a total of fifty male wistar rats ( taconic ) , 12 weeks old , with a weight of approximately 
 360  g at arrival , were placed in makrolon iii cages in an open system , with five animals 
 in each cage .
they were kept under standard laboratory conditions with 12  h dark12  h 
 light cycles and temperature 22    1c , relative humidity 55    5  % and twenty air changes 
 per h. the rats had free access to food and tap water .
the experiment was conducted 
 according to the guidelines for care and use of experimental animals , and the protocol was 
 approved by the norwegian state board of biological experiments with living animals .
dss ( mw 44000 ; tdb consultancy ab ) at 50 g / l was administered in drinking water as 
 previously described 
  for 7  d to induce colitis .
the rats were acclimatised for 7  d and then separated into five groups of ten rats .
the 
 following diets were given : ( 1 ) control , ( 2 ) dss  +  control , ( 3 ) dss  +  fo ( 5  % ) , ( 4 ) 
 dss  +  fp ( 35  % ) and ( 5 ) dss  +  fo  +  fp . all groups had free access to food on days 129 , 
 and dss was administered during the last week of the experiment in groups 25 .
all rats 
 were killed the day after dss treatment was discontinued  on day 30 . at that time
the 
 animals were anaesthetised by inhalation of isoflurane ( 2  % ;  isoba vet , 
 intervet / schering - plough animal health ) in an anaesthesia chamber .
the control diet consisted of a standard casein diet with 20  % ( w / w ) protein 
 ( sigma - aldrich ) , and 7  % fat , composed of 5  % lard ( a generous gift from ten kate vetten 
 bv ) and 2  % soyabean oil ( dyets inc . ) .
lard was replaced by 5  % fo in group 3 ( epax 4020 
 tg , epax as ) , and casein partly by 35  % fp hydrolysate ( marine bioproducts as ) in group 
 4 , and both in group 5 .
the fp were produced from salmon by - products ( spine ) by enzymatic 
 hydrolysis using controlled autolysis with commercial proteases .
the resulting hydrolysate 
 was further fractionated using different forms of filtration including ultrafiltration . 

the sizes of the peptides were < 10  000  da , with 70  % of total peptides 
 < 1000  da .
the other 
 constituents of the diets were maize starch , dyetrose , sucrose , fibre , american institute 
 of nutrition ( ain)-93 g mineral mix , ain-93 vitamin mix , l - cysteine , choline 
 bitartrate ( dyets inc . ) , and tert - butyl - hydroquinone ( sigma - aldrich ) 
 ( table 1 ) .
diet)*ingredientscontrolfofpfo  +  fpfo5050lard5050soyabean oil20202020fp3535casein200200165165maize starch397397397397dyetrose132132132132sucrose100100100100fibre50505050ain-93 g mineral mix35353535ain-93 vitamin mix10101010l - cysteine3333choline bitartrate25252525tert - butyl - hydroquinone0014001400140014fo , fish oil ; fp , fish peptides ; ain , american institute of nutrition.*the diets were isonitrogenous and isoenergetic .
composition of the experimental diets ( g / kg diet ) * fo , fish oil ; fp , fish peptides ; ain , american institute of nutrition .
body weight and food intake were measured before dss administration ( day 23 ) and daily 
 during dss intake days 2429 .
the disease activity index ( dai ) is a composite score where 
 weight loss , stool consistency and rectal bleeding are rated from 0 to 4 , and the total 
 sum is divided by 3 
 .
the fatty acids were measured as previously described 
 . after killing , the major part of the colon , from the colocaecal junction to the anal 
 verge was removed , and the length was measured unstretched .
the colon was rinsed in pbs , 
 and samples from both the ends and the middle part were separated , then divided 
 longitudinally and placed in 10  % paraformaldehyde .
the samples were later embedded in 
 paraffin and sectioned before staining with haematoxylin and eosin for histopathological 
 examination .
pieces 
 from both segments were cooled in liquid n2 , freeze clamped and then stored at 
 80c for further analyses . in the haematoxylin and eosin - stained tissue samples , the crypt and inflammatory scores 
 were determined according to a validated scoring system 
  and examined by a pathologist unaware of the experimental protocol . 

