Identification of dietary patterns using factor analysis in an epidemiological study in São Paulo

Abstract

CONTEXT AND OBJECTIVE: Diet and nutrition are environmental foctors in health/disease relationships. From the epidemiological viewpoint, diet represents a complex sei oi highly correlated exposures. Our objective was to identify patterns oi food intake in a group oi individuais living in São Paulo, and to develop objective dietary measurements for epidemiological purposes. DESIGN AND LOCAL: Exploratory facto, analysis oi data in a case-control study in seven teaching hospitais in São Paulo. METHODS: The participants were 517 patients (260 oral cancer cases and 257 controls) admitted to the study hospitais between November 1998 and March 2001. The weekly intake lrequencies for dairy products, cereais, meat, processed meat, vegetables, pulses, fruits and sweets were assessed by means oi a semi<luantitative food frequency questionnaire. Dietary patterns were identified by loctor analysis, based on the intake oi the eight food groups, using principal component analysis as an extraction method followed by varimax rotation. RESULTS: Factor analysis identified three patterns that accounted for 55% oi the total variability within the sample. The lirst pattern ("prudent") was characterized by vegetable, lruit and meat intake; the second ("traditional") by cereais (ma inly rice) and pulses (mainly beans); and the third ("snacks") by dairy products and processed meat. CONCLUSION: This study identified food intake patterns through an a posteriori approach. Such analysis may be uselul for nutritional intervention programs and, alter computing scores for each individual according to the patterns identilied, for establishing a relationship between diet and other epidemiological measurements oi interest.