A dietary pigment the body cannot make and the eye concentrates in the retina's central patch. Taking it dependably raises that pigment level once intake passes a threshold, and the rise scales with amount. Slowed central vision loss is seen mainly in existing moderate disease. Safety is reassuring at common amounts, with digestive upset the main complaint. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Macular pigment optical density | 0.50 or above | The direct target tissue measure; predicts who will respond |
| Serum zeaxanthin | 0.06 µmol/L or above | Confirms absorption before concluding the retina failed to respond |
| Serum lutein | 0.30 µmol/L or above | Zeaxanthin is almost always co-dosed; lutein status contextualises the result |
| Skin carotenoid score | Upper tertile of the device's own scale | Cheap, repeatable proxy for total carotenoid status |
| High-sensitivity C-reactive protein | Below 1.0 mg/L | Captures the modest anti-inflammatory effect and flags competing inflammation |
| HDL cholesterol | Above 50 mg/dL (women), above 45 mg/dL (men) | The one lipid fraction that moved in pooled trials |
| Photostress recovery time | Under 10 seconds | Functional readout of whether denser pigment translates to better vision |
| Contrast sensitivity | No established target; track change from the individual's own baseline | Detects the functional gain that acuity testing misses entirely |
Cadence: Macular pigment density and serum carotenoids at six months, then annually; lipids and inflammatory markers at twelve months; dilated retinal examination every one to two years, or annually once intermediate disease is present.