Effects of supplementation with milk protein on glycemic parameters: a GRADE-assessed systematic review and dose-response meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 37798798 · doi:10.1186/s12937-023-00878-1
What was done
Systematic review and dose-response meta-analysis of randomized controlled trials (RCTs) published up to November 2022 evaluating the effect of milk protein supplementation on glycemic parameters in adults. Random-effects models were used to pool data across 36 RCTs totaling 1,851 participants.
What was found
Milk protein supplementation significantly decreased fasting blood glucose (weighted mean difference [WMD]: -1.83 mg/dL, 95% CI: -3.28 to -0.38, P = 0.013), fasting insulin (WMD: -1.06 uU/mL, 95% CI: -1.76 to -0.36, P = 0.003), and HOMA-IR (WMD: -0.27, 95% CI: -0.40 to -0.14, P < 0.001). It produced no significant change in overall HbA1c (WMD: 0.01%, 95% CI: -0.14 to 0.16, P = 0.891), although HbA1c declined significantly in subgroup analyses of participants with normal baseline BMI. HOMA-IR reductions were consistent across short- (<=8 weeks) and long-term (>8 weeks) durations at moderate-to-high doses (30-60 or >=60 g/day).
Why it matters
This review pools the randomized trial evidence to demonstrate that milk and whey protein supplementation can modestly improve acute markers of insulin resistance and fasting glycemia, though long-term glycemic control (HbA1c) remains largely unaffected overall.
Limits
The absolute reductions in fasting glucose and insulin are small and of questionable clinical significance on their own. Overall HbA1c did not change, duration of many included trials was limited (<=8 weeks), and heterogeneity exists regarding the source of milk protein (whole milk protein vs. whey protein isolate/concentrate), baseline metabolic status, and background diet.
Cited by
- supports Randomized controlled trials indicate that while whey protein causes an acute insulin response, long-term insulin sensitivity does not worsen and may improve.