Food preferences and reported frequencies of food consumption as predictors of current diet in young women.

BACKGROUND: Self-reported food preferences and frequencies of food consumption have served as proxy measures of the current diet in consumer research and in nutritional epidemiology studies, respectively. OBJECTIVE: The objective was to determine whether food preferences and food-frequency scores are associated variables that are predictive of nutrient intakes. DESIGN: College-age women (n = 87) completed a 98-item food-frequency questionnaire and rated preferences for many of the same foods on a 9-point category scale. Estimated intakes of fat, fiber, and vitamin C were obtained by using 3-d food records. RESULTS: For virtually all item pairs tested, food preferences and reported frequencies of consumption of the same foods were significantly correlated with each other. The median Pearson correlation coefficient was 0.40 (range: -0.04 to 0.62). Correlations improved when foods were aggregated into factor-based food groups. The slope of the relation between food preferences and frequency of consumption varied with food category. Both food preferences and food frequencies predicted dietary outcomes. Fat consumption was predicted equally well by either approach in a multiple regression model. Intakes of fiber and vitamin C were better predicted by food-frequency scores than by stated preferences for vegetables and fruit. CONCLUSIONS: Reported frequencies of food consumption, the core of the food-frequency approach, were associated with food likes and dislikes. Food preferences were a predictor of dietary intakes and may provide an alternative to the food-frequency approach for dietary intake assessment.     

Assessment of three brief methods of estimation of vitamin A and C intakes for a prospective study of cancer: comparison with dietary history

Three methods of estimating vitamin A and C intakes from food frequency data obtained in June 1981 were compared with estimates obtained from dietary histories taken in September 1982, in 50 elderly residents of a Southern California retirement community. The first method of estimating vitamin A and C intakes (Af and Cf) was to add the products of the frequency of use of foods and the vitamin content of an average serving. The second method of estimating the intakes of these vitamins (Ai and Ci) was to develop an index based on the sum of frequencies of consumption of foods rich in these vitamins. This was then converted to absolute amounts using a regression equation. The third method (Ar and Cr) was to use stepwise multiple regression with the estimated intakes from the history (Ah and Ch) as dependent variables and to develop an equation with a small number of foods as the independent variables. When intakes from food alone were examined, the Spearman correlations between Ah and Af, Ai, and Ar, respectively, were 0.03, 0.16, and 0.43; the correlations between Ch and Cf, Ci, and Cr were 0.29, 0.36, and 0.38. When supplemental vitamin intakes were included, the correlations were between 0.35 and 0.44 for vitamin A and between 0.62 and 0.64 for vitamin C. The results demonstrated the importance of including the contribution of supplemental vitamins in estimating total vitamin A and C intake and suggested that the index and regression approaches may be superior to Af and Cf for estimating dietary vitamin intakes from food frequency questionnaires.     

Contemporary diet and body weight of Navajo women receiving food assistance: an ethnographic and nutritional investigation

Preceded by 6 months of ethnographic research, a survey of 107 Navajo women, primarily food assistance participants, was conducted to describe and evaluate the contemporary Navajo diet. On the basis of results of 1-day dietary recalls, mean nutrient intakes were found to be below the RDA for calcium, phosphorus, iron, vitamin A, and energy. Sixty-three percent of the women in the sample were overweight or obese. The overall percentages of energy from fat, carbohydrate, and protein were closer to those recommended in the Dietary Goals than those in the current U.S. diet. The fat in the diet appeared to be primarily saturated, however, and fiber intake was lower than the U.S. average. Traditional foods were infrequently consumed. Women with higher incomes tended to have better diets. Commodity foods supplied by USDA's Food Distribution Program provided 43% of caloric intake and 37% to 57% of the intakes of all other nutrients except fat and vitamin C for the 72% of the sample participating in that program. It is concluded that the Food Distribution Program provides an important nutritional contribution to the contemporary Navajo diet.     

Dietary-fat intake in the US population.

