Enhancing the capacity of food consumption surveys of short duration to estimate long term consumer-only intakes by combination with a qualitative food frequency questionnaire

In principle, a proper risk assessment for a food chemical requires that th e time-frame for food chemical intake estimates matches the time-frame for the toxicological assessments upon which the safety statements (ADI, PTWI, etc.) are based. For food additives, the toxicological assessments are base d on exposure over a lifetime. While food consumption data cannot be collec ted over the lifetimes of individuals, the information should reflect habit ual intakes as closely as possible. This study investigated the possibility of combining a 3-day food diary with a food frequency questionnaire to est imate mean consumer-only food intakes comparable to estimates based on a 14 -day diary. The study population consisted of 948 teenagers and analysis wa s based on 32 clearly defined foods. For 47% of the foods, the difference w as less than or equal to 1 g/day. When expressed as portion sizes, 56% of t he foods showed differences representing <5% of an average portion and no f ood showed a difference >14% of an average portion. When between-method dif ferences (portions/day) were plotted against the mean of the methods, the m ean between-method difference was 0.02(+/-0.06) portions/day with limits of agreement of -0.10 to 0.14. This preliminary investigation suggests that t he combined 3-day diary and FFQ method provides comparable estimates of mea n consumer only intakes to a 14-day diary. Therefore, a qualitative FFQ may be a useful adjunct to a food consumption survey of short duration if esti mates of longer term food intakes are required.