Oral Capsules / Tablets
The most common and most-studied form — a standardized aqueous extract, typically 240mg per capsule, often branded as PLE, Fernblock, or sold as part of products like Heliocare.
Leaf Extract · Standardized
Oral Photoprotectant · Clinically Studied
Biological Overview
Polypodium leucotomos is an epiphytic tropical fern native to Central and South America, where it grows on trees and rocks at altitudes between roughly 700 and 2,500 meters. Its leaves are the source of the standardized extract studied in human clinical trials, most often under the commercial name Fernblock.
Life CycleEpiphytic perennial fern
HabitatCentral & South America
Oral Absorption~70–100%
Key CompoundsPhenolic acids
Botanical Classification
Taxonomy & Identification
- Clinical Name
- Polypodium leucotomos
- Related Synonym
- Phlebodium aureum
- Family
- Polypodiaceae
- Common Names
- PLE, Fernblock, Calaguala
- Other Names
- Golden Polypody, Hare's-foot Fern
- Parts Used
- Leaves (aerial parts)
- Habitat
- Tropical Central & South America
Background & Research History
History & Background
Polypodium leucotomos has a long history of traditional use in Central and South American folk medicine — known locally as "calaguala" — for inflammatory skin conditions. It was first introduced to Europe in 1788, following the return of a botanical expedition led by the Spanish naturalist Hipólito Ruiz López and funded by the Spanish Crown.[19]
Modern clinical interest began with the first published clinical study, on psoriasis, in 1974, but the bulk of today's evidence base — covering sunburn prevention, melasma, vitiligo, and atopic dermatitis — was built between 2004 and the present through a sustained program of human clinical trials.
⚠ Naming Note
"Polypodium leucotomos" is the name used throughout the clinical and commercial literature, though some taxonomic sources treat it as synonymous with or closely related to Phlebodium aureum. This monograph uses the terminology found in the cited clinical studies.
The Key Molecules
Ferulic & Caffeic Acid — Deep Dive
The two phenolic acids identified as the extract's most powerful antioxidants — the same antioxidant family found in many topical vitamin-C-style serums, but delivered systemically through an oral capsule.
⚡
Most Potent Free-Radical Scavengers
Of the extract's identified phenolic compounds, ferulic and caffeic acid show the strongest, concentration-dependent antioxidant activity.[18]
🔥
Direct UVB Erythema Reduction
Ferulic and caffeic acid have been shown to reduce UVB-induced erythema (sunburn redness), a finding that also justifies their use in topical antioxidant formulations.
💊
Rapid, Efficient Oral Absorption
When taken orally, the extract is absorbed at roughly 70–100% efficiency and is largely metabolized in the liver within 24 hours.
🧪
The Same Family Found in Skincare Serums
Ferulic and caffeic acid are familiar to anyone who has read the ingredient list of a topical vitamin C serum — PLE concentrates them in a form designed for oral, systemic delivery.
⚠ A Complement, Not a Replacement
Oral PLE does not block UV rays.
Unlike a topical sunscreen, Polypodium leucotomos extract does not physically absorb or reflect UV radiation. The clinical evidence supports it as an oral adjunct that reduces UV-induced cellular damage — used alongside sunscreen, protective clothing, and sun avoidance, not instead of them.
Available Forms
Parts Used & Available Forms
Only the leaves are used to produce the standardized extract studied clinically.
Topical Formulations
The same extract is also incorporated into some topical creams and serums for direct skin application, often alongside oral use.
Topical · Combined Use
Aqueous Extract (Fernblock)
The raw material form most commonly studied — an aqueous extract of the leaves, used as the standardized base for both capsule and topical products.
Aqueous · Raw Material
Clinical Dosimetry
Dosages
Dosing reflects three different research contexts — general photoprotection, single-dose UV-exposure research, and phototherapy adjunct use.
