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Amy F Subar

Publications and source records attributed to Amy F Subar.

At least 19 recordsLinked to original sources
PubMed2007

Adaptation and evaluation of the National Cancer Institute's Diet History Questionnaire and nutrient database for Canadian populations.

BACKGROUND AND OBJECTIVE: Despite assumed similarities in Canadian and US dietary habits, some differences in food availability and nutrient fortification exist. Food-frequency questionnaires designed for the USA may therefore not provide the most accurate estimates of dietary intake in Canadian populations. Hence, we undertook to evaluate and modify the National Cancer Institute's Diet History Questionnaire (DHQ) and nutrient database. METHODS: Of the foods queried on the DHQ, those most likely to differ in nutrient composition were identified. Where possible these foods were matched to comparable foods in the Canadian Nutrient File. Nutrient values were examined and modified to reflect the Canadian content of minerals (calcium, iron, zinc) and vitamins (A, C, D, thiamin, riboflavin, niacin, B6, folate and B12). DHQs completed by 13 181 Alberta Cohort Study participants aged 35-69 years were analysed to estimate nutrient intakes using the original US and modified versions of the DHQ databases. Misclassification of intake for meeting the Dietary Reference Intake (DRI) was determined following analysis with the US nutrient database. RESULTS: Twenty-five per cent of 2411 foods deemed most likely to differ in nutrient profile were subsequently modified for folate, 11% for vitamin D, 10% for calcium and riboflavin, and between 7 and 10% for the remaining nutrients of interest. Misclassification with respect to meeting the DRI varied but was highest for folate (7%) and vitamin A (7%) among men, and for vitamin D (7%) among women over 50 years of age. CONCLUSION: Errors in nutrient intake estimates owing to differences in food fortification between the USA and Canada can be reduced in Canadian populations by using nutrient databases that reflect Canadian fortification practices.

Adult↗
PubMed2006

A comparison of two dietary instruments for evaluating the fat-breast cancer relationship.

BACKGROUND: Previous research suggests food diaries may be more efficient than food frequency questionnaires (FFQ) in detecting a dietary fat-breast cancer relationship. We assessed this further using 4 day food records (FRs) and FFQs in a large sample. METHODS: Participants were from the non-intervention group of the dietary modification component of the Women's Health Initiative Clinical Trial: 603 breast cancer cases and 1206 controls matched on age, clinic, and length of follow-up. Relative risks (RRs) were estimated using unconditional logistic regression, adjusted for confounders and for the selection into the trial of women with an FFQ report exceeding 32% calories from fat. Direct comparison of the statistical power of the two instruments used the standardized log RR. An alternative analysis after removing subjects with missing covariate data was also conducted. RESULTS: The RR estimate for breast cancer in the top quintile of total fat intake, adjusted for confounders and total energy, was 1.82 (P for trend 0.02) for the FR but 0.67 for the FFQ (P for trend 0.24). Following adjustment for selection, estimates were 2.09 (P for trend 0.008) for the FR (alternative: 2.54, P for trend 0.006) and 1.71 (P for trend 0.18) for the FFQ (alternative: 1.24, P for trend 0.41). Similar results were seen for fat subtypes, particularly unsaturated fats. Comparisons showed higher statistical power for the FR than the FFQ (e.g. total fat, P = 0.08: alternative P = 0.01). CONCLUSIONS: Alternative instruments, such as FRs, may be preferable to FFQs for evaluating diet-disease relationships in cohort studies. The results support a positive association between dietary fat and breast cancer.

Aged↗
PubMed2006

Supplemental and dietary vitamin E, beta-carotene, and vitamin C intakes and prostate cancer risk.

