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Cp7.5
Casein Protein Research
Too few graded studies
129 peer-reviewed studies
What the evidence says
Too few graded studies
Casein Protein doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from high-quality meta-analyses and randomised trials published 1985–2026 with a typical study size of 32 participants.
Based on 129 studies · 8 meta-analyses · 117 RCTs · 11,844 total participants
Confidence
High confidence
By outcome
Lean body mass & muscle growthReduced muscle breakdown, sustained muscle protein synthesis · 4-8 weeks
RecoveryOvernight muscle recovery and repair · Overnight (8 hours)
Too few graded studies7 studies
Endurance & exercise performance
Too few graded studies7 studies
Heart & blood pressure
Too few graded studies7 studies
Cholesterol & lipids
Too few graded studies6 studies
Digestive health
Too few graded studies5 studies
Safety profile
Too few graded studies2 studies
By the numbers
Pulled from 14 studies with measurable effects
Likely real effects
100%
across studies
People studied
12k
typical study: 32 people
Strongest designs
125
8 pooled, 117 randomised
How long studies ran
Under a week
3
1–3 months
5
Populations Studied
Resistance training participants2
General population1
Adults following endurance exercise1
Older adults with or at risk of undernutrition1
Steady research
26 studies in the last 5 years · Latest meta-analysis: 2026
198520052026
1Meta-AnalysisCited 11×n=1,851 · large study2023
In plain English: The findings of this study suggest that supplementation with MP may improve glycemic control in adults by reducing the values of fasting insulin, FBG, and HOMA-IR.
Mohammadi S et al. · Nutrition journal (2023)
Meta-analysis of 36 RCTs in 1,851 adults of milk protein supplementation, whey and casein included.
Milk protein lowered fasting glucose (WMD -1.83 mg/dL), fasting insulin (-1.06 µU/mL) and HOMA-IR (-0.27), with no overall change in HbA1c.
The authors call for longer trials to confirm the findings.
In plain English: When applied during a prolonged period of resistance-type exercise training, protein supplementation prior to sleep can further augment gains in muscle mass and strength.
Trommelen J, van Loon LJ. · Nutrients (2016)
Protein ingested prior to sleep is effectively digested and absorbed, and thereby stimulates muscle protein synthesis rates during overnight recovery.
Recent studies investigating the impact of pre-sleep protein ingestion suggest that at least 40 g of protein is required to display a robust increase in muscle protein synthesis rates throughout overnight sleep.
When applied during a prolonged period of resistance-type exercise training, protein supplementation prior to sleep can further augment gains in muscle mass and strength.
8Digestive health effectsSystematic ReviewCited 52×2019
In plain English: Human-based evidence from clinical trials and epidemiological studies published prior to October 2017 provides moderate certainty for adverse digestive health effects of A1 β-casein compared with A2 β-casein but low or very low certainty for other health effects.
Küllenberg de Gaudry D et al. · Nutrition reviews (2019)
Systematic review of 15 RCTs, 2 case-control studies and 8 ecological studies on A1 β-casein and health outcomes in humans.
Most trials and case-control studies found no significant difference between A1 and A2 milk on intermediate markers, while most ecological studies linked population A1 exposure to adverse outcomes.
GRADE certainty was moderate for adverse digestive effects of A1 compared with A2 β-casein, and low to very low for every other outcome.
9Systematic ReviewCited 6×n=11 · very small study2021
In plain English: A summary of the main findings shows limited to no effects on metabolism or appetite when ingesting 24-48 g of casein 30 min before sleep, but data are limited, and future research is needed to clarify the relationships observed.
Dela Cruz J et al. · Nutrients (2021)
However, it remains unclear what the effect of this nutritional strategy is on non-muscular parameters such as metabolism and appetite in both healthy and unhealthy populations.
The purpose of this systematic review is to understand the effects of pre-sleep casein protein on energy expenditure, lipolysis, appetite, and food intake in both healthy and overweight or obese individuals.
A systematic review following PRISMA guidelines was conducted in CINAHL, Cochrane, and SPORTDiscus during March 2021, and 11 studies met the inclusion criteria.
11Meta-AnalysisCited 204×n=9,030 · very large study2015
In plain English: High-protein supplementation does not seem to be beneficial and may be harmful to the fetus.
Ota E et al. · Cochrane Database Syst Rev (2015)
17 trials, 9,030 women: balanced energy and protein supplementation reduced stillbirth (RR 0.60, 95% CI 0.39 to 0.94) and small-for-gestational-age babies (RR 0.79, 95% CI 0.69 to 0.90), moderate-quality evidence
High-protein supplementation (one trial, 505 women) increased small-for-gestational-age babies, RR 1.58 (95% CI 1.03 to 2.41), moderate-quality evidence
Balanced-protein supplementation alone had no significant effects on perinatal outcomes
In plain English: These results suggest that hemp protein consumption, as well as in combination with bioactive peptides, may have a role in the dietary management of hypertension.
Samsamikor M et al. · The American journal of clinical nutrition (2024)
Double-blind crossover trial in 35 adults with mild hypertension, with 50 g a day of casein for 6 weeks as the comparator for 50 g of hemp seed protein or hemp protein plus hemp-derived peptides.
Compared with casein, 24-hour systolic and diastolic blood pressure were lower after both hemp treatments, falling from 135.1/80.0 to 128.1/76.0 mmHg with the peptide-enriched version.
Casein was the control, so the trial does not test casein's own effect on blood pressure.