Effect of social desirability on dietary intake estimated from a food questionnaire.

Abstract

Self-report of dietary intake could be biased by social thus affecting risk estimates in epidemiological studies. The objective of study was to assess the effect of social desirability on dietary intake from a food frequency questionnaire (FFQ).A convenience sample of 483 Portuguese university students was recruited. Subjects were invited to complete a two-part self-administered questionnaire: the first part included the Marlowe-Crowne Social Desirability Scale (M-CSDS), a physical activity questionnaire and self-reported height and weight; the second part, included a semi-quantitative FFQ validated for Portuguese adults, that should be returned after fulfillment. All subjects completed the first part of the questionnaire and 40.4% returned the FFQ fairly completed.In multiple regression analysis, after adjustment for energy and confounders, social desirability produced a significant positive effect in the estimates of dietary fibre, vitamin C, vitamin E, magnesium and potassium, in both genders. In multiple regression, after adjustment for energy and confounders, social desirability had a significant positive effect in the estimates of vegetable consumption, for both genders, and a negative effect in white bread and beer, for women.Social desirability affected nutritional and food intake estimated from a food frequency questionnaire.