OBJECTIVE: This article looks at the food group choices by individuals grouped based on fat intake, saturated fat intake, and use of lowfat foods. METHODS: Food consumption data from USDA's National Food Consumption Surveys (NFCS) and the Continuing Survey of Food Intakes by Individuals (CSFII) were used to look at changes in the mean energy, percent calories from fat and saturated-fat and total-fat intakes over time. USDA's 1995 CSFII data were used to evaluate the diets of individuals grouped based on percent calories from fat and use of low-fat foods. Individuals six to 50 years old who had complete food intake records were included and five age-gender classifications were used. RESULTS: The percent of calories from total fat and saturated fat have steadily declined over the last 30 years, and the amount of fat in the diet has increased from 1989 to 1995. Those whose diets met the Dietary Guidelines Recommendations for fat and saturated fat had lower fat intakes. Except for adult males, those with low-fat diets had higher intakes of total-food amount. Also, lower saturated-fat intakes were associated with lower energy intakes. In general, high-fruit-and-grain-products consumption were seen in groups with low-fat intake. For those who included low-fat foods in their diets and also had low-fat intakes, rice and pasta were the major foods of choice for calories. Fried potatoes were one of the main sources of calories for high-fat groups. CONCLUSION: The study showed individuals whose diets included low-fat foods are more likely to have a diet that meets the dietary guidelines recommendations for fat and saturated fat.     

Nutrient intakes and food consumption patterns among Ontario students in grades six, seven, and eight

BACKGROUND: The increased prevalence of overweight in Canadian children has stimulated interest in their lifestyle behaviours. The purpose of this research was to investigate dietary intake and food behaviours of Ontario students in grades six, seven, and eight. METHODS: Males and females from grades six to eight were recruited from a stratified random selection of schools from Ontario. Data were collected using the web-based "Food Behaviour Questionnaire", which included a 24-hour diet recall and food frequency questionnaire. Nutrients were analyzed using ESHA Food Processor and the 2001 Canadian Nutrient File database. Body Mass Index (BMI) was calculated based on self-reported weight and height, and classified according to the Centers for Disease Control BMI for age percentiles. RESULTS: The sample included males (n = 315) and females (n = 346) in grades 6, 7, and 8 from 15 schools in Ontario. According to Canada's Food Guide to Healthy Eating (CFGHE), median intakes were below recommendations for all participants, with the exception of meat and alternatives. Participants consumed a median of 54%, 15%, 31%, 11%, and 8% of total energy from carbohydrates, protein, total fat, saturated fat, and added sugars, respectively. Participants consumed 25% of total energy from foods from the "other" food group (CFGHE). Males had higher intakes of energy, carbohydrates, fat, saturated fat, monounsaturated fat, protein, thiamine, niacin, iron, and zinc than females (all p < 0.05), and consumed more grain products servings (p < 0.05). CONCLUSION: The high consumption of "other" foods, at the expense of nutrient-dense food groups, may ultimately be contributing to the increased weights in childhood and adolescence.     

Comparison of intakes of US Chinese women based on food frequency and 24-hour recall data

The objective of this cross-sectional study was to compare dietary reports from a food frequency questionnaire (FFQ) for US Chinese women with 24-hour recall estimates. The subjects were 56 women recruited through organizations in Philadelphia's Chinese community. Spearman correlations were used to describe FFQ estimates of food servings per month and nutrient intake per day vs estimates from three 24-hour recalls over 1 month. On average, women reported at least weekly consumption of 28 of 96 FFQ food items. The three most frequently consumed were rice (38 times/month), tea (29 times/month), and dark green, leafy vegetables (18 times/month). Comparing reported frequencies of the 28 foods to 24-hour recall estimates, the median Spearman correlation was 0.36. For nutrient estimates, correlations were high (r >0.5) for dietary fiber and calcium; moderate ( r =0.25 to 0.5) for energy, saturated fat, cholesterol, carbohydrates, protein, folic acid, and iron; but poor (r <0.25) for total fat, vitamin C, vitamin A, and carotene. These findings provide some assurance of the FFQ's adequacy for describing US Chinese women's intake of commonly consumed foods and selected nutrients. They also provide a basis for further improvements to, and evaluations of, the FFQ.     

