I.Marilyn Buzzard

Computerized collection and analysis of dietary intake information.

A computer system has been developed which facilitates standardized and in-depth collection and analysis of dietary intake information required for nutritional research. The system uses a hierarchically arranged database of food descriptions. A user identifies a consumed food by traversing a hierarchy and reaching a leaf node food item via a succession of selections from menu displays. If a food contains ingredients or was cooked with additional fat or salt, multiple traversals of the food hierarchies are necessary. The system assigns one or more food codes and determines the gram weight of the food consumed using everyday measures such as cups, slices, ounces, etc. It then uses these food codes and gram weights to calculate nutrient content. Utilizing binary trees and physical pointers to expedite data retrieval from this nearly 10 Mbyte database permits the systems use in conducting real-time interactive interviews.

Monitoring Dietary Change in a Low-Fat Diet Intervention Study: Advantages of Using 24-Hour Dietary Recalls vs Food Records

OBJECTIVE The purpose of the study was to evaluate two methods of dietary assessment for monitoring change in fat intake in a low-fat diet intervention study. DESIGN The two dietary assessment methods were a 4-day food record (4DFR) and an unannounced 24-hour dietary recall conducted by telephone interview (referred to as a telephone recall [TR]). Subjects were assigned randomly to either a low-fat diet intervention group or a control group that received no counseling about fat intake. Dietary data were collected at baseline, 6 months, and 12 months. SUBJECTS Two hundred ninety postmenopausal women with localized breast cancer were recruited at seven clinical centers in the United States. STATISTICAL ANALYSIS Analysis of variance was used to test for significant differences in mean fat and energy intakes. RESULTS Three sources of error were identified: (a) an instrument effect, suggesting underreporting at baseline of approximately 8% in mean energy intake and 11% in mean fat intake in the TR group compared with the 4DFR group (P = .0001); (b) a repeated measures effect observed for the 4DFR, suggesting underreporting of approximately 7% for energy intake and 14% for fat intake in the control group at 6 and 12 months compared with baseline values (P < .001); and (c) an adherence effect (or compliance bias), suggesting greater compliance to the low-fat intervention diet when subjects were keeping food records than when estimates were based on the unannounced TR. Compared with the TR, the 4DFR overestimated the extent of fat reduction in the low-fat diet intervention group by 41% (P = .08) and 25% (P = .62) at 6 and 12 months, respectively. APPLICATION Multiple days of unannounced 24-hour recalls may be preferable to multiple-day food records for monitoring dietary change in diet intervention studies.

The effects of a low-fat dietary intervention and tamoxifen adjuvant therapy on the serum estrogen and sex hormone-binding globulin concentrations of postmenopausal breast cancer patients.

SummaryThe purpose of the study was to determine the effect of a low-fat dietary intervention, with or without concomitant tamoxifen adjuvant therapy, on serum estrogen and sex hormone-binding globulin (SHBG) levels in postmenopausal patients with resected breast cancer. Ninety-three patients were randomized to either reduce their fat intake to 15–20% of total calories, or to a dietary control group. Serum estradiol, estrone, estrone sulfate, and SHBG concentrations were assayed at baseline, and at 6, 12, and 18 months thereafter. In 19% of patients, the preintervention serum estradiol levels were below the sensitivity of the assay (5 pg/ml). Tamoxifen had no significant effect on serum estrogen levels, but produced an elevation in SHBG. Patients with reliably quantifiable preintervention estradiol concentrations (≥ 10 pg/ml) showed a significant reduction in serum estradiol after 6 months on the low-fat diet (average, 20%; p < 0.005); this was sustained over the 18 month study period. Serum SHBG levels were increased by tamoxifen therapy, but were reduced significantly (p = 0.01) after 12 months on the low-fat diet in patients not receiving tamoxifen. No changes in serum estrone or estrone sulfate resulted from the dietary intervention. While the low-fat diet produced significant weight loss, patients treated with tamoxifen without dietary intervention showed a gain in body weight. These weight changes produced disruptions in the normal positive correlation between body weight and serum estrone sulfate, and the negative correlation with SHBG concentration.

A food frequency questionnaire can detect pregnancy-related changes in diet

OBJECTIVE To determine whether a food frequency questionnaire (FFQ) can detect changes in dietary intake before pregnancy to mid-pregnancy relative to a 4-day food record. DESIGN FFQs and 4-day, weighed food records (4DRs) were completed during similar time intervals before pregnancy and again near mid-pregnancy by women served by a large health maintenance organization in the Minneapolis-St Paul, Minn, area. The outcome of interest was change in the intake of energy and 16 nutrients. Participants were members of the Diana Project, a prospective study of relationships among prepregnancy and pregnancy nutritional and other exposures and reproductive outcomes. Fifty-six (51%) of the eligible women completed the study. SUBJECTS Well-educated, healthy, white women. STATISTICAL ANALYSES PERFORMED Spearman rank order correlations. RESULTS Mean energy and nutrient intake levels estimated using the 4DR were generally higher than those estimated using the FFQ. Correlations between change in energy and nutrient intakes measured by the 4DR and FFQ ranged from .75 for vitamin C to .02 for cholesterol and averaged .48. APPLICATIONS Comparisons with 4DRs indicate that the FFQ used in this study is appropriate for obtaining reliable estimates of prepregnancy to mid-pregnancy changes in intake of energy and a number of nutrients in similar groups of women.

