Scientific Report of the 2015 Dietary Guidelines Advisory Committee

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Part D. Chapter 1: Food and Nutrient Intakes, and Health: Current Status and Trends - Continued

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Dietary Patterns Composition

Dietary patterns with positive health benefits are described as high in vegetables, fruit, whole grains, seafood, legumes, and nuts; moderate in low- and non-fat dairy products; lower in red and processed meat; and low in sugar-sweetened foods and beverages and refined grains. The primary dietary patterns examined and described in Part D. Chapter 2: Dietary Patterns, Foods and Nutrients, and Health Outcomes included both a priori, investigator-derived scoring systems such as DASH/OMNI, Mediterranean diet scores, and the Healthy Eating Index, as well as data-driven approaches using factor/cluster analysis or reduced rank regression. The findings presented come from controlled intervention trials, cohort studies, and nested case-control studies. The DGAC examined these patterns in an attempt to quantify, for the first time, the approximate amounts of each food group in these patterns. The DGAC also examined the range of and commonalities across food group intakes in healthy dietary patterns and compared these ranges to the range of usual adult consumption in the United States and to the range recommended by the USDA Food Patterns.

Question 18: What is the composition of dietary patterns with evidence of positive health outcomes (e.g., Mediterranean-style patterns, Dietary Approaches to Stop Hypertension-style patterns, patterns that closely align with the Healthy Eating Index, and vegetarian patterns), and of patterns commonly consumed in the United States? What are the similarities (and differences) within and among the dietary patterns with evidence of positive health outcomes and the commonly consumed dietary patterns?

Source of evidence: Data analysis

Conclusions

Dietary patterns with varying food group composition, but certain common elements were observed across intervention and cohort studies to have health benefits. A healthful diet can be achieved by following any of these dietary patterns.

In general, the ranges of intake in dietary patterns with positive health benefits are very close to those recommended by the USDA Food Patterns, but amounts of some specific food groups vary across the various diet pattern types.

  • DASH-style diets, Mediterranean-style diets, and the USDA Food Patterns are similar with respect to amounts of fruits and vegetables, and the OMNI diets are slightly higher than the USDA Food Patterns.
  • Dairy intake is comparable between DASH-style diets and the USDA Food Patterns, but dairy is lower for Mediterranean-style diets than for the USDA Food Patterns.
  • Red and processed meats are higher in the Mediterranean-style diets but lower in the DASH-style diet than is recommended by the USDA Food Patterns.
  • Seafood intake is similar in DASH-style and higher in Mediterranean-style diets than in the USDA Food Patterns.

The data from the intervention trials and the cohort studies examined provide empirical data that the USDA Food Patterns provide an evidence-based guide to healthy patterns of food consumption.

Implications

The quality of the diets currently consumed by the U.S. population is suboptimal overall and has major adverse health consequences. Several options exist for dietary patterns that can be followed to improve the population’s diet quality. The approaches that can be taken are varied and can be adapted to personal and cultural preferences. The ability to offer the U.S. population alternative dietary pattern options and to tailor them to personal preferences may increase the likelihood of long term success of maintaining a healthy diet pattern, ultimately leading to improved health in the U.S. population.

Review of the Evidence

The DGAC analyzed data on food group composition reported in research articles on dietary patterns and health outcomes. These articles were drawn from those included in the questions on dietary patterns and health examined by the Committee (see Part D. Chapter 2: Dietary Patterns, Food and Nutrients, and Health Outcomes). The studies reported in that chapter D2 were reviewed to identify those that reported semi-quantitative data on food group intakes among the sample or population group with positive health outcomes (Table D1.31).93-112 These sample or population groups included the intervention group in intervention studies, the highest category (usually the top quintile) in cohorts and nested case-control studies measuring diet with an a priori index, or a specific cluster or factor analysis group. Approximate quantified food group intakes for these subsets of the population or samples with a beneficial health outcome were identified. These intakes were converted to grams per day if not reported this way in the original manuscripts. Then, all data were converted to grams per 1000 calories to allow for comparisons across studies.

For comparison to usual intake levels of each food group in the United States., data from NHANES 2007-2010 for usual intake by adult age/sex groups41 in cup or ounce equivalents were converted into grams using average weights based on Food Patterns Equivalents Database (FPED) data.48 49 The gram weights were divided by the usual calorie intake for that group, and multiplied times 1000 for an estimate of the food group intake per 1000 calories for each adult age/sex group. The range of these intakes was used as a comparator. For comparison to the food group amounts recommended in the USDA Food Patterns (also called the Healthy U.S.-style Patterns; see Question 20) the recommended amount for adult age/sex groups in the patterns at 1600 to 2400 calories were converted to grams per 1000 calories by the same procedure used for the usual intakes (see Figures D1.56 to D1.60).

Vegetable intake in the OMNI diets was higher than both the USDA Food Patterns and current consumption estimates, but DASH-style, PREDIMED, most of the Mediterranean scores, and data driven approaches were very similar to vegetable amounts recommended by the USDA Food Patterns. Fruit intake was higher in the OMNI diets and PREDIMED relative to the USDA Food Patterns and current consumption, but DASH, the Mediterranean score diets, and many of the data driven scores are all within the range of the USDA Food Pattern recommendations. Dairy intakes in OMNI, DASH, and some of the Mediterranean and data driven scores were all within the ranges recommended by the USDA Food Patterns, while PREDIMED and some other scores had lower intakes of dairy. Consumption of red and processed meats was higher in PREDIMED and in some studies using Mediterranean diet scores relative to the USDA Food Patterns, whereas several cohorts using data-driven approaches to assessing diet patterns reported ranges of red and processed meat intake that aligned very well with the USDA Food Pattern recommendations. Intakes of red and processed meat were lower in the OMNI and DASH dietary interventions than in either the USDA Food Patterns or the range of usual intake in the United States. Seafood intakes for the OMNI diets and some of the data-driven dietary pattern studies aligned very well with the USDA Food Patterns. Seafood intake ranges for all the other studies were much higher than both the USDA Food Patterns and the ranges of usual intake in the United States.

