Casein
Useful mainly for people wanting a slow-digesting protein, especially before sleep.
Quick decision guide
May help most
people wanting a slow-digesting protein, especially before sleep
Common dosing range
20-40 g per serving
When to expect effects
Hours (per serving); weeks for body composition
Watch out for
avoid with cow's milk allergy
What is it
Casein is the main protein in milk, accounting for about 80 percent of milk protein (the other 20 percent is whey). It is a slow-digesting protein, releasing amino acids gradually over hours after consumption, making it popular as a 'nighttime' protein supplement.
Is it worth it for you?
Use this as a quick fit check, not a diagnosis.
Worth considering if…
Probably skip if…
Evidence at a glance
| Goal | Effect | Best fit | Time |
|---|---|---|---|
muscle building Good Evidence | Modest; mainly via meeting protein needs | Resistance-training adults using casein to reach adequate protein intake | Weeks |
overnight muscle protein synthesis Limited Evidence | Measurable rise in synthesis rates | People training in the evening who take 30-40 g before sleep | Hours (overnight) |
satiety and appetite control Limited Evidence | Modest increase in fullness | People using protein to manage appetite between meals | Hours |
muscle building
- Effect
- Modest; mainly via meeting protein needs
- Best fit
- Resistance-training adults using casein to reach adequate protein intake
- Time
- Weeks
overnight muscle protein synthesis
- Effect
- Measurable rise in synthesis rates
- Best fit
- People training in the evening who take 30-40 g before sleep
- Time
- Hours (overnight)
satiety and appetite control
- Effect
- Modest increase in fullness
- Best fit
- People using protein to manage appetite between meals
- Time
- Hours
Evidence for 3 uses
AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.
muscle building
Supplement benefitCasein is a complete, high-quality protein, and supplementing it supports gains in lean mass and strength when it helps reach adequate daily protein during resistance training. Most of the benefit comes from total protein sufficiency rather than a unique property of casein.
Bottom line: Supports muscle gains mainly by helping you hit daily protein targets.
overnight muscle protein synthesis
Mechanism onlyCasein forms a stomach curd that releases amino acids over 4-6 hours, versus 1-2 hours for whey. Studies show 30-40 g of pre-sleep casein raises overnight muscle protein synthesis rates. This is a metabolic measurement; whether it improves long-term muscle outcomes is addressed separately and is more modest.
Bottom line: Pre-sleep casein measurably raises overnight protein synthesis, a mechanistic effect.
satiety and appetite control
Supplement benefitAs a slow-digesting protein, casein produces a prolonged amino acid release that can increase satiety and reduce subsequent intake in short-term feeding studies. Effects on appetite are consistent but modest and depend on overall diet.
Bottom line: Slow digestion makes casein modestly filling, useful for appetite control between meals.
How it works
How to take it
What to track
3 commercial forms
Compare the main delivery options and what they’re best suited for.
Micellar casein
Standard 'nighttime' protein. Forms slow-digesting curd.
Most natural form; slow-release.
Calcium caseinate
Used in many protein blends and ready-to-drink beverages.
More soluble; mixes easier than micellar.
Casein hydrolysate
Used for specific peptide effects (e.g., blood pressure) or in hypoallergenic infant formulas.
Pre-digested; faster absorption.
Safety
Know the common side effects, key cautions, and who should avoid it.
Common side effects
Serious risks
Allergic reactions in people with cow's milk allergy
Who should avoid it
- People with cow's milk allergy
- People with milk protein intolerance
Pregnancy & breastfeeding
Dietary milk protein is generally considered safe in pregnancy for those without milk allergy.
Interactions
Calcium content can reduce absorption; separate by 2-4 hours
Food sources
| Food | Amount | %DV |
|---|---|---|
| Cottage cheese | 1 cup | — |
| Greek yogurt | 1 cup | — |
| Milk | 1 cup | — |
| Hard cheese (cheddar, parmesan) | 1 oz | — |
Cottage cheese
- Amount
- 1 cup
- %DV
- —
Greek yogurt
- Amount
- 1 cup
- %DV
- —
Milk
- Amount
- 1 cup
- %DV
- —
Hard cheese (cheddar, parmesan)
- Amount
- 1 oz
- %DV
- —
Choosing a product
What to look for on the label — and what to be skeptical of.
Look for…
Be skeptical of…
Frequently asked questions
When should I take casein?⌄
Most commonly before bed for sustained overnight amino acid availability. Can also be used between meals as a long-lasting protein source.
Casein vs whey - which is better?⌄
Different uses. Whey is fast-absorbing (good post-workout). Casein is slow-absorbing (good before bed or between meals). Many people use both.
Can lactose-intolerant people take casein?⌄
Most casein isolates are very low in lactose and well-tolerated. Check the label for specific lactose content.
References by claim
Track Casein with Pilora
Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.
Coming to App StoreDisclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.