Serum biomarker-based validation of a self-administered diet history questionnaire for Japanese subjects

Although several self-administered dietary assessment questionnaires have been developed for Japanese subjects, they have seldom been validated with objective measures. We validated a recently developed self-administered diet history questionnaire (DHQ) with fatty acids in serum phospholipid fractions, alpha- and beta-carotenes and alpha-tocopherol in serum as a gold standard using 86 university workers (42 men and 44 women, age-range=24-67 y). The age-adjusted Pearson partial correlation coefficients between the intakes of marine origin n-3 polyunsaturated fatty acids (PUFA) (crude values, energy-adjusted values by residual method, energy density, and fat density) and the serum phospholipid concentrations (percentage of total fatty acids) were 0.49, 0.51, 0.52, 0.48, and 0.58, 0.69. 0.66, 0.69 in men and women respectively. The correlation coefficients between intakes (microg/d) and the corresponding serum concentrations (micromol/L) were 0.43 and 0.40 in men and 0.42 and 0.60 in women for alpha- and beta-carotene respectively. It was -0.23 in men and -0.22 in women for alpha-tocopherol. The intakes of major foods (g/d) of marine origin n-3 PUFA, alpha- and beta-carotenes showed a relatively high level of correlation with the corresponding serum concentrations, whereas the level was generally lower than those observed in the analysis with the nutrient intakes. The results suggest that DHQ ranks individual adequately for marine origin n-3 PUFA, alpha- and beta-carotene intakes.     

Validity of retrospective diet history: Assessing recall of midlife diet using food frequency questionnaire in later life

Objectives

Limited information exists on the validity of dietary information given by elderly people on their past diet. Here we test the relative validity of a food frequency questionnaire asking older persons about their midlife diet.

Design

Retrospective food intake of 56–72-year-old subjects was estimated using a food frequency questionnaire designed for the AGES-Reykjavik Study (AGES-FFQ), an epidemiological study of older individuals. Results were compared with detailed dietary data gathered from the same individuals 18–19 years previously, i.e., in midlife, as part of a national cohort. Spearman correlation and cross-classifications were used to assess the ability of the AGES-FFQ to rank subjects according to their intake.

Setting

Nationwide, Iceland.

Participants

Subjects, born 1937–1952 (n=174), who participated in the 1990 Icelandic National Dietary Survey.

Measurements

Dietary intake, estimated by the AGES-FFQ (2008–2009), and dietary history obtained from the 1990 Icelandic National Dietary Survey as a reference method.

Results

The strongest correlation between the AGES-FFQ and the reference method was found for cod liver oil, r=0.53, p<0.001 and r=0.56, p<0.001, for men and women, respectively. For men the corresponding correlation coefficient for milk and dairy products was r=0.43, p<0.001. The correlation coefficients were lower but within a reasonably acceptable range (r=0.26–0.40) for meat, fish and potatoes for both genders, as well as fresh fruits and milk/dairy products for women and whole-wheat bread, oatmeal/muesli and blood/liver-sausage for men. No correlation was found between the AGES-FFQ and the dietary history for rye bread and vegetable consumption. Subjects were categorized into five groups according to level of consumption by the two methods. Cross-classification showed that 16–59% were classified into same group and 43–91% into same or adjacent group, 0–14% were grossly misclassified into opposite groups.

Conclusion

The AGES-FFQ on midlife diet was found suitable to rank individuals by their intake of several important food groups.     

Estimating nitrate intake in the Australian diet: Design and validation of a food frequency questionnaire

Background

Dietary nitrates may play a role in mediating several key physiological processes impacting health and/or exercise performance. However, current methods for assessing dietary nitrate (NO₃⁻) consumption are inadequate. The present study aimed to examine the dietary nitrate intake in a sample of 50 healthy adults, as well as test the validity of a purposefully developed food frequency questionnaire (FFQ).

Methods

Dietary nitrate intake was estimated over a week using (i) three 24-h dietary recalls; (ii) a short-term (7-day) FFQ; and (iii) a biomarker (urinary nitrate), in conjunction with a nitrate reference database.