both the crypt and inflammatory score include a measure of 
 involvement : grade 1 , 125  % ; grade 2 , 2650  % ; grade 3 , 5175  % ; grade 4 , 76100  % .
the 
 score is the product of either the crypt grade by involvement grade or inflammation 
 grade by the involvement grade .
the histological combined score ( hcs ) was the sum of the 
 crypt and inflammation scores , and was measured in all three locations of the colon .
full wall sections of the colon were used , and 50  mg samples were homogenised and 
 prepared as described previously 
 .
custom - made rat cytokine four - plex kits including il-1 , il-5 , interferon- and 
 keratinocyte chemoattractant ( kc)/growth - regulated oncogene ( gro ) and single - plex kits 
 with tnf ( meso scale discovery ) were used to measure cytokines in the supernatant from 
 the homogenisate .
chemicals , solutions and sample preparation of frozen colon tissue samples ( 1235  mg ) 
 were performed as described 
 .
the lc system was an agilent 1200 series with a binary pump , a variable volume injector 
 and a thermostated autosampler .
masshunter software ( agilent ) was used for hplc system control , data 
 acquisition and data processing .
glutamic semialdehyde is a carbonyl product that results from direct oxidative damage 
 of amino acids ( arginyl and prolyl residues ) .
carboxyethyl - lysine is derived from 
 glycosylation reactions on proteins and carboxymethyl - lysine from both glycoxidation and 
 lipoxidation reactions .
glutamic semialdehyde , carboxymethyl - lysine and 
 carboxyethyl - lysine concentrations were determined as trifluoroacetic acid methyl esters 
 derivates in acid - hydrolysed , delipidated and reduced intestine protein samples . 

quantification was performed by external standardisation using 
 standard curves constructed from mixtures of h - labelled and 
 non - h - labelled standards .
the amounts of products were expressed as the ratio of micromol per 
 mol lysine .
total cellular rna was purified from 20  mg frozen tissue samples from distal colon , rna 
 was quantified spectrophotometrically , and the quality was evaluated as 
 described 
 . for each sample , 4  g total rna
real - time pcr was performed with custom - made 384-well microfluidic 
 plates ( taq - man low density arrays ; applied biosystems ) on the following genes : 
 il-1b , rn00580432_m1 ; il-6 , rn 00561420 ; kc - gro 
 ( kc / gro , cxcl1 ) , rn00578225_m1 ; inducible nitric 
 oxide synthase 2 ( nos2 ) , rn00561646_m1 ; ppar ( pparg ) , 
 rn00440945 ; ppar cofactor 1 ( ppargc-1a ) , rn00580241 ; sirtuin 1 
 ( sirt1 ) , rn01428093_m1 ; pgd2 synthase 
 ( ptgds ) , rn00564605_m1 ; pge synthase ( ptges ) , 
 rn00572047_m1 ; pg - endoperoxide synthase 2 ( cox-2 , 
 ptgs2 ) , rn01483828_m1 . all probes and primers were obtained from applied biosystems .
two different control 
 genes were included : 18s ( kit - fam - tamra ( reference rt - ckft-18s ) ) from 
 eurogentec ; and rplp0 ( rn00821065_g1 ) from applied biosystems .
to 
 normalise the absolute quantification according to the reference genes , a second set of 
 pcr was performed for all experimental samples , and the relative abundance values were 
 calculated for the reference genes as well as for the target genes using standard curves 
 derived from universal rat reference rna ( agilent technologies inc . ) . 

normfinder 
  software was used to evaluate the reference genes , and the relative 
 abundance value of each gene in each sample was normalised against the value of the most 
 stable reference gene , rplp0 .
the student 's 
 t test or one - way anova was used to analyse differences between two or 
 more groups , respectively .
wallis test was 
 applied in not normally distributed data for two or more groups . post hoc 
 tests were performed by the mann  whitney rank test .
a total of four pre - determined 
 pairwise differences were analysed : fp v. dss , fo v. 
 dss , fp v. fo and fo v. fo  +  fp .
spss 15.0 and pasw statistics 18 statistical software packages were used for 
 analyses ( spss inc . ) .
as intended , the fo and fo  +  fp diets contained large relative amounts of epa and dha , as 
 well as a high total level of n-3 pufa .
the fp diet had low levels of 
 n-3 pufa , similar to the control diet . in the fo - containing diets
, we 
 observed a relative decrease in levels of 18 : 1n-9 as the 
 n-3 pufa levels increased ( table 
 2 ) .
