Validation and Comparison of Nutrient Intakes from Two Dietary Questionnaires Developed for the Multiethnic Cohort Study.

BACKGROUND: Quantitative food frequency questionnaires (QFFQs) are often used to measure dietary intakes in large cohort studies but the impact of updating these questionnaires over time is not often examined. OBJECTIVE: This study compared nutrient intakes estimated from two different QFFQs to each other and to intakes calculated from three 24-hour dietary recalls (24HDRs). DESIGN: This study used a cross-sectional design. PARTICIPANTS/SETTING PARTICIPANTS: Participants (N = 352) were members of the Multiethnic Cohort Study from five racial and ethnic groups (African American, Japanese American, Latino American, Native Hawaiian, and White) who lived in Hawaii and Los Angeles. They were recruited in 2010 and asked to complete two QFFQs, two months apart, and three 24HDRs in the time between completion of the QFFQs. One questionnaire had been developed for a baseline survey (baseline QFFQ) at the start of the Multiethnic Cohort Study during 1993-1996, and the other was updated for a follow-up study 10 years later (10-year QFFQ). MAIN OUTCOME MEASURES: Daily intakes of energy and nine nutrients were estimated from both QFFQs, and from the average of three 24HDRs. STATISTICAL ANALYSES PERFORMED: Pearson's correlation coefficients were calculated between log-transformed nutrient intakes from each QFFQ and the 24HDRs and between the two QFFQs overall, by sex, and by race and ethnicity. RESULTS: Correlations for the 10-year QFFQ with the 24HDRs (average = 0.45) were higher than for the baseline QFFQ (average = 0.41), although the differences were not statistically significant. The increase in correlations was particularly pronounced for Native Hawaiian and African American participants. When absolute values were adjusted for energy intake, the average correlations were higher at 0.57 for the baseline QFFQ and 0.58 for the 10-year QFFQ overall and this pattern was seen in most racial and ethnic subgroups. The average correlations between the two QFFQs were 0.73 for both absolute intakes and nutrient densities overall. CONCLUSIONS: Correlations of nutrient intakes between the two QFFQs and 24HDRs were similar, and intakes from the two QFFQs were highly correlated. QFFQs updated for changes to the food supply may provide improved assessment for cohort studies that include diverse populations.

A Dietary Supplement Frequency Questionnaire Correctly Ranks Nutrient Intakes in US Older Adults When Compared to a Comprehensive Dietary Supplement Inventory.

BACKGROUND: Dietary supplements are commonly taken by adults in the United States and can contribute substantially to daily nutrient intakes. Short supplement-use questionnaires are often used in dietary surveys, but their accuracy has not been well studied. OBJECTIVES: The primary objective was to evaluate the accuracy of a short, self-administered supplement frequency questionnaire (SFQ) relative to a comprehensive 1-y inventory of supplement use. A secondary objective was to compare SFQ responses for participants in the intensive measurement study to those from a control group to investigate a possible research participation effect. METHODS: The Supplement Reporting study enrolled 1029 older adults in 2005-2006, with a mean age of 67.8 y, who participated in the Multiethnic Cohort and reported regular use of dietary supplements. Of these, 375 were interviewed quarterly to collect detailed information on types and amounts of dietary supplements used, while 654 served as the control group. All participants completed 2 SFQs, 1 y apart. RESULTS: Agreement between the 2 instruments in use at least weekly ranged from 88% to 97% for 15 of 16 supplement types, with a lower agreement of 74% for vitamin D. The correlations of nutrient intakes from supplements between the 2 instruments were high, ranging from 0.48 to 0.75, except for iron (r = 0.29). However, mean nutrient intakes as reported on the SFQ were higher than intakes from the inventory for most nutrients, sometimes twice as high. Nutrient intakes based on the SFQ were similar for the inventory and control groups, at both baseline and the end of the study. CONCLUSIONS: A self-administered short SFQ can be used in large surveys to identify participants who use 16 categories of dietary supplements at least once a week and can correctly rank participant intakes of nutrients. However, the SFQ does not accurately estimate absolute levels of nutrient intakes from supplements.

