Dietary omega-3 fatty acid intake impacts peripheral blood DNA methylation -anti-inflammatory effects and individual variability in a pilot study.
Level 4 - case-series / case-control
Uncontrolled pre-post pilot study / single-arm trial
PubMed 34411715 · doi:10.1016/j.jnutbio.2021.108839
What was done
In a pilot study using samples from a previous dose-finding trial, researchers evaluated peripheral blood mononuclear cells (PBMCs) from 10 women at high risk for breast cancer at baseline and after 6 months of 5 g/day omega-3 polyunsaturated fatty acid supplementation (EPA+DHA). Genome-wide DNA methylation at the single-nucleotide level was measured using reduced representation bisulfite sequencing (RRBS), with focused analysis on candidate genes associated with inflammation signaling and breast cancer.
What was found
The authors identified 24,842 differentially methylated CpGs (DMCs) in the promoter regions of 5,507 genes, showing significant enrichment for hypermethylation in candidate gene and genome-wide analyses. Pathway analysis identified significant hypermethylation of inflammatory signaling networks, including the Toll-like Receptor pathway. Individual baseline DNA methylation patterns and responses to supplementation showed substantial heterogeneity.
Why it matters
This study provides preliminary human mechanistic evidence that high-dose omega-3 supplementation may downregulate inflammatory pathways through epigenetic promoter hypermethylation in immune cells.
Limits
The sample size was very small (n=10) with no placebo control arm, making it impossible to rule out time-dependent confounding or batch effects. The study was restricted to women at high risk for breast cancer receiving a high dose (5 g/day), limiting generalizability. Downstream gene expression or protein-level inflammatory markers were not reported in the abstract.
Cited by
- contradicts A six-month trial of 5 grams per day of EPA/DHA fish oil in women genetically predisposed to breast cancer showed hypomethylation in inflammatory pathways such as TNF-alpha in PBMCs.