Nutrient contributions of dairy foods in the United States, Continuing Survey of Food Intakes by Individuals, 1994-1996, 1998

OBJECTIVE: This study was designed to quantify the impact of dairy foods on nutrient intakes in the United States. SUBJECTS: Data were from 17959 respondents to the 1994-1996, 1998 Continuing Survey of Food Intakes by Individuals (CSFII).Statistical analyses Nutrient intakes were quantified by quartile of dairy food intake. Also, dairy intakes were compared in people who met vs did not meet intake recommendations for select nutrients. Finally, the direct contribution of dairy foods/ingredients to calcium and lipid intakes was determined. SAS and SUDAAN software were used. Data were weighted. Energy intake was a covariable in regression models. RESULTS: Intake of all micronutrients examined, except vitamin C, was higher with increasing quartile of total dairy and milk intake, controlling for energy intake. Calcium was the only micronutrient positively associated with cheese intake. Fat intake either did not differ or was lower among people in quartile 2, 3, or 4 vs quartile 1 of total dairy and milk intake, whereas fat was higher as quartile of cheese intake increased. Dietary cholesterol was lower as intakes of any of the dairy categories increased; the opposite was true for saturated fat. Dairy foods/ingredients directly contributed an average of 51% of dietary calcium, 19% of total fat, 32% of saturated fat, and 22% of cholesterol. CONCLUSIONS: Total dairy and milk intakes were associated with higher micronutrient intakes without adverse impact on fat or dietary cholesterol. Results reinforce the strong nutritional profile of dairy-rich diets, although results with saturated fat and with cheese suggest that it would be useful to modify product composition and/or eating patterns to optimize nutritional contributions of dairy products.     

Food consumption patterns of rural older African American, Native American, and white adults in North Carolina

This paper describes the major food sources of selected nutrients for an ethnically diverse sample of older adults in rural North Carolina. A representative sample of 130 elders (> 70 years) completed semi-quantitative food frequency questionnaires. Percentages of foods most frequently consumed as the lead source of seven nutrients were calculated overall, by gender and ethnic group. Foods eaten at least one time per week were identified, and percentages of participants consuming that frequency were calculated. Major food sources included: salad oil/cooking oil for calories, total fat and saturated fat; miscellaneous vegetables for dietary fiber and folate; and orange/grapefruit juice for vitamin C. Heterogeneity in food sources was greatest for zinc and least for vitamin C. Variation across gender and ethnic groups was observed only in the degree to which specific food sources contributed to nutrient intake. These data provide greater insight into the dietary patterns of rural elders than examining nutrient intakes.     

Food ads on TV: a health hazard for children?

OBJECTIVE: To examine the nutritional quality of food in television food advertisements that are targeted at children. METHOD: We videotaped 42 hours of children's programs and analysed the food advertisements' content and nutrient composition using the New Zealand Food Composition Database. RESULTS: Of 269 food advertisements, 63% were for foods 'high in fat and/or sugar'. Children who ate only the advertised foods would eat a diet too high in fat, saturated fat, protein, free sugars and sodium. Furthermore, their diets would have suboptimal levels of fibre and suboptimal intakes of a number of important micronutrients (depending on age), including magnesium, selenium and vitamin E. The food products advertised on this channel rarely included nutritious low-cost foods that are necessary for food security in low-income groups. There were also no food advertisements that included any of the healthy foods consumed by Maori and Pacific peoples. CONCLUSIONS: Food advertisements targeted at children generally reflect the dietary pattern associated with an increased risk of obesity and dental caries in childhood; and cardiovascular disease, diabetes and cancers in adulthood.     

Agreement on nutrient intake between the databases of the First National Health and Nutrition Examination Survey and the ESHA Food Processor

The objective of this study was to assess agreement on nutrient intake between the nutrient database of the First National Health and Nutrition Examination Survey (NHANES I) and an up-to-date (December 1998) nutrient database, the ESHA Food Processor. Analysis was conducted among 11,303 NHANES I participants aged 25-74 years in 1971-1975 who had undergone dietary assessment. A list of all unique foods consumed was obtained from a single 24-hour dietary recall questionnaire administered during the baseline NHANES I visit. Foods on the list were matched to foods in the ESHA Food Processor software. Agreement between participants' nutrient intakes as calculated with the NHANES I and ESHA nutrient databases was assessed using intraclass correlation analysis, linear regression analysis, and graphic methods. Intraclass correlation analysis demonstrated excellent concordance between most nutrient intakes, with coefficients above 0.95 for intakes of energy, carbohydrates, protein, cholesterol, and calcium; coefficients between 0.90 and 0.95 for intakes of total fat, saturated fat, potassium, and vitamin C; and coefficients of approximately 0.85 for intakes of sodium and vitamin A. Graphic methods and regression analyses also showed good-to-excellent correspondence for most nutrients. These findings support the validity of expanding existing nutrient intake databases to explore current hypotheses, provided that food formulation, enrichment, and fortification practices have not changed substantially over time.     