table 2.fatty acid compositions of the diets*controlfofpfo  +  fp14  :  012906913106516  :  02076555218355216  :  1n-712110512810818  :  01230331131033118  :  1n-9295310493121105818  :  1n-719321820522318  :  2n-6221014992323152218  :  3n-325722427022718  :  4n-30003128000613220  :  4n-601413101513320  :  5n-30022563007260822  :  5n-300135000335022  :  6n-300319240071935sfa3564108537531071mufa3360162135521637pufa ( n-3)27454312985498pufa ( n-6)2269184823861781pufa ( n-3:n-6)012294012309dbi088344093344fo , fish oil ; fp , fish peptides ; dbi , double bond index.*values are represented as % ( w / w ) of total fatty acids .
fatty acid compositions of the diets * fo , fish oil ; fp , fish peptides ; dbi , double bond index .
values are represented as % ( w / w ) of total fatty acids . during dss intake
all animal groups lost weight significantly compared with the control 
 group , which in contrast gained weight .
feed intake was similar in the dss - exposed groups , 
 while the controls had higher food consumption ( table 
 3 ) .
of the animals in the fo  +  fp group , two died during the dss week .
table 3.average weight gain ( % ) and feed intake per wistar rat ( g / d ) during the dextran 
 sodium sulfate ( dss ) week(mean values with their standard errors for nine or ten animals per group)weight gain in dss week ( % per week)feed intake in dss week ( g / d per rat)treatmentmean 
 sem 
 mean 
 sem 
 dss intake in dssweek ( ml / g rat)control4621482155075control  +  dss650 * 3161570082030fo  +  dss988 * 2691454118036fp  +  dss684 * 5341617063027fo  +  fp  +  dss890 * 5001618086047fo , fish oil ; fp , fish peptides . *
mean value was significantly different from that of the control group 
 ( p    005 ; one - way anova , performed only on the weight 
 results).diets were fo , fp or a combination ( fo  +  fp ) for 4 weeks , with dss exposure in 
 the last week of the experiment .
average weight gain ( % ) and feed intake per wistar rat ( g / d ) during the dextran 
 sodium sulfate ( dss ) week ( mean values with their standard errors for nine or ten animals per group ) fo , fish oil ; fp , fish peptides .
* mean value was significantly different from that of the control group 
 ( p    005 ; one - way anova , performed only on the weight 
 results ) .
diets were fo , fp or a combination ( fo  +  fp ) for 4 weeks , with dss exposure in 
 the last week of the experiment .
when dividing all dss - exposed rats into groups according to the proximal , middle or 
 distal colon segment , there was a significant difference in hcs between the three segments 
 ( p =  0001 ) .
post hoc analyses showed a significantly 
 higher hcs in the distal and middle colon segments v. the proximal 
 segment ( p  =  0002 for both differences ) . in the distal colon ,
there was an almost significant difference between dss - exposed groups 
 ( p  =  007 ) .
post hoc analyses showed a reduced hcs 
 after the fp diet ( median 135 ; range 821 ) v. the fo diet ( median 19 ; 
 range 1528 ) ( p  =  003 ) .
neither fo nor fp reduced hcs 
 v. dss ( median 175 ; range 120 ) ( p  =  10 for both 
 differences ) .
hcs did not differ significantly between fo and fo  +  fp ( median 15 ; range 
 421 ) ( p = 008 ) ( table 4 ) . 

( b ) 
 colonic mucosa from a rat with dextran sulfate sodium ( dss ) colitis showing crypt 
 destruction and moderate inflammation , with almost intact epithelium .
( c ) colonic 
 mucosa from a rat after dss and fish oil ( fo ) diet showing crypt destruction , severe 
 inflammation and ulcerated surface .
( d ) colonic mucosa from a rat after dss and fish 
 peptides ( fp ) diet showing some preserved normal crypts and some crypt destruction , 
 moderate inflammation and intact epithelium .
( e ) colonic mucosa from a rat after 
 fo  +  fp diet showing destruction of most crypts , moderate inflammation and lost 
 epithelium .
table 4.histological combined scores ( hcs ) and disease activity index ( dai ) in distal colon 
 sections of wistar rats fed fish oil ( fo ) , fish peptides ( fp ) or a combination 
 ( fo  +  fp ) for 4 weeks , and treated with dextran sodium sulfate ( dss ) during the last 
 week of the experiment(median values and ranges)hcsdaihcs post hoc*dai post hoc*treatmentmedianrangemedianrangepair 
 p 
 pair 
 p 
 control40012000control  +  dss175120100330fo v. dss10fo v. dss004fo  +  dss1901528281337fo v. fp003fo v. fp007fp  +  dss135821130737fp v. dss10fp v. dss10fo  +  fp  +  dss150421130737fo v. fo  +  fp008fo v. fo  +  fp06 * post hoc tests analysed by the mann  whitney rank test .
