Nutrition for Healthy Living 5th Edition (Wendy Schiff)

1. Nutrition
For Healthy Living
Fifth Edition
Wendy J. Schiff, MS,
RDN
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Chapter 2
Evaluating Nutrition
Information
Lecture Outline

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Quiz Yourself
True or False1
1. Scientists use anecdotes as scientific
evidence to support their findings. True or
false?
2. Popular health-related magazines typically
publish articles that have been peer-
reviewed. True or false?
3. By conducting a prospective
epidemiological study, medical researchers
can determine risk factors that may
influence health. True or false?

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Quiz Yourself
True or False2
4. Dietary supplements include vitamin pills
as well as products that contain
echinacea, ginseng, and garlic. True or
false?
5. In general, registered dietitian nutritionists
are reliable sources of food and nutrition
information. True or false?

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How Did You Do?1
1. False Scientists do not use anecdotes as
scientific evidence to support their
findings.
2. False Popular health-related magazines
typically publish articles that have not
been peer-reviewed.

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How Did You Do?2
3. True By conducting a prospective
epidemiological study, medical
researchers can determine risk factors that
influence health outcomes.
4. True Dietary supplements include vitamin
pills as well as products that contain
echinacea, ginseng, and garlic.
5. True In general, registered dietitian
nutritionists are reliable sources of food
and nutrition information.

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Section 2.1 Nutrition: Science
for Consumers
Learning Outcomes
• Explain the basic steps of the scientific method.
• Explain the importance of having controls when
performing experiments.
• Design a nutrition-related study that involves
human subjects.
• Explain why nutrition information derived from
anecdotes is not evidence based.
• Discuss why similar scientific studies often have
different results.

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Understanding the Scientific Method
In the past, nutrition facts and dietary practices
were often based on:
• Intuition
• Common sense
• Conventional wisdom (“tradition”)
• Anecdotes (personal reports)
Today, nutrition experts rely on results collected
from scientific research (evidence-based results).
Scientific investigations involve the basic steps
shown in Figure 2.2.

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Scientific Method: Basic Steps
Figure 2.2

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Laboratory Experiments
Figure 2.1
An experiment is a
systematic way of
testing a hypothesis
(question).
Experiments are often
conducted on rats or
mice before
performing similar
research on humans.
©Adam Gault/Getty Images RF

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Key Terms1
Evidence based: information that is based on
results of scientific studies
Anecdotes: reports of personal experiences
Treatment group: group being studied that
receives a treatment
Control group: group being studied that does
not receive a treatment
Variable: personal characteristic or other feature
that changes and can influence an outcome

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Key Terms2
In vitro experiments or “test tube” experiments
are conducted on parts derived from living
organisms, such as cells.
In vivo experiments are conducted on whole
living organisms, such as lab rodents.

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Treatment and Control Groups
Most experiments that involve animals or humans have
a treatment group as well as a control group. Having
the two groups allows scientists to compare results.
Figure 2.3

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Human Research: Experimental
(Intervention) Studies
Experimental studies in humans may be used
to obtain information about health outcomes
related to specific dietary practices.
A large group of human subjects are
randomly assigned to either the treatment or
control group.

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Key Terms for Human Intervention
Studies1
Placebo: fake treatment, such as a sham
pill, injection, or medical procedure.
Placebo effect: effect that occurs when a
person reports a positive reaction to a
treatment even though he or she received
the placebo.

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Key Terms for Human Intervention
Studies2
Double-blind study: experimental design in
which neither the participants nor the
researchers are aware of each participant’s
group assignment.
Single-blind study: researchers know
which subjects are in the treatment and
control groups.

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Human Research: Epidemiological
Studies
Epidemiology: the study of the occurrence,
distribution, and causes of health problems in
populations.
Observational Epidemiological Studies:
Case-control study: Individuals who have a health
condition are compared with individuals with similar
characteristics who do not have the condition.
Cohort study: Collects information about people,
analyzes the information, and measures changes
in variables of a group of people over time.

