Polypodium leucotomos (Fernblock)
Oral fern extract with multiple RCTs for photoprotection, increases minimal erythema dose and used as dermatology adjunct in polymorphic light eruption.
Why
Polypodium leucotomos (Fernblock, also marketed as Heliocare) is a fern extract from Central and South America with photoprotective effects on skin. Multiple RCTs (Middelkamp-Hup 2004 J Am Acad Dermatol, Aguilera 2013 J Am Acad Dermatol, Caccialanza 2007) document increases in minimal erythema dose and reduced phototoxicity. Used in dermatology as oral adjunct for polymorphic light eruption (PLE), solar urticaria, vitiligo (with phototherapy), and as photoprotection supplement to topical sunscreen.
How it works
Polyphenols (caffeoylquinic acids) provide systemic antioxidant capacity that reduces UV-induced reactive oxygen species in skin. Modulates UV-induced inflammatory cytokines, preserves Langerhans cell density after UV exposure, and reduces matrix metalloproteinase expression.
Expected onset · Photoprotective effect within 1–2 hours of dosing; sustained-use effects on skin biomarkers over weeks
How to take
Dosage
240 mg twice daily (Fernblock standardised extract). Many products: one 240 mg capsule 30 min before sun exposure and a second mid-day.
Timing
30 minutes before sun exposure; second dose mid-day for extended exposure
On the label
'Fernblock' (the standardised extract used in the published trials), or 'PLE' standardised extract. Heliocare is the dominant retail brand.
Ideal for
Adults prone to polymorphic light eruption or photosensitive conditions; people seeking systemic photoprotective adjunct alongside topical sunscreen, not a sunscreen replacement.
Safety
Evidence
Middelkamp-Hup 2004 J Am Acad Dermatol RCT: Polypodium leucotomos significantly reduced UV-induced erythema, sunburn cells and DNA damage in human skin. Aguilera 2013 RCT in idiopathic photodermatoses (PLE, solar urticaria) reported reduced disease severity. Used clinically across dermatology as photoprotection adjunct.
- Middelkamp-Hup et al., J Am Acad Dermatol 2004, oral Polypodium leucotomos extract decreases UV-induced damage of human skin (RCT)
- Aguilera et al., J Am Acad Dermatol 2013, Polypodium leucotomos in patients with idiopathic photodermatoses (RCT)
- Berman et al., J Clin Aesthet Dermatol 2016, safety, efficacy, and potential of Polypodium leucotomos as a photoprotective and antioxidant supplement: a review
Where to get it
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