Gender differences in social desirability and social approval bias in dietary self-report

A review of methods to measure dietary sodium intake

With the rising prevalence of heart failure, it is imperative to investigate reasons for dietary sodium nonadherence and to develop evidence-based interventions to promote adherence. However, one of the biggest obstacles in studying adherence to a low sodium diet is the imprecision in measurement of dietary sodium intake. The purpose of this article is to critically review current methods used to measure dietary sodium intake. Specifically, 24-hour urine, single- and multiple-day food records, and 24-hour dietary recalls are compared and contrasted. The reliability and validity of these methods are discussed. When choosing a method to measure dietary sodium, it is important also to consider other strengths and weaknesses of each method. The "best" method to be used in research may depend not only on the above information, but also on the research question as well as characteristics of the population under study.

Recall Strategies Used by Respondents to Complete a Food Frequency Questionnaire: An Exploratory Study

The purpose of this study was to identify strategies used to recall dietary intake on a food frequency questionnaire by adults in a multiethnic sample. One-on-one interviews were conducted to identify strategies used to recall intake on the Fred Hutchinson Food Frequency Questionnaire. Twenty-eight men and 26 women in San Diego, CA (average age, 41 years), were recruited from the general community with approximately equal numbers of non-Hispanic white, African-American, and English- and Spanish-speaking Hispanic participants. Recall of food intake was most commonly guided by routines. Recall strategies differed primarily by food type and not by ethnic or sex groups. Each of nine food categories on the questionnaire was associated with a distinct pattern of recall strategies. The recall strategies identified in this study may serve as cues to be included on food frequency questionnaires to aid recall and thus improve accuracy of self-reported dietary intake.

The Psychosocial and Behavioral Characteristics Related to Energy Misreporting

Energy underreporting occurs in 2% to 85% and overreporting in 1% to 39% of various populations. Efforts are needed to understand the psychosocial and behavioral characteristics associated with misreporting to help improve the accuracy of dietary self-reporting. Past research suggests that higher social desirability and greater eating restraint are key factors influencing misreporting, while a history of dieting and being overweight are more moderately associated. Eating disinhibition, body image, depression, anxiety, and fear of negative evaluation may be related to energy misreporting, but evidence is insufficient. This review will provide a detailed discussion of the published associations among psychosocial and behavioral characteristics and energy misreporting.

How does a suicide attempter eat differently from others? Comparison of macronutrient intakes

OBJECTIVE

Issues of the subtle effects of diet and nutrition on suicidal behaviors are rarely examined. This study describes the differences in dietary intakes of macronutrients between individuals who had ever made a suicide attempt and those who never had.

METHODS

We examined the data of 7631 non-institutionalized adults ages 17 to 39 y who completed a mental disorder diagnostic interview and a 24-h dietary recall as a part of the Third National Health and Nutrition Examination Survey, 1988 to 1994. Multivariable adjusted means of daily caloric intake and energy percentage from macronutrients were calculated for individuals who had a history of lifetime suicide attempt(s) (n = 408) and compared with those who did not.

RESULTS

After adjustment for covariates, including socioeconomic indicators, health risk factors, and history of medical and psychiatric illnesses, we observed that the means of daily caloric intake, cholesterol, and energy percentages from carbohydrate, total fat, saturated fat, monounsaturated fat, and protein did not differ significantly between attempters and non-attempters. However, energy percentage from polyunsaturated fat was lower in attempters than in non-attempters. Mean percentages +/- standard error for smoking attempters, non-smoking attempters, smoking non-attempters, and non-smoking non-attempters were 5.5 +/- 0.4 (P = 0.01), 6.7 +/- 0.2 (P = 0.02), 7.5 +/- 1.4 (P = 0.78), and 7.2 +/- 0.1 (reference), respectively, in men, and 6.3 +/- 0.4 (P = 0.01), 7.2 +/- 0.2 (P = 0.07), 7.3 +/- 1.0 (P = 0.89), and 7.5 +/- 0.1 (reference), respectively, in women. Dietary fiber intake was also lower in attempters than in non-attempters. These differences were independent of daily caloric intake.

CONCLUSIONS

Individuals with a history of suicide attempt have low intakes of polyunsaturated fat and fiber. Potential deleterious effects of low intake of polyunsaturated fat and fiber among suicide attempters merit further investigation.

Does contextual information influence positive and negative schizotypy scores in healthy individuals? The answer is maybe

Defensive responding in schizotypy questionnaires might depend on context. Students completed a schizotypy questionnaire in a "psychiatric" context or a "creativity" context. Positive, but not negative, schizotypy scores were lower in the psychiatry than in the creativity group, but findings applied mainly to male participants. The implications of these findings are critically discussed.

Dietary fat intake is associated with psychosocial and cognitive functioning of school-aged children in the United States

Using cross-sectional data from the Third National Health and Nutrition Survey, 1988-1994, we examined whether dietary fat intake is associated with cognitive and psychosocial functioning in school-aged children. Based upon 24-h diet recall interviews, dietary intakes of total fat, SFA, monounsaturated fatty, PUFAs, and cholesterol were estimated in 3666 participants aged 6 to 16 y. Psychosocial functioning was evaluated in interviews of each child's mother. Cognitive functioning was measured using achievement and intelligence tests. Overall, total fat and saturated fat were unrelated to measures of cognitive and psychosocial functioning. Compared with equivalent energy intake from saturated fat or carbohydrate, each 5% increase in energy intake from PUFAs was associated with lower risks of poor performance on the digit span test (replacing SFA, OR = 0.58, 95% CI = 0.37-0.91; replacing carbohydrate, OR = 0.61, 95% CI = 0.43-0.88). Cholesterol intake was associated with an increased risk of poor performance on the digit span test (OR = 1.25, 95% CI = 1.11-1.42 for each 100-mg increment intake of cholesterol). The associations were independent of socioeconomic status, maternal education and marital status, and children's nutrition status and were consistent across different methods of energy adjustment in regression models. We conclude that high intake of PUFAs may contribute to an improved performance on the digit span test. In contrast, increased intake of cholesterol may be associated with a poorer performance.

Effects of the mediterranean lifestyle program on multiple risk behaviors and psychosocial outcomes among women at risk for heart disease

BACKGROUND

The Mediterranean Lifestyle Program was evaluated for its effects on multiple behavioral risk factors for coronary heart disease (CHD) among postmenopausal women with diabetes.

PURPOSE

Our purpose is to test a comprehensive lifestyle management intervention to reduce CHD risk in postmenopausal women with type 2 diabetes.

METHODS

Participants (N = 279) were randomized to usual care (UC) or Mediterranean Lifestyle Program, a lifestyle change intervention aimed at the behavioral risk factors (eating patterns, physical activity, stress management, and social support) affecting risk for CHD in postmenopausal women with type 2 diabetes.

RESULTS

In original and intent-to-treat analyses, Mediterranean Lifestyle Program participants showed significantly greater improvement in dietary behaviors, physical activity, stress management, perceived support, and weight loss at 6 months compared to UC.