Results

Daily dietary nitrate intake estimates were 130.94 mg (average of three 24-h recalls) and 180.62 mg (FFQ). The mean urinary NO₃⁻ excretion was 1974.79 µmol day^–1 (or 917.9 µmol L^–1). Despite the difference between the two dietary assessment methods, there was a moderate positive correlation (r = 0.736, ρ < 0.001) between the two tools. There was also a positive correlation between urinary NO₃⁻ and 24-h recall data (r = 0.632, ρ < 0.001), as well as between urinary NO₃⁻ and FFQ (r = 0.579, ρ < 0.001).

Conclusions

The ability to accurately estimate nitrate intakes depends on having suitable reference methods to estimate the concentrations of nitrate in the food supply, coupled with valid and reliable dietary assessment tools. Based on the findings from the present study, at an individual level, dietary recalls or records may be more accurate in estimating intakes of NO₃⁻. However, given the lower cost and time needed for administration relative to recalls, the FFQ has merit for estimating NO₃⁻ intakes in health interventions, dietary surveys and surveillance programs.

     

Validation of a self-administered diet history questionnaire using multiple diet records

The validity of a self-administered diet history questionnaire has been estimated using as the reference data the mean of three 4-day diet records collected over the year prior to the administration of the questionnaire, in 1985–1986. Subjects were women ages 45–70 years, participants in the Women's Health Trial Feasibility Study, a multi-center clinical trial in which some women were randomized to be taught to adopt and maintain a low-fat diet, while others maintained their usual diet. The questionnaire produced group mean nutrient estimates closely approximating the values obtained by three 4-day records, e.g. in the usual-diet group, 37.7% of calories from fat by both food records and by questionnaire, and in the low-fat, group, 21.3% of calories from fat by food records and 23.7% of calories from fat by questionnaire. Correlations between questionnaire and diet records for per cent of calories from fat were 0.67 and 0.65 respectively in the two groups; most correlations were in the 0.5–0.6 range, and were similar to those achievable by a single 4-day food record.     

Comparative validation of the Block, Willett, and National Cancer Institute food frequency questionnaires : the Eating at America's Table Study.

Researchers at the National Cancer Institute developed a new cognitively based food frequency questionnaire (FFQ), the Diet History Questionnaire (DHQ). The Eating at America's Table Study sought to validate and compare the DHQ with the Block and Willett FFQs. Of 1,640 men and women recruited to participate from a nationally representative sample in 1997, 1,301 completed four telephone 24-hour recalls, one in each season. Participants were randomized to receive either a DHQ and Block FFQ or a DHQ and Willett FFQ. With a standard measurement error model, correlations for energy between estimated truth and the DHQ, Block FFQ, and Willett FFQ, respectively, were 0.48, 0.45, and 0.18 for women and 0.49, 0.45, and 0.21 for men. For 26 nutrients, correlations and attenuation coefficients were somewhat higher for the DHQ versus the Block FFQ, and both were better than the Willett FFQ in models unadjusted for energy. Energy adjustment increased correlations and attenuation coefficients for the Willett FFQ dramatically and for the DHQ and Block FFQ instruments modestly. The DHQ performed best overall. These data show that the DHQ and the Block FFQ are better at estimating absolute intakes than is the Willett FFQ but that, after energy adjustment, all three are more comparable for purposes of assessing diet-disease risk.     

Let the pyramid guide your food choices: capturing the total diet concept

This paper discusses how the guideline "Eat a variety of foods" became "Let the Pyramid guide your food choices," presents background information on the food guidance system upon which the Food Guide Pyramid is based and reviews methods that have been used to assess aspects of the total diet, i.e., the variety, moderation and proportionality, promoted by this guidance. The methods include measures of dietary variety, patterns based on Pyramid food group intakes and scoring methods comprised of multiple dietary components. Highlights of results from these methods include the following. Although approximately one third of the U.S. population eat at least some food from all Pyramid food groups, only approximately 1-3% eat the recommended number of servings from all food groups on a given day. Fruits are the most commonly omitted food group. Vegetables and meat are the groups most commonly met by adults, and dairy the most commonly met by youth. Intakes of specific types of vegetables (i.e., dark green, deep yellow) and of grains (i.e., whole grains) are well below that recommended; intakes of total fat and added sugars exceed current recommendations. Scoring methods show those diets of the majority of the population require improvement, and that diets improve with increases in education and income. This paper also discusses the limitations and strengths of these approaches, and concludes with suggestions to improve current food guidance and methods to assess the total diet.     

