Effects of 6 weeks of n-3 fatty acids and antioxidant mixture on lipid peroxidation at rest and postexercise


Journal Title (Medline/Pubmed accepted abbreviation): Eur J Appl Physiol
Year: 2011
Volume: 111
Number: 8
Page numbers: 1829-1839
doi: 10.1007/s00421-010-1807-x

Summary of background and research design:

Background:  Strenuous exercise causes structural muscle damage and leads to inflammatory reactions that may prolong exercise recovery. Very long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFAs) may decrease the production of cytokines and reactive oxygen species (ROS) involved in the inflammatory response. Moreover, supplementation with antioxidant combinations has shown more promise than single substances; however, little data exist from trained individuals.

Hypothesis: Antioxidant and n-3 LCPUFA supplementation will reduce oxidative stress and improve antioxidant properties following an intensive training session.

Subjects: Thirty-six male national-level judo competitors (training, 9 hr/wk) participated in this study. Baseline characteristics were similar between groups: mean age, ~22.8 years; height, ~172.5 cm; weight, ~76.9 kg; and body fat, ~17.3 %.

Experimental design: Randomized

Treatments and protocol: Volunteers were randomized to 1 of 4 supplementation groups for 6 weeks; placebo, n-3 LCPUFA, n-3 LCPUFA + vitamins (containing antioxidants), or vitamins alone. Each n-3 LCPUFA capsule contained 150 mg eicosapentaenoic acid (EPA) and 100 mg docosahexanoic acid (DHA).  Daily doses of supplements were 600 mg EPA, 400 mg DHA, 30 mg vitamin E, 60 mg vitamin C, and 6 mg beta-carotene.  Dietary intake was controlled for foods high in vitamins E and C. The 2-hour training session consisted of a 20-minute warm-up and 10-minute rest, followed by judo drills and randori (maximal oxygen uptake [VO2max] > 85% to 90%). Immediately after the training, a 5-minute judo match was conducted. Blood samples were collected at rest before supplementation (T1),  at rest after supplementation (T2), and after supplementation at 10 minutes following judo match (T3) for PUFA susceptibility to peroxidation (conjugated dienes [CD] and maximum rate of oxidation [Rmax]) and malondialdehyde (MDA), nitric oxide, and lipid peroxide (POOL) levels.

Summary of research findings:
  • 4 volunteers in the vitamin-alone group did not complete the study, and results were not presented for this group.
  • In the n-3LCPUFA group, supplementation increased Rmax, MDA, and POOL.   Exercise further increased these parameters, as evidenced by significant exercise x group interactions (P < 0.05) for these parameters, as well as for CDmax and markers of nitric oxide.
  • In the n-3LCPUFA + vitamins group, supplementation alone also increased Rmax, MDA, and POOL.  However, the additive effect of the exercise for increasing oxidative stress markers, which was observed in the n-3LCPUFA group, was blunted by the antioxidant vitamins.  The POOL levels at T3 were lower than the T3 values for placebo or n-3LCPUFA.
  • Serum levels of retinol and α-tocopherol were elevated by supplementation alone, with additional increases observed via the combination of supplementation and exercise.  

Interpretation of findings/Key practice applications:

Supplementation with EPA and DHA increased baseline oxidative stress and did not attenuate exercise-induced oxidative stress; combined with antioxidants, lipid peroxidation decreased. However, evidence suggests that effective antioxidant supplementation may occur at a higher dose and longer duration than was evaluated in this study. In addition, beneficial effects of vitamin E and n-3 LCPUFAs may not occur until exercise induces a high level of oxidative stress.
 
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