CONCLUSIONS

This study demonstrated the effectiveness of the Mediterranean Lifestyle Program in improving self-care among women with type 2 diabetes, showed that postmenopausal women could make comprehensive lifestyle changes, and provided evidence that a program using social-cognitive strategies and peer support can be used to modify multiple lifestyle behaviors.

The effect of social desirability and social approval on self-reports of physical activity

The purpose of this investigation was to examine social desirability and social approval as sources of error in three self-reported physical activity assessments using objective measures of physical activity as reference measures. In 1997, women (n = 81) living in Worcester, Massachusetts, completed doubly labeled water measurements and wore an activity monitor for 14 days. They also completed seven interviewer-administered 24-hour physical activity recalls (PARs) and two different self-administered 7-day PARs. Measures of the personality traits "social desirability" and "social approval" were regressed on 1) the difference between physical activity energy expenditure estimated from doubly labeled water and each physical activity assessment instrument and 2) the difference between monitor-derived physical activity duration and each instrument. Social desirability was associated with overreporting of activity, resulting in overestimation of physical activity energy expenditure by 0.65 kcal/kg/day on the second 7-day PAR (95% confidence interval: 0.06, 1.25) and overestimation of activity durations by 4.15-11.30 minutes/day (both 7-day PARs). Social approval was weakly associated with underestimation of physical activity on the 24-hour PAR (-0.15 kcal/kg/day, 95% confidence interval: -0.30, 0.005). Body size was not associated with reporting bias in this study. The authors conclude that social desirability and social approval may influence self-reported physical activity on some survey instruments.

Intentional mis-reporting of food consumption and its relationship with body mass index and psychological scores in women

BACKGROUND

The reasons for mis-reporting food consumption warrant investigation.

OBJECTIVE

To document intention to mis-report food consumption and its associations with psychological measures in women.

DESIGN

A total of 184 female volunteers aged 18-65 years, comprising 50 seeking help in primary care to lose weight with a body mass index (BMI) >/=30 kg m(-2) (obese-clinical group) and 134 nurses (nonclinical groups) (BMI <25 kg m(-2), n = 52; BMI 25-29.9 kg m(-2), n = 45; BMI >/=30 kg m(-2), n = 37) were studied. A questionnaire was administered containing three psychological tests (self-esteem, psychological well-being and Stunkard's three-factor eating questionnaire) and new items to address food intake mis-reporting.

RESULTS

Overall, 68% of participants declared an inclination to mis-report (64% nonclinical, 78% clinical). Inclination to under-report was 29, 33 and 51% in the three nonclinical groups; and 46% among the obese clinical patients. Among the same groups, inclination to over-report were 39, 29, 11 and 32%. After adjusting for social deprivation and BMI, women inclined to mis-report had higher hunger (P = 0.008) and disinhibition (P = 0.005) scores than those intending to report accurately. These variables were associated with current dieting, frequency of dieting, self-reported bingeing and dissatisfaction with body weight.

CONCLUSIONS

These findings indicate that intentional under-reporting and over-reporting of food consumption are common in women of all BMI categories and are associated with eating behaviour. Current dieting, frequency of dieting in the past, self-reported bingeing and dissatisfaction with body weight seem to mediate this relationship.

Effects of a tailored follow-up intervention on health behaviors, beliefs, and attitudes

BACKGROUND

The high rates of relapse that tend to occur after short-term behavioral interventions indicate the need for maintenance programs that promote long-term adherence to new behavior patterns. Computer-tailored health messages that are mailed to participants or given in brief telephone calls offer an innovative and time-efficient alternative to ongoing face-to-face contact with healthcare providers.

METHODS

Following a 1-year behavior change program, 22 North Carolina health departments were randomly assigned to a follow-up intervention or control condition. Data were collected from 1999 to 2001 by telephone-administered surveys at preintervention and postintervention for 511 low-income, midlife adult women enrolled in the Well-Integrated Screening and Evaluation for Women Across the Nation (WISEWOMAN) program at local North Carolina health departments. During the year after the behavior change program, intervention participants were mailed six sets of computer-tailored health messages and received two computer-tailored telephone counseling sessions. Main outcomes of dietary and physical activity behaviors, beliefs, and attitudes were measured.

RESULTS

Intervention participants were more likely to move forward into more advanced stages of physical activity change (p = 0.02); control participants were more likely to increase their level of dietary social support at follow-up (p = 0.05). Both groups maintained low levels of reported saturated fat and cholesterol intake at follow-up. No changes were seen in physical activity in either group.

CONCLUSIONS

Mailed computer-tailored health messages and telephone counseling calls favorably modified forward physical activity stage movement but did not appreciably affect any other psychosocial or behavioral outcomes.

Social desirability bias in self-reported dietary, physical activity and weight concerns measures in 8- to 10-year-old African-American girls: results from the Girls Health Enrichment Multisite Studies (GEMS)

BACKGROUND

Social desirability (SocD) may bias children's self-reported health behaviors and attitudes and confound relationships with health outcome measures.

METHODS

Ninety-five, 8- to 10-year-old African-American girls completed dietary recalls, a physical activity checklist, psychosocial questionnaires related to diet, and physical activity; and 3 days of physical activity monitoring. Potential SocD construct bias was investigated by comparing designated criterion measures of physical activity, beverage intake, and body mass index (BMI) with respective self-reported measures related to activity, beverage preferences, and body image and weight concerns in cross-sectional regression models. Potential confounding by SocD of associations between self-reported behaviors with BMI was assessed using change-in-coefficient regression analyses.

RESULTS

Controlling for age and BMI, overestimates of self-reported activity (P = 0.02), underestimates of sweetened beverage preferences (P = 0.02), and lower ratings of weight concerns and dieting behaviors (P's < 0.05) were related to SocD. Confounding by SocD of associations between self-reported physical activity and energy intake with BMI was found.

CONCLUSIONS

In 8- to 10-year-old African-American girls, SocD was found to bias self-reports of diet and physical activity and confound associations between BMI and self-reported physical activity and energy intake. Methods to measure and control SocD bias are needed to reduce potential distortion of relationships between diet and physical activity and health outcomes.

Low energy reporting may increase in intervention participants enrolled in dietary intervention trials

OBJECTIVE

To examine differences in low energy intake reporting between intervention and control groups during a dietary intervention trial.

DESIGN

Retrospective data analysis from a subcohort of participants in the Polyp Prevention Trial (PPT), a 4-year, multisite, randomized, controlled dietary intervention trial. Intervention consisted of educational material and counseling sessions supporting a low-fat, high-fiber diet. Baseline and annual demographics, behavioral characteristics, energy intake (EI) based on self-reported 4-day food records, and height and weight of participants were collected at baseline and annually. Basal metabolic rate (BMR) was estimated (using the Schofield equation) to calculate EI/BMR.

SUBJECTS

Of the 443 participants (302 male, 141 female) at baseline, 195 (43.3%) were younger than 60 years, and 394 (91%) were white. At Year 4, 383 participants remained: 186 (122 men, 64 women) in the intervention group, and 197 (133 men, 64 women) in the control group.

