Abstract
The purpose of this study was: aim 1) compare insulin and leucine serum responses after feeding a novel hydrolyzed whey protein (WPH)-based supplement versus a whey protein isolate (WPI) in rats during the post-absorptive state, and aim 2) to perform a thorough toxicological analysis on rats that consume different doses of the novel WPH-based supplement over a 30-day period. In male Wistar rats (~250 g, n = 40), serum insulin and leucine concentrations were quantified up to 120 min after one human equivalent dose of a WPI or the WPH-based supplement. In a second cohort of rats (~250 g, n = 20), we examined serum/blood and liver/kidney histopathological markers after 30 days of feeding low (1human equivalent dose), medium (3 doses) and high (6 doses) amounts of the WPH-based supplement. In aim 1, higher leucine levels existed at 15 min after WPH vs. WPI ingestion (p = 0.04) followed by higher insulin concentrations at 60 min (p = 0.002). In aim 2, liver and kidney histopathology/toxicology markers were not different 30 days after feeding with low, medium, high dose WPH-based supplementation or water only. There were no between-condition differences in body fat or lean mass or circulating clinical chemistry markers following the 30-day feeding intervention in aim 2. In comparison to WPI, acute ingestion of a novel WPH-based supplement resulted in a higher transient leucine response with a sequential increase in insulin. Furthermore, chronic ingestion of the tested whey protein hydrolysate supplement appears safe.
Highlights
More than 150 million US residents consume dietary supplements and many of those are products including whey protein, creatine, and branched-chain amino acids (BCAAs) [1]
Limited evidence to our knowledge has compared the postprandial effects that exist between a whey protein isolate relative to a hydrolyzed whey protein derived from WPI [7]
For post-WPI gavage, relative to the control rats that were not gavage-fed, no significant increases occurred in serum insulin at 60 minutes, and 120 minutes, there tended to be an increase at 30 minutes post-gavage (p = 0.09)
Summary
More than 150 million US residents consume dietary supplements and many of those are products including whey protein, creatine, and branched-chain amino acids (BCAAs) [1]. Recent evidence suggests that the consumption of whey protein elicits the greatest appearance of essential amino acids and insulin and is the seemingly most influential known protein source capable of augmenting muscle anabolism [2,3,4]. There is still conflicting evidence as to whether or not WPH elicits a more favorable serum anabolic response (i.e., greater insulin and leucine values) relative to other whey protein forms. Data comparing the effects of different protein sources on serum amino acid and hormone concentrations typically examine these phenomena after overnight fasting period, which is not applicable to those who consume supplemental protein between meals. Lockwood et al [8] studied the effects of ingesting 60 g/day of WPH versus two different whey protein concentrate supplements on body composition after 8 weeks of progressive resistance training. While WPH may elicit transient increases in circulating leucine and insulin relative to other protein sources, data is lacking with regard to how a WPHbased supplement affects these variables in the postabsorptive state
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