BACKGROUND: Vitamin E, beta-carotene, and vitamin C are micronutrient antioxidants that protect cells from oxidative damage involved in prostate carcinogenesis. In separate trials, supplemental vitamin E was associated with a decreased risk of prostate cancer among smokers and supplemental beta-carotene was associated with a decreased risk of prostate cancer among men with low baseline plasma beta-carotene levels. METHODS: We evaluated the association between intake of these micronutrient antioxidants from foods and supplements and the risk of prostate cancer among men in the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. At baseline, trial participants completed a 137-item food frequency questionnaire that included detailed questions on 12 individual supplements. Cox proportional hazards models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs). All statistical tests were two-sided. RESULTS: We identified 1338 cases of prostate cancer among 29 361 men during up to 8 years of follow-up. Overall, there was no association between prostate cancer risk and dietary or supplemental intake of vitamin E, beta-carotene, or vitamin C. However, among current and recent (i.e., within the previous 10 years) smokers, decreasing risks of advanced prostate cancer (i.e., Gleason score > or = 7 or stage III or IV) were associated with increasing dose (RR for > 400 IU/day versus none = 0.29, 95% CI = 0.12 to 0.68; Ptrend = .01) and duration (RR for > or = 10 years of use versus none = 0.30, 95% CI = 0.09 to 0.96; Ptrend = .01) of supplemental vitamin E use. Supplemental beta-carotene intake at a dose level of at least 2000 microg/day was associated with decreased prostate cancer risk in men with low (below the median of 4129 microg/day) dietary beta-carotene intake (RR = 0.52, 95% CI = 0.33 to 0.81). Among smokers, the age-adjusted rate of advanced prostate cancer was 492 per 100,000 person-years in those who did not take supplemental vitamin E, 153 per 100,000 person-years in those who took more than 400 IU/day of supplemental vitamin E, and 157 per 100,000 person-years in those who took supplemental vitamin E for 10 or more years. Among men with low dietary beta-carotene intake, the age-adjusted rate of prostate cancer was 1122 per 100,000 person-years in those who did not take supplemental beta-carotene, and 623 per 100,000 person-years in those who took at least 2000 microg/day of supplemental beta-carotene. CONCLUSIONS: Our results do not provide strong support for population-wide implementation of high-dose antioxidant supplementation for the prevention of prostate cancer. However, vitamin E supplementation in male smokers and beta-carotene supplementation in men with low dietary beta-carotene intakes were associated with reduced risk of this disease.

Adult↗
PubMed2006

Methodology for adding glycemic load values to the National Cancer Institute Diet History Questionnaire database.

BACKGROUND: A growing interest exists in using glycemic index and glycemic load as potentially important exposures in investigations of risk for a variety of chronic diseases. OBJECTIVE: We added values for glycemic index and glycemic load to the nutrient database of a commonly used dietary assessment instrument, the Diet History Questionnaire (DHQ). DESIGN: The nutrient database for the DHQ is based on 4,200 individual foods reported by adults in the 1994-1996 US Department of Agriculture Continuing Survey of Food Intakes by Individuals (CSFII). This list was condensed into 225 nutritionally similar groupings of individual foods. Using published glycemic index values we assigned glycemic index values to each of the individual CSFII foods in these food groups. In cases where CSFII foods did not correspond tightly to foods with published glycemic index values, we used decision criteria to assign glycemic index values. We then calculated sex- and serving size-specific glycemic load for each of the 225 food groups using the weighted mean method. Quality assessments were made to help evaluate the success of this method for assigning glycemic load values. RESULTS: Seventy-one percent of the top carbohydrate-contributing food groups had in excess of 90% of the CSFII mentions linked directly to a published glycemic index value (ie, no imputation was required), and 100% of these food groups had at least 50% of total mentions linked directly. CONCLUSIONS: Using this method, it is now possible to use DHQ responses to assess the associations between reported glycemic load and glycemic index and risk of many chronic diseases in epidemiologic studies.

Adult↗
PubMed2006

The food propensity questionnaire: concept, development, and validation for use as a covariate in a model to estimate usual food intake.

