NP107  

Human Nutrition  

Action Plan 2004-2008

Goal Statement

The goal of NP107 (Human Nutrition) is to improve the nutrition and health of the American people through enhancing the quality of the American diet and related health behaviors.  Unique aspects of NP107 are that it emphasizes a food-based approach to improving health; it has the core capability to sustain long-term research in areas deemed of high priority for the Nation’s health; and it conducts multidisciplinary research to improve the American food supply.  USDA’s Food Composition Lab, National Nutrient Databank Lab, and the “What We Eat in America” survey group are unique national resources which also reside within NP 107.  Research in this program is relevant to Strategic Goal 4: Improve the Nation’s Nutrition and Health in the USDA, REE and ARS Strategic Plans. 

The United States food supply provides high quality foods that allow people to meet their nutritional requirements at lower relative cost than in any setting in history.  Because of the wide variety of inexpensive and tasty foods available it is also easy for people to consume too many calories and insufficient essential nutrients unless they have access to and implement relevant knowledge.  The ARS Human Nutrition Program aims to identify nutritive and health-promoting components in foods, to evaluate the nutritional value of diets eaten by people in America, and to determine how consumption of specific foods or nutrients in combination with appropriate physical activity is related to health of the population.  This knowledge provides valuable information to policy makers, farmers, food processors and manufacturers, and consumers. 

Improper nutrition in combination with a sedentary lifestyle are contributing risk factors for obesity, type-2 diabetes, cardiovascular disease, some types of cancer, gallbladder disease, and osteoarthritis.  More than 7 in 10 Americans will be affected by one or more of these conditions.  The USDA Economic Research Service estimated that the cost of poor nutrition in 1994 was $71 billion in medical costs, lost productivity, disability and premature death from heart disease, diabetes, cancer, and stroke.  Based on greatly increased costs in 2003 and the same proportion of each disease or condition attributable to faulty nutrition (ranging from 17 to 30%), the estimate is now $267 billion annually resulting from suboptimal diet as the portion of total costs of cardiovascular disease, cancer, diabetes, arthritis, gallbladder disease, and hypertension.  

The Human Nutrition program is not aimed at treating or curing disease.  Rather, it is focused on maintaining health and preventing disease through food-based recommendations. In the past, nutrition questions asked by ARS and other scientists addressed nutrient requirements to avoid deficiencies.  Generally, deficiencies are no longer of concern in the United States.  Rather, over-consumption and caloric imbalance have become more imperative issues for the average American. Further, differing responses of individuals to dietary interventions has prompted the need to move towards “personalizing” nutrient requirements by applying recent genomic and metabolomic technologies to nutrition. Non-nutrient (i.e., those with no known human requirement) components of foods, such as a variety of plant chemicals, have health-promoting activities that are also being actively investigated.  But new information and healthier foods must be combined with essential knowledge on how to beneficially alter food choices and increase physical activity in order to promote health.

Relationship of NP107 to the ARS Strategic Plan: Results of NP107 research support the “Actionable Strategies” associated with the performance measures shown below from the ARS Strategic Plan for 2003-2007, Objective 4.1: Promote Healthier Individual Food Choices and Lifestyles and Prevent Obesity; Improve Human Health by Better Understanding the Nutrient Requirements of Individuals and the Nutritional Value of Foods; Determine Food Consumption Patterns of Americans. 

Performance Measures 4.1.1: Scientifically assess the efficacy of enhancements to the nutritional value of our food supply and identify, conduct, and support intramural and extramural research to develop, test, and evaluate effective clinical and community dietary intervention strategies and programs for modifying diet, eating behavior, and food choices to improve the nutritional status of targeted populations.  A special emphasis is to prevent obesity and promote healthy dietary behaviors.  Targets: Scientifically assess the health benefits to humans of two new functional foods introduced via ARS research programs. Execute and report on two completed Delta NIRI projects.

Performance Measures 4.1.2: Define functions, bioavailability, interactions, and human requirements (including effects such as genetic, health status, and environmental factors) for known, emerging, and new classes of nutrients in the food supply and provide that information in databases.  Targets: Develop research information and technology on human requirements and functions of known and emerging classes of nutrients and on the relationships between diet and health needed to support Departmental food policy reflective of revised Dietary Guidelines 2005.  Expand the Nutrient Database for Standard Reference to include phytochemicals and release the joint ARS-NIH Dietary Supplement Ingredient Database (DSID).

Performance Measures 4.1.3: Determine food consumption patterns of Americans, including those of different ages, ethnicity, regions, and income levels.  Provide sound scientific analyses of the U.S. food consumption information to enhance the effectiveness and management of the Nation’s domestic food and nutrition assistance programs.  Target: Provide food consumption information from the “What We Eat in America” dietary survey for 10,000 individuals.      

