Title: The Dietary Guidelines Advisory Committee: From molecules to dietary patterns
1The 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
2Focus 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
3Mandate 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.
4Overview 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.
5Overview 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.
6Use 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.
7Who 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.
8Who 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
9Who 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.
10The 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.
11Major 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
12Major 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
13Major 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
14Major 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)
15The 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
16Nutrient-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
17How 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
18How 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
19How 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
20How 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
21How 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
22Two 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
23Two 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
24Two 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
25From 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.
26From 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.
27From 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
28From 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
29There 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.
30Calcium 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
31From 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.
32From 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.
33From 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.
34One 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.
35Discretionary calories available for females by
age and activity level
Kcals
Gray area Kcals required to meet Nutrient
adequacy
36Discretionary calories by age and activity level
- females
Kcals
Active
Low Active
Sedentary
37Summary 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.