STATISTICAL ANALYSES

Using either paired t tests or analysis of variance, the differences between the means for EI, weight, and EI/BMR were compared at baseline, Year 1, and Year 4 for the participants who remained at Year 4. The Goldberg EI/BMR cutoff value of 1.06 (for plausible EI) identified participants who reported low EI. Linear regression was used to quantify the association of various risk factors to EI/BMR and for multivariate analyses within groups. chi(2) contingency table analysis quantified differences of low energy reporting within groups.

RESULTS

At baseline, 46.8% of women and 11.6% of men reported lower than plausible EI. Only men had a significant increase in low energy reporting after randomization. At Year 1, 18.9% of intervention group men reported low EI compared with 9.8% of control group men (P<.05). At Year 4, 23.0% of intervention group men reported low EI compared with 12.8% of control group men (P<.05).

CONCLUSIONS/APPLICATIONS

Difference in low EI reporting between intervention and control groups could distort results from dietary intervention trials; interpretation of findings from dietary trials must include this potential bias. Intervention study design should include dietary intake data collection methods that are not subject to such bias (ie, biomarkers and performance criteria) to measure intervention compliance.

Children's Social Desirability and Dietary Reports

We investigated telephone administration of the Children's Social Desirability (CSD) scale and our adaptation for children of the Social Desirability for Food scale (C-SDF). Each of 100 4th-graders completed 2 telephone interviews 28 days apart. CSD scores had adequate internal consistency and test-retest reliability, and a 14-item subset was identified that sufficiently measures the same construct. Our C-SDF scale performed less well in terms of internal consistency and test-retest reliability; factor analysis revealed 2 factors, 1 of which was moderately related to the CSD. The 14-item subset of the CSD scale may help researchers understand error in children's dietary reports.

Differences between estimated caloric requirements and self-reported caloric intake in the women's health initiative

PURPOSE

To compare energy intake derived from a food frequency questionnaire (FFQ) with estimated energy expenditure in postmenopausal women participating in a large clinical study.

METHODS

A total of 161,856 women aged 50 to 79 years enrolled in the Women's Health Initiative (WHI) Observational Study (OS) or Clinical Trial (CT) [including the Diet Modification (DM) component] completed the WHI FFQ, from which energy intake (FFQEI) was derived. Population-adjusted total energy expenditure (PATEE) was calculated according to the Harris-Benedict equation weighted by caloric intakes derived from the National Health and Nutrition Examination Survey. Stepwise regression was used to examine the influence of independent variables (e.g., demographic, anthropometric) on FFQEI-PATEE. Race, region, and education were forced into the model; other variables were retained if they increased model explanatory ability by more than 1%.

RESULTS

On average, FFQEI was approximately 25% lower than PATEE. Regression results (intercept=-799 kcal/d) indicated that body mass index (b=-23 kcal/day/kg.m(-2)); age (b=15 kcal/day/year of age); and study arm (relative to women in the OS, for DM women b=169 kcal/d, indicating better agreement with PATEE) increased model partial R(2)>.01. Results for CT women not eligible for DM were similar to those of women in the OS (b=14 kcal/d). There also were apparent differences by race (b=-152 kcal/d in Blacks) and education (b=-67 kcal/d in women with<high school).

CONCLUSION

This large, carefully studied population confirms previous observations regarding underestimates in self-reported caloric intake relative to estimates of metabolic need in younger women, and those with higher weight, with less education, and in Blacks. These differences, along with effects related to intervention assignment, underline the need for additional research to enhance understanding of errors in dietary measurement.

Energy intake in Swedish adolescents: validation of diet history with doubly labelled water

OBJECTIVE

To compare habitual energy intake (EI) estimated from diet history (DH) with total energy expenditure (TEE) measured with doubly labelled water (DLW) in adolescents.

DESIGN

DH included a detailed questionnaire and an interview. TEE was measured during a 14-day period. Adequate (AR), under- (UR) and over-reporters (OR) were defined from the ratio EI/TEE: AR 0.84-1.16, UR <0.84 and OR >1.16.

SETTING

Participants were recruited from grade 9 in a compulsory school in Göteborg, Sweden. All data were collected at school and DLW dosages were distributed at Sahlgrenska University Hospital.

SUBJECTS

A total of 35 adolescents (18 boys, 17 girls), 15.7 (0.4) y.

RESULTS

EI was 11.0 (3.6) MJ and TEE was 11.4 (2.1) MJ (P=0.42). DH was able to rank EI compared to TEE (Spearman's r=0.59, P< or =0.001). For girls, EI was 18% lower (P=0.0067) and for boys, EI was 7% higher (P=0.26) compared to TEE. The 95% limits of agreement for difference between TEE and EI were -5.6 to 6.5 MJ. In total, 20 subjects were defined as AR (57%), nine as UR (26%) and six as OR (17%). Energy from in-between meals was 33% lower (P=0.0043) in UR girls and 57% higher (P=0.026) in OR boys, compared to adequate reporting girls and boys, respectively. In UR girls, energy-adjusted intake (10 MJ) of specific foods did not differ significantly, fat was lower and carbohydrate and vitamin C were higher compared to AR girls (all P<0.05). OR boys had no significant differences in food and nutrient intake in 10 MJ compared to AR boys.

CONCLUSION

The diet history was able to capture EI for the group and to rank subjects. There was a wide individual range in reporting-accuracy related to gender.

SPONSORSHIP

The Ingabritt and Arne Lundberg Foundation, The Wilhelm and Martina Lundgren Foundation.

Association of education with dietary intake among young adults in the bi-ethnic Coronary Artery Risk Development in Young Adults (CARDIA) cohort

OBJECTIVE

To examine associations of changes in dietary intake with education in young black and white men and women.

DESIGN

The Coronary Artery Risk Development in Young Adults (CARDIA) study, a multi-centre population-based prospective study. Dietary intake data at baseline and year 7 were obtained from an extensive nutritionist-administered diet history questionnaire with 700 items developed for CARDIA.

SETTING

Participants were recruited in 1985-1986 from four sites: Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and Oakland, California.

SUBJECTS

Participants were from a general community sample of 703 black men (BM), 1006 black women (BW), 963 white men (WM) and 1054 white women (WW) who were aged 18-30 years at baseline. Analyses here include data for baseline (1985-1986) and year 7 (1992-1993).

RESULTS

Most changes in dietary intake were observed among those with high education (>or=12 years) at both examinations. There was a significant decrease in intake of energy from saturated fat and cholesterol and a significant increase in energy from starch for each race-gender group (P<0.001). Regardless of education, taste was considered an important influence on food choice.

CONCLUSION

The inverse relationship of education with changes in saturated fat and cholesterol intakes suggests that national public health campaigns may have a greater impact among those with more education.

Personality characteristics as predictors of underreporting of energy intake on 24-hour dietary recall interviews

OBJECTIVE

To identify characteristics associated with misreporting of energy intake during 24-hour dietary recalls (24 HR).

DESIGN

Ninety-eight subjects were administered two 24 HRs. Energy expenditure was determined by doubly labeled water (44 subjects) or intake balance (54 subjects). Data on subjects' physical, lifestyle, and psychosocial characteristics were also collected. Subjects/setting At the Beltsville Human Nutrition Research Center 52 women and 46 men were administered 24HR and completed lifestyle and personality questionnaires and a memory test. Physical characteristics such as weight, percent body fat, and total energy expenditure were measured. Statistical analysis The influences of subject parameters on energy misreporting were assessed by linear regression and Pearson product-moment correlation analysis for continuous variables and by ANOVA for discrete variables. Stepwise regression was used to identify key factors in underreporting.

