Assessment of liver and kidney safety of silver fir (Abies alba) branch extract : an open-label human study of a dietary supplement

Schoss, Katja (author), Kreft, Samo (author)

Extracts of silver fir (Abies alba) branches are rich in polyphenolic compounds and are increasingly used as dietary supplements. Despite their growing consumption, systematic human data on their safety remain limited. This study evaluated the effects of a standardized silver fir branch extract on biochemical markers of liver and kidney function in healthy adults. An open-label, single-arm human study was conducted in 15 healthy volunteers (eight men and seven women; mean age 48 years). Following a two-week comparison period, participants consumed 900 mg/day of a standardized silver fir branch extract for 14 days. Serum markers of liver function (AST, ALT, GGT, ALP, and total bilirubin) and kidney function (urea, creatinine, and uric acid) were measured at baseline, after the comparison period, and after supplementation. The study was retrospectively registered at ClinicalTrials.gov. All participants completed the study without reported adverse events. Mean values of all measured liver and kidney markers remained within established reference ranges throughout the study. No statistically significant changes were observed following supplementation, and minor fluctuations were consistent with normal physiological variability. Short-term consumption of a standardized silver fir branch extract at a daily dose of 900 mg did not adversely affect biochemical markers of liver or kidney function in healthy adults. These findings provide human evidence supporting the short-term safety of this polyphenol-rich dietary supplement.

• Language: English
• Keywords: dietary supplements, human safety study, liver and kidney function, polyphenols, safety assessment, silver fir (Abies alba)
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FFA - Faculty of Pharmacy
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: Str. 1755-1769
• Numbering: Vol. 14, iss. 7, art. e71991
• PID: 20.500.12556/RUL-185197
• UDC: 547.56:613.292
• ISSN on article: 2048-7177
• DOI: 10.1002/fsn3.71991
• COBISS.SI-ID: 285776387
• Publication date in RUL: 28.07.2026

Record is a part of a journal

• Title: Food science & nutrition
• Shortened title: Food sci. nutr.
• Publisher: J. Wiley & Sons
• ISSN: 2048-7177
• COBISS.SI-ID: 520369177

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: prehranska dopolnila, študija varnosti za ljudi, delovanje jeter in ledvic, polifenoli, ocena varnosti, srebrna jelka (Abies alba), prehranska dopolnila, polifenoli

Projects

• Funder: Other - Other funder or multiple funders
• Funding programme: SFBE (Belinal)