An oral fern extract modestly raises how much sunlight skin tolerates before reddening, and lowers that redness. Added to sunscreen, it reduced precancerous sun-damage patches. The claim that it shields skin’s genetic material was not confirmed. Well tolerated: mild stomach upset and itching in a small minority. The small margin could cost more than it gives if sunscreen use slips. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Alanine aminotransferase | 10–20 U/L (men), 8–17 U/L (women) | Detects any hepatic load from a daily botanical polyphenol |
| Complete blood count with eosinophils | Eosinophils below 3% of white cells | Flags a hypersensitivity pattern behind reported itching |
| 25-hydroxyvitamin D | 40–60 ng/mL | Confirms that raised ultraviolet tolerance has not been accompanied by reduced sun exposure |
| High-sensitivity C-reactive protein | Below 0.5 mg/L | Tracks the systemic inflammatory tone the extract is proposed to lower |
| Minimal erythema dose | No established target; change from own baseline, aiming for the 25% rise seen in trials | The only direct measure of the extract's primary demonstrated effect |
| Modified Melasma Area and Severity Index | No established target; change from own baseline, with a 50% fall treated as meaningful | Quantifies facial pigmentation where melasma is the reason for use |
| Standardised facial photography | No numeric range exists; serial images under identical lighting and polarisation | Captures texture, pigment evenness and fine-line change that no blood test reflects |
| Full-skin examination lesion count | No established target; actinic keratosis count against own baseline | Reducing this count is the best-evidenced visible benefit |
Cadence: Blood work at 3 months, then every 6 to 12 months; photography at 8 weeks, 6 months and annually thereafter; full-skin examination annually, or every 6 months with prior actinic keratoses