OBJECTIVE: Twenty-four-hour recalls capture rich information on food consumption, but suffer from inadequately measuring usual intakes of episodically consumed foods. We explore using food frequency questionnaire (FFQ) data as covariates in a statistical model to estimate individual usual intakes of episodically consumed foods and their distributions and describe the development of the Food Propensity Questionnaire, an FFQ introduced in the 2003-2004 National Health and Nutrition Examination Survey. DESIGN: We analyzed data from 965 adult participants in the Eating at America's Table Study who completed four 24-hour recalls and an FFQ. We assessed whether or not increasing FFQ-reported frequency was associated with both number of 24-hour recall consumption days and amounts reported. RESULTS: For 52 of 56 food groups (93%), and 218 of 230 individual foods (95%), there were significant monotonically increasing relationships between FFQ frequency and 24-hour recall probability of consumption. For 47 of 56 food groups (84%) and 55 of 230 (24%) individual foods, there were significant positive correlations between FFQ frequencies and consumption-day mean intake. CONCLUSIONS: We found strong and consistent relationships between reported FFQ frequency of food and food-group consumption and probability of consumption on 24-hour recalls. This supports the premise that frequency data may offer important covariate information in supplementing multiple recalls for estimating usual intake of food groups.

Adolescent↗
PubMed2006

A new statistical method for estimating the usual intake of episodically consumed foods with application to their distribution.

OBJECTIVE: We propose a new statistical method that uses information from two 24-hour recalls to estimate usual intake of episodically consumed foods. STATISTICAL ANALYSES PERFORMED: The method developed at the National Cancer Institute (NCI) accommodates the large number of nonconsumption days that occur with foods by separating the probability of consumption from the consumption-day amount, using a two-part model. Covariates, such as sex, age, race, or information from a food frequency questionnaire, may supplement the information from two or more 24-hour recalls using correlated mixed model regression. The model allows for correlation between the probability of consuming a food on a single day and the consumption-day amount. Percentiles of the distribution of usual intake are computed from the estimated model parameters. RESULTS: The Eating at America's Table Study data are used to illustrate the method to estimate the distribution of usual intake for whole grains and dark-green vegetables for men and women and the distribution of usual intakes of whole grains by educational level among men. A simulation study indicates that the NCI method leads to substantial improvement over existing methods for estimating the distribution of usual intake of foods. CONCLUSIONS: The NCI method provides distinct advantages over previously proposed methods by accounting for the correlation between probability of consumption and amount consumed and by incorporating covariate information. Researchers interested in estimating the distribution of usual intakes of foods for a population or subpopulation are advised to work with a statistician and incorporate the NCI method in analyses.

Analysis of Variance↗
PubMed2006

Statistical methods for estimating usual intake of nutrients and foods: a review of the theory.

Although 24-hour recalls are frequently used in dietary assessment, intake on a single day is a poor estimator of long-term usual intake. Statistical modeling mitigates this limitation more effectively than averaging multiple 24-hour recalls per respondent. In this article, we describe the statistical theory that underlies the four major modeling methods developed to date, then review the strengths and limitations of each method. We focus on the problem of estimating the distribution of usual intake for a population from 24-hour recall data, giving special attention to the problems inherent in modeling usual intake for foods or food groups that a proportion of the population does not consume every day (ie, episodically consumed foods). All four statistical methods share a common framework. Differences between the methods arise from different assumptions about the measurement characteristics of 24-hour recalls and from the fact that more recently developed methods build upon their predecessor(s). These differences can result in estimated usual intake distributions that differ from one another. We also demonstrate the need for an improved method for estimating usual intake distributions for episodically consumed foods.

Data Interpretation, Statistical↗
PubMed2006

Carbohydrate, glycemic index, and glycemic load and colorectal adenomas in the Prostate, Lung, Colorectal, and Ovarian Screening Study.

