Nutrition: wading through current
controversies and confusion
Heidi Wengreen, R.D., Ph.D.,
Assistant Professor of Nutrition, Utah State University
Heidi.Wengreen@usu.edu
Objectives
• Part I: Guidelines and tools for the critical
interpretation of nutrition “news”
• Part II: Current topics of controversy/confusion
• Part III: Probiotics  self discovery
Top 3 sources of consumer information
Common forms of inaccuracy in Media
reports on nutrition information:
1. Reporting a correlation as a causation.
2. Generalizing a study’s results to a broader
population, not represented by the study.
3. Exaggerating the size of an effect.
4. Using a single link in a chain of events to make
predictions and events in the future.
Terminology
• Meta-analysis
• Randomized, controlled, double-blind
study – “gold-standard”
• Prospective cohort study
• Case-control study
• Cross-sectional study
• Case-study
• Phase1 study
Questions to ask about a research report
(American Dietetic Association position paper):
Things to remember…
• The latest study isn’t the greatest study
• Don’t just look at the “bricks”, look at the
whole “house”
Can’t see the forest for the trees…
Fruit Juice Consumption Not Related To
Overweight In Children, Study Suggests (May
23, 2008) — Despite studies that assert
otherwise, 100% fruit juice consumption is not
related to overweight in children, according to a
new ..
Study Shows Fruit Juice/Drink Link To
Children's Weight Gain (Mar. 29, 2007) —
Australian schoolchildren who drink fruit juices
and fruit drinks are more likely to be overweight
or obese than those who don't, Deakin
researchers have ..
• Read the following news story with a
critical eye.
“Good news for the summer:
Beta-carotene helps to protect
against sunburn” (June 3, 2008,
PRNewswire)
• Be prepared to discuss your impressions.
Find the source of the information:
• Use the media as a way to know WHAT is
being talked about but don’t draw
conclusions from media or “popular”
reports, always go to the ORIGINAL
SOURCE – usually a report of the study
in a peer-reviewed journal.
Heidi’s favorites nutrition news sites:
• NutraIngredients
http://www.nutraingredients.com/
• Science Daily
http://www.sciencedaily.com/
Scholarly vs. Popular magazines
• Scholarly journals – present new,
previously un-published research that
includes bibliography, author’s name and
academic credentials. Articles go through
a peer review process before publication.
• Popular magazines – articles are written
by staff writers (not experts), are often
geared towards a general audience, and
are not peer reviewed before publication.
List of high impact peer-reviewed
journals in nutrition
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Journal of the American Dietetic Association
American Journal of Clinical Nutrition
Journal of Nutrition
Journal of the American Medical Association
Nutrition Reviews
Annals of Nutrition
Journal of Nutrition, Health and Aging
Journal of Nutrition Education and Behavior
International Journal of Obesity
Refining a pubmed search
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Use limits effectively
Use the related article link
Use MeSH Terms
Automatic search updates using My NCBI
(National Center for Biotechnology
Information)
• Conduct a pubmed search on betacarotene and sunburn
• Can you find the original publication from
the news-report you reviewed on this
topic?
• Have other research papers been
published on this topic?
Credible sources of nutrition
information on the internet
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Professional health organizations
Government health agencies
Volunteer health agencies
Consumer groups
Credible: Professional Health Organizations
• American Dietetic Association:
www.eatright.org/ncnd.html
• Society for Nutrition Education:
www.sne.org
• American Medical Association
www.ama-assn.org
• Federation of
Credible: Government health agencies
• Federal Trade Commission
www.ftc.gov
• The U.S. Department of Heatlh and Human Services
(DHHS)
www.os.dhhs.gov
• The Food and Drug Administration
www.fda.gov
• The U.S. Department of Agriculture (USDA)
www.usda.gov
• National Institute of Health’s Office of Dietary
Supplements
http://ods.od.nih.gov/
Credible: Volunteer health agencies
• American Cancer Society
http://www.cancer.org/
• American Alzheimer’s Association
http://www.alz.org/
• American Diabetes association
http://www.diabetes.org
• American Heart Association
http://www.americanheart.org
Credible: Reputable consumer groups
• The Better Business Bureau
www.bbb.org
• The Consumers Union
www.consumersunion.org
• The American Council on Science and Health
www.acsh.org
• National Council Against Health Fraud
www.ncahf.org
Credible: Universities
• Utah State University Extension
http://extension.usu.edu/
Questions to ask to assess the credibility of Web
sites (ADA position paper):
• Critically review the following website
• DSM nutritional products
http://www.dsm.com/en_US/html/dnp/hom
e_dnp.htm
• Be prepared to share your impressions
Current topics of controversy or
confusion in nutrition
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Vitamin D – how much do I need?
