The role of diet in inflammatory bowel disease (IBD) is supported by migration studies and increasing incidences in line with Westernisation.
Dr Jonker and colleagues from the Netherlands gave a complete overview of studies associating habitual diet with the onset or relapses in ulcerative colitis or Crohn's disease.
A structured search in Pubmed, the Cochrane Library and EMBASE was performed using defined key words, including only full text papers in English language.
The team identified 41 studies, investigating onset, relapses or both.
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Several studies reported high intake of sugar or sugar-containing foods, and low intake of fruits and/or vegetables to be associated with an increased onset risk.
However, these findings could not be confirmed by similar or higher numbers of other studies.
The team found a possible protective role for grain-derived products in Crohn's disease onset, but results were inconsistent for dietary fibre in ulcerative colitis and Crohn's disease and grain-derived products in ulcerative colitis.
No definite conclusions could be drawn for unsaturated fatty acids (UFA), protein and energy intake due to limited and/or inconsistent results.
The research team identified 6 studies reported on diet and relapse risk, of which only 2 had a prospective follow-up.
Dr Jonker's team concludes, "The current evidence is not sufficient to draw firm conclusions on the role of specific food components or nutrients in the aetiology of IBD."
"Furthermore, large prospective studies into the role of habitual diet as a trigger of relapses are needed, to identify new therapeutic or preventive targets."