( b ) 
 colonic mucosa from a rat with dextran sulfate sodium ( dss ) colitis showing crypt 
 destruction and moderate inflammation , with almost intact epithelium .
( c ) colonic 
 mucosa from a rat after dss and fish oil ( fo ) diet showing crypt destruction , severe 
 inflammation and ulcerated surface .
( d ) colonic mucosa from a rat after dss and fish 
 peptides ( fp ) diet showing some preserved normal crypts and some crypt destruction , 
 moderate inflammation and intact epithelium .
( e ) colonic mucosa from a rat after 
 fo  +  fp diet showing destruction of most crypts , moderate inflammation and lost 
 epithelium .
histological combined scores ( hcs ) and disease activity index ( dai ) in distal colon 
 sections of wistar rats fed fish oil ( fo ) , fish peptides ( fp ) or a combination 
 ( fo  +  fp ) for 4 weeks , and treated with dextran sodium sulfate ( dss ) during the last 
 week of the experiment ( median values and ranges ) * post hoc tests analysed by the mann  whitney rank test .
the median dai value in the dss group was higher than in the control 
 group 
 .
dai differed significantly between dss - exposed groups 
 ( p  =  002 ) . post hoc tests showed no significant 
 reduction of dai in the fp group ( median 13 ; range 0737 ) v. the fo 
 group ( median 28 ; range 13    37 ) ( p  =  007 ) .
dai was higher after the 
 fo diet than after dss alone ( median 10 ; range 03   
dai did not differ between fp and dss ( p  =  10 ) , and did not differ in 
 the fo v. the fo  +  fp group ( median 13 range 07   
the controls had a significantly longer colon than the dss group , reflecting a 
 colitis - induced shortening after dss exposure 
 .
there were no differences in colon length between the dss - exposed 
 groups ( p  =  020 ) , but there was a tendency to have a longer colon in the 
 fp group ( data not shown ) .
pge3 levels were significantly different between the dss - exposed groups in the 
 distal colon ( p  =  0001 ) .
post hoc analyses showed that 
 the fo diet increased pge3 levels v. dss alone . 

the combined fo  +  fp group gave an additional increase of pge3 as 
 compared with the fo group ( table 5 ) .
in the 
 case of pge2 , the difference between dss groups was significant 
 ( p  =  004 ) in the distal colon .
the largest difference in 
 pge2 levels occurred between the dss and the fo  +  fp group . for 
 pgd2 , a significant difference ( p  =  004 ) , was detected 
 between dss groups . in the distal colon ,
the fo  +  fp diet increased pgd2 
 compared with fo ( table 5 ) .
table 5.selected gene expression , and cytokine and prostaglandin levels in distal colon 
 sections of wistar rats fed fish oil ( fo ) , fish peptides ( fp ) or a combination 
 ( fo  +  fp ) for 4 weeks , and treated with dextran sodium sulfate ( dss ) during the last 
 week of the experiment(median values and ranges)controldssdss  +  fodss  +  fpdss  +  fo  +  fpmedianrangemedianrangemedianrangemedianrangemedianrangegene 
 nos2 
 100033204585**095251272998442cytokinekc / gro070038112503**047180120507124320113646prostaglandinspge3000000731382503461530172359102111pgd2962275507102208272793414156210519343nos2 , inducible nitric oxide synthase 2 ; kc , keratinocyte 
 chemoattractant ; gro , growth - regulated oncogene .
median values for the dss groups with unlike superscript letters 
 were significantly different ( p  <  005 ( kruskal  wallis 
 test / mann  whitney post hoc test ) except kc / gro : 
 p  =  007 ( kruskall  wallis test ) ) . *
* median value was significantly different from that of the control treatment 
 ( p  <  001 ; mann  whitney rank test).nos2 expression values were normalised against an endogenous 
 control , and variables are given as medians relative to control 
 ( n 78 ) .
cytokine and prostaglandin levels ( g / kg wet tissue ) are 
 given as medians ( n 810 ) .
selected gene expression , and cytokine and prostaglandin levels in distal colon 
 sections of wistar rats fed fish oil ( fo ) , fish peptides ( fp ) or a combination 
 ( fo  +  fp ) for 4 weeks , and treated with dextran sodium sulfate ( dss ) during the last 
 week of the experiment ( median values and ranges ) nos2 , inducible nitric oxide synthase 2 ; kc , keratinocyte 
 chemoattractant ; gro , growth - regulated oncogene .  
