Table 1

In vivo pre-clinical studies of ω-3 PUFA supplementation for the prevention of CRC

Study	Model	N	Treatment groups	Timing/duration	Outcome measure(s)	Results (maximal changes ω-3 PUFA group vs Ctrl unless stated)
Carcinogen-induced models
Nelson et al44	Sprague-Dawley rat DMH	50	17% MO₁ vs 17% CO vs Ctrl	7 wk pre- and 17 wk post-DMH	Tumour incidence and multiplicity Incidence of metastases	↔ Tumour incidence, 35% ↓ tumour multiplicity, ↔ incidence of metastases
Minoura et al45	Donryu rat AOM	100	4.7% EPA vs 5% LA	15 wk pre- and 20 wk post-AOM	Tumour incidence Tumour and colonic mucosal PUFA + PGE₂ content	50%↓Tumour incidence, 75%↓multiplicity, ↑ EPA & ↓ AA in tumour and mucosa, 80%↓tumoural PGE₂
Reddy46	F344 rat AOM	234	4%–12% MO₁ vs 24% & 5% CO	38 wk post-AOM	Tumour incidence Tumour PUFA content	50% ↑ Tumour incidence + multiplicity in 24% CO vs all other grps, ↑ tumoural EPA+DHA with MO diets
Deschner et al47	CF1 mouse AOM	300	4–16% Max EPA vs 4% and 20% CO	2 wks pre- & 1–45 wk post-AOM	Colonic mucosa PI & FAD 1 wk Tumour incidence 45 wk	Dose dependent ↓ FAD, 38%↓ PI in 16% MO grp vs 20% CO, 50%↓ tumour incidence 16%/10% MO grp
Reddy48	F344 rat AOM	273	18% MO₂ vs 23.5% and 5% CO	2 wk pre- & 36 wk post-AOM. Diet crossover 3/7 post-AOM.	Tumour incidence	↓ Tumour incidence and multiplicity when MO vs 23.5% CO given in either initiation or post-initiation phases
Takahashi et al49	F344 rat DMH	97	0.7 ml DHA vs 0.7 ml H₂O ig daily	1 day pre- and 4/8/12 wk post-DMH	No. of colonic ACFs Serum chol and PUFA content	60% ↓ ACFs (↓ ACFs seen when DHA given in either initiation or post-initiation phase), 50%↓ AA, 50%↑ DHA and EPA, 20%↓ chol
Hendrickse50	Wistar rat + colon anastomosis vs sham AOM	160	20% FO₁ vs 20% CO	3 wk pre- and 15/23 wk post-AOM	Colonic mucosal PI Tumour incidence, size, no. Mucosal PUFA content	40%↓ Tumour incidence, 50%↓ multiplicity, 60%↓ peri-anastamotic tumours. ↓PI ↑EPA/DHA & 90%↓ AA in tumour/mucosa
Chang19	Sprague-Dawley rat AOM	260	11.5% FO₂ vs 15% CO ± 6% cellulose vs 6% pectin	1 week pre- & 16/32 wk post-AOM	Colonic tumour incidence Crypt PI/AI/cell differentiation	20%↓ Tumour incidence, ↔ PI, 20%↑AI, ↑ cell differentiation, ↑AI FO-pectin grp vs all other fat-fibre grps
Takahashi et al51	F344 rat AOM	96	1 ml DHA vs 1 ml water ig daily	4/12/36 wk	No. of ACF and tumours Plasma PUFAs and PGE₂	25%↓ ACF (wk 4/12) & 35%↓ tumour multiplicity, 50%↓ plasma PGE₂, 75%↓ plasma AA, 30×↑ EPA, 6×↑DHA (wk 36)
Good et al52	F344 rats AOM	161	18% MO₃ vs 5% and 23% CO	5% CO 12 wk post-injection then 6–12 wk experimental diet	No. ACF No. + size colonic tumours	15–20%↑ ACF vs both CO grps, 25%↓ tumour incidence but 50%↑ tumour size MO vs CO grps (both NS)
Singh53	F344 rat AOM	144	21% FO₃ vs 24% CO vs Ctrl	1/12/36 wk post-AOM	Tumour incidence and multiplicity	FO grp 30%↓ tumour incidence and multiplicity. 23.5% CO grp 33%↑tumour incidence and 90% ↑multiplicity
Latham 54	Wistar rat DMH	68	8% FO₄ vs 8% CO	FO vs CO 24/48hrs post-DMH then 18 wk CO	Crypt cell AI & PI (24/48 h) No. ACF (18 wk)	↑ AI and ↓ PI at 24/48 h, 50% ↓ACF at 18 wk
Rao et al55	F344 rat AOM	360	17% FO₃ vs 5% CO vs 20% mixed lipids	CO 2 wk pre-AOM Experimental diets for 8–38 wk post-AOM	No. ACF, tumour incidence Colonic mucosa AI	44%↓ ACFs, 30%↓ tumour incidence, 60% ↓ tumour multiplicity 2× ↑AI vs 20% mixed lipid diet
Crim et al20	Sprague-Dawley rat AOM	80	11.5% FO₂ vs 15% CO ± 5% butyrate	3 wk pre- and 8 wk post-AOM	No. ACF, colonic mucosa AI	↑ ACFs CO + butyrate vs all grps, ↓ large ACFs and ↑AI in FO + butyrate grp vs FO alone or control
Vanamala et al12	Sprague-Dawley rat AOM	20	15% FO₅ + pectin vs 15% CO + cellulose	32 days pre- and 31 wk post-AOM	Colonic mucosa AI Colonic mucosa PGE₂/PGE₃ β-catenin and PPARδ expression	2×↑ AI and 78%↓ mucosal PGE₂, ↑PGE₃ (PGE₃ not detected in CO group), ↓ β-catenin and PPARδ expression
Moreira et al56	Wistar rat DMH	20	18% FO₆ vs 18% SOYO	2 wk pre- & 36 wk post-DMH	No. ACFs, adenoma incidence Colon/liver PUFA content	47%↓ ACF, 80%↓ adenoma incidence, 5 ×↑ ω-3-PUFA in colon + liver, 60–75%↓ n-6 PUFA in colon + liver
Woodworth et al57	SMAD3^−/− mouse Helicobacter induced colitis	122	0.75%–6% DHA vs 6% SAFO vs 7% CO vs Ctrl	8 wk pre-infection 8 wk pre- and 4 wk post-infection	Colon inflammation/dysplasia Hepatic PUFA content Body wt	↑ Inflammation/dysplasia 2.25–6% DHA vs Ctrl. 5×↑ hepatic DHA content, 85% less wt gain and 10–18% ↓4wk survival in 6% DHA grp vs CO/SAFO/Ctrl
Apc mouse models
Oshima et al58	Apc^∆716	20	3% DHA vs Ctrl	7 wk	Colonic polyp no. and size	69%↓ Polyp no. in female mice only, ↔ polyp no. in male mice, ↓ polyp size, more marked in female mice
Paulsen et al59	Apc^Min/+	51	0.4–2.5% FO₇ vs 12% CO	17 wk	No. ACFs and adenomas	48–66%↓ no. and 26–38%↓ size of tumours, ↓ACFs in female mice on 2.5% diet only
Petrick et al60	Apc^Min/+	77	3.1% EPA vs 3.1% DHA vs Ctrl	7 wk	Tumour size + no. Mucosal PUFA + PGE₂	30%/50%↓ Tumour no. DHA/EPA grp vs Ctrl, 15%↓tumour size EPA/DHA grp vs Ctrl, 50%↓ PGE₂ in EPA/DHA grp vs Ctrl
Petrick et al61	Apc^Min/+	20	1.5% EPA vs 1.5% AA vs Ctrl	8 wk	Tumour size + no. Mucosal PUFA + PGE₂	54–68%↓ Tumour no. & 18%↓ tumour size EPA vs Ctrl and AA grps. 74%↓ mucosal PGE₂ EPA vs AA grp
Bose et al62	Apc^Min/+	95	12% MO₄ vs 20% mixed lipid diet	9 wk	Tumour no. + size Tumour PI, AI, PGE₂, β-catenin	↔ Tumour no, 50%↓ no. tumours >2 cm, 3.7×↑AI, ↔ PI, 89%↓ PGE₂, 62%↓β-catenin
Fini et al63	Apc^Min/+	48	2.5% and 5% EPA vs Ctrl	12 wk	Mucosal PUFA + COX-2 Polyp no. + size, body weight	72%/79%↓ Polyp size (2.5%/5% EPA grp) ↓COX-2 and ↑ EPA in EPA grps, ↓weight Ctrl grp

