Collagen broken into absorbable fragments. The firmest findings are less knee pain and stiffness, and a small bone density gain in women after menopause. The heavily promoted skin claim fades in independently funded studies. Harms are modest: digestive upset, and more stone-forming substance in urine for existing stone formers. Benefits build over months, only where something was already lacking. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Estimated glomerular filtration rate (eGFR) | Above 90 mL/min/1.73 m² | Sets whether the added oxalate load is safe |
| 24-hour urinary oxalate | Below 25 mg/24 h | The direct pathway by which collagen could cause harm |
| 24-hour urinary calcium | Below 200 mg/24 h | Combines with oxalate to form stones |
| Serum 25-hydroxyvitamin D | 40–60 ng/mL | Bone gains depend on adequate vitamin D |
| P1NP | No established target; change from own baseline | Shows whether bone formation is rising |
| CTX-I | No established target; change from own baseline | Shows whether bone breakdown is falling |
| Bone mineral density T-score, spine and femoral neck | Above −1.0 | The only hard structural endpoint collagen has moved |
| High-sensitivity C-reactive protein (hs-CRP) | Below 0.5 mg/L | Context for joint symptom change |
Cadence: Baseline panel before the first dose, including bone turnover markers. Kidney and stone-risk chemistry at three months, minerals every six to twelve months, bone density scan no sooner than twelve months. P1NP and CTX-I after a fourteen-day pause.