Phytochemistry
Composition
The standardized aqueous extract (Fernblock) is dominated by antioxidant phenolic acids, identified by HPLC analysis.[19]
Cinnamic Acid Derivatives
Ferulic Acid3-methoxy-4-hydroxycinnamic acid; most potent antioxidant identified
Major
Caffeic Acid3,4-dihydroxycinnamic acid; most potent antioxidant identified
Major
p-Coumaric Acid4-hydroxycinnamic acid
Present
4-Hydroxycinnamoylquinic AcidCinnamic-quinic acid conjugate
Present
Benzoic Acids & Chlorogenic Isomers
Chlorogenic Acid (5 Isomers)3-caffeoylquinic acid family
Present
Vanillic Acid4-hydroxy-3-methoxybenzoic acid
Present
3,4-Dihydroxybenzoic AcidAlso known as protocatechuic acid
Present
4-Hydroxybenzoic Acid & Organic AcidsPlus quinic, shikimic, glucuronic, and malic acids
Present
⚗️
Antioxidant
Phenolic acids inhibit UV-induced reactive oxygen species formation and lipid peroxidation.[3][18]
☀️
Photoprotective
Reduces UVB- and UVA-induced erythema and sunburn cell formation when taken orally before UV exposure.[2][10]
🔥
Anti-Inflammatory
Inhibits UV-induced cyclooxygenase-2 (COX-2) expression and reduces inflammatory cytokine activity.[11]
🛡️
Immunomodulatory
Preserves Langerhans cell density after UV exposure and modulates the Th1/Th2 cytokine balance.[4][1]
🧬
DNA-Protective / Antimutagenic
Reduces cyclobutane pyrimidine dimer formation and UVA-induced mitochondrial "common deletion" mutations; activates the p53 tumor-suppressor pathway.[2][11]
⏳
Anti-Photoaging
Inhibits matrix-metalloproteinase activity and supports collagen deposition in UV-irradiated skin.[11]
🎨
Pigmentary Adjunct (Melasma)
Improves outcomes as an adjunct to standard melasma treatment in multiple randomized, placebo-controlled trials.[8][9]
🔆
Repigmenting Adjunct (Vitiligo)
Improves repigmentation when combined with narrow-band UVB phototherapy, particularly in the head and neck area.[6][15]
🩹
Anti-Psoriatic
Documented in the first published clinical study on the extract, with effects linked to Th1 cytokine modulation.[16]
🧒
Corticosteroid-Sparing (Atopic Dermatitis)
Reduced the percentage of days requiring topical corticosteroid use in a pediatric randomized controlled trial.[7]
Clinical Applications
Clinical Indications
Indications studied across more than a dozen randomized and controlled human trials.[14]
☀️
Sunburn Prevention & Photoaging
General Photoprotection
🎨
Pigmentary Disorders
Melasma & Vitiligo
Pharmacodynamics
Mode of Action
A multi-pathway mechanism combining direct antioxidant action with immune and DNA-protective effects.[13]
⚗️
🛡️
🧬
DNA Repair & p53 Activation
Reduces UV-induced DNA damage and activates the p53 tumor-suppressor pathway, decreasing abnormal cell proliferation after UV exposure.[11]
🔥
Inflammatory Pathway Inhibition
Inhibits UV-induced COX-2 expression and matrix-metalloproteinase activity, reducing inflammation and supporting collagen integrity.[11]
Clinical Safety
Safety, Interactions & Precautions
One of the better-characterized safety profiles among botanical extracts, backed by formal human and animal toxicology data.
Adverse Effects & Toxicology
- Human safety trial: a 60-day randomized, double-blind, placebo-controlled study found no significant abnormalities in hematology, metabolic panels, or clotting studies at 240mg twice daily. [10]
- Formal toxicology: no mutagenicity or genotoxicity observed in bacterial, chromosomal, or mouse micronucleus tests; a 90-day rodent study found no adverse effects at doses up to 1200 mg/kg body weight per day. [20]
- Pediatric data: studied in children as young as 2 years for atopic dermatitis under medical supervision over 6 months, with only non-serious adverse events reported. [7]
- Pregnancy & breastfeeding: not specifically studied for safety in these populations; use only under healthcare provider guidance.
