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The Dietary Guidelines Advisory Committee: From molecules to dietary patterns

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Title: The Dietary Guidelines Advisory Committee: From molecules to dietary patterns


1
The Dietary Guidelines Advisory Committee From
molecules to dietary patterns
  • Joanne R. Lupton, PhD, Regents Professor and
    William W. Allen Endowed Chair in Nutrition
  • Texas AM University

SNEF Food Guide Pyramid A Call-to-Action July
19, 2004
2
Focus of the talk
  • What is the Dietary Guidelines Advisory Committee
    (DGAC)
  • Its mandate
  • How it does its job
  • The challenge Translating dietary guidance
  • nutrient ? food based
  • Food based ? dietary patterns
  • Examples, fiber and sugar

3
Mandate for the DGAC
  • Must produce a report that contains nutritional
    and dietary information and guidelines for the
    general public.
  • Must be based on the preponderance of scientific
    and medical knowledge current at the time of
    publication.
  • National Nutrition Monitoring and Related
    Research Act of 1990 (1990) Public Law 445,
    Section 301.

4
Overview of how the DGAC does its job
  • Five public meetings last one will be August 11,
    2004
  • Written public comments solicited, reviewed by
    committee and staff
  • Listened to oral public comments
  • Workload divided among subcommittees which
    reported back to the full committee at public
    meetings
  • Each subcommittee assisted by one or more staff.

5
Overview of how the DGAC does its job
  • Science review committee (Janet King, Larry
    Appel, Joanne Lupton) review all of the committee
    work for consistency and adherence to
    science-based standards.
  • Consulted outside experts where deemed necessary.
  • Requested modeling of food patterns as required.
  • Used an evidence-based system to come to
    conclusive statements on all questions asked.

6
Use of an evidence-based system
  • What is an evidence-based system?
  • A science-based systematic evaluation of the
    strength of the evidence behind a statement. In
    the case of the guidelines, the statement will be
    a guideline to help Americans eat healthier
    diets, with scientific documentation for the
    guideline provided in the DGAC report.

7
Who uses an evidence-based system?
  • The National Academy of Sciences, Institute of
    Medicine, for the DRI reports.

IOM (2002) Introduction to DRIs. In DRIs
Energy, carbohydrates, et al., NAP, Washington,
DC.
8
Who uses an evidence-based system?
  • The Food and Drug Administration (FDA) to
    evaluate health claims
  • Guidance for industry and FDA Interim
    Evidence-based ranking system for scientific data
    online www.FDA.Gov

9
Who uses an evidence-based system?
  • Professional organizations that issue
    evidence-based practice guidelines
  • American Dietetic Association
  • American Diabetes Association
  • American Heart Association

Myers, EF et al. (2001) Evidence guides vs
protocols Whats the difference? J Am Diet
Assoc 101 1085-1090.
10
The philosophy behind an evidence-based system
  • Rules are set up front then followed rather
    than having a preconceived idea, then finding the
    papers to support the idea.
  • If one follows the rules, any trained scientist
    should come to the same conclusion.

11
Major components of evidence-based systems
  • Define the question/statement
  • Collect all relevant studies
  • Evaluate each study independently for
  • Type of study (e.g. randomized clinical trial v
    observational study)
  • Quality of study

12
Major components of evidence-based systems
  • Define the question/statement
  • Collect all relevant studies
  • Evaluate each study independently for
  • Type of study (e.g. randomized clinical trial v
    observational study)
  • Quality of study

13
Major components of evidence-based systems
  • Define the question/statement
  • Collect all relevant studies
  • Evaluate each study independently for
  • Type of study (e.g. randomized clinical trial v
    observational study)
  • Quality of study

14
Major components of evidence-based systems
  • Rate the strength of the body of evidence
  • Report the strength of the science and make a
    recommendation
  • (DGAC called this a conclusive statement)

15
The challenge moving from molecules to food
patterns
  • How do we get from a recommendation for a
    nutrient, e.g.
  • Carbohydrates
  • Fiber
  • Potassium
  • To a recommendation for foods and then for food
    patterns

16
Nutrient-based recommendations come from the DRI
process
  • National Academy of Sciences, Institute of
    Medicine
  • There are now DRI values for all nutrients
  • However, these values (EAR, RDA, AI, UL) are for
    individual nutrients, not foods, not food
    patterns

17
How the DGAC Uses the DRI values
  • Reviews the DRI values for the nutrients of
    interest
  • Does an evidence-based review on studies since
    each DRI report
  • Decides whether or not to use the DRI value for
    establishing food patterns

18
How nutrient-based guidelines are translated into
food-based guidelines
  • Foods that are significant sources of the
    nutrient are identified
  • Evidence-based reviews are done on the foods,
    rather than the nutrients
  • Recommendations for amounts of foods must be
    based on dose-response data

