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Whole Grains and Health: Does the
evidence support current guidelines?
Joanne Slavin
Professor
Department of Food
Science and Nutrition
December 6, 2013
Disclosures for Joanne Slavin
AFFILIATION/FINANCIAL
INTERESTS
Grants/Research Support:
CORPORATE
ORGANIZATION
MN Beef Council,
USAPears, MN Wild Rice
Council , Novartis
Consumer Health, Egg
Board (graduate student
support)
Scientific Advisory
Board/Consultant:
Tate and Lyle, Adkins,
Kelloggs
Speakers Bureau:
NA
Stock Shareholder:
NA
Other
NA
From the Science to Me
The Science
Policy
Me
Nutrient Adequacy
- Meet nutrient needs without exceeding calorie
needs
- Dietary Reference Intakes (DRIs)
- Acceptable Macronutrient Distribution Ranges (AMDR)
- Protein – 10-35% of kcal
- Carbohydrates – 45 – 65% of kcal
- Fat – 20 – 35% of kcal
- Recommended Dietary Allowance (RDA)
- Adequate Intake (AI)
- Tolerable Upper Limit (UL)
USDA grain guidance over time
• 1916 – Cereals and starchy foods – 20% of kcal
• 1940s – Basic 7 – Bread, flour, and cereal –
every day
• 1950s – Basic 4 – bread, cereal – 4 or more
servings
• 1984 – Food Guide Pyramid – 6 – 11 servings –
whole grain, enriched
• 2005 DGA – make half of your grain whole
5
Nutritional science – nutrients/deficiency diseases
• 1941: National Academy of Sciences began issuing
“Recommended Dietary Allowances” – quantity of
nutrients a person needed to consume daily to ensure
basic good health, proper growth and reproductive
success, and to prevent nutrient deficiency diseases
– Nutritional deficiency diseases have been virtually eliminated
in the US, thanks to enrichment of refined grains (thiamin,
riboflavin, niacin, iron), fortification (folate) and other
fortification strategies
– Grains are source of B vitamins, Fe, Ca, Mg, P, and fiber
There is no perfect diet!
• Humans are omnivores, like pigs, and are adaptable
to a wide range of foods
• Humans have survived and prospered on all kinds of
diets, mostly reflecting access to food supply
– Traditional Arctic diet: 80% of kcals from fat
– Traditional African diet: 80% of kcals from carbohydrate
Grains are low in lysine and legumes are low in methionine –
so vegan diets combine grains and legumes to provide high
quality protein – most cultures have grains as the base of the
diet – bread, rice, pasta, tortillas, etc.
Dietary Fiber = Whole Grain
• Deficient intake of both whole grains & dietary fiber
• Dietary fiber not synonymous with whole grain
– Both being encouraged, creates consumer confusion
• Whole grains contain vitamins, minerals, phytochemicals
above and beyond fiber
– Foods with dietary fiber are more than just whole grains;
also legumes, fruits, vegetables; and foods with
functional fibers
– Whole grains contain more nutrition than just dietary
fiber (not on Nutrition Facts – food, not nutrient)
Dietary fiber intake is low in U.S.1
• Usual intake only 15 g/day – recommended intakes 25 –
38 g/day – 14 g/1000 kcal
• Most fiber-containing foods: 1 – 3 g
–
–
–
–
Apple – 3 grams
Lettuce – 1 gram
WW bread – 2 grams
Oatmeal – 3 grams
• White flour and white potatoes provide the most fiber in
the U.S. diet
– Not b/c concentrated fiber sources, but because widely consumed
There’s a need to add functional fiber to foods to reach the recommended dietary
fiber goals.
1. Slavin J. Position of the American Dietetic Association: Health Implications of Dietary Fiber…Dietary
Am Diet Assoc. 2008;108:1716-1731.
Fiber, J
What is a Whole Grain?
Bran
“Outer shell”
protects seed
Aleurone
• Fiber
• B vitamins
• Trace minerals
•Phytochemicals
Germ
Endosperm
Nourishment
for the seed
Provides energy
• B vitamins
• Vitamin E
• Trace minerals
• Phytochemicals, antioxidants
•Lipids
• Carbohydrate
• Protein
• Some B vitamins
Whole grains
• Grains and grain products made from the entire grain
seed, usually called the kernel, which consists of the
bran, germ, and endosperm. If the kernel has been
cracked, crushed, or flaked, it must retain nearly the
same relative proportions of bran, germ, and
endosperm as the original grain in order to be called
whole grain. Many, but not all, whole grains are also
a source of dietary fiber (Appendix E-2, 2010 DGAC
Report)
Whole Grains Dietary Guidance
NAS Diet and Health links
whole grains to reduced risk
for heart disease and some
cancers
1980
Whole Grains
promoted as a
source of fiber
Dietary Guidelines (5th ed.)
• separate grain guideline
• emphasis on whole grain
1990
FDA permits whole
grain health claim
2000
2005 Dietary
Guidelines
recommend
3 servings of
whole grains
per day
2005
2010 Healthy
People objective to
 whole grain
consumption
Whole Grains and health
• 2010 Dietary Guidelines
– Recommends consuming 3 or more servings of
whole grains/day as part of your total grain
servings to reduce the risk of CHD and help with
weight maintenance.
