A deeply pigmented European fruit used at the first sign of a winter respiratory illness. Small studies report shorter, milder illness, but most were funded by extract makers and the one independent trial found no benefit. Raw or home-pressed plant material can cause cyanide-type poisoning, and many products contain far less genuine berry than the label states. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Fasting glucose | 75–86 mg/dL | Detects the measured post-meal glucose effect |
| HbA1c | 4.8–5.4% | Confirms whether any glucose change persists |
| Fasting insulin | 2–5 µIU/mL | Separates a real insulin-sensitivity change from a diet artifact |
| TSH | 1.0–2.0 mIU/L | Detects the measured rise in thyroid signaling |
| Free T4 | 1.0–1.5 ng/dL | Confirms whether a TSH shift reflects hormone output |
| hs-CRP | Below 1.0 mg/L | Tracks the inflammation claim in either direction |
| ALT | Below 20 U/L | Covers the isolated liver-injury interaction report |
| Respiratory episode log | No established target; track episode count and symptom-days against prior seasons | Converts the only replicated benefit into something measurable |
Cadence: Baseline before elderberry is introduced. For continuous daily intake, repeat at 8–12 weeks, then every 6–12 months; for seasonal or acute use, repeat at the end of each season. Thyroid hormones warrant a check at 12 weeks in anyone already treated for thyroid disease.