Component 1.             Composition of Foods

ARS is the primary provider of the food nutrient composition information for the United States. To reflect the dynamic nature of the American diet, the USDA National Nutrient Databank must be continually updated to include the changing array of foods eaten in the United States from both domestic and international sources.  No other facility does this and this database is the “gold standard” for all others in the world.  Besides the need for information on essential nutrients, there is a growing need for new data on food components known to impart health benefits in people.  Identification of these health promoting compounds is inextricably interwoven with the development of new analytical methodology to quantitatively measure the food constituents found in the American diet.  Following identification and analysis, values are incorporated into computer databases and publicly released for use by consumers, professionals, universities, government agencies, and private industry.

Problem Area: Analysis of key foods, defined as the major contributors of calories and nutrients in the Nation’s diet, is required because of changes in the composition of foods over time and changing choice of foods.  For example, the amount of fat in beef and pork has decreased over time as a result of changes in production and processing methods but consumers choose chicken now more than other meats. Changes in agricultural practices like selecting faster maturing crops can alter the amount of nutrients in the final product.  Likewise, changes in manufactured foods such as breakfast cereals and crackers have resulted in increased fiber and decreased trans fatty acids, respectively.  In order to assess the contribution of eating these foods to health, it is essential to have current data on the composition of the foods.  In addition, as analytical instruments and methods are improved and become less expensive, more accurate and more specific tests for the nutrients of interest are developed.  This problem area encompasses the following researchable issue.

Researchable Issue: To analyze key contributors of nutrients affecting obesity and to monitor nutrient changes in high priority foods over time.  Foods will be assayed to monitor changes resulting from modification in agricultural practices, processing, reformulation and fortification.  Nutrients targeted in these foods include those identified by the 2005 Dietary Guidelines Advisory Committee as “shortfall” (e.g., vitamin D) or “excess” (e.g., trans fatty acids) nutrients.  Sufficient sampling of food products from diverse geographical regions is necessary to generate data representative of food commonly consumed around the country.  These foods are assayed for up to 65 nutrients. 

Inputs/Resources:  Scientists assigned to this problem area are from the Beltsville Human Nutrition Research Center, Beltsville, MD; the Human Nutrition Research Center on Aging, Boston, MA, and the Grand Forks Human Nutrition Research Center, Grand Forks, ND.

Outputs/Outcomes:

·    Updates to the food composition values in the National Nutrient Database for Standard Reference on a yearly basis

·    Production of special interest databases providing information on specific nutrients such as choline, fluoride, and a variety of chemicals found in foods that have health-promoting activities

·    Development of new and more accurate analytical methods for compounds in foods

·    Generation of a Dietary Supplement Ingredient Database

Impact: Better knowledge of food composition will allow scientists to more accurately link nutrient intake and food patterns with health outcomes. This, in turn, guides food producers and processors to offer healthier food options. This knowledge also helps consumers make better food choices because the databases are freely available via the Internet and can be downloaded to a personal computer or a personal digital assistant (PDA).  The databases produced are made available at no cost to private industry which uses the information for analysis of nutrients in their products and for development of computer programs to analyze diet.  All databases are used by other Federal scientists involved in research on diet and health in agencies including the National Institutes of Health and the Centers for Disease Control and Prevention; the USDA Food Safety and Inspection Service and the Food and Drug Administration use these databases for enforcement of food labeling laws.

Component 2.             Bioavailability of Nutrients and Food Components

Problem Area: Consumption of nutrients does not mean they are fully absorbed from the intestine and available for use in the rest of the body.  Bioavailability is one of the factors that determine nutrient requirements (see Component 4 below) because it affects how much of a nutrient must be consumed to meet the true requirement.  Numerous factors affect biological availability and these differ for each compound of interest.  For example, heme-iron in red meat is more readily absorbed than iron from plant sources when the same amount of the mineral is eaten. Some of the food components being studied in this program include iron, zinc, vitamin K, carotenoids, vitamin A and polyphenols.  The latter are plant pigments and include a variety of compounds, such as anthocyanins, with health-promoting activity. This problem area encompasses the following researchable issues.

