Background: The extent to which long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) from fish oil such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exert their anti-inflammatory effects by down-regulating intestinal inflammation in humans is unknown. We investigated the impact of LCn-3PUFA supplementation on inflammatory gene expression in the duodenum of obese patients with type 2 diabetes.
Findings: This placebo-controlled randomized crossover study included 12 men with type 2 diabetes. After a 4-week run-in period, patients received in a random sequence 5 g/d of fish oil (providing 3 g of EPA + DHA) and a placebo (corn and soybean oil) for 8 weeks each. The two treatment phases were separated by a 12-week washout period. Gene expression was assessed by real-time polymerase chain reaction in duodenal biopsy samples obtained in the fasted state at the end of each treatment phase. Intestinal mRNA expression levels of interleukin (IL)-6 and tumor-necrosis factor (TNF)-α were hardly detectable after either treatment (<100 copies/105 copies of the reference gene ATP5o). Intestinal mRNA expression of IL-18 and of the transcription factor signal transducer and activator of transcription 3 (STAT3) was higher (>5000 copies/105 copies ATP5o) but still relatively low. EPA + DHA supplementation had no impact on any of these levels (all P ≥ 0.73).
Conclusions: These data suggest that duodenal cells gene expression of pro-inflammatory cytokines is low in patients with type 2 diabetes and not affected by EPA + DHA supplementation. Further studies are warranted to determine if inflammatory gene expression in other tissues surrounding the intestine is modulated by EPA + DHA supplementation.
Trial registration: ClinicalTrials.gov ID: NCT01449773.