Drug Interactions & Precautions
- CYP3A4 pathway checked directly: a controlled human pharmacokinetic study found that short-term oral PLE (240mg, three doses) did not inhibit CYP3A4-mediated metabolism of midazolam, a standard CYP3A4 probe drug — no measurable food-drug interaction was detected. [21]
- Broader interaction data still limited: beyond this specific pathway, comprehensive drug-interaction studies remain limited in the literature reviewed.
- Theoretical immune caution: given its documented Th1/Th2 cytokine-modulating effect, a degree of caution is reasonable for people on immunosuppressant therapy or with autoimmune conditions, though this has not been directly studied as an interaction. [1]
- Not a sunscreen substitute: it does not block UV radiation directly and should not replace topical sunscreen, protective clothing, or sun avoidance.
Clinical Disclaimer: This monograph is for educational and professional reference only. It does not constitute medical advice, diagnosis, or treatment guidance. Always consult a qualified healthcare provider before initiating any phytotherapeutic regimen, particularly during pregnancy or breastfeeding, in children, or if you are taking immunosuppressant medication.
Common Questions
Frequently Asked Questions
What is Polypodium leucotomos?
Polypodium leucotomos is a tropical fern native to Central and South America. A standardized aqueous extract of its leaves — sold under names like PLE or Fernblock, and used as the key ingredient in supplements such as Heliocare — has been studied in over a dozen human clinical trials as an oral, systemic complement to topical sunscreen.
Is there a pill that helps prevent sunburn?
Yes — oral Polypodium leucotomos extract has been shown in multiple randomized, placebo-controlled human trials to reduce UV-induced erythema (sunburn redness), sunburn cell formation, and DNA damage when taken before sun exposure. It's intended as a complement to sunscreen, not a replacement for it.
What is the active ingredient in Heliocare?
Heliocare's core active ingredient is Fernblock, a standardized aqueous extract of Polypodium leucotomos leaves rich in antioxidant phenolic acids, including ferulic acid and caffeic acid.
Does oral sun protection actually work, or do I still need sunscreen?
Clinical studies show oral Polypodium leucotomos extract measurably reduces UV-induced skin damage and erythema, but it does not block UV rays the way a topical sunscreen does. It's studied and used as an adjunct to topical sunscreen and sun-protective behavior, not a substitute for either.
What is PLE or Fernblock?
PLE and Fernblock both refer to standardized extracts of Polypodium leucotomos leaves. Fernblock is a specific commercial brand name for the extract, while PLE (Polypodium Leucotomos Extract) is the general term used across the clinical literature.
What is the recommended dosage of Polypodium leucotomos?
The most-studied human dosing regimen, evaluated in a randomized, double-blind, placebo-controlled 60-day trial, is 240 mg taken twice daily. Single research doses of approximately 7.5 mg/kg have also been used before controlled UV exposure in clinical studies. Always confirm dosing with a qualified healthcare provider.
Is Polypodium leucotomos safe?
Clinical and toxicological studies have found it to be well tolerated. A 60-day randomized human safety trial found no significant abnormalities in blood counts, metabolic panels, or clotting studies, and formal toxicology testing found no genotoxicity or mutagenicity, with a no-observed-adverse-effect level far above typical human supplement doses.
Can Polypodium leucotomos help with melasma or dark spots?
Yes, as an adjunct. Randomized, placebo-controlled trials found that oral Polypodium leucotomos extract improved outcomes when added to standard melasma treatment (topical hydroquinone and sunscreen), including in studies specifically conducted in Asian skin.
Can Polypodium leucotomos help with vitiligo?
It has shown benefit as an adjunct to phototherapy. Randomized controlled trials combining oral Polypodium leucotomos extract with narrow-band UVB phototherapy found greater repigmentation, particularly in the head and neck area, compared to phototherapy alone.
What is calaguala fern used for?
Calaguala is a common Central and South American name for Polypodium leucotomos. It has a long history of traditional use for inflammatory skin conditions, and modern clinical research has focused specifically on its photoprotective, antioxidant, and anti-inflammatory effects.