Researchable Issues:  It is not known if many of the recently discovered compounds in plants are absorbed and, if they are, to what extent.  Further, there are few studies on the metabolic fate of the compounds after uptake from the intestine. Several types of research studies are being conducted to address this problem, including plant growth/nutrient accumulation, animal models, human feeding trials, quantitative chemistry, intestinal cell culture studies and kinetic mathematical modeling techniques. Studies of mineral availability from plants encompasses research on soil distribution and chemical form, absorption by plant roots, transport to and deposition in edible parts of the plant, identification of genetic factors controlling accumulation in the plant, and identifying food substances that affect availability to humans. Many of these same factors are being assessed for other compounds such as the anthocyanins.

Inputs/Resources:  Scientists working on these studies are located at the Beltsville Human Nutrition Research Center, Beltsville, MD; the US Plant, Soil and Nutrition Laboratory, Ithaca, NY; the Grand Forks Human Nutrition Research Center, Grand Forks, ND; the Human Nutrition Research Center on Aging, Boston, MA, the Western Human Nutrition Research Center, Davis, CA, and the Children’s Nutrition Research Center, Houston, TX.

Outputs/Outcomes:

·    Identification of soil and growing conditions that optimize uptake and deposition of minerals into edible plants

·    Determination of genetic traits of plants that affect concentration of target compounds

·    Recognition of other dietary factors that alter absorption of these nutrients from the intestine

·    Discovery of pathways used by intestinal cells to take up and metabolize these nutrients for distribution throughout the body

Impact:  Studies conducted under this area will assist farmers in choosing crops that have the potential to accumulate more of the desirable nutrients and to use fertilization protocols that optimize the nutrient quality for people.  Better understanding of the bioavailability of nutrients will allow scientists to make more meaningful recommendations about nutrient requirements for humans. 

Component 3.             Nutrition Monitoring

Problem Area: The USDA’s “What We Eat in America” survey provides continuous monitoring of the energy, nutrients, and foods consumed by the American population. From this cross-sectional survey, usual nutrient intakes of the American population are measured and nutritional adequacy can be determined. This is the only nationally representative diet survey conducted in the United States.  Linkage in the same population of dietary data with health endpoints collected by the National Health and Nutrition Examination Survey (NHANES) now generates more useful information accessible to researchers studying diet and health.  The problem area encompasses the following researchable issues.

Researchable Issues: Currently, 5,000 Americans participate in the dietary arm of the NHANES study.  The major aim of the dietary component of this study is to determine food consumption patterns of Americans, including those of different ages, ethnicity, regions, and income levels.  A further goal is to provide sound scientific analyses of the U.S. food consumption information to enhance the effectiveness and management of the Nation’s domestic food and nutrition assistance programs.  Despite the relatively high number of survey participants, which allows general conclusions about diet of the population as a whole, there are currently not enough surveyed to provide high statistical accuracy for the subgroups described above so one goal is to double the number of subjects who participate in the main dietary survey.

Inputs/Resources:  ARS scientists working on these studies are located at the Beltsville Human Nutrition Research Center, Beltsville, MD.

Outputs/Outcomes:

·    Generation of data sets containing dietary intake and demographic information are made available to the food industry, researchers and the general public through the National Center for Health Statistics web site

·    Correlation of dietary information with health status, blood levels of nutrients, risk factors for chronic diseases will help focus on foods and nutrients associated with better health status

·    Development of national nutrition policy, including programs such as Food Stamps,  Women, Infants and Children (WIC) and School Meals, is based to a large extent on data collected by the dietary survey

Impact: This unique national resource is the only systematic, nationally representative sampling of American dietary habits.  Knowledge of eating patterns allows determination of nutrient intake for those considered inadequate (e.g., calcium) and those viewed as excessive (e.g., sodium and saturated fat).  Knowledge of nutrient intakes is used in establishing the U.S. Dietary Reference Intakes (DRIs) and the U.S. Dietary Guidelines, the dietary standards for the American public.  Also, USDA has an important responsibility to ensure that its food-related assistance programs are formulated and operated in a way that ensures health and minimizes obesity for the low-income populations targeted by the programs. The ARS “What We Eat in America” survey is the primary dataset and the Dietary Guidelines and DRIs are the reference standards used to evaluate the efficacy of the USDA food assistance and education programs.  Also, this information is used by food industry and government regulators to determine levels of fortification/enrichment with vitamins or minerals or for reducing a nutrient in food to improve the health profile. As eating habits change over time, the continuous collection of dietary survey data allows stakeholders to evaluate changes in nutrients in the American diet and correlate them with a variety of health parameters.

Component 4.             Nutrient Requirements

Problem Area: Although Dietary Reference Intakes (DRI’s) have been set for many nutrients, knowledge gaps remain and updates are needed as new research becomes available. Of particular importance is the need for DRIs for children which are absent due to a lack of studies in this area. Also, periodic changes in the DRI’s often reflect modifications of what scientists believe is the best parameter to use for assessing health, e.g., short-term calcium balance studies instead of long-term changes in bone density or incidence of fractures in older women. Similarly, the required amounts of calories and macronutrients such as protein vary with age and level of physical activity. This problem area includes the following researchable issues.

