Casein is milk's main protein, slow-digesting and top-quality. Its strongest value is building and preserving muscle alongside strength training, with a popular before-bed use for overnight repair. It also modestly helps fullness and blood sugar and seems neutral for inflammation. Inexpensive and widely available; milk-allergic people must avoid it. (Full Review)

Protocol

Standard Dose

30–40 g per serving

Range 20–40 g; higher end favored for older adults with anabolic resistance

Pre-Sleep Protocol

~40 g before sleep

Within ~30 minutes of bed, ideally after evening resistance exercise

Daily Distribution

Spread across 3–4 feedings

Distribute total daily protein across meals to repeatedly stimulate muscle protein synthesis

Time to effect

Lean Mass & Strength

8–12 weeks

Measurable changes require consistent use alongside resistance training

Overnight Muscle Repair

Same day

Acute rise in overnight muscle protein synthesis the night of dosing

Satiety

Same day

Prolonged fullness from slow gastric emptying occurs acutely

Benefits

High: Supports muscle protein synthesis and lean mass; high-quality complete protein source

Medium: Overnight muscle protein synthesis when taken before sleep; improved satiety and appetite control; modest improvement in blood sugar control

Low: Calcium absorption via casein phosphopeptides; inflammation-neutral to mildly anti-inflammatory

Speculative: A2 casein for digestive comfort and broader healthspan

Contraindications

Diagnosed cow's milk protein allergy

Advanced chronic kidney disease (stage 4–5, eGFR <30)

Severe milk-protein intolerance

Key Interactions

Tetracyclines (doxycycline), fluoroquinolones (ciprofloxacin)

Levothyroxine

Bisphosphonates (alendronate)

Oral iron and zinc supplements

Glucose-lowering agents (metformin, berberine)

Risk & Side Effects

High: Allergic reaction in milk-allergic individuals

Medium: Digestive discomfort

Low: Excess protein burden in kidney impairment; saturated fat and caloric load from whole-dairy sources

Speculative: A1 β-casein and chronic disease risk

Monitoring

Marker	Target	Why
eGFR	>90 mL/min/1.73m²	Confirms kidneys can handle increased protein load
Blood Urea Nitrogen (BUN)	10–16 mg/dL	Reflects protein metabolism and hydration status
Creatinine	0.7–1.1 mg/dL (sex-dependent)	Marker of kidney filtration and muscle mass
Fasting glucose	75–86 mg/dL	Tracks casein's modest glucose effect and overall metabolic health
Body composition (lean mass)	Individualized; maintain or increase	Defines success for muscle-preservation goals

Cadence: Every 6–12 months at high doses for muscle goals; more frequent if kidney impairment is present

Qualitative Assessment

Subjective fullness and reduced late-night hunger after pre-sleep dosing
Maintained or improved strength and gym performance over training blocks
Ease of meeting daily protein targets
Absence of bloating, gas, or other digestive discomfort
Stable energy and recovery between training sessions

Casein for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment