Pamela S. Haines

Diet quality index: Capturing a multidimensional behavior

OBJECTIVE Data for 5,484 adults (aged 21 years and older) who participated in the 1987-88 Nationwide Food Consumption Survey (NFCS) were used to develop an index of overall dietary intake that related to the major, diet-related, chronic diseases in the United States. The low response rate of the 1987-88 NFCS has raised concerns about potential bias, but this large data set is useful for methodologic studies and research that does not attempt to generalize the results to the US population. ANALYSES Dietary recommendations from the 1989 National Academy of Sciences publication Diet and Health were stratified into three levels of intake for scoring. Individuals who met a dietary goal were given a score of zero. Those who did not meet a goal, but had a fair diet, were given one point, and those who had a poor diet were given two points. These points were summed across eight diet variables to score the index from zero (excellent diet) to 16 (poor diet). RESULTS Lower index scores were positively associated with high intakes of other important measures of diet quality (eg, fiber, vitamin C). We found that single nutrients (such as dietary fat) were not necessarily associated with other measures of diet quality. CONCLUSION We concluded that this index ranking of overall dietary patterns was reflective of total diet quality, though substantial misclassification can result from using single nutrients or foods as indicators of diet quality.

The Diet Quality Index Revised: A Measurement Instrument for Populations

OBJECTIVE To evaluate a revision of the Diet Quality Index called the Diet Quality Index Revised (DQI-R). DESIGN The original Diet Quality Index was revised to reflect current dietary guidance, to incorporate improved methods of estimating food servings, and to develop and incorporate measures of dietary variety and moderation. The scoring of the original scale was reversed in direction and expanded to a 100-point scale to improve interpretability. METHODS/SUBJECTS Data from the 1994 Continuing Survey of Food Intakes by Individuals were used. A sample of 3,202 adults aged 18 and older contributed 2 days of dietary intake data based on 24-hour recalls for the development and revision of various components of the DQI-R. STATISTICAL ANALYSES Pearson correlation analyses, ordinary least squares regression analyses, and a nonparametric test to determine trends across ordered groups were used. RESULTS The mean DQI-R score for the 1994 sample was 63.4 of a possible 100-point score. Sample respondents were more likely to have met dietary guidance in the areas of dietary cholesterol (66.9% met goal) and iron intakes (59.6% met goal) relative to the Recommended Dietary Allowances but less likely to have met goals related to fruit servings (19.6% met goal), grain servings (23.1% met goal), and calcium intakes (16.6% met goal) relative to the Recommended Dietary Allowance. There is a statistically significant quantitative and qualitative improvement in all components of the DQI-R as one moves from the lowest grouping of scores to the highest. For example, persons with DQI-R scores less than 40 consumed 43.9% of energy from fat, 72% of the Adequate Intake for calcium, and 6.7% of the recommended servings of fruit per day. In contrast, those with DQI-R scores greater than 80 consumed 24.2% of energy from fat, 101% of the Adequate Intake for calcium, and 137% of the recommended servings of fruit per day. APPLICATIONS The DQI-R reflects the dietary guidance principles of macronutrient distribution, moderation, variety, and proportionality. Although the index was designed to monitor dietary changes in populations rather than individuals, each index component reflects an aspect of national dietary guidance. Calculation of DQI-R scores for an individual should provide an estimate of diet quality relative to national guidelines, and differences in scores over time should suggest improvement or decline in overall diet quality.

A comparison of dietary trends among racial and socioeconomic groups in the United States