Planning Nutritionally Adequate Diets for Groups: Methods Used to Develop Recommendations for a Child and Adult Care Food Program.

Planning nutritionally adequate intakes for large groups of people presents many challenges. Because of between-person variations in both food choices and nutrient requirements, it is necessary to examine nutrient intake distributions and select a Target Median Intake (TMI) that will lead to a low prevalence of inadequate nutrient intakes. The TMI may then be used to guide a feeding or education program. A comprehensive report from the Institute of Medicine evaluated nutrient intakes from the NHANES and recommended new meal patterns for all age groups (other than infants) served by the Child and Adult Day Care Food Program, which provides meals and snacks to children and adults in a variety of care settings. The Estimated Average Requirement, a DRI value, for each nutrient of interest was used to estimate both the prevalence of inadequate intakes as well as the changes in the intake distribution that are needed to reduce unacceptably high levels of inadequacy. For nutrients with an Adequate Intake (AI), the prevalence of inadequacy could not be estimated, but the AI could be used as the TMI. Simultaneously, it was important to ensure that the new intake distributions did not result in intakes that exceeded the Tolerable Upper Intake Level for any nutrient. Data for 2- to 4-y-old children are presented in detail to illustrate this process. Of 18 nutrients examined, analyses showed that intakes of vitamin E, potassium, and fiber should be increased, while intakes of sodium should be decreased. If more recent nutrient standards are used, revised assessments show that calcium intake should also be increased, while potassium intake is adequate. These methods and results should be useful when designing feeding programs for other population groups within the United States, as well as in other countries.

Perspective: Proposed Harmonized Nutrient Reference Values for Populations.

Two core nutrient intake reference values (NRVs) are required for assessing the adequacy and safety of nutrient intakes for population groups: the average requirement (AR) and the tolerable upper level of intake (UL). Applications of such assessments include providing advice to improve intakes, formulating complementary foods, estimating the amounts of nutrients to be added to fortified foods and monitoring changes in intake, and product labeling at the global, national, or regional level. However, there is a lack of unity across country-level organizations in the methodological approach used to derive NRVs, and ARs and ULs are lacking in many compilations, thus limiting the ability to assess nutrient intakes for their population groups. Because physiological requirements vary little across populations globally, and setting reference values requires determining an acceptable level of uncertainty, it is feasible to adapt current recommendations from different sources to harmonize these core reference values. The objective of this review is to demonstrate an approach for harmonizing the NRVs for ARs (here termed "H-ARs") and ULs ("H-ULs") that can be applied on a global scale to assessing intakes across populations. The approach incorporates the framework and terminology recommended by reports from the United Nations University, the National Academies of Sciences, Engineering, and Medicine (NASEM), the Institute of Medicine (IOM), and the European Food Safety Authority (EFSA). After reviewing available alternatives, the proposed harmonized values were selected from standards set by EFSA (for Europe) and the IOM (for the United States and Canada), giving priority to those published most recently. Justifications for the proposed values are presented, along with discussion of their limitations. Ideally, these methods should be further reviewed by an international group of experts. Meanwhile, the H-ARs and H-ULs suggested in this review can be used to assess intakes of populations for many applications in global and regional contexts.

Ratios of Food Amounts across Three Portion Size Categories on a Food Frequency Questionnaire in Men and Women.

