nutrition: wading through current controversies and confusion heidi wengreen, r.d., ph.d., assistant...
TRANSCRIPT
Nutrition: wading through current controversies and confusion
Heidi Wengreen, R.D., Ph.D.,
Assistant Professor of Nutrition, Utah State University
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
• 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
• 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 beta-carotene 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
• 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 Commissionwww.ftc.gov
• The U.S. Department of Heatlh and Human Services (DHHS)www.os.dhhs.gov
• The Food and Drug Administrationwww.fda.gov
• The U.S. Department of Agriculture (USDA)www.usda.gov
• National Institute of Health’s Office of Dietary Supplementshttp://ods.od.nih.gov/
Credible: Volunteer health agencies
• American Cancer Societyhttp://www.cancer.org/
• American Alzheimer’s Associationhttp://www.alz.org/
• American Diabetes associationhttp://www.diabetes.org
• American Heart Associationhttp://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/home_dnp.htm
• Be prepared to share your impressions
Current topics of controversy or confusion in nutrition
• 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. Whole-meal products are made from whole-grain flour.
• Common whole-grain products include oatmeal, popcorn, brown rice, whole-wheat flour, sprouted grains, and whole-wheat 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• 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 protectiveproperties of whole grains from dietary fiber and other components, the disease protectionseen from whole grains in prospective epidemiological studies far exceeds the protectionfrom 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-white-wheat-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 STATEMENTIt 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.
(c) Fasting baseline
(b) Low glycemic index
Glucose mealHours
(a) Glucose(reference food)
Blo
od
glu
cose
(m
g/d
L)
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
• 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