Researchable Issues: Essential nutrient requirements for human health at various stages of life still need to be established, particularly for children and the elderly. Optimal levels of energy, protein, carbohydrate, lipid, fiber, vitamins and minerals are being studied.  Some specific examples include the following: The dietary requirement for calcium is affected not only by the amount of calcium in the diet and the age of the individual but by other components of the diet including protein, vitamin D, magnesium, copper and zinc.  In addition, vitamin K levels in food and its bioavailability have an impact on bone density.  Another issue is that protein requirements in the elderly may be higher than currently recommended by the DRI’s in order to prevent a decline in muscle mass that often accompanies aging.

Inputs/Resources:  Scientists working on these studies are located at all six Human Nutrition Research Centers at Beltsville, MD, Boston, MA, Davis, CA, Grand Forks, ND;  Houston, TX, and Little Rock, AR..

Outputs/Outcomes:

·    Identify interactions of calcium with other nutrients such as protein, magnesium, copper and zinc that affect its uptake and deposition in bone.

·    Determine the quantitative requirement of vitamin D in older men and women

·    Establish the amount of vitamin K in foods, its bioavailability and impact on bone density

·    Quantify the amount of dietary protein needed in older men and women to prevent loss of muscle mass

Impact: Research results in this component will help establish more accurate Dietary Reference Intakes in future reports from the Food and Nutrition Board of the National Academies of Science. More accurate targets for DRI’s will enable better planning for food assistance programs and for consumers to choose a diet more likely to prevent degenerative conditions associated with aging.  This information is also used by the Food & Drug Administration in preparation of the Nutrition Facts panel mandated on packages of most foods and, in combination with research under national program components Nutrition Monitoring and Composition of Foods, to determine what level of enrichment/fortification of processed foods with vitamins or minerals should be allowed or mandated.

Component 5.             Health Promoting Properties of Plant and Animal Foods

Problem Area: A more nutritious food supply can be developed by lowering caloric density and increasing nutrients and health-promoting non-nutrient constituents of the diet.  This can be achieved by traditional breeding or genetic modification of crops and animals, changes in food production or processing, and development of new foods or processing methods for commonly eaten foods. This problem area includes the following researchable issues.

Researchable Issues: Changes in water availability, temperature, atmospheric carbon dioxide and other factors affect the nutritional value of crops.  Only when the impact of such alterations is quantified will food producers and researchers understand how environmental changes affect nutrient concentration in crops.  A number of specific foods or extracts from foods is being studied by scientists in this national program. Examples include: effects of barley on glucose utilization and insulin sensitivity as well as risk factors for cardiovascular disease (CVD) and weight loss; whether different types of tea reduce inflammation and risk for CVD; how beneficial bacteria called probiotics, found in yogurt and other fermented dairy foods, modify the immune response and prevent infection by pathogenic bacteria like Salmonella; and if compounds found in berries, tea and other antioxidant-rich foods reduce the risk of age-related eye disease and cognitive decline..

Inputs/Resources: ARS scientists working on these studies are located at the Beltsville Human Nutrition Research Center, Beltsville, MD, the Human Nutrition Research Center on Aging at Tufts University, Boston, MA, the Western Human Nutrition Research Center, Davis, CA, and the Children’s Nutrition Center at Little Rock, AR.

Outputs/Outcomes:

·    Determine effects of changes in agricultural conditions on nutrients in crops

·    Assess the influence of consuming barley, tea, berries, vitamin E, and probiotic bacteria on reducing the risk for common chronic diseases or for infections

·    Ascertain if following the Dietary Guidelines for Americans reduces the risk of eye disease commonly associated with aging

Impact: As environmental conditions for agriculture change over time, the amount of nutrients consumed by the American people may be altered.  It is essential for the food industry, scientists and public policy makers to understand if this is of nutritional significance and, if so, to modify production practices.  Many foods with health benefits have been identified in animal or cell culture models but the impact on human health is still debatable. Studies conducted in ARS labs will help to resolve a number of outstanding issues by linking human studies with more basic models to understand mechanisms by which food components may protect health. If studies in this program demonstrate additional benefits of following the Dietary Guidelines for Americans, this will give additional credence to government recommendations for a healthy diet.

