The Validity of Questionnaire-Based Micronutrient Intake Estimates Is Increased by Including Dietary Supplement Use in Swedish Men

Abstract

Although many validation studies of FFQ have been reported, only a few addressed the effect of inclusion of dietary supplement use on the validity of micronutrient estimates. The purpose of the present study was to assess reproducibility and validity of a self-administered FFQ, intended to measure total nutrient intake from diet and from dietary supplements, in a random population-based sample of 248 middle-aged and elderly men (40-74 y old) in central Sweden. Fourteen 24-h recall interviews were used as the reference method. Participants were telephoned about once a month for 1 y, covering every day of the week, twice in random order. Spearman correlation coefficients increased 13% (from 0.49 to 0.62), between FFQ-based micronutrient estimates and the fourteen 24-h recall interviews (reference method) when supplement use was included. Correct classification into highest quintiles was also improved by 14% (from 37 to 51%). There were no differences in mean intraclass correlation coefficients for 1-y reproducibility between total micronutrient intake and micronutrients from foods only. The increase in the validity of micronutrient estimates due to inclusion of supplements in nutrient intake assessment has important implications for sample size in epidemiologic studies. Because a dramatic increase in dietary supplement use has occurred in recent decades in many countries, the issue of including supplements in dietary assessment should be of highest priority in nutritional epidemiologic studies of chronic diseases.

Validation of the assessment of folate and vitamin B12 intake in women of reproductive age: the method of triads

“…The macronutrient intakes estimated by both methods were in line with the Dutch dietary reference intakes for women between 19 and 50 years of age (Health Council of the Netherlands, 2001Netherlands, , 2003 and the data of the Dutch national food consumption survey of 2003 (Hulshof et al, 2004) and, therefore, we conclude that the FFQ is a valid method to estimate macronutrient intakes. The correlation coefficients between the FFQ and 24HR for folate were comparable with other studies (0.40 versus 0.37 and 0.49, respectively) (Bacardi- Gascon et al, 2003;Sevak et al, 2004) or even higher (0.29) (Messerer et al, 2004) and the correlation coefficient for vitamin B 12 was slightly lower, that is, 0.49 versus 0.58 (Sevak et al, 2004). In the latter study, more than three 24HR have been applied through which the overall day-to-day variation of B-vitamin intake is minimized, resulting in a higher correlation coefficient.…”

“…The correlation coefficients between the FFQ and 24HR for energy and fat were lower (Feunekes et al, 1993) or comparable with other studies (Johansson et al, 2002;Sevak et al, 2004). The correlation coefficient for carbohydrates was higher (Johansson et al, 2002;Messerer et al, 2004;Sevak et al, 2004) and the coefficient for proteins was similar to (Sevak et al, 2004) or even higher than the coefficients reported by others (Johansson et al, 2002;Messerer et al, 2004). The macronutrient intakes estimated by both methods were in line with the Dutch dietary reference intakes for women between 19 and 50 years of age (Health Council of the Netherlands, 2001Netherlands, , 2003 and the data of the Dutch national food consumption survey of 2003 (Hulshof et al, 2004) and, therefore, we conclude that the FFQ is a valid method to estimate macronutrient intakes.…”

“…The size of the study population is comparable with other validation studies (53 versus 34 and 36, respectively) (Pufulete et al, 2002;Bacardi-Gascon et al, 2003). However, validation studies were performed in 100 up to 200 subjects, but in those studies the method of triads was not applied (Messerer et al, 2004;Sevak et al, 2004). The sample size was relatively small with wide confidence intervals of the validity coefficients as a consequence.…”

Dietary glycemic index, dietary glycemic load and mortality among men with established cardiovascular disease

“…On average, the first cardiovascular event occurred 8.8 years prior to baseline, 1 January 1998, (range 1 day-33 years). The Cohort of Swedish Men population and exposure assessment have been described previously (Messerer et al, 2004;Larsson et al, 2006). The ethics committees for the Karolinska Institute, Uppsala University Hospital, and the Ö rebro region approved the Cohort of Swedish Men.…”

Diet quality and mortality: a population-based prospective study of men

“…Relative validity of the FFQ has been evaluated among 248 men, 40-74 years of age from central Sweden, by using fourteen 24-h recall telephone interviews (Messerer et al, 2004). The Spearman's correlation coefficients (r) between nutrient intake obtained by FFQ and 24-h recall ranged from 0.37 (a-tocopherol) to 0.77 (calcium).…”