Whole grains – what are they?
Supplements – to take or not to take?
Glycemic index – useful tool?
Probiotics – bacteria for breakfast?
Vitamin D
* Current DRI (AI) for vitamin D for infants through adults age 50 is
200 IU/day. The current UL (upper limit) is 2000 IU.
Vitamin D Insufficiency May Be Present In Pediatric Patients With Low
Bone Density
• June 2, 2008 — Vitamin D insufficiency is common in adults and is
emerging in the world of pediatrics. A mild degree of vitamin D deficiency,
also known as vitamin D insufficiency, causes rickets in children and .
Low Vitamin D Levels Appear Common In Healthy Children
• June 2, 2008 — Many healthy infants and toddlers may have low levels of
vitamin D, and about one-third of those appear to have some evidence of
reduced bone mineral content on X-rays, according to a new .
Current Vitamin D Recommendations Fraction Of Safe, Perhaps Essential
Levels For Children
• May 28, 2008 — The current recommended daily allowance of vitamin D for
children is 200 International Units, but new research reveals that children
may need and can safely take ten-times that amount. According to a .
No Association Found Between Vitamin D Concentration In Blood And
Risk Of Prostate Cancer
• May 27, 2008 — High vitamin D concentration in the blood is not associated
with a reduced risk of prostate cancer, researchers report in a new article.
Laboratory studies suggested that high doses of vitamin D may .
Extra Vitamin D In Early Childhood Cuts Adult Diabetes Risk
• March 13, 2008 — Vitamin D supplements in early childhood may ward off
the development of type 1 diabetes in later life, reveals new research. Type
1 diabetes is an autoimmune disorder, in which insulin producing
• Age
• Dark skin –
melanonin
• Sunscreen
• Time of day
• Season of year
• Latitude of location
How much sun exposure?
• 1 MED dose of UVB radiation (enough to cause
a mild sunburn) = 10,000 – 20,000 IU Vit D
• Caution: melanoma, wrinkles?
• Suncreen decreases Vit D production by 95%
• Recommendation: unprotected sun exposure on
arms, neck, face for 5-15 minutes between the
hours of 1-5 pm during the spring, summer, and
fall on most days for lighter skinned individuals is
enough. After that time, apply sunscreen.
Points to remember
• You can’t get enough vitamin D from food alone.
• If you aren’t in the sun, or if don’t effectively
make Vit D when in the sun, you need a
supplement (vitamin D3 cholecalciferol).
• Most experts agree a dose of 2000 IU is save
and prudent for most.
• The only way to know your vitamin D status, is to
have your physician check your 25 OH D2 (25
hydroxyvitamin D) levels.
Whole-grains
http://www.wholegrainscouncil.org/
Definition: Whole grains
• Whole grains or foods made from them
contain all the essential parts and
naturally-occurring nutrients of the entire
grain seed. If the grain has been
processed (e.g., cracked, crushed, rolled,
extruded, and/or cooked), the food product
should deliver approximately the same rich
balance of nutrients that are found in the
original grain seed.
http://en.wikipedia.org/wiki/Whole_grain
Whole grains are cereal grains that
retain the bran and germ as well as the
endosperm, in contrast to refined grains,
which retain only the endosperm. Wholemeal products are made from whole-grain
flour.
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• Common whole-grain products include
oatmeal, popcorn, brown rice, wholewheat flour, sprouted grains, and wholewheat bread. Common refined-grain
products include white rice, white bread,
hominy, and pasta (although whole-grain
varieties of pasta are available).
List of whole grains
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Amaranth
Barley
Buckwheat
Corn, including whole cornmeal
and popcorn
Millet
Oats, including oatmeal
Rice, both brown rice and colored
rice
Rye
Sorghum (also called milo)
Wheat, including varieties such as
spelt, emmer, farro, einkorn,
Kamut®, durum and forms such
as bulgur, cracked wheat and
wheatberries
Wild rice
Why whole-grains?
Although it is difficult to
separate the protective
properties of whole
grains from dietary fiber
and other components,
the disease protection
seen from whole grains
in prospective
epidemiological studies
far exceeds the
protection
from isolated nutrients
and phytochemicals in
whole grains.
• High in fiber  SCFA in gut
• High in vitamins and minerals
• High in antioxidants
• High in other phytochemicals with known protective properties
• Lower Glycemic Index  mediates insulin response
How much do you need?