Does Polypodium leucotomos interact with medications?
A controlled human study found that short-term oral PLE did not inhibit CYP3A4-mediated drug metabolism, suggesting no interaction through that pathway. Broader interaction data remain limited, and because the extract has documented immune-modulating effects on Th1/Th2 cytokine balance, some caution is reasonable for people on immunosuppressant therapy or with autoimmune conditions.
Can children or pregnant women take Polypodium leucotomos?
It has been studied in children as young as 2 years old for atopic dermatitis under medical supervision. However, it has not been specifically studied for safety in pregnancy or breastfeeding, so use during pregnancy should only occur under a healthcare provider's guidance.
Primary Literature
Bibliography
↑
1.
Middelkamp-Hup MA, Pathak MA, Parrado C, Garcia-Caballero T, Rius-Díaz F, Fitzpatrick TB, González S. Orally administered Polypodium leucotomos extract decreases psoralen-UVA-induced phototoxicity, pigmentation, and damage of human skin. J Am Acad Dermatol. 2004 Jan;50(1):41-9.
PubMed PMID:14699363 →
↑
2.
Middelkamp-Hup MA, Pathak MA, Parrado C, Goukassian D, Rius-Díaz F, Mihm MC, Fitzpatrick TB, González S. Oral Polypodium leucotomos extract decreases ultraviolet-induced damage of human skin. J Am Acad Dermatol. 2004 Dec;51(6):910-8.
PubMed PMID:15583582 →
↑
3.
González S, Pathak MA. Inhibition of ultraviolet-induced formation of reactive oxygen species, lipid peroxidation, erythema and skin photosensitization by Polypodium leucotomos. Photodermatol Photoimmunol Photomed. 1996 Apr;12(2):45-56.
PubMed PMID:8897589 →
↑
4.
González S, Pathak MA, Cuevas J, Villarrubia VG, Fitzpatrick TB. Topical or oral administration with an extract of Polypodium leucotomos prevents acute sunburn and psoralen-induced phototoxic reactions as well as depletion of Langerhans cells in human skin. Photodermatol Photoimmunol Photomed. 1997 Feb-Apr;13(1-2):50-60.
PubMed PMID:9361129 →
↑
5.
Tanew A, Radakovic S, Gonzalez S, Venturini M, Calzavara-Pinton P. Oral administration of a hydrophilic extract of Polypodium leucotomos for the prevention of polymorphic light eruption. J Am Acad Dermatol. 2012 Jan;66(1):58-62.
PubMed PMID:21696853 →
↑
6.
Middelkamp-Hup MA, Bos JD, Rius-Diaz F, Gonzalez S, Westerhof W. Treatment of vitiligo vulgaris with narrow-band UVB and oral Polypodium leucotomos extract: a randomized double-blind placebo-controlled study. J Eur Acad Dermatol Venereol. 2007 Aug;21(7):942-50.
PubMed PMID:17659004 →
↑
7.
Ramírez-Bosca A, Zapater P, Betlloch I, Albero F, Martínez A, Díaz-Alperi J, Horga JF. Polypodium leucotomos extract in atopic dermatitis: a randomized, double-blind, placebo-controlled, multicenter trial. Actas Dermosifiliogr. 2012 Sep;103(7):599-607.
PubMed PMID:22560125 →
↑
8.
Ahmed AM, Lopez I, Perese F, Vasquez R, Hynan LS, Chong B, Pandya AG. A randomized, double-blinded, placebo-controlled trial of oral Polypodium leucotomos extract as an adjunct to sunscreen in the treatment of melasma. JAMA Dermatol. 2013 Aug;149(8):981-3.
PubMed PMID:23740292 →
↑
9.
Goh CL, Chuah SY, Tien S, Thng G, Vitale MA, Delgado-Rubin A. Double-blind, placebo-controlled trial to evaluate the effectiveness of Polypodium leucotomos extract in the treatment of melasma in Asian skin: a pilot study. J Clin Aesthet Dermatol. 2018 Mar;11(3):14-19.
