Keep food safe to eat: healthful food must be safe as well as nutritious.

The inclusion of food safety in the 2000 edition of the Dietary Guidelines for Americans is an important step toward ensuring their continued relevance for health promotion and disease prevention. The inclusion of food safety is consistent with the original intent of the Guidelines and the increased focus on food safety today; it also better reflects current knowledge about diet and long-term health. A wide spectrum of surveillance methods can be used to monitor progress in reducing the incidence of foodborne illness, from surveys of food safety attitudes to epidemiologic data on foodborne illness. Surveillance data show that progress is being made, but that much work remains to be done. Strategies for reducing foodborne illness require a farm-to-table approach and the involvement of all those who have a responsibility for food safety, i.e., government, industry and the public. Federal agencies and others are finding it useful to use a risk analysis framework, i.e., risk assessment, risk management and risk communication, as a means of organizing available information, identifying data gaps, quantifying risks for specific pathogens and foods, and presenting strategies for improvement. Food safety education is a critical part of the overall strategy to reduce the incidence of foodborne illness and complements regulatory, research and other activities.

The administration's responsibility to the consumer.

Biotechnology offers the promise of good jobs that produce products fulfilling the public's need for food, fiber and pharmaceuticals. It could provide a growing market for American products abroad, and it also offers the potential of environmentally sound solutions to some current problems. Government is therefore accountable for implementing policies to protect the public health, while at the same time promoting the growth and development of the industry. Such policies should stimulate research, ensure the safety of new products, protect the environment, encourage business to innovate and invest and lead to a literate public capable of holding those high technology jobs. Stewardship of the federal government's $70 billion annual investment in science and technology entails the following: 1) setting an overall policy framework and managing the effort efficiently within that framework; 2) supporting the conduct of fundamental science critical to achieving the stated goals; and 3) providing an environment that encourages private investment in innovation and technology development.

Applications of antioxidants in physiologically functional foods. Consumption, intake patterns, and exposure.

Despite the wide public and scientific interest in antioxidant nutrients and their roles in disease prevention, limited data are available to assess population consumption, individuals' intake patterns, and trends in exposure. This article reviews data on levels of these nutrients in the food supply, intake patterns from food and supplement use derived from national surveys, and trends in exposure. The food supply and intake data indicate that levels of vitamins E and C and the carotenoids in the diet have increased since the 1970s, but the increases are not consistent among all age groups. Dietary supplements make a major contribution to intakes of vitamins E and C. Nutrient and nonnutrient antioxidants added to the food supply do not contribute appreciably to antioxidant exposure. Groups at high risk of poor dietary intakes of antioxidant nutrients are the poor, tobacco users, nonsupplement users, and the elderly, especially those living alone.

Issues in the long-term evaluation of diet in longitudinal studies.

Longitudinal studies are very useful for studying diet/disease relationships. The fundamental components of a longitudinal study are that: 1) data are collected for two or more distinct time periods; 2) the subjects are the same or comparable from one time period to the next; and 3) data are compared between or among time periods in the analysis. A longitudinal study is often assumed to be synonymous with a cohort study, but there are at least four possible definitions for a longitudinal study. While focusing on cohort studies, the paper describes the nature of longitudinal studies, including a discussion of how the different definitions differ from a cohort study and a set of important assumptions necessary to cohort studies. It also highlights some of the major issues associated with such studies, including the selection of a dietary survey methodology; data collection issues in multicultural, multilingual societies; the importance of nutrient databases; measurement error and misclassification in nutrient intake and energy adjustment.

Measuring dietary patterns in surveys.

This paper reviews the strengths, weaknesses, and limits to interpretation of dietary intake methods used in national nutrition surveys, including per capita consumption of food and nutrients and the 24-hour recall. These dietary assessment methods make up but one of five categories of nutritional assessment techniques. The other four are body measurements, hematological and biochemical tests, medical examination for the presence of clinical signs of deficiency or toxicity, and medical history. No one method alone is sufficient for assessing the nutritional status of individuals or groups. In the hypothesis-generating phases of research on diet and cardiovascular diseases and diet and cancer, correlations of per capita availability of food and nutrients with mortality from these diseases in several countries proved useful. However, the approach is limited to the extent that similar data are available from several other countries and that the association observed is true and not spurious. The 24-hour recall method has proved to provide accurate and reproducible estimates of the mean intakes of population groups, but multiple-day information is necessary for characterizing an individual's usual nutrient intake. Food frequency questionnaires are useful when one is interested in food rather than nutrient consumption of individuals or groups. The 24-hour recall, food diary, and food frequency methods can be used to develop a descriptive epidemiology of food intake within U.S. population groups with specified fitness and activity characteristics or to monitor the prevalence of dietary risk factors within the population. They are limited to the extent that food composition data are available. When selecting a dietary assessment method to be used in a nutrition survey, three points must be kept in mind: Practicality in terms of respondent burden and analysis resources, reliability, and validity.