Comparison of a food frequency questionnaire with a diet record

The associations between levels of nutrients derived from a 24-hour diet record and a food frequency questionnaire were assessed in a sample of 433 men and women. The food frequency questionnaire was administered three years after the completion of the diet record. Spearman correlations were all statistically significant; they varied from 0.36 for energy to 0.15 for vitamin A. Comparison of distributions into fifths showed few people grossly misclassified. A model was developed to assess the correlations which would be expected under various conditions of within and between subject variance for each nutrient, errors in measurements and drift in intake over time. The best possible correlation that could be obtained using the within and between subject variations in intake previously published, and with no measurement error or drift over time, was 0.60 for energy and 0.34 for vitamin A. Using a realistic measure of measurement error (standard deviation on log scale of 0.12 for diet record method, 0.06 for drift over time and 0.18 for food frequency method) the correlations obtained in the modelling were very similar to that observed. This study shows that it may be appropriate to use a food frequency questionnaire instead of a diet record to estimate intakes in population based epidemiological studies.     

Development and validation of a food frequency questionnaire for Korean Americans

A food frequency questionnaire for Korean Americans (KFFQ) was developed by modifying Block's Health Habits and History Questionnaire (HHHQ). The final KFFQ contained 118 food items taking into account culturally specific dietary patterns. Validation of the KFFQ was conducted to compare the nutrient intakes assessed by the KFFQ against those measured by seven-day dietary records in 73 Korean Americans. The mean nutrient values from the KFFQ differed at most by 25% from those of the dietary records with the exception of vitamin A, and 70% of the nutrients (16 out of 23 nutrients) were within 15%. Adjusted Spearman rank-order correlation coefficients for nutrients ranged between 0.45 and 0.84. The overall degree of agreement between the KFFQ and the dietary records was 68% with a range 56% to 79%. This validation study indicates that the KFFQ gives reasonably accurate estimates of the usual dietary intakes among the study population. The results also verify that it is possible to use a FFQ that is both culturally specific and comprehensive with the benefit of being easy to self-administer. This high degree of correlation between the KFFQ and the dietary records demonstrates that the KFFQ provides an easier yet accurate method in large-scale epidemiological studies of relationships between nutrition intakes and diseases in Korean Americans.     

Food predictors of plasma beta-carotene and alpha-tocopherol: validation of a food frequency questionnaire

Nutrient intakes from a food frequency questionnaire are usually calculated as the product of frequency of intake and nutrient composition of the food, summed over the food items. This involves assumptions about the accuracy of recording, food composition data, stability during storage and preparation, and bioavailability. This usual method of calculation was compared with one using empirical weights derived by multivariate linear regression. Food intakes reported on a food frequency questionnaire by Boston, Massachusetts, area subjects in 1982-1985 were used to predict plasma levels of beta-carotene among 370 male and female nonsmokers and plasma levels of alpha-tocopherol among 339 male and female nonusers of vitamin supplements. Nutrient intake computed using empirical weights yielded a significant correlation with plasma beta-carotene (r = 0.43, p = 0.0001), similar to the correlation using nutrient intake calculated from food composition tables (r = 0.38, p = 0.0001). However, the use of empirical weights significantly improved the correlation of vitamin E intake with plasma alpha-tocopherol levels (r = 0.32, p = 0.0001), compared with the weak correlation obtained using the food composition table method to calculate intake (r = 0.16). The results support the validity of published food composition data used to compute carotenoid intake and illustrate the potential utility of empirically derived weights for foods to predict plasma levels of some nutrients.