BACKGROUND: For some quantitative food frequency questionnaire (QFFQ) items, data may be insufficient to set gram weights for multiple portion size (PS) categories. Ratios of food amounts across PS categories may be used to quantify these PS for less frequently consumed food items. OBJECTIVE: To explore the ratios of food amounts reported in 24-hour dietary recalls (24HDRs) by a sample of participants in a cohort study who chose the A (smallest) or C (largest) PS category on the QFFQ, relative to the food amounts for those who chose the B PS category. DESIGN: This study was conducted as a cross-sectional design. PARTICIPANTS/SETTING: Data were from participants (n=2,360) who completed three 24HDRs and the QFFQ in a calibration study of the Multiethnic Cohort Study in 1994-1997. MAIN OUTCOME MEASURES: Median food amounts were calculated from 24HDRs for participants who selected each PS category (A, smallest; B; and C, largest) of items on the QFFQ. A-to-B and C-to-B ratios were computed if reported by five or more people in the 24HDRs: A-to-B ratios for 68 items (men) and 88 items (women); C-to-B ratios for 93 items (men) and 79 items (women). STATISTICAL ANALYSES PERFORMED: The t test was used to compare the mean A-to-B ratios and C-to-B ratios as preset on the QFFQ with those from the 24HDRs and to examine sex differences. Analysis of variance was used to compare the mean ratios among race and ethnicity groups. RESULTS: Mean A-to-B and C-to-B ratios were 0.71±0.15 and 1.45±0.35 in men and 0.71±0.15 and 1.44±0.40 in women based on the 24HDRs. Compared with the original QFFQ PS (A-to-B ratio=0.5±0.07; C-to-B ratio=1.8±0.30), the ratios were closer to 1 both in men and women (P<0.001). There were no significant sex differences or racial or ethnic differences. CONCLUSIONS: These results provide guidance on appropriate ratios to use to set values for small and large PS categories on a QFFQ, particularly for items with insufficient information on usual PS.

Considering Gender Differences in Portion Sizes to Improve the Accuracy of Nutrient Intakes from A Food Frequency Questionnaire.

The aim of this study was to examine whether using gender specific-portion size (GS-PS) improves the accuracy of nutrient intake assessment by a quantitative food frequency questionnaire (QFFQ). For GS-PS quantification, a gram amount was assigned to each PS category for each food item for men and women separately using data from three 24 h dietary recalls (24HDRs) in a calibration study of the Multiethnic Cohort (men = 1141, women = 1150). Nutrient intakes were calculated from the QFFQ using the original-PS and the GS-PS, and were compared with 24HDRs. When intakes of energy and 15 nutrients were compared, absolute intakes calculated using the GS-PS were closer to intake levels of 24HDRs in both men and women. Using GS-PS did not affect intakes expressed as nutrient density or correlations between 24HDRs and the QFFQ. The current findings indicate that considering gender in PS determination can increase the accuracy of intake assessment by QFFQ for absolute nutrient intakes, but not for nutrient densities.

Portion Sizes from 24-Hour Dietary Recalls Differed by Sex among Those Who Selected the Same Portion Size Category on a Food Frequency Questionnaire.

BACKGROUND: Accounting for sex differences in food portions may improve dietary measurement; however, this factor has not been well examined. OBJECTIVE: The aim of this study was to examine sex differences in reported food portions from 24-hour dietary recalls (24HDRs) among those who selected the same portion size category on a quantitative food frequency questionnaire (QFFQ). DESIGN: This study was conducted with a cross-sectional design. PARTICIPANTS/SETTING: Participants (n=319) were members of the Hawaii-Los Angeles Multiethnic Cohort who completed three 24HDRs and a QFFQ in a calibration study conducted in 2010 and 2011. MAIN OUTCOME MEASURES: Portions of individual foods reported from 24HDRs served as the outcome measures. STATISTICAL ANALYSES PERFORMED: Mean food portions from 24HDRs were compared between men and women who reported the same portion size on the QFFQ, after adjustment for race/ethnicity using a linear regression model. Actual amount and the assigned amount of the selected portion size in the QFFQ were compared using one-sample t test for men and women separately. RESULTS: Of 163 food items with portion size options listed in the QFFQ, 32 were reported in 24HDRs by ≥20 men and ≥20 women who selected the same portion size in the QFFQ. Although they chose the same portion size on the QFFQ, mean intake amounts from 24HDRs were significantly higher for men than for women for "beef/lamb/veal," "white rice," "brown/wild rice," "lettuce/tossed salad," "eggs cooked/raw," "whole wheat/rye bread," "buns/rolls," and "mayonnaise in sandwiches." For men, mean portions of 14 items from the 24HDRs were significantly different from the assigned amounts for QFFQ items (seven higher and seven lower), whereas for women, mean portions of 14 items were significantly lower from the assigned amounts (with five significantly higher). CONCLUSIONS: These sex differences in reported 24HDR food portions-even among participants who selected the same portion size on the QFFQ-suggest that the use of methods that account for differences in the portions consumed by men and women when QFFQs are quantified may provide more accurate absolute dietary intakes.