19
How nutrient-based guidelines are translated into
food-based guidelines
  • Foods that are significant sources of the
    nutrient are identified
  • Evidence-based reviews are done on the foods
  • Recommendations for amounts of foods must be
    based on dose-response data

20
How food-based recommendations are translated
into dietary pattern recommendations
  • Philosophical decision that food patterns should
    supply as close as possible to 100 of the
    nutrient requirements
  • Without exceeding energy requirements

21
How food-based recommendations are translated
into dietary pattern recommendations
  • Philosophical decision that food patterns should
    supply as close as possible to 100 of the
    nutrient requirements
  • Without exceeding energy requirements

22
Two examples of molecules to food patterns
(Example 1 fiber)
  • There is (for the first time) a DRI value, an AI,
    for fiber
  • 14 g/1000 Kcals
  • The AI is based on the strength of the
    relationship between fiber and decreased risk of
    CHD

23
Two examples of molecules to food patterns
(Example 1 fiber)
  • There is (for the first time) a DRI value, an AI,
    for fiber
  • 14 g/1000 Kcals
  • The AI is based on the strength of the
    relationship between fiber and decreased risk of
    CHD

24
Two examples of molecules to food patterns
(Example 1 fiber)
  • There is (for the first time) a DRI value, an AI,
    for fiber
  • 14 g/1000 Kcals
  • The AI is based on the strength of the
    relationship between fiber and decreased risk of
    CHD

25
From a DRI to a food-based recommendation
  • Good sources of fiber include whole grains.
  • When whole grains are refined, most fiber is
    lost.
  • There is a significant literature on whole grain
    intake and decreased risk of CHD and type II
    diabetes.
  • Three servings of whole grains put one into the
    decreased risk category.

26
From a food-based recommendation to a dietary
pattern based recommendation
  • 3 servings per day of whole grains might require
    decreasing the intake of refined grains to not
    exceed energy requirements.
  • Modeling needs to show that replacing refined
    grains with whole grains would not negatively
    affect micronutrient intake.

27
From molecules to food patterns Example 2
(Sugars)
  • There is (for the first time) a DRI value, an
    RDA, for carbohydate
  • 130 g/day
  • The RDA is based on the amount of glucose needed
    by the brain

28
From molecules to food patterns Example 2
(Sugars)
  • There is (for the first time) a DRI value, an
    RDA, for carbohydate
  • 130 g/day
  • The RDA is based on the amount of glucose needed
    by the brain

29
There is no UL for sugars, but there is a
recommendation
  • Added sugars should not be more than 25 of
    Kcals.
  • Added sugars are sugars and syrups that are
    added to foods during processing or preparation.
  • The recommendation was based on micronutrient
    dilution with increasing intakes of added
    sugars.

30
Calcium intake in children 4-8 Y as a function
of added sugar intake
Calcium, mg/day


0-5 5-10 10-15 15-20 20-25 25-30
30-35
added sugars
31
From a DRI to a food-based recommendation
  • Major sources include soft drinks, cakes,
    cookies, pies, fruitades, fruit punch, dairy
    desserts, and candy.
  • There may be a difference in compensation from
    sugar in beverages vs sugar in solid foods.
  • Added sugars generally result in added calories.

32
From a DRI to a food-based recommendation
  • Major sources include soft drinks, cakes,
    cookies, pies, fruitades, fruit punch, dairy
    desserts, and candy.
  • There may be a difference in compensation from
    sugar in beverages vs sugar in solid foods.
  • Added sugars generally result in added calories.

33
From a food-based recommendation to a dietary
pattern based recommendation
  • Subtract Kcals required to meet nutrient needs
    from Kcals required to meet energy needs.
  • What is left over are discretionary kcals.

34
One important food guidance system is the USDA
system
  • The form of the food that is used to set the
    recommended number of servings is the food item
    that is lowest in fat, added sugars and sodium.
  • For example, all dairy is represented by non
    fat milk, all meat is represented by the lowest
    fat version.

35
Discretionary calories available for females by
age and activity level
Kcals
Gray area Kcals required to meet Nutrient
adequacy
36
Discretionary calories by age and activity level
- females
Kcals
Active
Low Active
Sedentary
37
Summary and conclusions
  • The Dietary Guidelines Advisory Committee
  • Is mandated to produce a report based on the
    preponderance of scientific and medical knowledge
    current at the time of publication.
  • To do that it uses a form of an evidence-based
    system.
  • The challenge is to translate dietary guidance
  • Nutrient ? food based
  • Food based ? dietary patterns
  • Each of these translations raises a new set of
    issues, primary among which is meeting nutrient
    needs while not exceeding energy requirements.
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