Amy F. Subar

Fruit, vegetables, and cancer prevention: A review of the epidemiological evidence

Approximately 200 studies that examined the relationship between fruit and vegetable intake and cancers of the lung, colon, breast, cervix, esophagus, oral cavity, stomach, bladder, pancreas, and ovary are reviewed. A statistically significant protective effect of fruit and vegetable consumption was found in 128 of 156 dietary studies in which results were expressed in terms of relative risk. For most cancer sites, persons with low fruit and vegetable intake (at least the lower one-fourth of the population) experience about twice the risk of cancer compared with those with high intake, even after control for potentially confounding factors. For lung cancer, significant protection was found in 24 of 25 studies after control for smoking in most instances. Fruits, in particular, were significantly protective in cancers of the esophagus, oral cavity, and larynx, for which 28 of 29 studies were significant. Strong evidence of a protective effect of fruit and vegetable consumption was seen in cancers of the pancreas and stomach (26 of 30 studies), as well as in colorectal and bladder cancers (23 of 38 studies). For cancers of the cervix, ovary, and endometrium, a significant protective effect was shown in 11 of 13 studies, and for breast cancer a protective effect was found to be strong and consistent in a meta analysis. It would appear that major public health benefits could be achieved by substantially increasing consumption of these foods.

Fruit and Vegetable Intake in the United States: The Baseline Survey of the Five a Day for Better Health Program:

Purpose. The purpose of the Five A Day Baseline Survey was to assess fruit and vegetable intake and associated factors among US adults. Design. Questionnaires querying frequency of intake of 33 fruits and vegetables, as well as demographics, attitudes, and knowledge related to fruits and vegetables were administered by telephone. Setting. The study was a nationally representative random digit dial survey conducted by telephone in the summer of 1991; response rate was 42.8%. Subjects. Respondents were 2811 US adults (including an oversample of African-Americans and Hispanics). Measures. Mean and median self-reported intakes of fruits and vegetables were calculated. Estimated servings per week were adjusted on the basis of responses to summary questions regarding overall fruit and vegetable intakes. Results. Median intake of fruits and vegetables was 3.4 servings per day. Linear regressions (accounting for no more than 10% of the variation) showed that education, income, and smoking status were predictors of fruit and vegetable intake and that intake increased with education, income, and nonsmoking status. Women had higher intakes than men at all ages; these differences between men and women increased with age. Fruit and vegetable intakes increased with age for whites and Hispanics, but not for African-Americans. Conclusions. Fruit and vegetable intake among adults in the United States is lower than the recommended minimum of five daily servings. These data will be useful in targeting campaign efforts and in assessing progress of the Five A Day for Better Health Program.

The EPIC nutrient database project (ENDB): a first attempt to standardize nutrient databases across the 10 European countries participating in the EPIC study.

Objective:This paper describes the ad hoc methodological concepts and procedures developed to improve the comparability of Nutrient databases (NDBs) across the 10 European countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC). This was required because there is currently no European reference NDB available.Design:A large network involving national compilers, nutritionists and experts on food chemistry and computer science was set up for the ‘EPIC Nutrient DataBase’ (ENDB) project. A total of 550–1500 foods derived from about 37 000 standardized EPIC 24-h dietary recalls (24-HDRS) were matched as closely as possible to foods available in the 10 national NDBs. The resulting national data sets (NDS) were then successively documented, standardized and evaluated according to common guidelines and using a DataBase Management System specifically designed for this project. The nutrient values of foods unavailable or not readily available in NDSs were approximated by recipe calculation, weighted averaging or adjustment for weight changes and vitamin/mineral losses, using common algorithms.Results:The final ENDB contains about 550–1500 foods depending on the country and 26 common components. Each component value was documented and standardized for unit, mode of expression, definition and chemical method of analysis, as far as possible. Furthermore, the overall completeness of NDSs was improved (⩾99%), particularly for β-carotene and vitamin E.Conclusion:The ENDB constitutes a first real attempt to improve the comparability of NDBs across European countries. This methodological work will provide a useful tool for nutritional research as well as end-user recommendations to improve NDBs in the future.