BACKGROUND There may be dietary differences among racial and socioeconomic groups in the United States. METHODS Using data from a representative sample of adults, we compared dietary trends among blacks and whites of varying socioeconomic status. We developed comparable measures of diet and of the consumption of macronutrients and food groups for 6061 participants in the 1965 Nationwide Food Consumption Surveys, 16,425 in the 1977-1978 Nationwide Food Consumption Surveys, and 9920 in the 1989-1991 Continuing Survey of Food Intake by Individuals (all conducted by the U.S. Department of Agriculture). The primary outcome was the score (range, 0 to 16) on the Diet Quality Index, a composite of eight food-and-nutrient-based recommendations from the National Academy of Sciences. A score of 4 or less was considered to indicate a relatively more healthful diet, and a value of 10 or more a relatively less healthful diet. RESULTS Overall dietary quality improved in all groups, from a mean Diet Quality Index score of 7.4 in 1965 to 6.4 in 1989-1991. In 1965, blacks of low socioeconomic status and, to a lesser extent, whites of low socioeconomic status had better diets than whites of high socioeconomic status. By the 1989-1991 survey, the differences among racial and socioeconomic groups had narrowed. In 1965, 9.3 percent of whites of low socioeconomic status, 16.4 percent of blacks of low socioeconomic status, and 4.7 percent of whites of high socioeconomic status had mean scores of 4 or less. In the 1989-1991 survey the respective percentages were 19.9, 23.5, and 20.0. Fat consumption decreased in all groups. The consumption of fruits and vegetables varied little over time, except for an increase among blacks of medium and high socioeconomic status. The consumption of grains and legumes increased over time among whites of medium and high socioeconomic status and declined among blacks of low socioeconomic status. CONCLUSIONS In 1965, there were large differences among groups in dietary quality, with whites of high socioeconomic status eating the least healthful diet, as measured by the index, and blacks of low socioeconomic status the most healthful. By the 1989-1991 survey, the diets of all groups had improved and were relatively similar.

Modeling Food Consumption Decisions as a Two-Step Process

This article evaluates the suitability of tobit analysis of food consumption patterns by comparing results generated by a tobit model and a modification with a two-step decision process. Two samples of adult women were selected from the 1977–78 Nationwide Food Consumption Survey and the 1985 Continuing Survey of Food Intakes by Individuals. Results show strong statistical evidence for questioning tobit analysis in examining food consumption decisions. Determinants of the decision to consume food within a particular food group often differ from the determinants of how much to consume, particularly for more highly defined food groupings.

Trends in Breakfast Consumption if US Adults Between 1965 and 1991

OBJECTIVE To examine breakfast consumption patterns and trends between 1965 and 1991 for adults in the United States. DESIGN Trends analysis pooling three cross-sectional surveys. SETTING Nationally representative samples obtained from the Nationwide Food Consumption Survey (NFCS) of 1965, the NFCS of 1977-1978, and the 1989-1991 Continuing Survey of Food Intakes by Individuals. SUBJECTS Adults aged 18 years and older: 6,274 in 1965, 18,033 in 1977-1978, and 10,812 in 1989-1991. All results reflect use of sampling weights, so results reflect nationally representative samples in each time period. MAIN OUTCOME MEASURES Breakfast consumption, defined as the consumption of food and/or beverage between the hours of 5 AM and 9 AM, was the focus of the trends analysis. Population prevalence rates are reported for the entire population and population subgroups. STATISTICAL ANALYSIS PERFORMED Probit analysis was used to identify factors associated with changes in breakfast consumption over time. RESULTS Breakfast consumption declined in the 26-year period between 1965 and 1991 from 86% to 75% for US adults. Breakfast consumption increased with age, and the age differential increased over time. Urban-rural and South-non-South differences in breakfast consumption narrowed over time, whereas black-nonblack and college-noncollege differences increased slightly or remained constant. The nutritional quality of food consumed at breakfast has improved since 1965. CONCLUSIONS Although part of the decline in breakfast consumption can be explained by personal and demographic determinants, other unknown factors contributed to the trends. Elucidation of such factors is necessary to predict differences in breakfast as a health-related behavior.

Socioeconomic and behavioral correlates of body mass index in black adults: The Pitt County Study

BACKGROUND Obesity is more prevalent among Black women than Black men, but there is little information on the correlates of obesity in Blacks. This study describes the relations of sociodemographic factors and health behaviors to body mass index in a southern, Black population. METHODS In 1988, a community probability sample of 1784 Black adults, aged 25 to 50, was examined in Pitt County, NC. RESULTS More women than men were at least 20% overweight (57% vs 36%). The relation of socioeconomic status (a composite of education and occupation) to age-adjusted body mass index level was inverse in women but not in men. Body mass index did not differ with either current energy intake or energy expenditure. Smokers and drinkers had lower age-adjusted levels than non-smokers and abstainers. CONCLUSIONS Since the excess body mass index levels associated with low socioeconomic status in women could not be explained after controlling for adverse health behaviors, further epidemiologic study of risk factors for obesity in Black women is recommended.

