Carbohydrate ingestion augments skeletal muscle creatine accumulation during creatine supplementation in humans.
Level 3 - non-randomized controlled study
Controlled human trial with parallel groups without explicit mention of randomization in the abstract
PubMed 8944667 · doi:10.1152/ajpendo.1996.271.5.E821
What was done
Twenty-four males were assigned to ingest either 5 g creatine in solution (group A) or 5 g creatine followed 30 minutes later by 93 g simple carbohydrates in solution (group B) four times daily for 5 days. Muscle biopsies, urine samples, and plasma samples were collected before and after supplementation to measure muscle phosphocreatine (PCr), creatine (Cr), total creatine (TCr), urinary creatine excretion, and serum insulin concentrations.
What was found
Both groups showed increases in muscle PCr, Cr, and TCr concentrations. Group B achieved a 60% greater increase in muscle TCr compared to group A (P < 0.01). Group B also showed a significant reduction in urinary Cr excretion relative to group A (P < 0.001). Creatine alone did not alter serum insulin concentrations, whereas creatine plus carbohydrate ingestion dramatically elevated serum insulin (P < 0.001).
Why it matters
Co-ingesting simple carbohydrates with creatine substantially enhances muscle creatine accumulation and retention, an effect driven by elevated insulin levels.
Limits
The sample size was small (24 subjects) and limited entirely to males. Randomization was not specified in the abstract. The carbohydrate dose tested was exceptionally large (372 g per day), and the study did not evaluate exercise performance or clinical endpoints.
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.