The History and Future of Dietary Guidance in America.

Evidence-based dietary guidance in the United States has progressed substantially since its inception >100 y ago. This review describes the historical development and significance of dietary guidance in the United States, including the Dietary Guidelines for Americans (DGAs), and emphasizes the foundations upon which they were developed, the process in the formation of past and current guidelines, and present and future applications. Dietary guidance during the first half of the 20th century was focused primarily on food groups in a healthy diet, food safety, safe food storage, and the role of some minerals and vitamins in the prevention of disease. This was punctuated by World War II messaging to reduce food waste and increase food storage. In 1980, the first DGA report was released, and later, the USDA and the Department of Health and Human Services (HHS) were given a mandate for reissuance and reassessment every 5 y. An ad hoc advisory committee made up of nongovernmental experts was established for each edition to review the scientific evidence and provide content recommendations to the Secretaries of the USDA and the HHS. Wording was changed from negative (avoid) to positive (choose) and emphasis was increasingly placed on reducing the prevalence of overweight and obesity and prevention of chronic diseases. Today, the DGAs guide all federally funded feeding and educational programs, including food policies, food assistance programs, and consumer education programs, as well as these programs at the regional, state, and local levels. Additional users include dietitians and other health professionals, food service personnel, food and beverage manufacturers, schools, and day care facilities. Currently, the DGAs are intended for individuals aged ≥2 y. Future editions of the DGAs will include guidance for infants and children <2 y, as well as pregnant women.

Scanning for new evidence to prioritize updates to the Dietary Reference Intakes: case studies for thiamin and phosphorus.

BACKGROUND: Dietary Reference Intakes (DRIs) are fundamental to inform national nutrition policy. However, a regular systematic review of the 51 nutrients that have DRIs has limited feasibility, and many DRIs have not been reviewed in >15 y. OBJECTIVE: To address this issue, individuals (nutrient review group) who were members of the Food and Nutrition Board developed a streamlined, evidence-based methodology that could be used to identify nutrients potentially in need of a systematic review. DESIGN: The proposed methodology, termed an evidence scan, comprises several steps. First, an analytic framework is developed to identify markers of associations between intake of a nutrient and a corresponding clinical outcome. Next, the framework is used to direct the identification of keywords for a scan of published research that is potentially relevant to intake requirements or upper intake levels for a nutrient. Last, a panel of content experts selects the abstracts that are likely to be relevant and reviews the full publications. The results may be used to determine whether a revision of the nutrient's DRI is an immediate priority but would not supplant a comprehensive systematic evidence review. RESULTS: To illustrate the process, 2 nutrients were selected as case studies: thiamin and phosphorus (DRIs were last set in 1998 and 1997, respectively). Using the evidence scan for thiamin, we identified 70 potentially relevant abstracts, of which 9 full publications were reviewed. For phosphorus, 127 potentially relevant abstracts were identified, and 29 full publications were reviewed. CONCLUSIONS: From the review of these 2 nutrients, the nutrient review group concluded that there was insufficient new evidence to assign a high priority to a comprehensive systematic review for either thiamin or phosphorus. Evidence scanning is an efficient method of identifying DRI nutrients that are most in need of either a new or an updated systematic review.