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Types of Cohort Studies
Prospective
• Means “to look forward”
• Follows group of healthy people into the future
and looks for factors that may have contributed
to changes in their health
Retrospective
• Means “to look back”
• Examines people’s past exposures to explain
why some people are affected by a condition
and not others

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Epidemiological Studies:
Cohort Studies
Figure 2.4

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Limitations of
Epidemiological Studies
Epidemiological studies can show relationships,
but cannot establish causation, that is,
whether a practice is responsible (the cause)
for an effect.
Cause ⟶ Effect
When two events or observations occur
simultaneously within a population, it is not
necessarily an indication that one is related to
(or causes) the other.

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Correlations
What is a correlation?
• A relationship between variables
• Occurs when two variables change over the same
period
• A direct correlation results when two variables
change in the same direction.
• An inverse correlation occurs when two variables
change in opposite directions.
It is important to understand that some changes
could be coincidences (unrelated events) and
not the result of “cause-and-effect” relationships.

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Understanding Correlations
Figure 2.5

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Analyzing Data, Drawing Conclusions,
and Reporting Findings
Researchers use a variety of statistical methods to
analyze data.
These methods allow for finding relationships
between variables and health outcomes.
Researchers summarize findings and seek to
publish scientific articles.
Articles submitted for publication in scientific journals
undergo peer review before being published. Peer
review is a critical analysis of the study and its
findings conducted by another group of scientists in
the same field.

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Research Bias
Scientists are expected to collect and analyze
data in an honest and objective manner.
• Avoid the influences of personal attitudes or
biases.
• Sources of funding for research may influence
scientists involved in the study, making findings less
reliable.
• Peer-reviewed scientific journals require authors
to disclose funding sources.

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Confusion and Conflict
Conflicting study results are often the result
of different study methods.
The science of nutrition is constantly
evolving.
Old beliefs and practices are discarded and
advice changes as nutrition scientists
conduct more research and gain greater
understanding.

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Section 2.2 Nutrition Information:
Fact or Fiction
Learning Outcomes
• Explain why there is so much nutrition
misinformation.
• Discuss how people can become more critical
and careful consumers of nutrition information.
• Identify common “red flags” that are signs of
nutrition misinformation.

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Become a Critical Consumer of
Nutrition Information
Do not assume that information in popular media is
reliable.
Be wary of ads for nutrition-related products that
rely on testimonials and anecdotes.
The First Amendment to U.S. Constitution
guarantees freedom of speech.
• Information or claims do not need to be true.
Consumers are responsible for questioning and
researching the accuracy (reliability) of nutrition
information.

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Ask Questions
What motivates the authors, promoters, or
sponsors to provide the information?
Is the source scientific, such as an article in a
peer-reviewed nutrition journal?
If a study is cited, how was the research
conducted?
Does source cite respected nutrition or
medical journals or mention reliable experts?

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What Is Quackery?
Quackery is promoting useless medical
treatments.
• Practicing medicine without proper training is
illegal.
• However, providing nutrition information and
advice without proper training is legal.

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Look for Red Flags
Promises of quick and easy remedies
Claims that sound too good to be true
Scare tactics
Personal attacks on registered dietitian
nutritionists or conventional scientists
Statements about the superiority of certain
dietary supplements or unconventional
medical practices
Reliance on testimonials and anecdotes

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Finding Other Red Flags
Information that promotes a product’s
benefits while overlooking its risks
Vague, meaningless, or scientific-sounding
terms
Sensational statements without citing
references or sources

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Recognizing Other Red Flags
Recommendations based on a single study
Information concerning nutrients or human
physiology that are not supported by reliable
scientific evidence
Results disclaimers, usually in small or
difficult-to-read print

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Results Disclaimer
©Wendy Schiff
Figure 2.7

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Using the Internet Wisely
Be careful and consider sources of Internet
information.
Consider:
• Who or what organization sponsors the site?
• Is the information intended to promote sales?
• Is there a comprehensive disclaimer such as:
“The manufacturer is not responsible or
obligated to verify statements.”

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Tips for Searching Nutrition
Information on the Internet
Use multiple web sites, especially
government sites.
Be wary of sites that have personal surveys.
Rely on sites reviewed or managed by
health professionals.
Look for Health on the
Net (HonCode) symbol.
Do not trust a site that does
not indicate valid sources.

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More Tips for Searching Nutrition
Information on the Internet
Do not trust a site that attacks the medical or
scientific establishment.
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.

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Section 2.3 Reliable Nutrition
Experts
Learning Outcome
• