Effects of 30-day high-dose omega-3 fatty acid supplementation on plasma oxidative stress enzyme activities in recreational and trained runners : a pilot study

Martinšek, Bojan (author), Skitek, Milan (author), Kosjek, Tina (author), Bedrač, Leon (author), Benedik, Evgen (author)

Background: Physical activity induces the production of reactive oxygen species (ROS), which, at moderate levels mediate beneficial physiological adaptations, including insulin sensitivity and enhanced antioxidant defense. However, excessive ROS production during intense exercise may exceed endogenous antioxidant capacity, leading to oxidative stress and muscle damage. Objective: This study examined the effects of 30-day high-dose omega-3 fatty acid supplementation (9 g/day) on plasma fatty acid composition and the activity of antioxidant enzymes in recreational (n = 11) and trained (n = 10) runners, with emphasis on group- and time-specific responses. Methods: Plasma levels of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were assessed at three time points: pre-, during, and post-supplementation period. Enzymatic activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) were measured at six time points, including before and after exercise sessions involving a 2800 m run followed by a 400 m sprint. Results: Omega-3 supplementation increased plasma EPA and DHA. In trained runners, it was associated with a transient reduction in GPx and a pronounced mid-phase decline in SOD, whereas enzyme activities remained stable in recreational runners. CAT activity did not change significantly in either group. Conclusions: Short-term high-dose omega-3 supplementation modulates antioxidant enzyme activity in a group- and time-dependent manner. The observed downregulation of GPx and SOD in trained runners may reflect altered redox signaling; however, its relevance for exercise performance remains uncertain. Further studies are warranted to elucidate the physiological and functional consequences of these findings.

• Language: English
• Keywords: physical activity, running, reactive oxygen species, omega-3 fatty acids, polyunsaturated fatty acids, catalase, glutathione peroxidase, superoxide dismutase
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FFA - Faculty of Pharmacy
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: Str. 1-17
• Numbering: Vol. 17, issue 18, [article no.] 2985
• PID: 20.500.12556/RUL-175615
• UDC: 577
• ISSN on article: 2072-6643
• DOI: 10.3390/nu17182985
• COBISS.SI-ID: 250196483
• Publication date in RUL: 06.11.2025

Record is a part of a journal

• Title: Nutrients
• Shortened title: Nutrients
• Publisher: MDPI
• ISSN: 2072-6643
• COBISS.SI-ID: 2948140

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: omega-3 maščobne kisline, večkrat nenasičene maščobne kisline, katalaza, tek, telovadba, maščobne kisline

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P3-0395
• Name: Prehrana in javno zdravje

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0143
• Name: Kroženje snovi v okolju, snovna bilanca in modeliranje okoljskih procesov ter ocena tveganja