Fish oil

Fish-oil (marine omega-3 long-chain PUFAs — EPA and DHA) has plausible, biologic reasons to help with intestinal inflammation and barrier function that matters in celiac disease (CD), but there is not strong, direct clinical evidence that fish-oil is a proven treatment for celiac disease. Most human data are mechanistic, small, or indirect (work in cell/animal models, biomarker or gut-barrier studies, and large prevention trials of autoimmune disease generally). The proven and guideline therapy for celiac disease remains a strict gluten-free diet and medical follow-up. MDPI SpringerLink

• Anti-inflammatory action. EPA and DHA shift eicosanoid production away from pro-inflammatory arachidonic-acid metabolites, lower certain pro-inflammatory cytokines, and generate specialized pro-resolving mediators (SPMs) that help resolve inflammation — mechanisms that are directly relevant to the inflammatory intestinal damage of CD. MDPI ScienceDirect
• Improves intestinal barrier / tight junctions. Preclinical and some human data show n-3 PUFAs can increase expression of tight-junction proteins (occludin, ZO-1) and reduce biomarkers of permeability (LBP, zonulin), which matters because “leaky” mucosa and antigen passage are central to celiac pathogenesis. A randomized human study (LIBRE exploratory analysis) found higher DHA was associated with improved barrier biomarkers. SpringerLink
• Modulates gut microbiota. Omega-3s can alter gut microbial composition and metabolite production in ways that can reduce mucosal inflammation in models — a pathway that could plausibly benefit CD. Recent reviews summarize these microbiome–PUFA interactions. MDPI Frontiers
• Cellular / in-vitro evidence specific to celiac cells. Laboratory work shows DHA/EPA can reduce inflammatory responses in intestinal and immune cells derived from celiac patients (in vitro), supporting the mechanistic plausibility. Clinical Nutrition Journal

Summary: strong biological plausibility exists (anti-inflammatory, barrier-stabilizing, microbiome effects), but plausibility ≠ proven clinical efficacy in people with celiac disease. MDPI SpringerLink

• No formal, guideline-endorsed fish-oil dosing for treating celiac disease. There are no international celiac guidelines that recommend fish-oil as a treatment to replace a gluten-free diet. Any use is adjunctive and off-label. Always discuss with your gastroenterologist. Pediatrics Publications
• Doses used in relevant human research (for autoimmune / gut studies):
• VITAL trial (autoimmune disease prevention): 1,000 mg/day of marine omega-3 (EPA+DHA) — used in a large RCT that showed a non-statistically significant ~15% lower autoimmune disease rate (and vitamin D showed stronger effects). This dose is commonly used in prevention trials. BMJ
• Trials / RCTs aimed at gut barrier / diet interventions typically produce DHA/EPA changes via diet (Mediterranean diet) rather than very high supplement doses; human RCTs showing barrier improvement used dietary patterns that increased DHA (LIBRE analysis). If a clinician recommends supplementation for gut-barrier goals, they often start at ~1 g/day EPA+DHA (as in VITAL) and consider higher, supervised doses for particular metabolic targets. SpringerLink MDPI
• Practical administration tips (general, evidence-based):
• Take fish-oil with food (fat in the meal increases absorption). WebMD / Mayo Clinic and NIH resources discuss these practical points. WebMD Mayo Clinic
• Prefer third-party tested products (USP, NSF, IFOS) to reduce risk of contaminants (PCBs, mercury, dioxins). NIH and regulatory sites recommend product quality checks. Office of Dietary Supplements US EPA
• If considering a higher therapeutic dose (for example >2–3 g/day EPA+DHA), do so only under clinician supervision (see safety section below). Regulatory bodies place upper limits and prescription omega-3 medicines are used for specific indications (e.g., very high triglycerides). Office of Dietary Supplements AHA Journals

Practical recommendation for a person with celiac disease (typical): if you and your clinician decide to try fish-oil as an adjunct, a common, well-studied starting regimen is ~1,000 mg/day EPA+DHA (the VITAL RCT dose). Monitor symptoms, labs, and interactions with other meds; do not stop or relax your gluten-free diet. BMJ Pediatrics Publications

• VITAL randomized trial (large RCT; autoimmune outcomes): marine omega-3 1 g/day, 25,871 participants — vitamin D reduced incident autoimmune disease by ~22%; omega-3 supplementation reduced autoimmune disease incidence by ~15% (not always statistically significant in all comparisons). This is broad autoimmune prevention data, not celiac-specific, but it’s the strongest randomized human evidence linking fish-oil to lower autoimmune outcomes. BMJ ICHGCP
• LIBRE trial exploratory analysis (randomized lifestyle/Mediterranean diet trial): showed increased DHA (dietary) was associated with improved intestinal barrier biomarkers (lower LBP and fecal zonulin) over 12 months — human evidence that higher n-3 status can improve gut-barrier markers. Again, not a celiac-treatment trial, but directly relevant to mechanisms in CD. SpringerLink
• Small human/observational and lipidomic studies in celiac patients: biopsy-based work (Steel et al., 2006 and later lipidomics) showed altered intestinal mucosal fatty-acid patterns in children with active CD; these are descriptive and suggest altered PUFA biology in CD, not treatment evidence. DeepDyve SpringerLink
• In-vitro studies using celiac-derived cells: papers report DHA reduces inflammatory signalling triggered in celiac immune responses (cell models), supporting plausibility. These are laboratory (mechanistic) studies, not proof of clinical benefit. Clinical Nutrition Journal
• Ongoing/small RCTs: There are small or recruiting trials specifically studying omega-3 supplementation in celiac patients for outcomes such as tear-film/dry-eye (OmegaCelDED) or other symptom domains — these are exploratory and not yet practice-changing. ICHGCP ctv.veeva.com

What the total evidence means: there are no large RCTs showing that fish-oil cures or reliably improves intestinal healing in people with active celiac disease. The strongest human trials are either:

• broad autoimmune-disease prevention trials (VITAL), or
• dietary / biomarker studies showing improved gut-barrier markers (LIBRE), or
• small mechanistic studies (biopsy lipidomics, in-vitro).

So the evidence is promising but indirect — more celiac-specific RCTs are needed. BMJ SpringerLink DeepDyve