median values for the dss groups with unlike superscript letters 
 were significantly different ( p  <  005 ( kruskal  wallis 
 test / mann  whitney post hoc test ) except kc / gro : 
 p  =  007 ( kruskall  wallis test ) ) . *
* median value was significantly different from that of the control treatment 
 ( p  <  001 ; mann  whitney rank test ) .
nos2 expression values were normalised against an endogenous 
 control , and variables are given as medians relative to control 
 ( n 78 ) .
cytokine and prostaglandin levels ( g / kg wet tissue ) are 
 given as medians ( n 810 ) .
the expression of mrna was significantly increased after dss alone v. 
 control for several selected genes , including il-6 , il-1b , 
 cxcl1 and ptges 
 .
the fp diet reduced the mrna levels of these genes compared with dss 
 alone , although not reaching significant levels .
nos2 expression was 
 significantly different between the dss - exposed groups ( p  <  005 ) . 

fp , fo and fo  +  fp diets increased nos2 mrna levels v. 
 dss , although only significantly for the fo  +  fp diet ( table 5 ) .
the protein levels of tnf , il-1 and kc / gro in the distal colon were in accord with mrna 
 levels .
all three cytokines were significantly higher in the dss animals 
 v. the controls 
 .
kc / gro was close to significantly different between the dss - exposed 
 groups ( p  =  007 ) .
post hoc tests revealed that the fp 
 diet significantly lowered the kc / gro levels v. the fo diet .
the other 
 preselected pairs analysed showed no significant differences . no significant differences 
 in tnf or il- occurred between groups that received dss .
no significant differences were detected between the dss - exposed groups or between 
 selected pairs for the three markers ( data not shown ) .
the levels were higher in the dss 
 v. the controls for all three markers although not reaching 
 significance .
we noted that , compared with dss , median levels of all three markers tended 
 to decrease after fo , while carboxyethyl - lysine and carboxymethyl - lysine levels were lower 
 after fp , although not significantly .
the main findings of this study are that hydrolysed salmon peptides , a novel dietary 
 component used in ibd models , attenuated dss - induced colitis as compared with fo .
this was 
 observed by fewer signs of histopathological inflammation , less clinical disease activity , a 
 lowered inflammatory cytokine signature at the protein and mrna levels , and increased 
 pgd2 .
also , the fp diet improved a number of variables when compared with 
 animals fed dss alone , such as cytokines and markers of protein oxidation , although not 
 reaching statistical difference .
in addition , we observed that the expected increase of 
 pge3 induced through metabolism of epa from dietary fo increased further after 
 combining fo and fp in the diet .
although intake of fp has not been much investigated in experimental colitis , other dietary 
 bioactive peptides have shown anti - inflammatory effects in ibd animal 
 models 
 . an intestinal protective effect from fish hydrolysate
was suggested , as 
 proliferation of ht 29 cells increased , while indomethacin - induced apoptose and 
 small - intestinal villous damage were decreased in mice 
 .
80  % 
 protein constituents in healthy humans reduced small - intestinal damage caused by 
 indomethacin 
 .
the proposed mechanisms in these two studies were the presence of 
 glutamine ( 14    16  % of the total ) , an antioxidant effect , and an effect of the 6    10  % 
 content of fo in the hydrolysate .
g / l and 3  g daily used in their 
 studies are not directly comparable with 35  g / kg used in our study .
fp 
 contained  >  90  % peptides , but had a lower glutamine content of 85  % ( w / w ) . 

glutamine , a substrate for enterocyte metabolism , could act protectively by preserving 
 intestinal integrity and barrier function , as shown in previous experimental colitis 
 models 
 .
the n-3 content in fp was only 30  % , similar to the 
 controls in our study ( 27  % ) , and can probably not explain the beneficial changes after the 
 fp diet .
specific structural features have been linked to potentially bioactive peptides ; 
 the molecular weight should be < 10  kda , most preferably < 1  kda , and the size 
 of peptides between two and twenty amino acids 
 .
epithelial 
 injury is fundamental in this model , and during the acute colitis phase innate immune 
 responses are activated 
 .
the pro - inflammatory cytokine levels in the dss model were at their 
 lowest after the fp diet at both the protein and mrna levels , suggesting an 
 anti - inflammatory effect from bioactive fp , influencing innate immunity .
pgd2 
 reduces granulocyte infiltration in experimental colitis 
 , and its synthesis is up - regulated in uc patients in 
 remission 
 .
the tendency for pgd2 to increase after fp diets in our 
 study may point to a protective effect .