PubMed PMID:29606995 →
↑
10.
Nestor MS, Berman B, Swenson N. Safety and Efficacy of Oral Polypodium leucotomos Extract in Healthy Adult Subjects. J Clin Aesthet Dermatol. 2015 Feb;8(2):19-23.
PubMed PMID:25741399 →
↑
11.
Parrado C, Mascaraque M, Gilaberte Y, Juarranz A, Gonzalez S. Fernblock (Polypodium leucotomos extract): molecular mechanisms and pleiotropic effects in light-related skin conditions, photoaging and skin cancers, a review. Int J Mol Sci. 2016 Jun 29;17(7):1026.
PubMed PMID:27367679 →
↑
12.
Berman B, Ellis C, Elmets C. Polypodium Leucotomos — An Overview of Basic Investigative Findings. J Drugs Dermatol. 2016 Feb;15(2):224-8.
PubMed PMID:26885792 →
↑
13.
Sander M, Burbidge T, Beecker J. Role of oral Polypodium leucotomos extract in dermatologic diseases: a review of the literature. CMAJ. 2020 Dec 14;192(50):E1802-E1808.
PubMed PMID:33318091 →
↑
14.
Segars K, McCarver V, Miller RA. Dermatologic Applications of Polypodium leucotomos: A Literature Review. J Clin Aesthet Dermatol. 2021 Feb;14(2):50-60.
PubMed PMID:34221229 →
↑
15.
Pacifico A, Damiani G, Iacovelli P, Conic RRZ, Gonzalez S, Morrone A. NB-UVB plus oral Polypodium leucotomos extract display higher efficacy than NB-UVB alone in patients with vitiligo. Dermatol Ther. 2021 Mar;34(2):e14776.
PubMed PMID:33433041 →
↑
16.
Padilla HC, Lainez H, Pacheco JA. A new agent (hydrophilic fraction of Polypodium leucotomos) for management of psoriasis. Int J Dermatol. 1974 Sep-Oct;13(5):276-82.
PubMed PMID:4609374 →
↑
17.
Bhatia N. Polypodium leucotomos: a potential new photoprotective agent. Am J Clin Dermatol. 2015 Apr;16(2):73-9.
PubMed PMID:25666116 →
↑
18.
Gombau L, García F, Lahoz A, Fabre M, Roda-Navarro P, Majano P, Alonso-Lebrero JL, Pivel JP, Castell JV, Gómez-Lechón MJ, González S. Polypodium leucotomos extract: antioxidant activity and disposition. Toxicol In Vitro. 2006 Jun;20(4):464-71.
PubMed PMID:16263237 →
↑
19.
Garcia F, Pivel JP, Guerrero A, Brieva A, Martinez-Alcazar MP, Caamano-Somoza M, Fernandez-Lorente M, Gonzalez S. Phenolic components and antioxidant activity of Fernblock, an aqueous extract of the aerial parts of the fern Polypodium leucotomos. Methods Find Exp Clin Pharmacol. 2006 May;28(3):157-60.
PubMed PMID:16810341 →
↑
20.
Murbach TS, Béres E, Vértesi A, Glávits R, Hirka G, Endres JR, Clewell AE, Szakonyiné IP. A comprehensive toxicological safety assessment of an aqueous extract of Polypodium leucotomos (Fernblock®). Food Chem Toxicol. 2015 Dec;86:328-41.
PubMed PMID:26585922 →
↑
21.
Shinya K, Nishimura Y, Ryu K, Sambe T, Fujishiro M, Nakauchi A, Kashiwabuchi Y, Iwase M, Chokki H, Kurata N, Matsuyama T, Kiuchi Y. Short-term administration of Polypodium leucotomos extract does not inhibit CYP3A4-mediated metabolism of midazolam in healthy subjects: an open-label, two-period, fixed-sequence study. Int J Dermatol. 2023 Jun;62(6):694-699.
PubMed PMID:35751767 →