BACKGROUND: Diet regulates gene expression profiles by several mechanisms. The 
objective of this study was to examine gene expression in relation with dietary 
patterns.
METHODS: Two hundred and fifty four participants from the greater Quebec City 
metropolitan area were recruited. Two hundred and ten participants completed the 
study protocol. Dietary patterns were derived from a food frequency 
questionnaire (FFQ) by factor analysis. For 30 participants (in fasting state), 
RNA was extracted from peripheral blood mononuclear cells (PBMCs) and expression 
levels of 47,231 mRNA transcripts were assessed using the Illumina Human-6 v3 
Expression BeadChips®. Microarray data was pre-processed with Flexarray software 
and analysed with Ingenuity Pathway Analysis (IPA).
RESULTS: Two dietary patterns were identified. The Prudent dietary pattern was 
characterised by high intakes of vegetables, fruits, whole grain products and 
low intakes of refined grain products and the Western dietary pattern, by high 
intakes of refined grain products, desserts, sweets and processed meats. When 
individuals with high scores for the Prudent dietary pattern where compared to 
individuals with low scores, 2,083 transcripts were differentially expressed in 
men, 1,136 transcripts in women and 59 transcripts were overlapping in men and 
women. For the Western dietary pattern, 1,021 transcripts were differentially 
expressed in men with high versus low scores, 1,163 transcripts in women and 23 
transcripts were overlapping in men and women. IPA reveals that genes 
differentially expressed for both patterns were present in networks related to 
the immune and/or inflammatory response, cancer and cardiovascular diseases.
CONCLUSION: Gene expression profiles were different according to dietary 
patterns, which probably modulate the risk of chronic diseases.
TRIAL REGISTRATION: NCT: NCT01343342.