RESULTS

Factors particularly important in predicting underreporting of energy intake include factors indicating dissatisfaction with body image; for example, a 398 kcal/day underreport in subjects attempting weight loss during the past year with a nearly 500 kcal/day underreport in women. Overall, women underreported by 393 kcal/day relative to men and women evinced a social desirability bias amounting to a 26 kcal underreport for each point on the social desirability scale. Gender differences also were evident in the effect of percent body fat (with men underreporting about 16 kcal/day/percent body fat) and in departure from self-reported ideal body weight (with women underreporting about 21 kcal/day/kg).

APPLICATIONS/CONCLUSIONS

Body image and fatness are key factors on which health professionals should focus when seeking predictors of underreporting of dietary intake. Dietary interviews must be conducted to minimize bias related to subjects' tendencies to win approval and avoid censure by the interviewer. In addition, dissatisfaction with body image may lead to underestimation of food intake, therefore reducing likelihood of success in weight loss. Thus, health care professionals involved in weight loss counseling may achieve better success if treatment includes generating a more positive body image.

Social diversity of Irish adults nutritional intake

OBJECTIVE

The first health and lifestyle survey of Irish adults was carried out in 1998 and aimed to describe the health-related lifestyle behaviours of a cross-section of various population strata residing in the Republic of Ireland. This paper reports on the social variation in nutrient intake.

DESIGN

A self-administered postal questionnaire, including a 149 food item semiquantitative food frequency section, from which nutrient intakes were estimated based on McCance and Widdowson food composition tables.

SETTING

Community-based adults aged 18 years and over residing in the Republic of Ireland on the Register of Electors.

SUBJECTS

A stratified sample of adults on the Register of Electors received the questionnaire, of which 6539 (62%) were returned.

RESULTS

The contribution of fat to total energy intake increased with decreasing socioeconomic grouping, a finding reflective of the higher consumption levels of foods high in fat by respondents from socially disadvantaged groups. Energy from carbohydrates was greatest among those from socially advantaged groups, and was close to the recommended 50% of the total energy intake. Conversely, energy from protein decreased with increasing social status group. The mean intake of vitamins and minerals was generally close to or above the recommended values. Significant variation was observed among females across the different levels of education, whereas living with someone appeared to influence the micronutrient intake of males. The reported diets of males and females over the age of 65 years were lacking in vitamin D. Mean calcium levels among males were borderline and females over the age of 65 years had mean dietary iron levels below the recommended intake.

CONCLUSIONS

For the first time, quantification of nutrient intake in the different social groups in Ireland has been undertaken. A healthy balance of energy derived from fat, protein and carbohydrate is best achieved among respondents from higher social positions. The positive relation observed with healthy food intake and increasing education level was also present in macronutrient intake and a clear gender and social support interplay was seen in the nutrient intake levels.

Gender differences in dietary intakes, anthropometrical measurements and biochemical indices in an urban adult population: the Tehran Lipid and Glucose Study

BACKGROUND AND AIM

In order to investigate gender differences in health indices, dietary intakes and obesity in urban Iranian adults, we considered a sub-sample of the adult population of the Tehran Lipid and Glucose Study.

METHODS AND RESULTS

The randomly selected sub-sample consisted of 483 subjects aged 25-50 years (229 men and 254 women) and 153 aged more than 50 years (81 men and 72 women). Their anthropometrical variables were recorded, and their body mass index (BMI) and waist/hip ratio were calculated. Dietary intake was assessed by means of two-day dietary recall and the completion of dietary habit questionnaires during face-to-face interviews. Underreporting was defined as a ratio of energy intake (EI)/basal metabolic rate (BMR) < 1.27. The mean BMI of the women in both age groups was significantly higher than that of the men (p < 0.05). Central obesity was more frequent in the women and among older subjects. The women had higher plasma concentrations of high-density lipoprotein cholesterol, but lower levels of total and low-density lipoprotein cholesterol. Underreporting of EI was more frequent in the women than the men: 34.0% vs 15.4% in the younger group, and 40.3% vs 17.3% in the older group (p < 0.01). There were major gender differences in the mean daily intakes of energy, protein, carbohydrate, fat, fibre, cholesterol, iron, calcium and phosphorus. A higher proportion of women met the cholesterol intake guidelines. Data from the dietary habit questionnaires showed that more men than women usually sprinkle salt on their food.

CONCLUSIONS

The results of this study partially support the hypothesis of gender differences in dietary intakes, and the prevalence of obesity and some health-related indices, and suggest the need for gender-specific, targeted nutrition messages and behavioural interventions in developing prevention strategies for cardiovascular risk factors.

Markers of the validity of reported energy intake

Energy intake (EI) is the foundation of the diet, because all other nutrients must be provided within the quantity of food needed to fulfill the energy requirement. Thus if total EI is underestimated, it is probable that the intakes of other nutrients are also underestimated. Under conditions of weight stability, EI equals energy expenditure (EE). Because at the group level weight may be regarded as stable in the timescale of a dietary assessment, the validity of reported EI can be evaluated by comparing it with either measured EE or an estimate of the energy requirement of the population. This paper provides the first comprehensive review of studies in which EI was reported and EE was measured using the doubly labeled water technique. These conclusively demonstrate widespread bias to the underestimation of EI. Because energy requirements of populations or individuals can be conveniently expressed as multiples of the basal metabolic rate (BMR), EE:BMR, reported EI may also be expressed as EI:BMR for comparison. Values of EI:BMR falling below the 95% confidence limit of agreement between these two measures signify the presence of underreporting. A formula for calculating the lower 95% confidence limit was proposed by Goldberg et al. (the Goldberg cutoff). It has been used by numerous authors to identify individual underreporters in different dietary databases to explore the variables associated with underreporting. These studies are also comprehensively reviewed. They explore the characteristics of underreporters and the biases in estimating nutrient intake and in describing meal patterns associated with underreporting. This review also examines some of the problems for the interpretation of data introduced by underreporting and particularly by variable underreporting across subjects. Future directions for research are identified.

Evaluation of under- and overreporting of energy intake in the 24-hour diet recalls in the European Prospective Investigation into Cancer and Nutrition (EPIC)

OBJECTIVE

To evaluate under- and overreporting and their determinants in the EPIC 24-hour diet recall (24-HDR) measurements collected in the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN

Cross-sectional analysis. 24-HDR measurements were obtained by means of a standardised computerised interview program (EPIC-SOFT). The ratio of reported energy intake (EI) to estimated basal metabolic rate (BMR) was used to ascertain the magnitude, impact and determinants of misreporting. Goldberg's cut-off points were used to identify participants with physiologically extreme low or high energy intake. At the aggregate level the value of 1.55 for physical activity level (PAL) was chosen as reference. At the individual level we used multivariate statistical techniques to identify factors that could explain EI/BMR variability. Analyses were performed by adjusting for weight, height, age at recall, special diet, smoking status, day of recall (weekday vs. weekend day) and physical activity.