BACKGROUND: It is possible that high-glycemic-load diets, through their hyperinsulinemic effects, can increase the risk of colorectal cancer. OBJECTIVE: We analyzed data from a cancer screening study to determine whether persons with high-glycemic-load diets would be at an increased risk of distal adenomas. DESIGN: We included subjects with no prior adenoma or cancer from the Prostate, Lung, Colorectal, and Ovarian screening trial and whose results from flexible sigmoidoscopy exams indicated either no lesions (n = 34 817) or >/=1 distal adenoma (n = 3696). We used a 137-item food-frequency questionnaire to assess usual dietary intake over the preceding 12 mo. Using logistic regression analysis, we calculated, separately for men and women, prevalence odds ratios (ORs) and 95% CIs of sigmoidoscopy-detected, distal adenomas for quintiles of energy-adjusted dietary carbohydrate, glycemic index, and glycemic load. RESULTS: ORs decreased with increasing intakes of carbohydrate for both the men and the women in unadjusted models, but these associations were attenuated in multivariate-adjusted models. Among the men, the association remained significant after adjustment (OR: 0.71; 95% CI 0.60, 0.84; P for trend < 0.0001), but in the women it did not (OR: 0.89; 95% CI: 0.73, 1.10; P for trend = 0.30). The results for glycemic index showed no associations in either men or women. Results for glycemic load closely mirrored those for carbohydrate. CONCLUSION: Despite expectations that increasing glycemic load and glycemic index would increase the risk of adenoma, we observed no association in women and even an inverse association in men.

Adenoma↗
PubMed2006

Carotenoid and tocopherol estimates from the NCI diet history questionnaire are valid compared with multiple recalls and serum biomarkers.

To improve the measurement of usual dietary intake, the National Cancer Institute developed a cognitively based Diet History Questionnaire (DHQ), which has been validated against four 24-h dietary recalls (4 24-HR) for energy, macronutrients, and several vitamins and minerals. This analysis used data from The Eating at America's Table Study (EATS) to determine the validity of estimates for carotenoids and tocopherols from the DHQ. Over the course of a year, 163 participants provided 1 or 2 blood samples and completed the DHQ and 4 24-HR. For both the DHQ and the 4 24-HR, crude correlations between serum and diet were modest to strong for the provitamin A carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin), low to modest for lycopene, and very low for lutein. The individual dietary tocopherols were weakly correlated with the serum tocopherols, but vitamin E from food and dietary supplements was strongly and positively correlated with serum alpha-tocopherol and strongly and inversely correlated with serum gamma-tocopherol for both instruments. Adjustment for energy, BMI, smoking status, serum total cholesterol, and serum triacylglycerol did not appreciably change the correlations. Using the method of triads, validity coefficients for the DHQ were comparable to the 4 24-HR and were especially strong for alpha-carotene, beta-cryptoxanthin, lutein + zeaxanthin, and total vitamin E in men and gamma-tocopherol and total vitamin E in women. In this study, there was no advantage of 2 blood samples over 1, suggesting reasonably stable ranking of individuals for these biomarkers, which is important for large epidemiologic studies that typically obtain only 1 blood sample for biomarker status.

Adult↗
PubMed2006

Consumption of aspartame-containing beverages and incidence of hematopoietic and brain malignancies.

