Protein- and carbohydrate-induced augmentation of whole body creatine retention in humans.
Level 2 - randomized trial
Within-subject crossover experimental trial in humans
PubMed 10956365 · doi:10.1152/jappl.2000.89.3.1165
What was done
Twelve men consumed 4 x 5 g of creatine on four separate occasions combined with: 1) 5 g carbohydrate (CHO), 2) 50 g protein and 47 g CHO, 3) 96 g CHO, or 4) 50 g CHO. Plasma creatine, serum insulin concentrations, and whole-body creatine retention were measured.
What was found
Serum insulin increases did not differ between the protein-CHO and high-CHO treatments, but both were significantly higher than the low-CHO treatment (P < 0.05). Body creatine retention was augmented by approximately 25% for both protein-CHO and high-CHO treatments compared with the 5 g CHO condition. The areas under the creatine- and insulin-time curves correlated during the first dose (r = -0.920, P < 0.05), but not after the fourth dose (r = -0.342).
Why it matters
Co-ingesting creatine with approximately 50 g each of protein and carbohydrate promotes insulin-mediated creatine retention as effectively as ~100 g of carbohydrate alone. This offers a practical alternative that avoids excessive simple sugar intake.
Limits
The study tested only 12 healthy men over a 24-hour period, with no female participants. Functional performance, long-term muscle saturation beyond 24 hours, and varying protein sources were not assessed.
Cited by
- supports Taking creatine with food or carbohydrates increases its absorption via insulin-mediated mechanisms.
- supports More than 75 grams of carbohydrates is required to augment creatine uptake into muscle.