ACSM and DuPont Nutrition & Health recently hosted a webinar presented by Dr. Blake Rasmussen entitled "Blending proteins to build muscle: What does the research tell us?"
Blends of dairy and soy protein are commonly used in sports nutrition products. These proteins vary in amino acid composition and digestibility rates; thus, combinations of soy and dairy proteins may have advantages for muscle recovery.
The webinar highlighted recent research evaluating the effects of consuming a soy-dairy protein blend versus single source proteins on muscle protein synthesis. To watch a free recorded version of the webinar, click here. The webinar is also available for two CECs via ACSMceOnline.
Below are some questions from webinar participants as well as Dr. Rasmussen's answers:
As for blended proteins, is it more beneficial to ingest them all at once or would it be more beneficial to take all of these protein sources separately timed out throughout the day to make them most physiologically beneficial?
The research findings indicate a benefit received from consuming the blend of proteins as one product 1 hour after resistance exercise extends muscle recovery compared to a single sources of protein. Thus, separating out each protein out to individual sources over the course of the day in differing doses would diminish the beneficial effects observed from blending. Consumption of a blend of proteins after workout should not be the only protein in the day, but part of a diet that includes a variety of protein sources.
Can you discuss the controversy of soy protein and its effects on estrogen levels and so forth?
Isoflavones are natural, bioactive plant compounds found in chick peas and legumes. Soybeans are the richest source of isoflavones, and soy foods and ingredients contain varying concentrations of isoflavones. Soy isoflavones are only a small constituent of soy protein ingredients and thus soy protein and soyfoods should not be equated with isoflavones. Research shows that although there are common characteristics, the effect isoflavones have on the expression of many genes is distinct from estrogen. Thus, isoflavones can't be equated with estrogen. The clinical literature is abounding with examples of differences between the effects of estrogen and soy on an assortment of biological measures. For example, soy does not significantly impact levels of sex hormones, whereas estrogen does. In our longer term study (the only one where duration would potentially elicit an effect), sex hormones were analyzed in participants with no increases observed from consuming the blend.
Please see this reference for more information: Hamilton-Reeves JM, Rebello SA, Thomas W, Slaton JW, Kurzer MS. Isoflavone-Rich Soy Protein Isolate Suppresses Androgen Receptor Expression without Altering Estrogen Receptor-14 Expression or Serum Hormonal Profiles in Men at High Risk of Prostate Cancer. J Nutr 2007;137:1769-75.
How old would you start increasing the leucine?
The aging muscle is a complex and thus far understudied area; more research is needed to determine when and what amounts of protein and leucine may be needed to alleviate muscle lose with age
I am allergic to dairy and soy (as are some of my clients) - will plant-based protein alone be effective?
High quality protein sources that are well digested and supply essential amino acids in appropriate amounts are the most studied for support of muscle health. This includes many animal sources of protein, including egg, meat and dairy but the only widely available plant source of protein that has these characteristics is soy. As demonstrated in explanation of our research approach, we matched groups to provide the leucine threshold, so slightly more protein was needed from the blended source than dairy alone. If you were to utilize other plant sources, it would take quite a bit more protein to reach the protein (leucine) threshold.
I know there is a window range of when you should consume protein post exercise. What is your suggestion for post exercise protein consumption for both?
My presentation highlighted the fact that there is NO window of opportunity to consume protein following exercise. Rather, the focus should be on consuming sufficient high quality protein over the next 24-48 hours for allows for proper muscle recovery.
I work with older adults. Are there any chronic disease states that protein supplementation would be contraindicated?
As I am sure you are aware there is concern about protein intake in patients with chronic kidney disease. Please consider the very recent resource titled Soy-based renoprotection, published in the World Journal of Nephrology, found here.
If someone wants to supplement at a low cost, is dehydrated milk something that might be appropriate? Is there a way to check the quality of the protein content, or the percentage of the particular amino acid components?
Checking for protein quality is based on digestion rate and amino acid levels available for use. Many labs have the ability to perform amino acid content of a specific protein; however, determining digestion rate requires a preclinical study. Protein Digestibility Corrected Amino Acid Score (PDCAAS) is the accepted method for determining protein quality so the dehydrated milk would need to be evaluated to determine its PDCAAS. Casein, whey and isolated soy protein all score a 1.0 PDCAAS.
Is there a product on the market that has the 25;50;25 blend you spoke of with 1.8-2.2 g of leucine?
Many products combine protein sources but there are few with these exact percentages currently in the market
Is there any difference between men & women during the protein uptake post exercise? Any idea of effects on women taking protein in this manner?
Young men and women respond similarly to protein supplementation for muscle synthesis.
Outside of the effects on lipid profile, is there really a benefit to supplementing with
Clinical research has demonstrated benefits of replacing carbs with protein or increasing protein intake for the following areas: Blood pressure, body composition and glucose metabolism, in addition to lipid levels.
Was it the soy-dairy protein that contributed to the improvement in blood lipids or the reduction in body fat percentage?
Thank you for your point regarding impact of body composition. However, the lipid improvements were observed in the blend group only while body composition improvements were also observed in whey group and carb control groups as well, from participation in resistance exercise. Soy protein has well-documented heart health effects, improving serum LDL-C, total cholesterol, triglycerides without lowering HDL-C. The amount of soy delivered in the blend was less than the amount that has been studied in numerous clinical trials, 25g of soy protein per day.
What does "isolate" means?
Isolated soybean proteins (ISP), or soybean protein isolates are the most concentrated form of commercially available soybean protein products. To be considered an isolate, the product should be composed 90% of protein.
What's your opinion of combining other proteins, such as rice & pea? And is too much soy protein bad for you?
High quality protein sources that are well digested and supply essential amino acids in appropriate amounts are the most studied for support of muscle health. This includes many animal sources of protein, including egg, meat and dairy but the only widely available plant source of protein that has these characteristics is soy. Pea and rice are lacking in specific amino acids and are less well-digested than soy protein. In addition, as demonstrated in explanation of our research approach, we matched groups to meet the leucine threshold, so slightly more protein was needed from the blended source than dairy alone. If you were to utilize other plant sources such as rice or pea, it would take quite a lot more protein to reach the protein threshold.
Regarding your second question, too much of anything can be bad. However, there would be no detrimental effects if all your dietary protein came from soy, however, we know that a diverse diet is best, no matter what nutrient/source is of concern. Soy has been safely consumed for thousands of years, and in greater quantities by Asian populations with no observed detrimental effects.
Blake Rasmussen, PhD is the current Chair of the Department of Nutrition and Metabolism at the University of Texas - Medical Branch (UTMB) in the School of Health Professions. Dr. Rasmussen holds the Lloyd and Sue Ann Hill Endowed Professorship in Healthy Aging and is currently the Director of the Department's Muscle Biology & Metabolism Laboratory and the Leader of the NIH funded Claude D. Pepper Older Americans Independence Center Pilot and Exploratory Studies Core at UTMB.
Dr. Rasmussen's research is focused on how nutrition and exercise influence muscle biology and in developing clinical interventions to prevent muscle loss during aging and other muscle wasting conditions. Dr. Rasmussen has published over a 100 papers in the fields of Nutrition, Metabolism and Exercise Physiology and has trained several postdoctoral fellows and PhD students.