BACKGROUND: In a few animal experiments, aspartame has been linked to hematopoietic and brain cancers. Most animal studies have found no increase in the risk of these or other cancers. Data on humans are sparse for either cancer. Concern lingers regarding this widely used artificial sweetener. OBJECTIVE: We investigated prospectively whether aspartame consumption is associated with the risk of hematopoietic cancers or gliomas (malignant brain cancer). METHODS: We examined 285,079 men and 188,905 women ages 50 to 71 years in the NIH-AARP Diet and Health Study cohort. Daily aspartame intake was derived from responses to a baseline self-administered food frequency questionnaire that queried consumption of four aspartame-containing beverages (soda, fruit drinks, sweetened iced tea, and aspartame added to hot coffee and tea) during the past year. Histologically confirmed incident cancers were identified from eight state cancer registries. Multivariable-adjusted relative risks (RR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression that adjusted for age, sex, ethnicity, body mass index, and history of diabetes. RESULTS: During over 5 years of follow-up (1995-2000), 1,888 hematopoietic cancers and 315 malignant gliomas were ascertained. Higher levels of aspartame intake were not associated with the risk of overall hematopoietic cancer (RR for >/=600 mg/d, 0.98; 95% CI, 0.76-1.27), glioma (RR for >/=400 mg/d, 0.73; 95% CI, 0.46-1.15; P for inverse linear trend = 0.05), or their subtypes in men and women. CONCLUSIONS: Our findings do not support the hypothesis that aspartame increases hematopoietic or brain cancer risk.

Aged↗
PubMed2005

The National Cancer Institute diet history questionnaire: validation of pyramid food servings.

The performance of the National Cancer Institute's food frequency questionnaire, the Diet History Questionnaire (DHQ), in estimating servings of 30 US Department of Agriculture Food Guide Pyramid food groups was evaluated in the Eating at America's Table Study (1997-1998), a nationally representative sample of men and women aged 20-79 years. Participants who completed four nonconsecutive, telephone-administered 24-hour dietary recalls (n = 1,301) were mailed a DHQ; 965 respondents completed both the 24-hour dietary recalls and the DHQ. The US Department of Agriculture's Pyramid Servings Database was used to estimate intakes of pyramid servings for both diet assessment tools. The correlation (rho) between DHQ-reported intake and true intake and the attenuation factor (lambda) were estimated using a measurement error model with repeat 24-hour dietary recalls as the reference instrument. Correlations for energy-adjusted pyramid servings of foods ranged from 0.43 (other starchy vegetables) to 0.84 (milk) among women and from 0.42 (eggs) to 0.80 (total dairy food) among men. The mean rho and lambda after energy adjustment were 0.62 and 0.60 for women and 0.63 and 0.66 for men, respectively. This food frequency questionnaire validation study of foods measured in pyramid servings allowed for a measure of food intake consistent with national dietary guidance.

Adult↗
PubMed2005

Dietary intake estimates in the National Health Interview Survey, 2000: methodology, results, and interpretation.

OBJECTIVES: To describe the implementation of the Multifactor Screener in the 2000 National Health Interview Survey (NHIS); to provide intake estimates for fruits and vegetables, fiber, and percentage of energy from fat by various demographic and behavioral characteristics; and to discuss the strengths and weaknesses of the method. DESIGN/SUBJECTS: The 2000 NHIS was conducted in 38,632 households in a clustered sample representative of the 48 contiguous states in the United States. The Cancer Control Module was administered to adults (18 years and older) and included 17 dietary intake questions. ANALYSES: After excluding individuals with missing data or unlikely values on the diet questions, we computed individual intake of servings of fruits and vegetables, percentage of energy from fat, and grams of fiber. We estimated median intakes and distributions of intakes using adjusted variance estimates. We present bivariate relationships between diet and demographics and diet and behavioral characteristics in almost 30,000 adults in the United States. RESULTS: In general, intakes of these dietary factors were closer to recommendations among well-educated individuals, those engaged in other healthful behaviors, and underweight and normal weight individuals. Latinos had higher intakes of fruits and vegetables (men: 6 servings; women: 4.8 servings) and fiber (men: 23 g; women: 17 g), and generally a lower percentage of energy intake from fat (men: 33.7%; women: 32.1%) than did non-Latino whites (men: 5.4 servings; women: 4.5 servings; men: 19 g; women: 14 g; men: 33.9%; women: 32.0%) and non-Latino blacks (men: 5.4 servings; women: 4.4 servings; men: 19 g; women: 13 g; men: 34.7%; women: 33.5%). The strengths and limitations of the short dietary assessment method are discussed. CONCLUSIONS: The Multifactor Screener in NHIS, when used in conjunction with external reference data, provides reasonable estimates for three dietary factors and suggests relationships between intakes and other characteristics that are consistent with other data. Thus, these NHIS estimates could provide useful national benchmarks for local surveys using the same instrument.