↔, no significant difference; ↓, decrease; ↑, increase.
AA, arachidonic acid; ACF, aberrant crypt foci; AI, apoptosis index; AOM, azoxymethane; chol, cholesterol; CO, corn oil; Ctrl, control; CRC, colorectal cancer; DHA, docosahexaenoic acid; DMH, 1,2-dimethylhydrazine; EPA, eicosapentaenoic acid; FAD, focal area of dysplasia; FO, fish oil (FO₁= 18% EPA/15% DHA; FO₂= unspecified ω-3 PUFA content; FO₃ = 31% ω-3 PUFA; FO₄= 18% EPA/8% DHA; FO₅= 18%EPA/11%DHA; FO₆= 24%EPA/20%DHA; FO₇= 54% EPA/30% DHA); ig, intragastric; LA, linoleic acid; MaxEPA, 18%EPA + 12% DHA; MO, menhaden oil (MO₁ 16% EPA + 11% DHA; MO₂ 2.4% EPA + 11% DHA; MO₃= unspecified ω-3 PUFA content; MO₄ = 13%EPA/12%DHA); PG, prostaglandin; PI, proliferation index; PPAR, peroxisome proliferator-activated receptor; PUFA, polyunsaturated fatty acid; SAFO, safflower oil; SOYO, soybean oil; wk, weeks; wt, weight.