Selection of nutrition status indicators for field surveys: the NHANES III design.

Planning a multipurpose survey in which nutritional status is assessed requires a series of scientific and practical decisions that are constrained by available resources of money and time and by the limits to what can be expected from the respondents. This paper describes the planning process for a multipurpose survey using our experience with the third National Health and Nutrition Examination Survey (NHANES III) as an example. Ideally, the goals and objectives are well defined at the outset, and these guide the development of the survey content and statistical design. Because the needs for information are so great, criteria need to be developed for evaluating which topics will be included in the survey and what tests will be used. In planning the NHANES III, the evaluation criteria used were the scientific merit of the topic, its public health importance, its practical utility to the government, and the feasibility of implementing it within the survey's mode of operation. After the topics to be covered in a survey have been selected, questionnaires and examination protocols are developed, pilot tested, and revised prior to implementing the survey. Procedures are established for providing for informed consent and assuring the confidentiality of findings.

Ethnic and racial differences in serum vitamin A levels of children aged 4-11 years.

Interpretation of differences in serum vitamin A levels observed between Hispanic and non-Hispanic children may be complicated by confounding environmental factors. Data from the Mexican-American portion of the Hispanic Health and Nutrition Examination Survey and the second National Health and Nutrition Examination Survey were used to explore these differences in 4-11-y-old Mexican Americans and non-Hispanic blacks and whites before and after accounting for vitamin-mineral supplement use and poverty status. Initial differences in mean serum vitamin A levels and prevalences less than 20 micrograms/dL (0.70 mumol/L) or less than 25 micrograms/dL (0.87 mumol/L) among the three ethnic or racial groups were reduced or eliminated after accounting for the two descriptive variables. These results support the hypothesis that differences in serum vitamin A levels between Mexican-American and non-Hispanic children in the United States are due more to environmental factors than to ethnicity.

Federal monitoring of the nation's nutritional status. Contributions of the National Center for Health Statistics.

The National Center for Health Statistics conducts a broad program of record-based systems and population surveys providing information on the health and nutritional status of the US population. The record-based systems include vital statistics and health-care surveys. Population surveys include the National Health and Nutrition Examination Survey (NHANES), the National Health Interview Survey, the National Survey of Family Growth, and epidemiologic follow-back surveys. Although all of these data systems provide nutrition-related information, the NHANES collects the most directly relevant nutritional status data through interview and examination of a national probability sample of children and adults. The third NHANES is scheduled to begin in September 1988 and is designed to provide cross-sectional estimates of dietary intake and nutritional status for nutrition-monitoring purposes and to serve as the baseline for longitudinal studies of diet and health.

Estimates of available iron in diets of individuals 1 year old and older in the Nationwide Food Consumption Survey.

Levels of total iron and available iron were estimated in the diets of individuals 1 year and older. The source of data was 1-day dietary recall records from the U.S. Department of Agriculture's 1977-78 Nationwide Food Consumption Survey. Total iron intakes of 1- to 2- and 3- to 5-year-old children were 51% and 77% of their respective RDAs. Total iron intakes of 12- to 50-year-old girls and women averaged only 55% to 61% of their RDA. Total iron intakes of other groups came close to or exceeded their respective RDAs. The proportion of total iron calculated to be available ranged from 6.5% to 8.7%, which is less than the 10% assumption of availability used as a basis for setting the iron RDA. When compared with the RDAs, total iron presented a more favorable picture of dietary iron intake than available iron. In relation to the RDAs, proportions of available iron were consistently lower than proportions of total iron. Available iron was lower than total iron in relation to recommended allowances because less than 10% of total dietary iron was available.