Adolescent↗
PubMed2004

Dietary sources of nutrients among US adults, 1994 to 1996.

OBJECTIVE: To identify major food sources of 30 nutrients and dietary constituents among US adults during 1994 to 1996, and to compare them with those identified for 1989 to 1991. DESIGN: A total of 6419 foods were assigned to 112 food groups based on similarities in nutrient content or use. These foods included 3778 food mixtures disaggregated by the US Department of Agriculture's (USDA) FoodLink computerized research tool, so ingredients could be assigned to the appropriate groups and nutrient values ascribed accordingly.Subjects/setting Single 24-hour dietary recalls from a nationally representative sample of 10019 adults aged 19 years or older in USDA's 1994 to 1996 Continuing Survey of Food Intakes by Individuals were used. Statistical analyses performed The population proportion formula was used to determine weighted nutrient intakes by food groups. Results were tabulated in descending rank order for food groups providing at least 1% of total nutrient intake. RESULTS: Dietary food sources found for 1994 to 1996 were fairly consistent with 1989 to 1991 results for the rank order and proportion these sources made to total nutrient intakes. Remarkable changes were seen in the higher proportion of energy from alcoholic beverages, in the shifts in the proportion of total fat and fatty acids from oil (higher ranked) and margarine (lower ranked), and in the lower proportion of vitamins and minerals from ready-to-eat cereals. CONCLUSIONS: Despite changes in survey methodology, the food supply, and eating patterns, food sources of nutrients among US adults in 1994 to 1996 and 1989 to 1991 were similar. The 1994 to 1996 data are the first known national population estimates for dietary sources of vitamin A (retinol equivalents), selenium, caffeine, and theobromine among US adults.

Adult↗
PubMed2004

Use of vitamin, mineral, nonvitamin, and nonmineral supplements in the United States: The 1987, 1992, and 2000 National Health Interview Survey results.

OBJECTIVE: To describe trends in use of specific vitamin and mineral (VM) supplements. DESIGN: The nationally representative National Health Interview Survey queried adult respondents about their use of VM supplements in 1987, 1992, and 2000. Statistical analysis Trends in use of VM supplements from 1987 to 2000 were determined using linear contrasts. RESULTS: The percentage of adults using any VM supplement daily increased from 23.2% (1987) to 23.7% (1992) to 33.9% (2000). This pattern was consistent for both sexes, all race/ethnic groups, and adults aged >or=25 years. The increase in the percentage of daily users of multivitamins, vitamin A, and vitamin E was 10.5, 1.2, and 7.3 percentage points, respectively, from 1987 to 2000. Increases in daily use of vitamin C (3.3 percentage points) and calcium (6.1 percentage points) occurred between 1992 and 2000. All trend analyses were significant at P<.001. In the 2000 National Health Interview Survey personnel queried the use of nonvitamin/nonmineral supplements for the first time. At that time, 6.0% of respondents reported using them daily. CONCLUSION: The increasing trend in supplement use over time and the notable use of nonvitamin/nonmineral supplements in 2000 indicates the continued need to monitor the use of all types of dietary supplements for purposes of dietary surveillance and nutrition-related research.

Adolescent↗
PubMed2004

Performance of a short tool to assess dietary intakes of fruits and vegetables, percentage energy from fat and fibre.

