Planning Nutritionally Adequate Diets for Groups: Methods Used to Develop Recommendations for a Child and Adult Care Food Program.

Planning nutritionally adequate intakes for large groups of people presents many challenges. Because of between-person variations in both food choices and nutrient requirements, it is necessary to examine nutrient intake distributions and select a Target Median Intake (TMI) that will lead to a low prevalence of inadequate nutrient intakes. The TMI may then be used to guide a feeding or education program. A comprehensive report from the Institute of Medicine evaluated nutrient intakes from the NHANES and recommended new meal patterns for all age groups (other than infants) served by the Child and Adult Day Care Food Program, which provides meals and snacks to children and adults in a variety of care settings. The Estimated Average Requirement, a DRI value, for each nutrient of interest was used to estimate both the prevalence of inadequate intakes as well as the changes in the intake distribution that are needed to reduce unacceptably high levels of inadequacy. For nutrients with an Adequate Intake (AI), the prevalence of inadequacy could not be estimated, but the AI could be used as the TMI. Simultaneously, it was important to ensure that the new intake distributions did not result in intakes that exceeded the Tolerable Upper Intake Level for any nutrient. Data for 2- to 4-y-old children are presented in detail to illustrate this process. Of 18 nutrients examined, analyses showed that intakes of vitamin E, potassium, and fiber should be increased, while intakes of sodium should be decreased. If more recent nutrient standards are used, revised assessments show that calcium intake should also be increased, while potassium intake is adequate. These methods and results should be useful when designing feeding programs for other population groups within the United States, as well as in other countries.

Why the Derivation of Nutrient Reference Values Should be Harmonized and How It Can be Accomplished.

The adoption of a panel of Nutrient Reference Values (NRVs) in place of a single recommended intake allowed for assessment of nutritional adequacy and safe upper intake levels for nutrients on a population level and for individuals. The Average Requirement (AR) and Tolerable Upper Intake Level (UL) comprise 2 core NRVs needed to obtain accurate, comparable estimates of population-level nutrient intakes, which are necessary to plan and evaluate nutrition support programs globally. Harmonizing the derivation of NRVs, particularly the AR and UL, is essential to ensure inclusion of all countries, whether high-, middle-, or low-income, in the process and to improve access for all users to the tools and data needed to carry it out. The NRV process today is more rigorous and transparent than the first derivation of DRIs because of adoption of systematic reviews and bias assessment methodologies, updated food and nutrient databases, data on cultural and context-specific dietary patterns, and better metabolic markers of nutritional status. A proposed framework for the derivation of NRVs builds on available methodologies to support the NRV process; however, this is not sufficient to achieve harmonization of the process. Fundamental to moving forward toward harmonization is removing existing barriers, including limited access to resources and databases and variance in terminology used to identify specific NRVs; adoption of more rigorous and transparent methodologies, including chronic disease endpoints, in the review process; and creating a central repository for easily accessible evidence. Chief among the barriers to harmonization is a willingness of global bodies to support an agreed-upon approach to the derivation process. Improving access to tools and data resources and providing guidance and support to encourage their adoption are critical to achieving harmonization of the NRV process. The factorial approach for calculating a nutrient requirement is described as the sum of total endogenous nutrient loss (endogenous fecal, urinary, integumental, seminal, menstrual) divided by its bioavailability or fractional absorption.

Milestones in DRI Development: What Does the Future Hold?

The state of nutritional health in the United States in the early part of the twentieth century was very different from today. Nutrient deficiencies and dental caries were prevalent health concerns for many Americans. In 1940, the US National Defense Advisory Commission asked the National Academy of Sciences for help in studying problems of nutrition in the United States. The outcome was issuance of the first RDAs. The goal of the RDAs was to recommend "…allowances sufficiently liberal to be suitable for maintenance of good nutritional status." In the subsequent decades, a very different nutritional health challenge began to emerge for an increasing proportion of the population, that of overweight and obesity and risk of diet-related chronic disease. In part, as a response to this challenge, the RDA process was revised and the Dietary Reference Intakes (DRIs) were developed. The DRIs are a set of reference values that, when adhered to, predict a low probability of nutrient inadequacy or excessive intake. Recently, new DRI guidelines were proposed to define reference points for nutrient and food component intakes that influence risk of chronic disease. Developing DRIs for chronic disease endpoints presents unique challenges, notably, chronic diseases are multifactorial in nature and not directly nutrient-specific; the body of evidence supporting nutrients and other food substances as modifiers of risk of chronic disease is generally limited; and there is a lack of consistency in findings across study types. In addition, the latency of dietary exposures and chronic disease outcomes makes it difficult to demonstrate causality. Adapting the DRI model to meet the needs of the general population in the current context suggests a need to redefine the boundaries that describe the health of the population and to re-examine how indicators of chronic disease can be integrated effectively into the DRI process.

Scanning for new evidence to prioritize updates to the Dietary Reference Intakes: case studies for thiamin and phosphorus.