• IOM and WHO/FAO reports reinforce
importance of whole grains in healthy diets
• Countries around the world now have WG
recommendations
Whole grains in the US
•
•
•
•
•
•
•
Whole wheat
Whole oats/oatmeal
Whole-grain corn
Popcorn
Brown rice
Whole rye
Whole-grain barley
•
•
•
•
•
•
•
Wild rice
Buckwheat
Triticale
Bulgur (cracked wheat)
Millet
Quinoa
Sorghum
Grain Refining
Milling
Endosperm
Removal of bran and germ layers.
Bran
Nutrients lost:
Vitamins
Minerals
Phenolics
Fiber
Enhance desirability.
Improve texture, flavor,
appearance.
Increase shelf life.
Germ
Comparison of 100 g of WG flour and enriched, white flour
•
•
•
•
•
•
•
WG flour
339 kcal
12.2 g dietary fiber
34 g calcium
138 mg magnesium
420 mg potassium
44 mcg folate
•
•
•
•
•
•
•
White flour
364 kcal
2.7 g dietary fiber
15 g calcium
22 mg magnesium
107 mg potassium
291 mcg folate
Whole grains and CHD
• Trowell (1972) – diets rich in whole grains
protect against CHD – interpreted as “fiber
hypothesis”
• Morris (1977) – cereal fiber (mostly wheat)
intake associated with significantly lower rates
of CHD in British men
• DeGroot et al (1963) - oats lower serum
cholesterol 5-8%
WG and Obesity Epidemiological Studies
• Harvard Nurses’ Health Study (75,000 women)
– Women who consumed more whole grains
consistently weighed less than women who
consumed fewer whole grains
• At baseline, women in highest quintile of whole grain intake
weighed less than did women in the lowest quintile
• Increases in whole grain intake associated with significantly less
weight gain over time
• Refined grain intake was linked to increased risk of weight gain
Liu et al., 2003
Dietary Guidelines for Americans 1980 - 2010
2000
2010
1990
1980
1985
1995
2005
Dietary Guidelines - always controversial
• Dr. Alfred Harper – University of Wisconsin – 1988
paper “Killer French Fries”
– The model used to learn about nutrient deficiency
diseases does not work for chronic diseases such as heart
disease and cancer
– You can cure scurvy with Vitamin C, but you won’t prevent
or cure heart disease with a low fat diet
Indexing/Search
Topics
Available at:
www.NutritionEvidenceLibrary.gov
NEL Process
Formulate
Systematic
Review
Questions
•Exploratory
searches
•Public
comment
•Dialogue
with
experts
•Analytical
Framework
•PICO
Literature
Search and
Sort
•Identify study
eligibility criteria
•Determine
search strategy
•Search for
relevant studies
•List included
studies
•List excluded
studies and
rationale
Extract
Evidence
From
Studies
Create
evidence
worksheets
Summarize
and
Synthesize the
Evidence
•Assess quality
of individual
studies
•Assess
applicability
•Summarize and
synthesize
evidence
Develop and
Grade
Conclusion
Statements
Define Research Recommendations
Hierarchy of
Evidence
Stronger
Evidence
RCT
Weaker
Evidence
Double Blinded
Clinical Study
Prospective, cohort study
Cross-sectional study
Case-control study
Case Report
Expert Opinion
What is the relationship between whole grain intake
and selected health outcomes?
• A moderate body of evidence from large prospective
cohort studies shows that whole grain intake, which
includes cereal fiber, protects against cardiovascular
disease.
• Limited evidence shows that consumption of whole
grains is associated with a reduced incidence of type
2 diabetes in large prospective cohort studies.
• Moderate evidence shows that intake of whole
grains and grain fiber is associated with lower body
weight
Chapter 4
Foods and Nutrients to Increase
The Whole Grain Consumption Gap
Recommendations
• The 2010 Dietary Guidelines recommends
“at least 3 servings of whole grains per
day…”
• Healthy People 2010 objectives aim for 3
servings/day
Average whole grain intake in US is less than 1 serving/day
ASN Scientific Statement
• Consumption of foods rich in cereal or
mixtures of whole grains, and bran is modestly
associated with a reduced risk of obesity, T2D,
and CVD. The data for whole grain alone are
limited primarily because of varying
definitions among epidemiological studies
what, and how much, was included in that
food category
– Cho et al. Am J Clin Nutr 2013;98:594-619
WGs have benefits beyond fiber?