SETTING

Twenty-seven redefined centres in the 10 countries participating in the EPIC project.

SUBJECTS

In total, 35 955 men and women, aged 35-74 years, participating in the nested EPIC calibration sub-studies.

RESULTS

While overreporting has only a minor impact, the percentage of subjects identified as extreme underreporters was 13.8% and 10.3% in women and men, respectively. Mean EI/BMR values in men and women were 1.44 and 1.36 including all subjects, and 1.50 and 1.44 after exclusion of misreporters. After exclusion of misreporters, adjusted EI/BMR means were consistently less than 10% different from the expected value of 1.55 for PAL (except for women in Greece and in the UK), with overall differences equal to 4.0% and 7.4% for men and women, respectively. We modelled the probability of being an underreporter in association with several individual characteristics. After adjustment for age, height, special diet, smoking status, day of recall and physical activity at work, logistic regression analyses resulted in an odds ratio (OR) of being an underreporter for the highest vs. the lowest quartile of body mass index (BMI) of 3.52 (95% confidence interval (CI) 2.91-4.26) in men and 4.80 (95% CI 4.11-5.61) in women, indicating that overweight subjects are significantly more likely to underestimate energy intake than subjects in the bottom BMI category. Older people were less likely to underestimate energy intake: ORs were 0.58 (95% CI 0.45-0.77) and 0.74 (95% CI 0.63-0.88) for age (> or =65 years vs. <50 years). Special diet and day of the week showed strong effects.

CONCLUSION

EI tends to be underestimated in the vast majority of the EPIC centres, although to varying degrees; at the aggregate level most centres were below the expected reference value of 1.55. Underreporting seems to be more prevalent among women than men in the EPIC calibration sample. The hypothesis that BMI (or weight) and age are causally related to underreporting seems to be confirmed in the present work. This introduces further complexity in the within-group (centre or country) and between-group calibration of dietary questionnaire measurements to deattenuate the diet-disease relationship.

Research strategies and the use of nutrient biomarkers in studies of diet and chronic disease

OBJECTIVE

To provide an account of the state of diet and chronic disease research designs and methods; to discuss the role and potential of aggregate and analytical observational studies and randomised controlled intervention trials; and to propose strategies for strengthening each type of study, with particular emphasis on the use of nutrient biomarkers in cohort study settings.

DESIGN

Observations from diet and disease studies conducted over the past 25 years are used to identify the strengths and weaknesses of various study designs that have been used to associate nutrient consumption with chronic disease risk. It is argued that a varied research programme, employing multiple study designs, is needed in response to the widely different biases and constraints that attend aggregate and analytical epidemiological studies and controlled intervention trials. Study design modifications are considered that may be able to enhance the reliability of aggregate and analytical nutritional epidemiological studies. Specifically, the potential of nutrient biomarker measurements that provide an objective assessment of nutrient consumption to enhance analytical study reliability is emphasised. A statistical model for combining nutrient biomarker data with self-report nutrient consumption estimates is described, and related ongoing work on odds ratio parameter estimation is outlined briefly. Finally, a recently completed nutritional biomarker study among 102 postmenopausal women in Seattle is mentioned. The statistical model will be applied to biomarker data on energy expenditure, urinary nitrogen, selected blood fatty acid measurements and various blood micronutrient concentrations, and food frequency self-report data, to identify study subject characteristics, such as body mass, age or socio-economic status, that may be associated with the measurement properties of food frequency nutrient consumption estimates. This information will be crucial for the design of a potential larger nutrient biomarker study within the cohort study component of the Women's Health Initiative.

SETTING AND SUBJECTS

The methodology under study is expected to be pertinent to a wide variety of diet and chronic disease association studies in the general population. Ongoing work focuses on statistical methods developed using computer simulations motivated by studies of dietary fat in relation to breast and colon cancer among post-menopausal women, and ongoing pilot studies to be described in detail elsewhere, involving post-menopausal women living in the Seattle area.

RESULTS AND CONCLUSION

A varied research programme appears to be needed to make progress in the challenging diet and chronic disease research area. Such progress may include aggregate studies of diet and chronic disease that include sample surveys in diverse population groups world-wide, analytical epidemiological studies that use nutrient biomarker data to calibrate self-report nutrient consumption estimates, and randomised controlled intervention trials that arise from an enhanced infrastructure for intervention development. New innovative designs, models and methodologies are needed for each such research setting.

A methodological report from the Malmö Diet and Cancer study: development and evaluation of altered routines in dietary data processing

BACKGROUND

In the Malmö Diet and Cancer study, information on dietary habits was obtained through a modified diet history method, combining a 7-day menu book for cooked meals and a diet questionnaire for foods with low day-to-day variation. Half way through the baseline data collection, a change of interview routines was implemented in order to reduce interview time.

METHODS

Changes concentrated on portion-size estimation and recipe coding of mixed dishes reported in the menu book. All method development and tests were carefully monitored, based on experiential knowledge, and supplemented with empirical data. A post hoc evaluation study using "real world" data compared observed means of selected dietary variables before and after the alteration of routines handling dietary data, controlling for potential confounders.

RESULTS

These tests suggested that simplified coding rules and standard portion-sizes could be used on a limited number of foods, without distortions of the group mean nutrient intakes, or the participants' ranking. The post hoc evaluation suggested that mean intakes of energy-adjusted fat were higher after the change in routines. The impact appeared greater in women than in men.

CONCLUSIONS

Future descriptive studies should consider selecting subsets assessed with either method version to avoid distortion of observed mean intakes. The impact in analytical studies may be small, because method version and diet assistant explained less than 1 percent of total variation. The distribution of cases and non-cases across method versions should be monitored.

Relative bias in diet history measurements: a quality control technique for dietary intervention trials

OBJECTIVE

Investigation of relative bias in diet history measurement during dietary intervention trials.

DESIGN

Retrospective analysis of human dietary data from two randomised controlled trials examining modified fat diets in the prevention and treatment of type II diabetes mellitus.

SETTING

Wollongong, Australia.

SUBJECTS

Thirty-five overweight, otherwise healthy subjects in trial 1 and 56 subjects with diabetes in trial 2.

INTERVENTIONS

Diet history interviews and three-day weighed food records administered at one-month intervals in trial 1 and three-month intervals in trial 2.

RESULTS

In a cross-sectional bias analysis, graphs of the association between bias and mean dietary intake showed that bias decreased in higher carbohydrate consumers in trial 1 (r = -0.344, P < 0.05). No other significant associations were found. In a longitudinal analysis, bias did not change over time in either trial. There were no significant differences in bias magnitudes between the trials, with the exception of monounsaturated fat measurement where bias was significantly greater and more positive in trial 2, indicating overestimation of monounsaturated fat intake with the diet history. Subjects in control and intervention groups underestimated energy, fat, saturated fat and alcohol intakes with the diet history in both trials. Overweight and obese individuals appeared to make the greatest contribution to the overall underestimation of saturated fat intake by the diet history regardless of whether they were in the control or intervention group and whether they were healthy or had diabetes.