OBJECTIVES: We describe the methods used to develop and score a 17-item 'screener' designed to estimate intake of fruit and vegetables, percentage energy from fat and fibre. The ability of this screener and a food-frequency questionnaire (FFQ) to measure these exposures is evaluated. DESIGN: Using US national food consumption data, stepwise multiple regression was used to identify the foods to be included on the instrument; multiple regression analysis was used to develop scoring algorithms. The performance of the screener was evaluated in three different studies. Estimates of intakes measured by the screener and the FFQ were compared with true usual intake based on a measurement error model. SETTING: US adult population. SUBJECTS: For development of instrument, n=9323 adults. For testing of instrument, adult men and women in three studies completing multiple 24-hour dietary recalls, FFQ and screeners, n=484, 462 and 416, respectively. RESULTS: Median recalled intakes for examined exposures were generally estimated closely by the screener. In the various validation studies, the correlations between screener estimates and estimated true intake were 0.5-0.8. In general, the performances of the screener and the full FFQ were similar; estimates of attenuation were lower for screeners than for full FFQs. CONCLUSIONS: When coupled with appropriate reference data, the screener approach described may yield useful estimates of intake, for both surveillance and epidemiological purposes.

Adult↗
PubMed2004

Psychosocial predictors of energy underreporting in a large doubly labeled water study.

BACKGROUND: Underreporting of energy intake is associated with self-reported diet measures and appears to be selective according to personal characteristics. Doubly labeled water is an unbiased reference biomarker for energy intake that may be used to assess underreporting. OBJECTIVE: Our objective was to determine which factors are associated with underreporting of energy intake on food-frequency questionnaires (FFQs) and 24-h dietary recalls (24HRs). DESIGN: The study participants were 484 men and women aged 40-69 y who resided in Montgomery County, MD. Using the doubly labeled water method to measure total energy expenditure, we considered numerous psychosocial, lifestyle, and sociodemographic factors in multiple logistic regression models for prediction of the probability of underreporting on the FFQ and 24HR. RESULTS: In the FFQ models, fear of negative evaluation, weight-loss history, and percentage of energy from fat were the best predictors of underreporting in women (R(2) = 0.09); body mass index, comparison of activity level with that of others of the same sex and age, and eating frequency were the best predictors in men (R(2) = 0.10). In the 24HR models, social desirability, fear of negative evaluation, body mass index, percentage of energy from fat, usual activity, and variability in number of meals per day were the best predictors of underreporting in women (R(2) = 0.22); social desirability, dietary restraint, body mass index, eating frequency, dieting history, and education were the best predictors in men (R(2) = 0.25). CONCLUSION: Although the final models were significantly related to underreporting on both the FFQ and the 24HR, the amount of variation explained by these models was relatively low, especially for the FFQ.

Adult↗
PubMed2004

Adjustments to improve the estimation of usual dietary intake distributions in the population.

We reexamined the current practice in estimating the distribution of usual dietary nutrient intakes from population surveys when using self-report dietary instruments, particularly the 24-h recall (24HR), in light of the new data from the Observing Protein and Energy Nutrition Study. In this study, reference biomarkers for energy (doubly labeled water) and protein [urinary nitrogen (UN)], together with multiple FFQs and 24HRs, were administered to 484 healthy volunteers. By using the reference biomarkers to estimate the distributions for energy and protein, the data confirmed previous reports that FFQs generally do not give an accurate impression of the distribution of usual dietary intake. The traditional method applied to 24HRs performed poorly because of underestimating the mean and overestimating the SD of the usual energy and protein intake distributions, and, although the National Research Council and the Iowa State University methods generally give better estimates of the shape of the distribution, they did not improve the estimates of the mean (10-15% underestimation for energy and 6-7% underestimation for protein). Results for urinary potassium, a putative biomarker for potassium intake, and reported potassium intake did not display this underestimation and may reflect either differential underreporting of foods or inadequacy of the potassium biomarker. A large controlled feeding study is required to validate conclusively the potassium biomarker. For energy intake, adjusting its 24HR-based distribution by using the UN biomarker appeared to capture the usual intake distribution quite accurately. Incorporating UN assessments into nutritional surveys, therefore, deserves serious consideration.

Adult↗