Traditional Nutrients, Vitamins,
& Minerals
Sphingolipids
Lignan
Resistant Starch
WHOLE
GRAIN
Plant Stanols and
Sterols
Antioxidants
Inulin and Fructooligosaccharides
Phytate
Whole grain and body weight changes
• Meta-analysis assessed the effects of whole-grain
compared with non-whole grain food on changes in
body weight, percentage of body fat, and waist
circumference
• 2516 articles screened for eligibility and relevant data
were extracted from 26 studies (# participants=2060)
• Whole grain intake did not affect body weight, but a
small effect on percentage of body fat was found
– Poi et al Am J Clin Nutr 2013;98:872-884
Whole grains and markers of subclinical inflammation
• Reviewed 13 epidemiological studies and 5
intervention studies
• Epidemiological studies found an association
between diet high in whole grains and lower Creactive protein (CRP) concentrations
• In contrast, intervention studies saw no effect of
whole grain intake and CRP or other markers of
inflammation
– Lefevre & Jonnalagadda. Nutr Rev 2012;70:387-396.
Fiber Content Varies by Grain
Dietary fiber in various types of grains
Brown
Rice
Whole Grain
Corn Meal
Whole
Oats
Whole
Grain
Wheat
100g
1.8g
7.3g
10.3g
12.2g
55g
1.0g
3.7g
5.7g
6.7g
30g
0.5g
2.2g
3.1g
3.7g
USDA National Nutrient Database for Standard Reference
Dietary Fiber = Whole Grain
• DG – make ½ grain svgs whole/16 g (epi), wheat, oats, corn,
rice, barley,
• Current food labeling difficult to find whole grains, not on
Nutrition Facts. Ingredients don’t clearly indicate the amount
of whole grain present. Whole Grains Council stamp program
• Health claim for whole grain:
– Contains all portions of the grain kernel
– At least 51% whole grain by weight
– Meet fat, saturated fat, and cholesterol restrictions
Labeling & Identifying Whole Grain Foods
• Product Name
• Amount of Whole Grain
– Grams or Ounce Equivalents – Factual Statements
• Symbols – Whole Grains Council Stamp
• FDA Approved Whole Grain Health Claim
– “Diets rich in whole grain foods and other plant foods, and low in total fat,
saturated fat and cholesterol may reduce the risks of heart disease and certain
cancers.”
– Product must conform to claim criteria (at least 51% of product weight is whole
grain & meets other composition criteria)
• Ingredients
– Look for whole grain ingredients as first or predominant in ingredients list
Three Levels of Whole-grain Goodness
Good Source
Excellent Source
100%/Excellent
At least 8 g whole
grain/serving
At least 16 g whole
grain/serving
At least 16 g whole
grain/serving, no
refined grains
www.wholegrainscouncil.org
“Diets rich in whole
grain foods and other
plant foods, and low in
saturated fat and
cholesterol, may help
reduce the risk of heart
disease.”
Developing a standard definition of “whole grain food”
• While the term “whole grain” is well defined, there has been
no universal standard to define what constitutes a “whole
grain food”, creating challenges for researchers, the food
industry, regulatory authorities, and consumers
• AACC International recommendation:
– Whole grain food product must contain 8 grams or more of
whole grain per 30 g serving
• May 2013
Whole grain key messages
• Whole grains provide more than fiber
• Scientific support for whole grains protecting against
CVD and obesity
• 2010 Dietary Guidelines recommends that at least
half of all grains come from whole grains – the rest
from enriched or whole grains
• 9 out of 10 Americans don’t consume 3 WG servings
per day
Dietary Guidance—A Historical Perspective
1894 - Dr. Atwater specified amount of protein and total calories
in a good diet, but left unspecified the division of calories
between fats and carbohydrates
1902 - “evils of overeating may not be felt at once, but sooner
or later they are sure to appear – perhaps in general debility,
perhaps in actual disease”
1902 - “ordinary food materials…make a fitting diet, and the
main question is to use them in the kinds and proportions
fitted to the actual needs of the body”
Recommended variety, proportionality and moderation,
measuring calories, and an affordable diet focused on
nutrient-rich foods, less fat, sugar and starch.
1943: Basic Seven
Margaret Mead:
“People don’t eat
nutrition – they eat
food”
Basic 7 did not specify
the number of
servings of each food
group needed daily
Food advice: Evolution of USDA’s
Food Guidance – Moderation and Variety
1950s-1960s
1940s
Food for
Young
Children
1970s
1992
1916
2005
MyPlate.gov
Toward Healthful Diets, FNB, 1980
• “The Board expresses its concern over
excessive hopes and fears in many current
attitudes toward food and nutrition. Sound
nutrition is not a panacea. Good food that
provides appropriate proportions of nutrients
should not be regarded as a poison, a
medicine, or a talisman. It should be eaten
and enjoyed.”
Conclusions
• Efforts to micromanage the diet by imposing strict dietary rules are
difficult to support with evidence-based nutrition science
– we do not have strong evidence-based support for many of our accepted
dietary practices
• We have moved from nutrient-based recommendations to food
recommendations – historically we have supported whole grains as a
source of fiber, rather than whole grains per se
– Dietary fiber is a short-fall nutrient and most Americans need to replace some
refined grains with whole grains, not eat more whole grains
• Our inability to define whole grains and analytically measure them
will continue to add to confusion
• Solving important nutrition problems will require partnerships
based on trust among academics, the government, commodity
groups, activists, and food companies