• The Dietary Guidelines for Americans,
released in January 2005, recommend
that all adults eat at least half their
grains as whole grains – that's at least 3
to 5 servings of whole grains.
• MyPyramid emphasizes whole grains
What’s a serving?
• 16 grams of whole grains = 1 serving
– 1 slice 100% whole grain break
– ½ cup brown rice
– 1 cup 1005 whole grain ready to eat cereal
• Every product with the Whole Grain Stamp
contains at least half a serving (8g) of
whole grains.
What you may see on the
ingredients label
What it means
whole grain [name of grain]
whole wheat
whole [other grain]
stoneground whole [grain]
brown rice
oats, oatmeal (including old-fashioned
oatmeal, instant oatmeal)
wheatberries
YES -- Contains all parts of the grain, so
you're getting all the nutrients of the whole
grain.
wheat flour
semolina
durum wheat
organic flour
multigrain (may describe several whole
grains or several refined grains, or a mix of
both)
MAYBE -- These words are accurate
descriptions of the package contents, but
because some parts of the grain MAY be
missing, you are likely missing the benefits
of whole grains.
enriched flour
degerminated (on corn meal)
bran
wheat germ
NO -- These words never describe whole
grains.
Learn about whole WHITE wheat at the
following website
http://www.wholegrainscouncil.org/whole-grains-101/whole-whitewheat-faq
Be prepared to share your impressions
Dietary supplements – to take
or not to take?
http://consensus.nih.gov/2006/2006MultivitaminMineralSOS028main.htm
Are MVM safe?
• Some ingredients in common MVM can
produce adverse effects in certain people
– Beta-carotene and smokers
– Vitamin A and women
– Vitamin E as alpha-tocopherol
• DSHEA
– No pre-market approval required
– Self-regulated industry
http://www.usp.org/USPVerified/dietarySupplements/
Conclusion from NIH report:
• Finally, the present evidence is insufficient
to recommend either for or against the use
of MVMs by the American public to
prevent chronic disease. The resolution of
this important issue will require advances
in research and improved communication
and collaboration among scientists, health
care providers, patients, the
pharmaceutical and supplement
industries, and the public.
POSITION STATEMENT
It is the position of the American Dietetic
Association (ADA) that the best nutritional
strategy for promoting optimal health and
reducing the risk of chronic disease is to
wisely choose a wide variety of foods.
Additional nutrients from fortified foods
and/or supplements can help some people
meet their nutritional needs as specified by
science-based nutrition standards such as
the Dietary Reference Intakes.
http://www.eatright.org/ada/files/fort.pdf
Glycemic index
http://www.glycemicindex.com/
Glycemic response to carbohydrate
• Glycemic index: the increase in blood glucose
level over the baseline level during a 2-hour
period for a defined amount of carbohydrate
(usually 50 g) compared with the same
amount of carbohydrate in a reference foods.
• Reference food typically white bread or
glucose.
• Glycemic load: the weighted average
glycemic index of individual foods - GI
multiplied by the dietary carbohydrate
content.
(a) Glucose
(reference food)
(b) Low glycemic index
(c) Fasting baseline
Hours
Glucose meal
Fig. 4-9, p. 83
Ludwig et al. 2002 Jama
Ludwig et al. 2002 Jama
GI/GL categories
GI
GL
Low
<50
<10.5
Moderate
51-69
11-19.9
High
>70
>20
GI controversy
• Foods can have different GI values as a result of
ripeness, variety and processing.
• Intra-individual variation.
• The GI of a food eaten alone is different than the
GI of the same food eaten with other foods.
• Standard test portions of foods used to
determine GI are NOT usual portions.
• Low GI foods are not necessarily nutrient dense
foods. Low GI does not = “healthy”
Factors known to influence glycemic
index of a food
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Fiber content
Ripeness
Type of carbohydrate
Fat content of food
Acid content of food
Physical form of food  processing etc.
The good and the bad…
High GI, the good:
• Better absorbed
during exercise
• Facilitates greater
glycogen storage
following exercise
• Easy to consume
given high kcal
requirements
High GI, the bad:
• Cancer
• CVD
• Diabetes
• Overweight/obesity
Ludwig et al. 2002 Jama
Probiotics – bacteria for breakfast?
• Find a recent news report on priobiotics
• Conduct a pubmed search to identify original
research on probiotics
– Look for a good review or meta-analysis
• Review this information
• Provide a critical analysis to the question: Should
probiotics be included in a healthy, balanced diet?
End of slides