A fast-digesting milk protein. Its strongest use is closing a protein shortfall in someone who also lifts weights, and in older people who have lost muscle or become frail. Where protein intake is already high, or training is absent, benefit shrinks toward nothing. Digestive upset and allergy are the common harms; blood pressure falls after large drinks matter past 65. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Creatinine and eGFR | Above 90 mL/min/1.73m² | The one group in whom protein loading is plausibly harmful |
| Urine albumin-to-creatinine ratio | Below 10 mg/g | More sensitive to early kidney damage than filtration rate |
| Blood urea nitrogen | 10–18 mg/dL | Reflects protein load; a rise without an eGFR fall means intake, not damage |
| Fasting insulin | Below 6 µIU/mL | The most responsive marker of the glycemic effect |
| HbA1c | Below 5.4% | Confirms whether the glucose effect holds over three months |
| Apolipoprotein B | Below 80 mg/dL | The most reliable readout of the lipid effect |
| Triglycerides | Below 80 mg/dL | The lipid fraction most consistently improved by whey |
| ALT | Below 25 U/L men, below 20 U/L women | Screens for the liver signal under chronic excessive intake |
| IGF-1 | Age-adjusted mid-normal, not upper quartile | The mechanistic link to the longevity concern |
| Seated and standing blood pressure | Below 120/80 mmHg with under 10 mmHg postural drop | Captures the mild lowering benefit and the post-drink fall risk |
| Appendicular lean mass index | Above 7.0 kg/m² men, above 5.5 kg/m² women | The primary efficacy endpoint |
| Grip strength | Above 35 kg men, above 20 kg women | Functional confirmation that lean mass gains are useful |
Cadence: Baseline panel first; blood pressure and symptoms at 2 and 4 weeks; metabolic and lipid markers at 12 weeks; body composition and grip strength at 12 weeks, then every 6 months; kidney markers annually, or 6-monthly if starting eGFR is below 60