CONCLUSION

Bias in diet history measurement appears to be macronutrient-specific, with energy, fat and saturated fat consistently underreported in the interview by subjects with and without diabetes and in both intervention and control groups in a dietary intervention trial. Relative bias analysis appears to be an informative tool in quality control for dietary intervention trials when biochemical markers are unavailable.

Comparability of epidemiological information between self- and interviewer-administered questionnaires

The aim of the present study was to determine the extent to which respondents provided the same answers to a health-related lifestyle questionnaire in self- and interviewer-administered forms. A total of 234 subjects completed a 110-item questionnaire in both interviewer and self-administered forms. Modes of administration were separated by a 2-week interval. The order was determined by random allocation. The presence and the extent of the tendency to give socially acceptable responses were evaluated using percentage of bias calculated as the ratio of the difference in proportion of positive responses or the mean between interviews and questionnaires and those in questionnaires. All percentages of bias were in the positive direction, ranging from 1.4% (physical exercise) to 26.1% (general life stress). The average percentage of bias was higher in women than in men and were stronger for younger respondents. The age differences between interviewer and respondent were inversely and most strongly related to percentage of bias. Self- and interviewer-administered questionnaires yield very similar results in discriminating between subjects, but the interviewer-administered questionnaire showed systematically more desirable responses to questions related to lifestyle factors. The differences in characteristics between interviewer and respondent may be important determinants of the socially desirability bias in the interview.

Dietary exposures and oral precancerous lesions in Srikakulam District, Andhra Pradesh, India

OBJECTIVE

To test the effect of dietary nutrients on oral precancerous lesions in a reverse-smoking (i.e. smoking with the glowing end inside the mouth) population in South India.

DESIGN

Case-control. Cases with precancerous lesions were matched to an equal number of lesion-free controls matched on age (+/- 5 years), sex and village. All subjects used tobacco in some form. Dietary data were obtained using an interviewer-administered food-frequency questionnaire, designed for use in this population. All interviews were conducted blinded to the disease status of the subject. Data were analysed using logistic regression.

SETTING

Nineteen rural villages in Srikakulam District, Andhra Pradesh.

SUBJECTS

From a survey of 6007 tobacco users, 485 (79% women) were found to have precancerous, mostly palatal, lesions (cases), and 487 lesion-free subjects were selected as controls.

RESULTS

All eligible subjects consented to participate and nearly all (> 99%) had complete data for analyses. Reverse smoking was the most common form of tobacco use among cases (81.9%) and controls (73.5%), and reverse smokers were 5.19 times more likely than chewers to have these lesions (95% confidence interval = 1.35, 19.9). After controlling for relevant covariates, including the type of tobacco use, protective linear effects were observed for zinc (70% reduction across the interquartile range, P < 0.002), calcium (34% reduction, P < 0.002), fibre (30% reduction, P < 0.009), riboflavin (22% reduction, P < 0.03) and iron (17% reduction, P < 0.05).

CONCLUSIONS

Several dietary nutrients appear to protect against oral precancerous lesions that are strongly associated with reverse smoking. The results of this study indicate scope for targeting dietary factors in preventing oral cancer, which should be coupled with aggressive anti-tobacco use efforts.

Food patterns and components of the metabolic syndrome in men and women: a cross-sectional study within the Malmö Diet and Cancer cohort

This study examined the relations between food patterns and five components of the metabolic syndrome in a sample of Swedish men (n = 2,040) and women (n = 2,959) aged 45-68 years who joined the Malmö Diet and Cancer study from November 1991 to February 1994. Baseline examinations included an interview-administered diet history, a self-administered questionnaire, blood pressure and anthropologic measurements, and blood samples donated after an overnight fast. Cluster analysis identified six food patterns for which 43 food group variables were used. Logistic regression analysis was used to examine the risk of each component (hyperinsulinemia, hyperglycemia, hypertension, dyslipidemia, and central obesity) and food patterns, controlling for potential confounders. The study demonstrated relations, independent of specific nutrients, between food patterns and hyperglycemia and central obesity in men and hyperinsulinemia in women. Food patterns dominated by fiber bread provided favorable effects, while food patterns high in refined bread or in cheese, cake, and alcoholic beverages contributed adverse effects. In women, food patterns dominated by milk-fat-based spread showed protective relations with hyperinsulinemia. Relations between risk factors and food patterns may partly depend on gender differences in metabolism or food consumption and on variations in confounders across food patterns.

The effect of social desirability trait on self-reported dietary measures among multi-ethnic female health center employees

PURPOSE

To evaluate the effect of social desirability trait, the tendency to respond in a manner consistent with societal expectations, on self-reported fruit, vegetable, and macronutrient intake.

METHODS

A 61-item food frequency questionnaire (FFQ), 7-item fruit and vegetable screener, and a single question on combined fruit and vegetable intake were completed by 132 female employees at five health centers in eastern Massachusetts. Intake of fruit and vegetables derived from all three methods and macronutrients from the FFQ were fit as dependent variables in multiple linear regression models (overall and by race/ethnicity and education); independent variables included 3-day mean intakes derived from 24-hour recalls (24HR) and score on the 33-point Marlowe-Crowne Social Desirability scale (the regression coefficient for which reflects its effect on estimates of dietary intake based on the comparison method relative to 24HR).

RESULTS

Results are based on the 93 women with complete data and FFQ-derived caloric intake between 450 and 4500 kcal/day. In women with college education, FFQ-derived estimates of total caloric were associated with under-reporting by social desirability trait (e.g., the regression coefficient for total caloric intake was -23.6 kcal/day/point in that group versus 36.1 kcal/day/point in women with education less than college) (difference = 59.7 kcal/day/point, 95% confidence interval (CI) = 13.2, 106.2). Except for the single question on which women with college education tended to under-report (difference =.103 servings/day/point, 95% CI = 0.003, 0.203), there was no association of social desirability trait with self-reported fruit and vegetable intake.

CONCLUSIONS

The effect of social desirability trait on FFQ reports of macronutrient intake appeared to differ by education, but not by ethnicity or race. The results of this study may have important implications for epidemiologic studies of diet and health in women.

Change in women's diet and body mass following intensive intervention for early-stage breast cancer

OBJECTIVE

To determine the effectiveness of an intensive dietary intervention on diet and body mass in women with breast cancer.

DESIGN

Randomized clinical trial.

SUBJECTS

172 women aged 20 to 65 years with stage I or II breast cancer.

INTERVENTION

A 15-session, mainly group-based and dietitian-led nutrition education program (NEP) was compared to a mindfulness-based stress reduction clinic program (SRC); or usual supportive care (UC).

MAIN OUTCOME MEASURES

Dietary fat, complex carbohydrates, fiber, and body mass were measured.

STATISTICAL ANALYSIS

In addition to descriptive statistics, analysis of variance was conducted to test for differences according to intervention group.

RESULTS

Of the 157 women with complete dietary data at baseline, 149 had complete data immediately postintervention (at 4 months) and 146 had complete data at 1 year. Women randomized to NEP (n = 50) experienced a large reduction in fat consumption (5.8% of energy as fat) at 4 months and much of this reduction was preserved at 1 year (4.1% of energy) (both P < .0002) vs no change in either SRC (n = 51) or UC (n = 56). A 1.3-kg reduction in body mass was evident at 4 months in the NEP group (P = .003) vs no change in the SRC and UC groups. Women who had higher-than-average expectations of a beneficial effect of the intervention experienced larger changes.