A rapid food screener to assess fat and fruit and vegetable intake

BACKGROUND: The U.S. Preventive Services Task Force recommends that Americans lower dietary fat and cholesterol intake and increase fiber and fruit/vegetables to reduce prevalence of heart disease, cancer, stroke, hypertension, obesity, and non-insulin-dependent diabetes mellitus in the United States. To provide preventive services to all, a rapid, inexpensive, and valid method of assessing dietary intake is needed. METHODS: We used a one-page food intake screener based on national nutrition data. Respondents can complete and score the screener in a few minutes and can receive immediate, brief feedback. Two hundred adults self-administered the food screener. We compared fat, fiber, and fruit/vegetable intake estimates derived from the screener with estimates from a full-length, 100-item validated questionnaire. RESULTS: The screener was effective in identifying persons with high-fat intake, or low-fruit/vegetable intake. We found correlations of 0.6-0.7 (p<0. 0001) for total fat, saturated fat, cholesterol, and fruit/vegetable intake. The screener could identify persons with high percentages of calories from fat, total fat, saturated fat, or cholesterol, and persons with low intakes of vitamin C, fiber, or potassium. CONCLUSIONS: This screener is a useful tool for quickly monitoring patients' diets. The health care provider can use it as a prelude to brief counseling or as the first stage of triage. Persons who score poorly can be referred for more extensive evaluation by low-cost paper-and-pencil methods. Those who still have poor scores at the second stage ultimately can be referred for in-person counseling.     

Reproducibility and validity of dietary assessment instruments. II. A qualitative food frequency questionnaire

The reproducibility and validity of a food frequency questionnaire designed to measure intakes of total fat, saturated and polyunsaturated fats, vitamins A, C, and E, selenium, and dietary fiber were tested from March to October 1984 among 297 Finnish men aged 55-69 years. The questionnaire asked about consumption of 44 food items. In the reproducibility study, 107 subjects filled in the questionnaire three times, at three-month intervals. Intraclass correlations varied from 0.52 for vitamin A to 0.85 for polyunsaturated fat. In the validity study, 190 subjects kept food consumption records for 12 two-day periods distributed evenly over a period of six months and filled in the questionnaire both before and after this period. Correlations between the nutrient intake values from the food records and those from the food frequency questionnaires ranged from 0.33 for selenium to 0.68 for polyunsaturated fat. On the average, 40-45% of the subjects in the lowest and highest quintiles based on food records were in the same respective quintiles when assessed by the food frequency questionnaire, and 70-75% were in the two lowest and two highest questionnaire quintiles, respectively. The food frequency questionnaire and a quantitative food use questionnaire tested in the same study were compared. Use of these two instruments in large-scale epidemiologic studies is discussed.     

Genetic sensitivity to 6-n-propylthiouracil has no influence on dietary patterns, body mass indexes, or plasma lipid profiles of women

BACKGROUND: Genetic sensitivity to the bitter taste of 6-n-propylthiouracil (PROP) has been reported to determine preferences for bitter, sweet, and fat-containing foods, affect dietary habits, influence body weight, and modify chronic disease risk. OBJECTIVE: To examine associations between PROP responsiveness, food choices, dietary intakes, and plasma chemistries in a clinical sample of adult women. SUBJECTS/DESIGN: This nested case-control study was based on female breast cancer patients (n=179) and cancer-free controls (n=179). MAIN OUTCOME MEASURES: Taste responsiveness measure was based on a 25:50:25 split of summed bitterness ratings of five PROP solutions. Food preferences were based on a 171-item checklist. Food and nutrient intakes were assessed using a food frequency questionnaire. Heights and weights were measured and plasma cholesterol and triglyceride levels were obtained. RESULTS: High PROP response was unrelated to reported preferences for sweet or high-fat foods. PROP responsiveness was unrelated to the reported frequency of food use, or to macronutrient composition of the diet. In regression models, PROP responsiveness had no influence on percent of dietary fat, body mass index, or plasma cholesterol, after adjusting for covariates. CONCLUSIONS: In this study PROP responsiveness was not associated with diets lower in sugar and fat, more favorable plasma lipid profiles, or with lower body mass indexes. The study provided no evidence to suggest that genetic PROP taster status had a measurable influence on health outcomes. The clinical utility of PROP taster screening is not supported by these study results.     