Comparison of 2 methods for estimating the prevalences of inadequate and excessive iodine intakes.

BACKGROUND: Prevalences of iodine inadequacy and excess are usually evaluated by comparing the population distribution of urinary iodine concentration (UIC) in spot samples with established UIC cutoffs. To our knowledge, until now, dietary intake data have not been assessed for this purpose. OBJECTIVE: Our objective was to compare 2 methods for evaluating the prevalence of iodine inadequacy and excess in sex- and life stage-specific subgroups of the US population: one that uses UIC cutoffs, and one that uses iodine intake cutoffs. DESIGN: By using the iodine concentrations of foods measured in the US Food and Drug Administration's Total Diet Study (TDS), dietary intake data from the NHANES 2003-2010, and a file that maps each NHANES food to a TDS food with similar ingredients, we estimated each NHANES participant's iodine intake from each NHANES food as the mean iodine concentration of the corresponding TDS food in samples gathered over the same 2-y period. We calculated prevalences of iodine inadequacy and excess in each sex- and life stage-specific subgroup by both the UIC cutoff method and the iodine intake cutoff method-using the UIC values and dietary intakes reported for NHANES participants who provided both types of data-and compared the prevalences across methods. RESULTS: We found lower prevalences of iodine inadequacy across all sex- and life stage-specific subgroups with the iodine intake cutoff method than with the UIC cutoff method; for pregnant females, the respective prevalences were 5.0% and 37.9%. For children aged ≤8 y, the prevalence of excessive iodine intake was high by either method. CONCLUSIONS: The consideration of dietary iodine intake from all sources may provide a more complete understanding of population prevalences of iodine inadequacy and excess and thus better inform dietary guidance than consideration of UIC alone. Methods of adjusting UIC for within-person variation are needed to improve the accuracy of prevalence assessments based on UIC.

Variation in the iodine concentrations of foods: considerations for dietary assessment.

BACKGROUND: Food-composition tables typically give measured nutrient concentrations in foods as a single summary value, often the mean, without providing information as to the shape of the distribution. OBJECTIVE: Our objective was to explore how the statistical approach chosen to describe the iodine concentrations of foods affects the proportion of the population identified as having either insufficient or excessive iodine intakes. DESIGN: We used food intake data reported by the 2009-2010 NHANES and measured iodine concentrations of Total Diet Study (TDS) foods from 4 US regions sampled in 2004-2011. We created 4 data sets, each by using a different summary statistic (median, mean, and 10th and 90th percentiles), to represent the iodine concentration distribution of each TDS food. We estimated the iodine concentration distribution of each food consumed by NHANES participants as the 4 iodine concentration summary statistics of a similar TDS food and used these, along with NHANES food intake data, to develop 4 estimates of each participant's iodine intake on each survey day. Using the 4 estimates in turn, we calculated 4 usual iodine intakes for each sex- and age-specific subgroup. We then compared these to guideline values and developed 4 estimates of the proportions of each subgroup with deficient and excessive usual iodine intakes. RESULTS: In general, the distribution of iodine intakes was poorly characterized when food iodine concentrations were expressed as mean values. In addition, mean values predicted lower prevalences of iodine deficiency than did median values. For example, in women aged 19-50 y, the estimated prevalence of iodine deficiency was 25% when based on median food iodine concentrations but only 5.8% when based on mean values. CONCLUSION: For nutrients such as iodine with highly variable concentrations in important food sources, we recommend that food-composition tables provide useful variability information, including the mean, SD, and median.

History of Nutrition: The Long Road Leading to the Dietary Reference Intakes for the United States and Canada.