contrary to expectations , fo did not improve signs of colitis . as compared to dss , hcs was 
 unaltered and dai increased .
this is in 
 contrast to previous trials with dietary n-3 pufa administration in 
 experimental colitis , which has generally shown beneficial effects 

 .
the fatty acid analysis of the diets confirmed large relative amounts 
 of epa and dha in the two fo diets , with an n-3:n-6 ratio 
 in the feed of 29 and 31 .
the relatively anti - inflammatory eicosanoid pge3 was 
 increased , which is expected after dietary intake of epa . in our study
however , vitamin e or 
 other anti - oxidants were not added to the diets containing fo .
this could result in 
 increased lipid peroxidation and oxidative stress in the colonic mucosa , which could 
 counteract an anti - inflammatory effect 
 .
however , the levels of oxidation markers in our study were not 
 increased , but rather tended to decrease , after the fo diet .
when combining fo and fp diets we observed that the pge3 levels increased as 
 compared to the fo diet .
the reason for this is unclear , as adding the fp diet did not 
 provide high amounts of epa .
fp , when combined with the fo diet , could possibly influence 
 the enzymatic activity of cox2 , thus leading to elevated pge3 
 synthesis .
we observed that the mrna levels of ptgs2/cox2 as well as 
 ptges were elevated in the combined fo  +  fp group v. fo , 
 but not reaching significance .
nos2 expression was elevated after dss v. controls , and 
 was significantly increased after the fo  +  fp diet v. dss alone .
no is a 
 result of inducible no synthase expression , and seems to have a dual role
thus , the higher nos2 levels after the fo  +  fp diet 
 may be a protective response , supported by the pge3 and pgd2 increase , 
 or it may be detrimental , as suggested by a tendency for elevated hcs and cytokine levels .
this study has its limitations : antioxidant added to the fo diets might have influenced the 
 results .
an increased number of rats in each group would have increased the statistical 
 power of the analyses .
we induced a severe colitis , leading to death in two animals , by administering 
 5  % dss for 1 week , which could limit the detection of modest beneficial effects .
the diets 
 used might affect the healing time of the colitis after stopping dss .
the effects observed 
 may be due to prophylactic as well as therapeutic potential of the diets , as the study 
 design can not differentiate between these aspects .
the dss model clearly has limitations as 
 a substitute for the human disease , as a chemically induced injury model instead of an 
 endogenously triggered inflammation . in conclusion
, dietary hydrolysed salmon peptides may offer protection against dss colitis 
 as compared with a fo diet , but do not improve inflammatory variables significantly when 
 compared with dss alone .
a combined diet may affect eicosanoid metabolism by increasing 
 pge3 levels , although not attenuating other signs of colon inflammation . 

hydrolysed salmon peptides should be further investigated as a dietary intervention against 
 inflammation in animal models , as well as in patients with ibd .
 fish oil ( fo ) has been shown to have anti - inflammatory properties in animal models of 
 inflammatory bowel disease , but how fish peptides ( fp ) influence intestinal inflammation 
 has been less studied . 
 male wistar rats , divided into five groups , were included in a 
 4-week dietary intervention study . of the groups , 
 four were exposed in the fourth week to 
 5  % dextran sulfate sodium ( dss ) to induce colitis , while one group was unexposed . 
 the 
 diets were : ( 1 ) control , ( 2 ) control  +  dss , ( 3 ) fo ( 5  % )  +  dss , ( 4 ) fp ( 35  % )  +  dss , ( 5 ) 
 fo  +  fp  +  dss . following dss intake , weight and disease activity index ( dai ) 
 were 
 assessed , and histological combined score ( hcs ) , selected colonic pg , cytokines , oxidative 
 damage markers and mrna levels were measured . 
 fp reduced hcs , tended to lower dai 
 ( p  =  007 ) and reduced keratinocyte chemoattractant / growth - regulated 
 oncogene levels , as compared with the fo diet . 
 fp also reduced mrna levels of 
 il-6 and cxcl1 , although not significantly . 
 fo intake 
 increased the dai as compared with dss alone . 
 pge3 levels increased after the 
 fo diet , and even more following fo  +  fp intake . 
 the fp diet seems to have a protective 
 effect in dss - induced colitis as compared with fo . a number of beneficial , but 
 non - significant , changes also occurred after fp v. dss . 
 a combined 
 fo  +  fp diet may influence pg synthesis , as pge3 levels were higher after the 
 combined diet than after fo alone . 
Experimental methods
Results
Discussion