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Question 19: To what extent does the U.S. population consume a dietary pattern that is similar to those observed to have positive health benefits [e.g., Mediterranean-style pattern, Dietary Approaches to Stop Hypertension (DASH)-style patterns, patterns that closely align with the Healthy Eating Index, and vegetarian patterns] overall and by age/sex and race/ethnic groups?

Source of evidence: Data analysis

Conclusion

Data from WWEIA show that the average HEI score in the U.S. population is 57 points out of a total of 100 points. The best scores (average scores) were observed for the following components: total protein foods (average score of 100 percent of possible points), seafood and plant protein (84 percent of possible points), and dairy (69 percent of possible points), while the poorest scores were observed for whole grains (25 percent of possible points), sodium (37 percent of possible points), fatty acid ratio (41 percent of possible points), greens and beans (46 percent of possible points), and empty calories (60 percent of possible points).

Young children ages 2 to 3 years and middle aged and older adults (ages 51 years and older) have the best HEI scores (total scores of 63 percent and 66 percent, respectively), while preadolescents and adolescents have the poorest HEI scores (total scores of 49 percent and 48 percent, respectively).

Implications

To improve diet quality, the U.S. population should replace most refined grains with whole grains, decrease sodium, decrease saturated fat, consume fewer calories from added sugars, and replace these calories with more varied vegetable choices, seafood, plant proteins, and low-fat dairy.

Young children and middle-aged and older adults have the highest HEI scores. These positive healthy eating habits should continue to be encouraged. Because preadolescents and adolescents have the lowest HEI scores, significant intervention is needed at the level of the individual, family, school, day care, and community settings to help this age group adopt and maintain healthful dietary patterns.

Review of the Evidence

The DGAC examined mean HEI scores and component scores for the entire U.S. population ages 2 years and older (see Appendix E-2.25: Average Healthy Eating Index-2010 scores for Americans ages 2 years and older). These data were examined for the entire population, for males and females and by age subgroups. In general, the best scores for the HEI components were for protein and seafood and plant proteins, while the poorest score was for whole grains. For nearly all of the component scores as well as the total HEI score, females tended to have better scores than males, indicating slightly healthier dietary patterns in females compared to males. Analyses by age showed that the youngest and oldest segments of the population had the best component and total HEI scores (Figure D1.61). For these groups, the component scores were very good to excellent for total fruit and whole fruit. Young children also had excellent scores for dairy, and middle-aged and older adults had excellent scores for total protein and seafood and plant protein. All age groups have poor scores for whole grains.

Data were not available to examine how closely the U.S. population’s dietary patterns align with a Mediterranean-style or DASH-style dietary pattern.

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Question 20: Using the Food Pattern Modeling process, can healthy eating patterns for vegetarians and for those who want to follow a Mediterranean-style dietary pattern be developed? How do these patterns differ from the USDA Food Patterns previously updated for potential inclusion in the 2015 DGAs?

Source of evidence: Food Pattern Modeling

Conclusion

Food Pattern Modeling demonstrates that healthy eating patterns can be achieved for a variety of eating styles, including the “Healthy U.S.-style Pattern,” the “Healthy Mediterranean-style Pattern,” and the “Healthy Vegetarian-style Pattern”. Although some differences exist across the three eating patterns, comparable amounts of nutrients can be obtained using nutrient dense foods while maintaining energy balance.

Implications

The U.S. population has a variety of options to help achieve healthful eating patterns that adhere to the Dietary Guidelines. These include the Healthy U.S.-style Pattern, Mediterranean-style Pattern, or Vegetarian Patterns. (Detailed information on these patterns can be found in Table D1.32 and Appendix E-3.7: Developing Vegetarian and Mediterranean-style Food Patterns.) These diets meet nutritional goals without excess calories and use a variety of foods. Importantly, these diets reflect the range of foods that can be used to achieve a healthful eating pattern, and they support the inclusion of diverse foods that are consistent with personal, cultural and religious preferences. These diets can be used in a variety of settings, including homes, schools, worksites, health care facilities, and places of worship.

Review of the Evidence

These conclusions were reached based on the results of the Food Pattern Modeling analysis for vegetarian and Mediterranean-style food patterns. Data from WWEIA from self-reported vegetarians were used to inform the vegetarian eating pattern (Figure D1.62) and data from the Dietary Patterns composition project reviewed above were used to select foods for the Mediterranean-style pattern.113

From three dietary patterns (“Healthy U.S.-style,” “Healthy Mediterranean-style Patter,” and “Healthy Vegetarian Pattern”), selected food group intakes across calorie levels were compared (Table D1.32). Notably, fruit and seafood were higher in the Mediterranean-style diet, while dairy was lower, based on the data presented above (Figures D1.56 to D1.60). For the Vegetarian Pattern, meat and seafood are absent, but eggs and dairy are included because self-reported vegetarians in WWEIA reported consumption of these foods. Legumes, nuts/seeds, and processed soy are all higher in the Vegetarian Pattern compared to the Healthy U.S.-style and the Healthy Mediterranean-style Patterns.

When comparing nutrient intake across these three dietary patterns, as a percent of the RDA using a woman age 19 to 30 years as an example, modest difference emerged (Table D1.33). The Vegetarian pattern is lower in sodium and all three patterns are low in vitamin D.

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