APPLICATIONS

Dietitians' use of group nutrition interventions appear to be warranted. Increasing their effectiveness and maintaining high levels of adherence may require additional support, including the involvement of significant others, periodic individual meetings, or group booster sessions.

Influence of body composition on the accuracy of reported energy intake in children

OBJECTIVE

Mis-reporting dietary intake is a substantial barrier to understanding the role of dietary behavior in disease. Work with adults indicates that heavier individuals under-report dietary intake and that under-reporting may be macronutrient-specific. Whether weight status and macronutrient intake influence the accuracy of dietary reports among children, however, is less clear. This research evaluated children's dietary reporting accuracy as a function of their relative weight, body composition, and macronutrient intake.

RESEARCH METHODS AND PROCEDURES

Participants included 146 4- to 11-year-old children. Reported energy intake was determined by interviewing children in the presence of parents, using three multiple pass, 24-hour recalls. Children were classified as having had an under-reported, accurately reported, or over-reported dietary intake relative to total energy expenditure, as measured by doubly labeled water. Reporting accuracy was examined as a function of children's body weight, body composition (using dual energy x-ray absorptiometry), and macronutrient intake.

RESULTS

Average reported intake was, on average, 14% greater than children's estimated expenditure (p < 0.01). Reporting accuracy varied as a function of children's relative weight and body composition; under-reporting tended to occur among heavier children, having the highest body fat content (p < 0.0001) and relative weight (p < 0.0001).

DISCUSSION

These findings suggest that weight status influences the accuracy of dietary reports made by children and their parents. More research is needed to address possible psychological and social factors that introduce bias in reporting children's dietary data.

Smoking behavior among casino employees: self-report validation using plasma cotinine

The veracity of behavioral self-reports is often challenged, particularly when the motivation to avoid stigma and win social approval holds potential to introduce bias into the data collected. This study employed plasma cotinine tests to validate the self-reports of tobacco use collected from 3,841 casino employees as part of a comprehensive health survey. Rates of discordance were calculated by comparing employee self-reports with results from plasma colinine tests. This study provides evidence that casino employees can provide valid self-report data. Further, discordance rates of self-reported tobacco use vary according to operational definitions of tobacco use. These findings highlight the methodological importance of recognizing the inherent heterogeneity of smoking behavior.

Prevalence and co-occurrence of health risk behaviors among high-risk drinkers in a primary care population

BACKGROUND

Approximately 10% of patients seen in the primary care setting meet criteria for high-risk (HR) drinking. Little data are available about the co-occurrence of other risk behaviors (RBs) in this population. This study examines the co-occurrence of smoking, poor diet, and sedentariness, and several change-related variables, among 479 HR drinkers participating in Project Health, a NIAAA-funded study testing the effectiveness of a provider-delivered intervention to reduce HR drinking.

METHOD

Data were collected at study entry via standardized interview and questionnaire.

RESULTS

The prevalence of additional RBs among HR drinkers was smoking, 35%; poor diet, 28%; and sedentariness, 44%. In addition to HR drinking, 67% of participants had at least one RB, and 61% reported smoking, sedentariness, or both. Perception of drinking as a problem was generally low (20%), as was intention to change drinking. Seventy-two percent of participants with multiple RBs perceived at least one of these RBs as a problem. Younger, unmarried, less-educated, blue-collar, and non-working participants were more likely to have multiple RBs than white-collar workers.

CONCLUSION

Additional RBs are common among HR drinkers and may increase their already elevated health risks. Implications of these findings for interventions integrating multiple RBs into primary care settings are discussed.

Parental prevention practices for young children in the context of maternal depression

OBJECTIVE

To assess the relationship between maternal depression and 4 parent-based prevention practices (use of car seats and electrical plug covers, presence of syrup of ipecac in the home, and reading to their child), using a large nationally representative follow-back sample.

METHODS

The maternal self-report components of 2 databases were used for this study, the 1988 National Maternal and Infant Health Survey and the linked companion 1991 Longitudinal Follow-Up Survey. A total of 7537 mothers with newborns in 1988 served as the subjects. Measures of the 4 prevention practices were extracted from the 1991 survey. Depressive symptom measures were derived from both surveys using the Center for Epidemiologic Studies-Depression Scale. Weighted bivariate and multivariate logistic analyses were used to assess the relationship between maternal depressive symptoms (trichotomized to depression at both time points, at 1 time point, and at neither time point) and parental prevention practices, while controlling for a wide variety of sociodemographic variables.

RESULTS

Mothers reporting a high level of depressive symptoms (Center for Epidemiologic Studies-Depression Scale score >/=16) reported significantly poorer prevention practices for car seat use, covering electrical plugs, and having syrup of ipecac in the home. High depressive symptoms were also related to a lower likelihood of daily reading, but only for those mothers presently living with a male partner. Engagement in all prevention practices, except having syrup of ipecac in the home, were less likely if the mother reported high levels of depressive symptoms at both time points versus a single time point.

CONCLUSION

Maternal depression may significantly impede parental prevention practices. As maternal depression is a treatable condition, screening and treating this disorder may contribute to improvement in childhood prevention practices and ultimately child health.

Future possibilities in the prevention of breast cancer: fat and fiber and breast cancer research

The potential for a reduction in dietary fat or for an increase in dietary fiber to reduce breast cancer risk has been debated for some years. It is argued here that available research data, even though extensive, leave open hypotheses ranging from little or no potential to major public health potential for breast cancer prevention by means of these dietary maneuvers. Some elements of a research strategy for testing these and other dietary breast cancer prevention hypotheses are described.

Psychosocial correlates of dietary intake: advancing dietary intervention

Psychosocial variables that predict dietary behavior become important targets for change in nutrition education programs. Psychosocial variables in models with higher predictability provide more effective levers to promote healthy dietary change. A review of the literature on models with psychosocial variables predicting dietary fat and fruit and vegetable consumption revealed generally low predictiveness, R2 < 0.3 (where R2 is the squared multiple correlation of the statistical model). No single theory provided models that regularly out-predicted others. When models predicted narrower categories of behavior (e.g. milk or salad consumption), predictiveness tended to be higher. Substantial problems were revealed in the psychometrics of both the independent and dependent variables. Little theory-based research has been conducted with adolescents, and the few studies done with children had low predictiveness. In order to increase the predictiveness of models, future research should combine variables from several theories, attend to the psychometrics of all variables, and incorporate variables that moderate the relationship of psychosocial to dietary behavior (e.g. genetics of taste, stage in the life course). Refinements on current research would include longitudinal designs and use of non-self-report methods of dietary behavior to supplement the self-report methods. Improved understanding of dietary behavior should lead to more effective dietary behavior change interventions.

