The Malmö Food Study: the reproducibility of a novel diet history method and an extensive food frequency questionnaire

Abstract

Objective: To assess the reproducibility of two diet assessment methods, an extensive quantitative food frequency questionnaire (method A) and a novel shorter quantitative food frequency questionnaire with a 14 day food record (method B).

Design: A randomized prospective cohort study.

Setting: General community.

Subjects: 241 residents of the town of Malmö, aged between 50-69 years, 126 men and 115 women who completed the methods one year apart.

Methods: Both diet methods were designed to cover the whole diet and portion sizes were estimated using a booklet with 120 photographs; method A comprised 250 items and method B combined a two-week food record measuring lunch and dinner meals and a shorter 130 item quantitative food frequency questionnaire for average consumption of foods, snacks and beverages during the past year;

Results: The percent difference between estimated energy intake one year apart were for men 10.7% for method A and 0.2% for method B, corresponding values for women 13.7% and 1.1%. Method B showed a good agreement between measurements for energy-providing nutrients, micronutrients and major food groups, i.e. meat products, edible fats, milk, fish, fruits and vegetables with correlation coefficients between 0.70-0.90 for women. The percent difference of average intake of edible fat was about 10%. Average energy-adjusted Pearson's correlation coefficients were of the order of 0.50-0.80 for most nutrients including 14 fatty acids. The correlation for the ratio between polyunsaturated and saturated fatty acids were about 0.70 for men and 0.80 for women;

Conclusion: A modified diet history method combining a food record and a food frequency questionnaire shows good reproducibility.