BACKGROUND: Dietary Reference Intakes (DRIs) are fundamental to inform national nutrition policy. However, a regular systematic review of the 51 nutrients that have DRIs has limited feasibility, and many DRIs have not been reviewed in >15 y. OBJECTIVE: To address this issue, individuals (nutrient review group) who were members of the Food and Nutrition Board developed a streamlined, evidence-based methodology that could be used to identify nutrients potentially in need of a systematic review. DESIGN: The proposed methodology, termed an evidence scan, comprises several steps. First, an analytic framework is developed to identify markers of associations between intake of a nutrient and a corresponding clinical outcome. Next, the framework is used to direct the identification of keywords for a scan of published research that is potentially relevant to intake requirements or upper intake levels for a nutrient. Last, a panel of content experts selects the abstracts that are likely to be relevant and reviews the full publications. The results may be used to determine whether a revision of the nutrient's DRI is an immediate priority but would not supplant a comprehensive systematic evidence review. RESULTS: To illustrate the process, 2 nutrients were selected as case studies: thiamin and phosphorus (DRIs were last set in 1998 and 1997, respectively). Using the evidence scan for thiamin, we identified 70 potentially relevant abstracts, of which 9 full publications were reviewed. For phosphorus, 127 potentially relevant abstracts were identified, and 29 full publications were reviewed. CONCLUSIONS: From the review of these 2 nutrients, the nutrient review group concluded that there was insufficient new evidence to assign a high priority to a comprehensive systematic review for either thiamin or phosphorus. Evidence scanning is an efficient method of identifying DRI nutrients that are most in need of either a new or an updated systematic review.

SNAP benefits: Can an adequate benefit be defined?

The Supplemental Nutrition Assistance Program (SNAP) increases the food purchasing power of participating households. A committee convened by the Institute of Medicine (IOM) examined the question of whether it is feasible to define SNAP allotment adequacy. Total resources; individual, household, and environmental factors; and SNAP program characteristics that affect allotment adequacy were identified from a framework developed by the IOM committee. The committee concluded that it is feasible to define SNAP allotment adequacy; however, such a definition must take into account the degree to which participants' total resources and individual, household, and environmental factors influence the purchasing power of SNAP benefits and the impact of SNAP program characteristics on the calculation of the dollar value of the SNAP allotment. The committee recommended that the USDA Food and Nutrition Service investigate ways to incorporate these factors and program characteristics into research aimed at defining allotment adequacy.

Aligning nutrition assistance programs with the Dietary Guidelines for Americans.

Nutrition assistance programs, including the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), the National School Lunch and School Breakfast Programs (NSLP/SBP), and the Child and Adult Care Food Program (CACFP), are intended to offer low-income families the opportunity for a healthier food pattern that promotes overall health and reduces risk for chronic disease. To be successful in improving the diets of underserved Americans requires a unified approach toward meeting the nutritional needs of program participants. Newly revised recommendations increase intakes of fruits, vegetables, and whole-grain-rich foods while reducing consumption of saturated fats, added sugars, and sodium. In addition to improving the nutritional profile of meals and snacks for NSLP and CACFP and meal patterns for WIC, the new recommendations ensure variety within food groups for menus across a week and allow for regional and cultural preferences and increased flexibility of choice within food groups. The newly revised meal pattern recommendations are broadly applicable to the design of feeding programs for any age group and for any combination of meals and snacks being provided.

Food and Nutrition Board update: What do SNAP allotments, physical fitness, and obesity prevention have in common?

The Institute of Medicine's Food and Nutrition Board had a productive year, with important expert committee reports on the Supplemental Food Assistance Program, physical fitness, and accelerating obesity prevention efforts that provided grounding for dietary guidance and nutrition policies and programs. This summary describes Food and Nutrition Board activities, including current thinking on dietary reference intakes. The summary also highlights consensus reports on defining and measuring Supplemental Food Assistance Program benefit adequacy and on physical fitness and health outcomes in youth. In addition, current and new activities related to obesity prevention and care are addressed. What do these activities have in common? All adhere to the Institute of Medicine report model by filling gaps and by being analytical, evidence-based, and challenging.

New guidelines for weight gain during pregnancy: what obstetrician/gynecologists should know.

PURPOSE OF REVIEW: To review the recently issued guidelines for weight gain during pregnancy. RECENT FINDINGS: These guidelines were developed to minimize the negative health consequences for both mother and fetus of inadequate or excessive weight gain. They call for categorizing women's prepregnancy BMI using the WHO/National Heart, Lung and Blood Institute cutoff points and provide ranges of recommended weight gain for underweight (28-40 lb), normal weight (25-35 lb), overweight (15-25 lb) and obese (11-20 lb) gravidas. Data were insufficient to construct specific guidelines for women with class II or class III obesity. Women should attempt to conceive at a normal weight for better obstetric outcomes. Improved comprehensive preconceptional care is necessary to help women reach this goal. Most American women currently gain weight below or above the new ranges, so changes are required in both women's behavior and how their care is managed. Data from a variety of interventions related to improved diet and increased physical activity show that individualized care can assist women in gaining weight within these guidelines. SUMMARY: The guidelines offer many opportunities for obstetrician/gynecologists, together with ancillary healthcare providers, to assume a larger role as 'women's healthcare physicians' and to conduct research that could improve the health of mothers and children.

Nutrient and contaminant tradeoffs: exchanging meat, poultry, or seafood for dietary protein.

When making food choices, consumers are faced with the dilemma of reconciling differences between health benefits and exposure to potential toxins. Analyses to estimate likely intake and exposure outcomes for young children and women of child-bearing age shows that seafood, chicken, and beef, while approximately equivalent in protein, vary in key nutrients of importance as well as in levels of certain contaminants. Increasing the variety of choices among meats, poultry, and seafood and consuming them in amounts consistent with current dietary guidelines and advisories will contribute toward meeting nutritional needs while reducing exposure to any single type of contaminant.

Reducing exposure to dioxins and related compounds through foods in the next generation.

Dioxins and related compounds are undesirable and unintended contaminants in the food supply, and dietary intake is the major route of exposure. Reducing dietary exposure to dioxins among the most vulnerable segments of the population (i.e., pregnant women, infants, and young girls) is an effective strategy for reducing body burdens in future generations. Exposure to dioxins through foods can be minimized by selecting lower-fat versions of meats, poultry, and dairy products. Consuming all foods, including fatty fish, in recommended amounts is congruent with the goal of reducing dioxin intake exposure and maintaining good health.