Seasonal variation of blood cholesterol levels: study methodology

This manuscript provides a description of the methodology used in the Seasonal Variation of Blood Cholesterol Levels (SEASON) study, with the intent of informing the scientific community of the available data sets and to invite a dialogue with scientists in complementary fields. The primary aim of the SEASON study is to describe and delineate the causes of seasonal variation of blood lipid levels in the general population. This research project is designed specifically to systematically collect and analyze a number of important variables necessary to study the role of seasonality in blood lipids and relevant covariates.

Serum vitamin C concentrations and diabetes: findings from the Third National Health and Nutrition Examination Survey, 1988-1994

BACKGROUND

Previous studies suggested that diabetes mellitus may lower serum vitamin C concentrations, but most of these studies used clinic-based populations with established diabetes of varying duration and did not adjust for important covariates.

OBJECTIVE

Using a population-based sample and adjusting for important covariates, we asked whether serum vitamin C concentrations in persons with newly diagnosed diabetes differed from those in persons without diabetes.

DESIGN

Data were obtained from the third National Health and Nutrition Examination Survey (1988-1994). Serum vitamin C was assayed by using reversed-phase HPLC with multiwavelength detection. Diabetes status (n = 237 persons with diabetes; n = 1803 persons without diabetes) was determined by oral-glucose-tolerance testing of the sample aged 40-74 y.

RESULTS

After adjustment for age and sex, mean serum vitamin C concentrations were significantly lower in persons with newly diagnosed diabetes than in those without diabetes. After adjustment for dietary intake of vitamin C and other important covariates, however, mean concentrations did not differ according to diabetes status.

CONCLUSION

When assessing serum vitamin C concentrations by diabetes status in the future, researchers should measure and account for all factors that influence serum vitamin C concentrations.

Potential underreporting of energy intake in the Ontario Health Survey and its relationship with nutrient and food intakes

This study investigated potential underreporting of energy intake in the 1990 Ontario Health Survey (OHS). Underreporting was higher in overweight individuals, Asian-born individuals, and respondents from urban areas. Intakes of underreporters were slightly closer to current dietary guidelines (less fat, more fruit and vegetables, fewer sweets). These results underline that caution is warranted when interpreting the association of dietary data with health outcomes.

A dietitian-delivered group nutrition program leads to reductions in dietary fat, serum cholesterol, and body weight: the Worcester Area Trial for Counseling in Hyperlipidemia (WATCH)

OBJECTIVE

To assess the effectiveness of a dietitian-based nutrition counseling and education program for patients with hyperlipidemia.

DESIGN

A 4-session program implemented as a complement to a randomized physician-delivered intervention.

SUBJECTS/SETTING

From 12 practice sites of the Fallon Clinic, 1,162 subjects with hyperlipidemia were recruited, 645 of whom had data sufficient for our primary analyses.

INTERVENTION

Two individual and 2 group sessions conducted over 6 weeks.

MAIN OUTCOME MEASURES

Total and saturated fat levels; serum low-density lipoprotein cholesterol levels; and body weight, measured at baseline and after 1 year.

STATISTICAL ANALYSES

Multiple linear regression was used to evaluate changes in outcome measures.

RESULTS

After 1 year, there were significant reductions in outcome measures for subjects attending 3 or 4 nutrition sessions vs subjects attending fewer than 3 sessions or those never referred to a nutrition session. Reductions (mean +/- standard error) in saturated fat (measured as percent of energy) were 2.7 +/- 0.5%, 2.1 +/- 0.5%, and 0.3 +/- 0.1%, respectively. These reductions correspond to roughly a 22% relative change from baseline in those attending 3 or 4 sessions. Corollary reductions were observed for total fat (measured as percent of energy): 8.2 +/- 1.4%, 5.0 +/- 1.4%, and 0.7 +/- 0.4%; low-density lipoprotein cholesterol: 0.48 +/- 0.11 mmol/L, 0.13 +/- 0.11 mmol/L, and 0.02 +/- 0.03 mmol/L; and body weight: 4.5 +/- 0.9 kg, 2.1 +/- 0.8 kg, and 1.1 +/- 0.2 kg. The specified changes were additive to those of the physician-delivered intervention.

APPLICATIONS/CONCLUSIONS

This investigation provides empirical data demonstrating the effectiveness of a dietitian-delivered intervention in the care of patients with hyperlipidemia.

Development and testing of a quantitative food frequency questionnaire for use in Gujarat, India

OBJECTIVE

To develop and test a quantitative, interviewer-administered food frequency questionnaire (FFQ) to ascertain nutrient intakes of individuals in northern India.

DESIGN

A 92-item FFQ was developed based on food use and market surveys of the study area. A validation study was conducted consisting of 24-h diet recalls (24HR) administered on 6 randomly selected days over 1 year. Two FFQs were administered, one each at the beginning and end of the 1-year period. FFQ and 24HR-derived nutrient scores were compared using correlation and regression analyses and by computing differences between nutrient intakes estimated by the two methods.

SETTING

Rural villages in Bhavnagar District, Gujarat, North India.

SUBJECTS

60 individuals who agreed to provide all necessary data.

RESULTS

Pearson (parametric) correlation coefficients averaged 0.69 in comparing nutrient scores derived from the 24HR with those from the first FFQ and 0.72 in comparing the second FFQ (P<0.0001). Spearman correlation coefficients were virtually identical to the Pearson correlations, averaging 0.68 and 0.72, respectively. In regression analyses, most coefficients were close to 1.0 (perfect linear association). Nutrient scores were significantly and consistently higher on both FFQs relative to the 24HR.

CONCLUSIONS

This FFQ produces results broadly comparable, and superior in some respects, to those commonly used in the West. Higher than average measures of association indicate its suitability for comparing exposures within this study population in reference to health-related endpoints.

A comparison of selected nutrient intakes derived from three diet assessment methods used in a low-fat maintenance trial

OBJECTIVE

In the vast majority of surveys and research in humans, dietary data are obtained from self-reports: recalls; records; or historical methods, usually food frequency questionnaires (FFQ). This study provides a rare opportunity to compare data derived from all three methods.

DESIGN

A crossover study of dietary fat in which data were collected using an average of 11.4 food records and 11.7 24-h diet recalls. Using simple subtraction and correlation, energy and nutrient intakes derived from the three methods were compared to each other and with those derived from a single FFQ. Analysis of variance was used to evaluate sources of variability in nutrient intakes estimated from the individual days of records and recalls.

SETTING

An independent, free-standing medical research institute.

SUBJECTS

13 men who were compliant with study procedures.

RESULTS

FFQ-derived estimates of energy and nutrient intake were highest (e.g. 1967 kcal versus 1858 kcal and 1936 kcal for the records and recalls, respectively). Mean differences in energy and nutrient intakes and their variances were lowest and correlation coefficients highest in comparing the records and recalls (e.g. for fat the mean difference was 5.0 g, and r = 0.85). Analysis of variance of individual days of record- and recall-derived data (n = 300) revealed that there was no effect due to either method (record or recall) or the sequence of administration.

CONCLUSIONS

Results of this study indicate that the FFQ overestimated dietary intake. Energy and nutrient results obtained from the records and recalls were interchangeable. However, based on smaller SDs around the means, it appears that the recalls may perform slightly better in estimating dietary intake in groups such as these well-educated, highly compliant men.