Enhancing data on nutrient composition of foods eaten by participants in the INTERMAP study in China, Japan, the United Kingdom, and the United States

The International Study of Macronutrients and Blood Pressure (INTERMAP) is a four-country study investigating relationships between individual dietary intakes and blood pressure. Dietary intake patterns of individuals were estimated for macronutrients (proteins, lipids, carbohydrates, alcohol) and their components (amino acids, fatty acids, starch), as well as minerals, vitamins, caffeine, and dietary fiber. The dietary assessment phase of the study involved collection of four 24-h recalls and two 24-h urine specimens from each of 4680 adults, ages 40-59, at 16 centers located in the Peoples Republic of China, Japan, the United Kingdom and the United States. For each country, an available database of nutrient composition of locally consumed foods was updated for use in the analysis of dietary data collected within the country. The four original databases differed in number and types of foods and nutrients included, analytic methods used to derive nutrients, and percentage of missing nutrient values. The Nutrition Coordinating Center at the University of Minnesota updated the original databases in several ways to overcome the foregoing limitations and increase comparability in the analyses of nutrient intake of individuals across the four countries: (1) addition of new foods and preparation methods reported by study participants; (2) addition of missing nutrient fields important to the study objectives; (3) imputation of missing nutrient values to provide complete nutrient data for each food reported by participants; and (4) use of adjustment factors to enhance comparability among estimates of nutrient intake obtained through each countrys nutrient-coding methodology. It was possible to expand, enhance, and adjust the nutrient databases from the four countries to produce comparable (60 nutrients) or nearly comparable (ten nutrients) data on composition of all foods reported by INTERMAP participants.

Maintenance of a nutrient database for clinical trials

Maintenance of a nutrient database for use in dietary analysis for clinical trials and other medical research studies is described. The database, maintained at the University of Minnesotas Nutrition Coordinating Center (NCC), has been used to calculate dietary intake data for a wide range of diet-disease related investigations including studies on cardiovascular disease, hypertension, cancer, gastroenterology, and osteoporosis. Potential sources of error associated with nutrient databases are identified. Criteria are provided for the selection of a nutrient database to meet study objectives and to minimize the potential for errors and inconsistencies. NCC database maintenance procedures, designed to provide updated and verified nutrient calculations for clinical research, involve adherence to standardized procedures for all aspects of database maintenance including data selection, imputations, quality control, recipe calculations, and documentation. By maintaining multiple versions of the database, the NCC is able to update and expand a working version of the database while providing database stability for individual research studies.

Reproducibility of a comprehensive diet history in the Diabetes Control and Complications Trial

OBJECTIVE To evaluate the reproducibility of a modified Burke-type diet history within the context of a long-term, randomized, 29-center clinical diabetes study. DESIGN Diet histories were collected by trained interviewers at the end of years 1 and 2 after subjects were randomly assigned to the intensive treatment group or the conventional treatment group. Mean daily intakes of energy, protein, carbohydrate, total fat, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, cholesterol, and dietary fiber were calculated for each treatment group at each time period. SUBJECTS The study population consisted of 139 subjects in the intensive treatment group and 128 subjects in the conventional treatment group. Ages ranged from 13 to 39 years; groups included men and women. Distribution by age, sex, race, proportion of smokers, weight reported as percent ideal body weight, and duration of IDDM were similar in both groups. STATISTICAL METHODS Differences in nutrient intake between the conventional and intensive treatment groups at each time period were tested for significance using the Wilcoxon rank-sum test. The Wilcoxon paired differences test was used to assess changes between time periods within treatment groups. Linear agreement between repeated administrations of the diet history was evaluated using Pearsons correlation coefficient, and the extent of within-subject reproducibility was assessed by intraclass correlation. RESULTS No statistically significant differences in energy and nutrient intakes were observed between the two groups at either year 1 or year 2. Within each treatment group, energy and nutrient intake differences between times were not statistically significant. Correlation coefficients between years 1 and 2 ranged from .51 for dietary fiber to .72 for dietary cholesterol; within-subject reproducibility was slightly higher. APPLICATIONS These results demonstrate long-term reproducibility for the meal-based diet history in the DCCT population.