes and active consumers are well-supported by competent science.
- Plant and animal proteins, protein blends, protein hydrolysates and amino-acid mixtures in solid or liquid form are effective in increasing MPS, provided there is a sufficient quantity of rapidly digested/absorbed, high-quality protein rich in leucine and other essential amino acids.
- The scientific link between increased dietary protein content and improved sports performance (via increased muscle mass and strength) isn’t well established and remains to be consistently verified by research.
To download the pdf version, click on this presentation’s title, “The Science of Muscle Protein Synthesis: Practical Takeaways for Product Developers,” courtesy Bob Murray, Ph.D., FACSM, Managing Principal, Sports Science Insights, LLC and Co-founder and former Director, Gatorade Sports Science Institute.
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