Objective: To study consumption of special diet (disease-related and non disease-related) among Finnish adolescents during 1979-2001.
Methods: Self-administered questionnaires were mailed to nationally representative samples of 12- (except in 1979), 14-, 16-, and 18-year-olds in 1979, 1993, 1997, 1999 and 2001.
Results: The total number of respondents was 33998. The response rate declined from 78% in 1979 to 70% in 2001. Consumption of special diet increased from 1979 to 2001: in 14-year-old girls from 4% to 24%, boys from 1% to 12%; 16-year-old girls from 5% to 29%, boys from 3% to 11%; and 18-year-old girls from 9% to 30%, boys from 3% to 16%. An increase was observed both in the consumption of disease-related diets (diabetic, lactose intolerance, allergies), and in non disease-related diets (weight reducing, sports and body-building, vegetarianism, other).
Conclusions: Adherence to special diet is partly explained by an increased prevalence of certain diseases (lactose intolerance, allergies, diabetes). Increase in vegetarianisms and diets related to body weight or shape are most likely explained by fads, ideals created by media, and by growing ecological awareness.