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 the 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 based on exposure over a lifetime. While food consumption data cannot be collected over the lifetimes of individuals, the information should reflect habitual intakes as closely as possible. This study investigated the possibility of combining a 3-day food diary with a food frequency questionnaire to estimate mean consumer-only food intakes comparable to estimates based on a 14-day diary. The study population consisted of 948 teenagers and analysis was based on 32 clearly defined foods. For 47% of the foods, the difference was < or = 1 g/day. When expressed as portion sizes, 56% of the foods showed differences representing < 5% of an average portion and no food showed a difference > 14% of an average portion. When between-method differences (portions/day) were plotted against the mean of the methods, the mean 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 the combined 3-day diary and FFQ method provides comparable estimates of mean 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 estimates of longer term food intakes are required.