Consuming A Whey Protein Supplement Two Hours After A Low Protein Breakfast Preserves Amino Acid Availability
Joshua L. Hudson FASEB 2017
Thirty grams of high quality dietary protein is generally needed to maximally stimulate muscle protein synthesis. However, this generally exceeds the amount of protein consumed at breakfast, in part, due to practical limitations. This issue may be mitigated by consuming an easily preparable whey protein supplement. Amino acids from a whey protein supplement appear sooner in circulation than amino acids from mixed meals. As a result, consuming a whey protein supplement after a low protein-containing meal may be an effective and convenient means to preserve available amino acids. Therefore, the primary aim of this proof-of-concept study is to assess whether consuming a 20 g whey protein supplement 120 min after consuming a 10 g protein breakfast would result in peak and composite postprandial amino acid responses that were not different to a 30 g protein mixed meal breakfast alone. In a randomized, crossover design, 12 subjects (6 males, 6 females; mean ± SEM; age: 29 ± 1 y; BMI: 26.0 ± 1.0 kg/m2) completed three 5-h acute postprandial feeding trials in which they consumed mixed meal breakfasts containing 10 g of dietary protein (LP), 30 g of dietary protein (HP), and 10 g of dietary protein with an additional 20 g of whey protein isolate consumed 120 minutes after the mixed meal breakfast (WP). Blood samples were collected at times −30, 0, 30, 60, 120, 150, 180, 240, and 300 min relative to breakfast intake.
Total amino acid (TAA) and essential amino acid (EAA) concentrations peaked 180 min after breakfast consumption in both the WP and HP trials, with greater peak concentrations in the WP trial than in the HP trial. Branched chain amino acid (BCAA) and leucine concentrations peaked earlier in the WP trial than in the HP trial (180 versus 240 min, respectively) and were greater in the WP versus HP trials. Composite iAUCpos over 300 min for TAA and all the amino acid subfractions were greater in the HP than LP trial, during which the postprandial amino acid concentrations did not increase above baseline. HP and WP trial composite iAUCpos over 300 min were not different for TAA, EAA, and BCAA and leucine iAUCpos was ~91% greater in the WP than HP trial. Therefore, the WP trial iAUCpos may be predominantly attributable to the whey protein supplement consumed 2 hours after the low-protein containing breakfast.
In conclusion, there was no increase in amino acid availability when consuming a 10 g protein breakfast and amino acid availability was not different when either consuming a single isonitrogenous high protein-containing breakfast or supplementing whey protein 2 hours after a low protein-containing breakfast. Consuming a whey protein supplement 2 hours after a low-protein breakfast may provide a convenient method to maximally stimulate muscle protein synthesis without having to consume a high protein-containing breakfast.