A mixed‐effects model approach for estimating the distribution of usual intake of nutrients: The NCI method

It is of interest to estimate the distribution of usual nutrient intake for a population from repeat 24-h dietary recall assessments. A mixed effects model and quantile estimation procedure, developed at the National Cancer Institute (NCI), may be used for this purpose. The model incorporates a Box-Cox parameter and covariates to estimate usual daily intake of nutrients; model parameters are estimated via quasi-Newton optimization of a likelihood approximated by the adaptive Gaussian quadrature. The parameter estimates are used in a Monte Carlo approach to generate empirical quantiles; standard errors are estimated by bootstrap. The NCI method is illustrated and compared with current estimation methods, including the individual mean and the semi-parametric method developed at the Iowa State University (ISU), using data from a random sample and computer simulations. Both the NCI and ISU methods for nutrients are superior to the distribution of individual means. For simple (no covariate) models, quantile estimates are similar between the NCI and ISU methods. The bootstrap approach used by the NCI method to estimate standard errors of quantiles appears preferable to Taylor linearization. One major advantage of the NCI method is its ability to provide estimates for subpopulations through the incorporation of covariates into the model. The NCI method may be used for estimating the distribution of usual nutrient intake for populations and subpopulations as part of a unified framework of estimation of usual intake of dietary constituents.

Higher Diet Quality Is Associated with Decreased Risk of All-Cause, Cardiovascular Disease, and Cancer Mortality among Older Adults

Increased attention in dietary research and guidance has been focused on dietary patterns, rather than on single nutrients or food groups, because dietary components are consumed in combination and correlated with one another. However, the collective body of research on the topic has been hampered by the lack of consistency in methods used. We examined the relationships between 4 indices--the Healthy Eating Index-2010 (HEI-2010), the Alternative Healthy Eating Index-2010 (AHEI-2010), the alternate Mediterranean Diet (aMED), and Dietary Approaches to Stop Hypertension (DASH)--and all-cause, cardiovascular disease (CVD), and cancer mortality in the NIH-AARP Diet and Health Study (n = 492,823). Data from a 124-item food-frequency questionnaire were used to calculate scores; adjusted HRs and 95% CIs were estimated. We documented 86,419 deaths, including 23,502 CVD- and 29,415 cancer-specific deaths, during 15 y of follow-up. Higher index scores were associated with a 12-28% decreased risk of all-cause, CVD, and cancer mortality. Specifically, comparing the highest with the lowest quintile scores, adjusted HRs for all-cause mortality for men were as follows: HEI-2010 HR: 0.78 (95% CI: 0.76, 0.80), AHEI-2010 HR: 0.76 (95% CI: 0.74, 0.78), aMED HR: 0.77 (95% CI: 0.75, 0.79), and DASH HR: 0.83 (95% CI: 0.80, 0.85); for women, these were HEI-2010 HR: 0.77 (95% CI: 0.74, 0.80), AHEI-2010 HR: 0.76 (95% CI: 0.74, 0.79), aMED HR: 0.76 (95% CI: 0.73, 0.79), and DASH HR: 0.78 (95% CI: 0.75, 0.81). Similarly, high adherence on each index was protective for CVD and cancer mortality examined separately. These findings indicate that multiple scores reflect core tenets of a healthy diet that may lower the risk of mortality outcomes, including federal guidance as operationalized in the HEI-2010, Harvards Healthy Eating Plate as captured in the AHEI-2010, a Mediterranean diet as adapted in an Americanized aMED, and the DASH Eating Plan as included in the DASH score.

Need for Technological Innovation in Dietary Assessment

In 2007, the National Institutes of Health developed the Genes, Environment and Health Initiative (GEI) (www.gei.nih.gov) to promote research to better understand the genetic and environmental contributions to health and disease. GEI funded technology-driven methodology to improve measures of diet, physical activity, chemical exposures, psychosocial measures, and biological response indicators for use in future large-scale population studies. Similarly, since 2004, the National Cancer Institute (NCI) has internally funded the development of another technology advance in dietary assessment: an automated self-administered 24-hour dietary recall (ASA). The purpose of this paper is to briefly overview issues related to the uses of technology in dietary assessment, as a backdrop for advances in the field.

Cognitive research enhances accuracy of food frequency questionnaire reports: results of an experimental validation study

OBJECTIVE To test whether changing a food frequency questionnaire (FFQ) on the basis of cognitive theory and testing results in greater accuracy. Accuracy was examined for 4 design issues: a) Grouping: asking about foods in a single vs multiple separate questions; b) different forms of a food: asking consumption frequency of each form of a food (eg, skim, 2%, whole milk) vs a nesting approach--asking frequency of the main food (eg, milk) and proportion of times each form was consumed; c) additions (eg, sugar to coffee): asking independent of the main food vs nested under the main foods; d) units: asking frequency and portion size vs frequency of units (eg, cups of coffee). DESIGN Participants in two randomly assigned groups completed 30 consecutive daily food reports (DFRs), followed by 1 of 2 FFQs that asked about foods consumed in the past month. One was a new, cognitively-based National Cancer Institute (NCI) Diet History Questionnaire; the other was the 1992 NCI-Block Health Habits and History Questionnaire. SUBJECTS/SETTING 623 participants, age range 25 to 70 years, from metropolitan Washington, DC. Statistical analyses performed Accuracy was assessed by comparing DFR and FFQ responses using categorical (percent agreement) and continuous (rank order correlation, discrepancy scores) agreement statistics. RESULTS Grouping: accuracy was greater using separate questions. Different forms of food: accuracy was greater using nesting. Additions: neither approach was consistently superior; accuracy of the addition report was affected by accuracy of the main food report. Units: both approaches were similarly accurate. CONCLUSIONS Accuracy of FFQ reporting can be improved by restructuring questions based on cognitive theory and testing.