Plasma vitamin C and food choice in the third Glasgow MONICA population survey

STUDY OBJECTIVE: To determine the contribution of different foods to the estimated intakes of vitamin C among those differing in plasma vitamin C levels, and thereby inform dietary strategies for correcting possible deficiency. DESIGN: Cross sectional random population survey. SETTING: North Glasgow, Scotland, 1992. PARTICIPANTS: 632 men and 635 women, aged 25 to 74 years, not taking vitamin supplements, who participated in the third MONICA study (population survey monitoring trends and determinants of cardiovascular disease). MEASUREMENTS AND MAIN RESULTS: Dietary and sociodemographic information was collected using a food frequency and lifestyle questionnaire. Plasma vitamin C was measured in non-fasted venous blood samples and subjects categorised by cut points of 11.4 and 22.7 micromol/l as being of low, marginal or optimal vitamin C status. Food sources of dietary vitamin C were identified for subjects in these categories. Plasma vitamin C concentrations were compared among groups classified according to intake of key foods. More men (26%) than women (14%) were in the low category for vitamin C status; as were a higher percentage of smokers and of those in the older age groups. Intake of vitamin C from potatoes and chips (fried potatoes) was uniform across categories; while the determinants of optimal versus low status were the intakes of citrus fruit, non-citrus fruit and fruit juice. Optimal status was achieved by a combined frequency of fruit, vegetables and/or fruit juice of three times a day or more except in older male smokers where a frequency greater than this was required even to reach a marginal plasma vitamin C level. CONCLUSION: Fruit, vegetables and/or fruit juice three or more times a day increases plasma vitamin C concentrations above the threshold for risk of deficiency.     

食物频率问卷法评估人群能量和营养素摄入量的准确性验证

目的:食物频率问卷法(FFQ)问卷评估人群膳食能量和营养素摄入量的准确性进行验证。方法:使用3d称重法(WFR)和FFQ收集北京市130名35～49岁健康成人食物摄入资料,计算出其能量和营养素的摄入量并加以比较。结果:由食物WFR计算到的研究对象能量摄入为9.6MJ/d,蛋白质、脂肪和碳水化物摄入分别为82.1、87.5和269.7g/d。由FFQ得到的能量摄入量为9.7MJ/d,蛋白质、脂肪和碳水化物摄入量分别为88.3g/d、113.9g/d和248.8g/d,两种方法调查的膳食能量、蛋白质及其供能比无显著性差异,FFQ显著高估膳食脂肪摄入量(高估27.2%),碳水化物摄入量则被低估(低估10.8%)。FFQ得到的膳食维生素和矿物质的摄入量普遍高于WFR,但低估维生素E、铁和硒的摄入量。由FFQ得到的能量和营养素摄入,除维生素C、胡萝卜素和视黄醇当量外,均与WFR显著正相关,相关系数在0.22~0.51之间,但在调整年龄、性别和膳食能量摄入量的影响后,FFQ对膳食脂肪、维生素B1、钠和磷摄入量的估计与WFR相关的显著性消失。结论:FFQ可以用于评估膳食能量、蛋白质、碳水化物、维生素A、维生素B2、尼克酸、钾、钙、锌和硒的摄入量,但FFQ不适于评估膳食脂肪、视黄醇当量、胡萝卜素、维生素B1、维生素C、维生素E、钠、铁和磷的摄入量。     

Reproducibility and validity of food intake measurements from a semiquantitative food frequency questionnaire

Few food frequency questionnaires have been evaluated for their ability to assess intakes of individual foods that may be related to disease independently of their nutrient content. The reproducibility and validity of food intake measurements by a 131-item semiquantitative food frequency questionnaire were evaluated in a sample of 127 men from the Health Professionals Follow-up Study, a large longitudinal study of diet and disease. Each subject completed two questionnaires 1 year apart and two 1-week diet records 6 months apart during the intervening year. Pearson correlations assessing reproducibility between food intakes from the two questionnaires ranged from .31 for pie to .92 for coffee (mean = .59). Validity was measured by comparing food intakes from the second questionnaire with those from the diet records. Pearson correlations corrected for within-person weekly variation in diet record data ranged from .17 for other nuts to .95 for bananas (mean = .63). Large within-person variation precluded the calculation of accurate validity correlations for 29 foods. As we previously observed in women, the foods most often overreported were fruits and vegetables, and meats and dairy products were most often underreported. With few exceptions, reasonable levels of reproducibility and validity were observed for intake of individual foods in this extensive food frequency questionnaire.     