Component 6.             Prevention of Obesity and Disease: Relationship between Diet, Genetics, and Lifestyle

Problem Area: There is considerable variation in health status of populations in response to consumption of specific types and amounts of nutrients.  Some of the reasons for this are genetic diversity, gender, behavior, and lifestyle.  Genetic variation as a factor in modifying response to nutrients is an area of intense research because studies have demonstrated the body responds to environmental factors such as diet and tobacco use as a result of single or multiple gene changes.

Researchable Issues:  Examples of some of the genetic differences being studied by researchers in this national program include: those that modify metabolism of the B vitamin folic acid which alter the risk for both cardiovascular disease (CVD) and cancer; those that contribute to intestinal resistance to the hormonal actions of vitamin D on calcium absorption; markers for CVD and obesity in the U.S. population and other countries; and genes that affect development of obesity in Hispanic children.  Dietary components that affect disease under study in this program include: types of fatty acids for effects on the inflammatory response; selenium as a protective agent against cancer; nutrient regulation of hormone receptors implicated in a variety of health conditions; and breast versus formula-feeding, school meals, and phytochemicals in fruits for effects on neurophysiological and psychological development in infants and children. Finally, the effects of physical activity on long-term food intake and maintenance of healthy weight are being assessed.

Inputs/Resources:  ARS scientists working on these studies are located at all six Human Nutrition Research Centers in this national program: the Beltsville Human Nutrition Research Center, Beltsville, MD; the Grand Forks Human Nutrition Research Center, Grand Forks, ND; the Human Nutrition Research Center on Aging, Boston, MA, the Western Human Nutrition Research Center, Davis, CA; the Children’s Nutrition Center, Little Rock, AR; and the Children’s Nutrition Research Center, Houston, TX.

Outputs/Outcomes:

·    Identify the effects of genetic variation on response of various risk factors for chronic disease to differences in diet

·    Determine how genetic factors affect development of obesity in children from an ethnic minority

·    Assess whether infant or childhood feeding practices alter brain development and function

·    Provide data that bear on whether selenium, vitamin A and other antioxidants reduce cancer risk or improve resistance to infection

·    Understand whether changes in physical activity alter long-term food intake and maintenance of healthy weight

Impact: Successful studies under this component of the national program will help to explain the variation in response often seen with large-scale dietary interventions.  If specific genes or gene combinations are identified, they can be used to tailor dietary recommendations for those at highest risk of chronic disease or development of obesity. Determination of even subtle differences in brain function in children who were fed differently will have profound effects on many government food assistance programs.

Component 7.             Health Promoting Intervention Strategies for Targeted Populations

Problem Area: Although nutrition knowledge is necessary to implement strategies to maintain healthy weight and meet other nutritional requirements, this information alone does not ensure proper nutrition for a variety of reasons including inadequate access to recommended foods, low income, low literacy, cultural beliefs and a variety of other factors.  Dietary interventions need to be created and tested that will improve the health of Americans. Research on the endpoints of interest is needed to identify effective ways of communicating food and nutrition knowledge to individuals and populations to elicit changes in food intake and other behaviors that are based on scientific evidence. 

Researchable Issues: Several approaches to this problem are taken by scientists in the national program. Development of databases on food consumption and use of them in identification of practical diet practices to avoid obesity, diabetes, osteoporosis and other chronic conditions is being done. Comparison of a diet and exercise program with physical activity alone is required to address the issues of whether fitness at any weight is as healthy as being in a specified healthy weight range and what interventions are sustainable over the long term. It is also necessary to address nutrition interventions in the context of local community issues because different demographic backgrounds will necessitate interventions of varying types.

Inputs/Resources:  ARS scientists working on these studies are located at: the Beltsville Human Nutrition Research Center, Beltsville, MD; the Children’s Nutrition Research Center, Houston, TX, the Western Human Nutrition Research Center, Davis, CA, and the Lower Mississippi Delta Nutrition Intervention Research Initiative, headquartered in Little Rock, AR.

Outputs/Outcomes:

·    Develop databases that can be used to identify diet practices to avoid obesity and other chronic health conditions

·    Show that an exercise program without intent to lose weight improves insulin sensitivity in adolescents

·    Identify, implement and test nutrition and physical activity interventions in low-income communities

Impact: Although the “answer” to obesity is always given as eating less and exercising more, implementation of these two factors has not been consistently effective in preventing development of obesity in most studies. Part of the explanation for this is that a single recommendation will not work for all individuals or all communities and implementation requires more than simple knowledge of what is recommended.  Successful achievement of interventions to prevent weight gain and its accompanying health consequences will serve as a model to institute those changes in other groups of people and will reduce the economic burden of obesity-related health costs that now fall disproportionately on those in lower socioeconomic groups.