The Dietary Reference Intakes (DRIs) are reference values to guide the planning and assessing of nutrient intakes in the United States and Canada. The DRI framework was conceptualized in 1994, and the first reports were issued from 1997­2004, based on work by expert panels and subcommittees under the guidance of the Food and Nutrition Board of the Institute of Medicine. Numerous conventions, challenges, and controversies were encountered during the process of defining and setting the DRIs, including the definition of the framework, the use of chronic disease endpoints, lack of data on requirements for children and youth, and methods for addressing nonessential bioactive substances with potential health benefits. DRIs may be used to plan and assess the nutrient intakes of both individuals and population groups, but the new paradigm particularly improved methods used for groups. It is now possible to estimate both the prevalence of inadequate intake and the prevalence of potentially excessive intake within a group. The DRIs have served as a potent influence on national nutrition policies, including those related to dietary guidance, food labeling, nutrition monitoring, food assistance programs, and military nutrition standards. Because of this important impact on nutrition policy, the DRIs must be based on the best possible and most up-to-date science. Unfortunately, no updates to specific DRIs are currently planned. Despite the long and challenging road that led to the current DRIs, it must not finish in a dead end. Monetary resources and political will are crucial to maintaining and continuously updating the DRIs.

Thirty years of progress in harmonizing and compiling food data as a result of the establishment of INFOODS.

The International Network of Foods Data Systems (INFOODS) has provided leadership on the development and use of food composition data for over 30years. The mission of INFOODS is the promotion of international participation, cooperation and harmonization in the generation, compilation and dissemination of adequate and reliable data on the composition of foods, beverages, and their ingredients in forms appropriate to meet the needs of various users. Achievements include the development of guidelines and standards, increased capacity development in generating and compiling food composition data, a food composition database management system, improvements in laboratory quality assurance, and development of several food composition databases and tables. Recently, INFOODS has led efforts to define and document food biodiversity. As new foods and food components come into prominence, and as analytical methods evolve, the activities of INFOODS will continue to advance the quality and quantity of food composition data globally into the future.

Determining minimum food intake amounts for diet diversity scores to maximize associations with nutrient adequacy: an analysis of schoolchildren's diets in rural Kenya.

OBJECTIVE: To explore multiple methods of calculating diet diversity scores (DDS) to maximize associations with predicted dietary micronutrient adequacy among schoolchildren in rural Kenya. DESIGN: Up to three 24 h recall interviews were administered for each child for a total of 1544 d of intake from all schoolchildren. Daily amounts of food consumed were assigned to one of eight food groups. Five DDS were developed based on various minimum intake amounts from each food group: (i) 1 g; (ii) 15 g; (iii) a variable minimum based on the content of a target nutrient for each group; (iv) the median intake level for each group; and (v) the 90th percentile intake level for each group. A diet was assigned 1 point towards the daily DDS if the food group intake was above the defined minimum level. Five scores were calculated for each child, and bivariate longitudinal random-effects models were used to assess the correlation between each DDS and the mean probability of adequacy for fourteen nutrients. SETTING: Embu District, Kenya. SUBJECTS: Schoolchildren (n 529), mean age 7·00 (sd 1·41) years. RESULTS: Only DDS based on a 15 g minimum and DDS based on nutrient content were significantly associated with mean probability of adequacy after adjusting for energy intake (0·21 and 0·41, respectively). CONCLUSIONS: A DDS using minimum intakes based on nutrients contributed by a food group best predicted nutrient adequacy in this population. These analyses contribute to the continued search for simpler and more valid dietary quality indicators among low-income nations.

Dietary reference intakes: cases of appropriate and inappropriate uses.

The dietary reference intakes (DRIs) are a set of reference intake levels for nutrients that can be used for planning diets and assessing nutrient inadequacies of individuals and groups. Since the publication of the DRI reports 1997-2004, the reference intake levels have been used for various purposes. While DRIs have been used appropriately for planning and assessing diets for many different situations, there have been instances in which specific DRI categories have not been applied as intended. In this review, cases are described in which DRIs were applied correctly, as well as cases from the growing number of examples in which the wrong DRI was used or DRIs were used incorrectly.