Lecture
Outline
Chapter 2
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Evaluating Nutrition Information
Chapter 2
Chapter Learning Outcomes
1. Define terms, including anecdote, variable,
epidemiology, placebo, placebo effect, peer
review, and quackery.
2. Understand the basis of the scientific method as
it is used in developing hypotheses and
conducting research in the field of nutrition.
3. Explain the importance of having controls when
performing experiments.
4. Define research bias.
5. Describe how to identify questionable sources of
nutrition information.
6. Identify reliable sources of nutrition information.
Quiz Yourself
True or False

1. Scientists generally do not raise questions
about or criticize the conclusions of their
colleagues’ research data, even when they
disagree with those conclusions. T F
2. Popular health-related magazines typically
publish articles that have been peerreviewed. T F
Quiz Yourself
True or False (continued)

3. By conducting a prospective
epidemiological study, medical researchers
can determine risk factors that influence
health outcomes. T F
4. A placebo contains ingredients that provide
no measurable effects. T F
5. In general, registered dietitians are reliable
sources of food and nutrition information.
T F
How Did You Do?

1. False Scientists generally do raise
questions about or criticize the conclusions
of their colleagues’ research data, even
when they disagree with those conclusions.
2. False Popular health-related magazines
typically publish articles that have not been
peer-reviewed.
How Did You Do? (continued)

3. True By conducting a prospective
epidemiological study, medical researchers
can determine risk factors that influence
health outcomes.
4. True A placebo contains ingredients that
provide no measurable effects.
5. True In general, registered dietitians are
reliable sources of food and nutrition
information.
Understanding the Scientific Method
In the past, nutrition facts and dietary
practices were based on:
• Intuition
• Common sense
• Tradition
• Anecdotes
Today, nutrition experts rely on the scientific
method to base nutrition recommendations.
Scientific Method
Epidemiological Studies
Epidemiology is the study of
• Disease rates among different
population groups
• Factors associated with disease
occurrence
• How diseases are spread
Designing Epidemiological
Epidemiological
studies are often:
Studies
 Case-control — involves 2 groups;
individuals are “matched”
 Prospective — follows group of people
into the future
 Retrospective — examines the past
to explain why some people
are affected and not others
Correlations
Correlations: Relationships between
variables
A correlation occurs when 2 variables change
over the same period.
Direct or positive relationship
 regular soft drink intake

 obesity
Inverse or negative relationship
 physical activity 
 obesity
Limitations of Epidemiological Studies
• Results could be a coincidence
• Cannot establish causation
Is the observation a cause, effect, or simply a
coincidence?
• Difficulty in determining which variable is
responsible for the condition
Experimentation
In vitro
“in test tube” testing on parts
of living organism, such as
cells
In vivo
testing on whole living
organisms, such as lab rodents
Basic Steps in Human Research
• Review scientific literature
• Develop a hypothesis
• Design study — review human subjects
research design
Double-blind studies
• Conduct research
• Analyze data, draw conclusions, report
findings
• Follow up with more research
Example of an Experiment
Involving Humans
Study Group of 2000 Females


1000 Females
1000 Females
Receive Treatment
Control (Receive Placebo)


Measure and record
changes then
compare results
of 2 groups
Peer Review
Before acceptance
for publication,
research articles
undergo critical
analysis by peer
experts in the field
who were not part of
the research team.
• Insert photo of journals
from bottom of page 35
Quality Nutrition Research Is…
• Peer reviewed
• Published in a respected nutrition-related
journal
• Reported at a nutrition or medical meeting
If findings are simple and sensational, they
may be reported as “sound bites” as TV and
radio news features or in newspaper articles.
Why All the Confusion and
Conflict?
• The science of nutrition is constantly
evolving.
• Old beliefs are discarded and advice
changes as nutrition scientists conduct
more research and gain greater
understanding.
Nutrition Information: Fact or Fiction
Be skeptical of claims and ask questions…
 What motivates the authors, promoters or
sponsors?
 Does the promoter/advertiser rely on anecdotes or
testimonials?
 Are there claims the product caused dramatic
results?
 Is the product touted as a new scientific
breakthrough?
More Questions…
 Does the source of information
have disclaimers?
 Is the source scientific?
 If a study is cited, how was the
research conducted?
 Does the source cite respected
medical journals or mention
reliable experts?
 Are only benefits of using the
product highlighted and harmful
side effects ignored?
Look for Red Flags
for Unreliable Nutrition Information
Promises of quick and easy remedies
Claims that sound too good to be true
Scare tactics
Attacks on conventional scientists and medical
practitioners
Statements about the superiority of natural
dietary supplements
Testimonials and anecdotes
Look for Red Flags
(continued)
Information that promotes a product’s benefits
while overlooking its risks
Vague, meaningless, or scientific-sounding
terms
Simplistic conclusions
Sensational statements without citing
references or sources
Recommendations based on a single study
Look for Red Flags
(continued)
Information not supported by scientific evidence
Sensational or frightening descriptions of
commonly eaten foods
References to natural cures
Dramatic generalizations
Look for Red Flags
(Continued)
Disclaimers,
usually in small or
difficult to read
print
Tips for Searching Nutrition
Information on the Internet
•
•
•
•
•
Use multiple web sites,
especially government sites.
Rely on sites reviewed or
managed by health
professionals.
Look for “HONcode” symbol.
Avoid sites that do not provide
scientific sources.
Do not trust sites that attack
scientific establishment.
Insert Figure 2.9
Tips for Searching Nutrition
Information on the Internet
(continued)
• Avoid sites that provide online diagnoses or
treatments.
• Be wary of commercial sites (*.com), even
those with links to reliable sites.
• Avoid providing your personal information.
Websites with Reliable Nutrition and
Health Information
American Dietetic Association
http://www.eatright.org
National Institutes of Health
http://www.nih.gov
Food and Drug Administration
http://www.fda.gov
Centers for Disease Control and Prevention
http://www.cdc.gov
More Websites with Reliable Nutrition
and Health Information (continued)
American Council on Science and Health
http://www.acsh.org
Quackwatch
http://www.quackwatch.org
National Council Against Health Fraud
http://www.ncahf.org
Why Consult Registered Dietitians?
 College-trained professionals
 Have extensive knowledge in foods, nutrition,
and dietetics
Credentials:
In the United States, look for “R.D.”
www.eatright.org/find.html
In Canada, look for “R.D., P.Dt., or R.Dt.”
www.dietitians.ca
Have You Considered Becoming a
Dietitian?
Professional divisions:
Clinical dietetics
Community nutrition
Food service systems management
Steps to become a dietitian:
1. Complete accredited baccalaureate degree
program: coordinated program or didactic
program
2. If necessary, complete supervised professional
practice experience (“internship”)
3. Pass the national registration examination
What’s a “Supervised Professional
Practice” Experience?
• Coordinated Program (CP)
– Classroom instruction with > 900 hrs of supervised
practice under an RD
• Didactic Program in Dietetics (DPD)
– Provides classroom instruction only
– After graduation, students must apply for a dietetic
internship program that includes > 900 hrs of
supervised practice