Validation of a short dietary questionnaire and a qualitative fat index for the assessment of fat intake.

In connection with a population-based study on familial and non-familial determinants of serum total cholesterol an interviewer-administered short questionnaire, including 21 food items, and a qualitative fat index based on four questions were developed. Subjects for the validation study, 51 women and 31 men, aged 16-71 years, were selected from the population-based study (n = 892). The short questionnaire and the qualitative fat index were validated with a 3 day food record as the reference method. The short questionnaire captured 90-97% of the mean intakes of total fat, saturated, monounsaturated and polyunsaturated fatty acids and cholesterol. The Pearson correlation coefficients between the fat intakes based on the questionnaire and the diet records were strongest for the intake of total fat (r = 0.80). The qualitative fat index was based on four questions concerning type of fat: the higher the scores the higher the intakes of polyunsaturated fatty acids. The Spearman correlation coefficients between the qualitative fat index and the intakes based on the diet records were -0.55 for saturated, 0.34 for monounsaturated and 0.52 for polyunsaturated fatty acids. The respective correlation for the P/S ratio (total amounts of polyunsaturated fatty acids/saturated fatty acids) and the PM/S ratio (total amounts of polyunsaturated and monounsaturated fatty acids/saturated fatty acids) were 0.50 and 0.53. An inverse association between serum total cholesterol and the qualitative fat index was found in the whole study population, suggesting the impact of dietary fat on serum cholesterol in this study population. In conclusion, the short questionnaire proved to be accurate in measuring the intake of different fatty acids at the group level, whereas the simpler fat index measured the quality of fat quite well.