Dietary Patterns and Trends in the United States: The UNC-CH Approach

Over the past 2 decades our group of nutrition and economics researchers at the University of North Carolina at Chapel Hill has used a wide array of methods to study eating patterns and dietary trends. Our focus has been on characterising the way diet has changed over time and identifying some of the major factors underlying these trends. The complexity of this undertaking has led us to develop a number of unique systems for classifying foods and assessing the overall quality of diet. We have also addressed the challenges that exist when measuring changes in both the food supply and food-related behaviors over time. This paper summarises some of the methodological work related to food grouping, overall diet quality indices, and trends research as well as the challenges we still face in this arena.

Unraveling the web: an evaluation of the content quality, usability, and readability of nutrition web sites.

OBJECTIVE To determine the content quality, general readability, and usability characteristics of consumer nutrition information on the World Wide Web. DESIGN Almost 500 Web sites were identified for evaluation through 2 different approaches. Of these, 150 were included for further evaluation. Each site was rated on a 27-item tool covering content quality, readability, and usability. ANALYSIS Summary statistics, means, ranges, and standard deviation were calculated for each study variable. The statistical significance of differences between item means by search strategy was determined using Students t tests. RESULTS Web sites identified using popular search engines scored significantly lower for content quality (P < .0001), were easier to navigate (P < .001), had better overall adherence to usability standards (P < .0001), and had lower reading levels compared with those sites identified using a government Web portal. CONCLUSIONS AND IMPLICATIONS Nutrition Web sites obtained using popular search engines may be aesthetically appealing and easy to use, but they often provide inaccurate nutrition information. As consumers increasingly turn to the World Wide Web for nutrition advice and education, it is imperative that the needs of diverse user populations be identified and addressed. Future nutrition education research should build on these findings by creating strategies that help users find reliable user-friendly gateways to accurate nutrition information on the Internet.

Socioeconomic status and electrolyte intake in black adults : the pitt county study

BACKGROUND Although the inverse association between socioeconomic status (SES) and blood pressure has often been observed, little is known about the relationship between SES and dietary risk factors for elevated blood pressure. Therefore, this study described the distribution of dietary intakes of sodium, potassium, and calcium and examined the association between electrolyte intake and SES among 1784 Black men and women aged 25 to 50 residing in eastern North Carolina. METHODS Household interviews were conducted in 1988 to obtain information on psychosocial and dietary correlates of blood pressure. Electrolyte intake (mg/day) was assessed using a food frequency questionnaire adapted to reflect regional and ethnic food preferences. SES was categorized into three levels defined by the participants educational level and occupation. RESULTS After adjustment for age and energy intake, potassium and calcium intake increased with increasing SES for both sexes. Sodium intake was high for all groups and did not vary markedly with SES, but sodium to potassium and sodium to calcium ratios decreased with increasing SES. In addition, high SES individuals were more likely to believe that diet affects risk for disease and to report less salt use at the table and less current sodium consumption than in the past. CONCLUSION These data indicate that nutritional beliefs as well as the consumption of electrolytes are associated with SES in Black adults.

Correlates of serum lycopene in older women

Abstract: Experimental and epidemiological evidence suggests that lycopene, a predominant carotenoid found in human serum, may reduce the risk of certain cancers. We examined the association of dietary, physiological, and other factors with serum lycopene concentrations in a subsample of 946 postmenopausal women participating in the Womens Health Initiative. Pearson partial correlation coefficients and linear regression coefficients were calculated after adjustment for age, ethnicity, and serum low-density-lipoprotein (LDL) cholesterol. Serum lycopene was correlated with serum LDL cholesterol (r = 0.23) and dietary lycopene (r = 0.17, both p < 0.001). Individual food items found to be correlated with serum lycopene after adjustment included fresh tomatoes or tomato juice (r = 0.11), cooked tomatoes, tomato sauce, or salsa (r = 0.17), and spaghetti with meat sauce (r = 0.19, all p < 0.01). Age and body mass index were negatively associated with serum lycopene levels (both p < 0.001). Serum lycopene levels were highest in the summer and highest for those living in the northeastern United States. If we postulate that high serum lycopene levels reduce cancer risk, it becomes apparent that we have limited ability to detect this association from studies of lycopene intake. An understanding of factors associated with serum lycopene levels can be useful for the interpretation of studies of dietary lycopene and disease risk.