How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Casein
Slow-digesting milk protein: 40 g before sleep increase muscle synthesis overnight, but post-workout, whey performs better in the short term.
Benefits
- Taken 30 minutes before sleep, 40 g of casein increase muscle protein synthesis overnight, in young men (about 22 % more than placebo) as well as in older men
- After a weight training session, 20 g of casein turn muscle protein balance from negative to positive, just as much as 20 g of whey
- Same muscle protein synthesis as whey from 1 to 6 hours after a session, at 0.3 g per kg of lean mass
- In 10 professional football players, 40 g before bedtime after a match accelerated jump recovery (−1.6 % vs. −6.6 % at 12 hours) and reduced muscle soreness
- Over 8 weeks of weight training, 24 g before and after training yielded the same gains as whey in 16 female basketball players (+1.4 kg of lean mass vs. +1.5 kg)
Precautions
No study in this review measures adverse effects. Trials on nighttime protein are small (9 to 48 people) and most measure protein synthesis over a single night, not bigger muscles. In 18 trained men, 40 g at bedtime changed neither strength nor markers of muscle damage the next morning. The systematic review notes that the compared groups did not all receive the same amount of protein per day, and considers the data insufficient to conclude in older adults. As a post-workout protein, whey performs better in the short term across three trials.
Recommended dosage
20 to 40 g; in the evening, 40 g about 30 minutes before sleep
How to take it
- In the evening: 40 g about 30 minutes before bedtime, the dose from trials that find stronger muscle synthesis overnight; the systematic review of 9 studies retains 20 to 40 g.
- Dose matters: in 48 older men, 20 g (even with 1.5 g of leucine) did not do better than placebo, only 40 g succeeded; in 36 young men, 30 g did not increase muscle synthesis overnight.
- Post-workout: 20 g, or 0.3 g per kg of lean mass, in trials comparing it to whey.
- Casein or whey: in the short term, whey stimulates muscle protein synthesis more (65 % more in older men at rest, 122 % more in young men across two trials); over 8 weeks of training, the only trial finds the same gains.
- For hunger: whey is more satiating than casein in three studies, without changing intake or weight over 12 weeks.
- In milk: casein taken in whey is digested more slowly than in water, without changing muscle synthesis in older men.
- The next morning: 40 g at bedtime changed neither appetite nor breakfast intake in 12 older individuals.
Did you know?
Taken right before sleep, casein is well digested during sleep: in 16 young men, 40 g made whole-body protein balance positive overnight, when it remained negative under placebo.
What the studies say
This systematic review analyzes clinical studies evaluating the effects of pre-sleep protein consumption on overnight muscle protein synthesis and gains in muscle mass and strength. It concludes that consuming 20 to 40 g of casein approximately 30 minutes before sleep stimulates whole-body protein synthesis during the night in young and older men. For young individuals, this may increase muscular adaptations (mass and strength) over 10-12 weeks of training, but more data are needed for older individuals.
Reis CEG, Loureiro LMR, Roschel H, da Costa THM. — Journal of science and medicine in sport (2021) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more