Nutrient and food group intakes of women with and without bulimia nervosa and binge eating disorder during pregnancy

BACKGROUND: Little is known concerning the dietary habits during pregnancy of women with eating disorders that may lie in the causal pathway of adverse birth outcomes. OBJECTIVE: We examined the nutrient and food group intakes of women with bulimia nervosa and binge-eating disorder during pregnancy and compared these with intakes of women with no eating disorders. DESIGN: Data on 30,040 mother-child pairs from the prospective Norwegian Mother and Child Cohort Study were used in cross-sectional analyses. Dietary information was collected by using a food-frequency questionnaire during the first half of pregnancy. Statistical testing by eating disorder categories with the non-eating-disorder category as the referent group was conducted by using log means adjusted for confounding and multiple comparisons. Food group differences were analyzed by using a Wilcoxon's two-sided normal approximation test that was also adjusted for multiple comparisons. RESULTS: Women with binge-eating disorder before and during pregnancy had higher intakes of total energy, total fat, monounsaturated fat, and saturated fat, and lower intakes of folate, potassium, and vitamin C than the referent (P < 0.02). Women with incident binge-eating disorder during pregnancy had higher intakes of total energy and saturated fat than the referent (P = 0.01). Several differences emerged in food group consumption between women with and without eating disorders, including intakes of artificial sweeteners, sweets, juice, fruit, and fats. CONCLUSION: Women with bulimia nervosa before and during pregnancy and those with binge-eating disorder before pregnancy exhibit dietary patterns that differ from those in women without eating disorders, that are reflective of their symptomatology, and that may influence pregnancy outcomes.     

Sources of fiber and fat in diets of US women aged 19 to 50: implications for nutrition education and policy.

INTRODUCTION. Many women are not meeting dietary recommendations for fiber and fat intakes. Health educators need to know which foods are major sources of these nutrients. METHODS. This study analyzed the contributions of 27 food groups to fiber, fat, saturated fat, and cholesterol intakes of 2134 women aged 19 to 50 years in USDA's Continuing Survey of Food Intakes by Individuals, the 1985 and 1986 surveys (CSFII 85-86). RESULTS. Major determinants of fiber intake include frequency of use of certain food groups (vegetables, including potatoes, bread, fruit, soups, ready-to-eat cereal) and choice of particular foods within the larger food groups (e.g., whole grain bread, high fiber cereal). Major determinants of total fat, saturated fat, and cholesterol intakes included frequency of use of certain foods (sweet grains, beef, eggs, cheeses/cream, whole milks) and additions to foods (regular salad dressing and butter/margarine). Demographic characteristics were related to various food group consumption parameters. CONCLUSIONS. Information about the relationships between food group and nutrient intake and the effects of household income, race/ethnicity, and region of residence on food group intake indicate opportunities to refine nutritional education programs.     

Errors in reported dietary intakes. I. Short-term recall

Measures for quantifying reproducibility and between-subject variability of nutrient intake data are applied to intakes reported in two interviews (1-3 months apart) by 44 male and 17 female healthy white subjects aged 45-75 years. Intakes were assessed by three methods: a dietary history that included consumption frequency and serving size for 71 food items (dietary history method); a combination of individual consumption frequencies with sex-specific mean serving sizes (frequency method); an extrapolation from frequencies and serving sizes of all foods reported for a "typical day" in the specified time period (typical day method). Intake variation within subjects, between subjects, and between methods was assessed by analysis of variance for each sex and for each of the nutrients: total calories, protein, fat, vitamin A, and protein and fat as percentage of total calories. Dietary history-assessed intakes exceeded those assessed by the other two methods. The dietary history versus frequency excess was greater than the dietary history versus typical day excess for calories, fat, and protein, while the reverse was true for vitamin A and fat as percentage of total calories. The typical day method was unreliable for vitamin A because it occasionally produced extremely high, unreproducible intakes. The intraclass correlation coefficient was used to measure a method's ability to distinguish interpersonal variation from within-person error. The frequency method produced less within-person error than did the dietary history method for all nutrients. For absolute intakes, the frequency method produced less interpersonal variation than did the dietary history method, while for relative intakes, the reverse was true. Females reported intakes with less within-person error than did males, and the interpersonal spread of their intakes was smaller. Consequences of these findings for the power and sensitivity of studies on the role of dietary factors in the etiology of chronic disease are explored.