The Automated Self-Administered 24-Hour Dietary Recall (ASA24): A Resource for Researchers, Clinicians, and Educators from the National Cancer Institute

Extensive evidence has demonstrated that 24-hour dietary recalls (24HDRs) provide high-quality dietary intake data with minimal bias, making them the preferred tool for monitoring the diets of populations and, increasingly, for studying diet and disease associations (1-3). Traditional 24HDRs, however, are expensive and impractical for large-scale research because they rely on trained interviewers, and multiple administrations are needed to estimate usual intakes. To address these challenges, the National Cancer Institute (NCI), in collaboration with the research firm Westat (Rockville, MD), and with the support of other institutes and offices at the National Institutes of Health, developed the Automated Self-Administered 24-hour dietary recall (ASA24) (4-6). ASA24 is a public-access, freely available, web-based tool for researchers, clinicians and educators, modeled on the Automated Multiple Pass Method (AMPM) (7). Development of an automated self-administered 24HDR for adults began in 2006 and was informed by input from stakeholders participating in an External Working Group and small-scale cognitive and usability testing (4,5). A Beta version released in August 2009 has been used by over 175 researchers to collect over 40,000 recalls; Version 1, which offers improved usability and new features, was released in September 2011 (8). A modified version intended for self-administration by children is under development by researchers at the Baylor College of Medicine (Houston, TX) and is expected to be available mid-2012 (9,10). This paper describes the features of ASA24 and planned evaluations.

Index-based Dietary Patterns and Risk of Colorectal Cancer The NIH-AARP Diet and Health Study

The authors compared how four indexes-the Healthy Eating Index-2005, Alternate Healthy Eating Index, Mediterranean Diet Score, and Recommended Food Score-are associated with colorectal cancer in the National Institutes of Health-AARP Diet and Health Study (n = 492,382). To calculate each score, they merged data from a 124-item food frequency questionnaire completed at study entry (1995-1996) with the MyPyramid Equivalents Database (version 1.0). Other variables included energy, nutrients, multivitamins, and alcohol. Models were stratified by sex and adjusted for age, ethnicity, education, body mass index, smoking, physical activity, and menopausal hormone therapy (in women). During 5 years of follow-up, 3,110 incident colorectal cancer cases were ascertained. Although the indexes differ in design, a similarly decreased risk of colorectal cancer was observed across all indexes for men when comparing the highest scores with the lowest: Healthy Eating Index-2005 (relative risk (RR) = 0.72, 95% confidence interval (CI): 0.62, 0.83); Alternate Healthy Eating Index (RR = 0.70, 95% CI: 0.61, 0.81); Mediterranean Diet Score (RR = 0.72, 95% CI: 0.63, 0.83); and Recommended Food Score (RR = 0.75, 95% CI: 0.65, 0.87). For women, a significantly decreased risk was found with the Healthy Eating Index-2005, although Alternate Healthy Eating Index results were similar. Index-based dietary patterns that are consistent with given dietary guidelines are associated with reduced risk.

Low energy reporters vs others: a comparison of reported food intakes.

Objective: To partition the food reports of low energy reporters (LERs) and non-LERs into four aspects—tendency to report a given food, frequency of reports per user, portion sizes per mention, and the qualitative (low-fat, low-sugar, low-energy) differences of the reports—in order to determine what differentiates them from one another.Assessment method: Two non-consecutive 24h dietary recalls. Low energy reporting was defined as energy intake lower than 80% of estimated basal metabolic rate.Setting:In-home personal interviews.Subjects: 8334 adults from a stratified, multi-stage area probability sample designed to be representative of noninstitutionlized persons residing in households in the United States.Results: Across all different types of foods, there are those food groups which LERs are less likely to report (28 of 44 food groups), those which they report less frequently when they do report them (15 of 44 groups), and those for which they report smaller quantities per mention (26 of 44). Qualitative differences in the food choices—that is, differences in fat, sugar, and/or energy content—were not so widespread (4 of 24 food groups).Conclusions: The practical application of analyses such as these is to improve the methods of gathering dietary data so that this kind of bias can be reduced. Further methodological research is needed to reduce the likelihood of respondents neglecting to mention foods and underestimating portion sizes.European Journal of Clinical Nutrition (2000) 54, 281–287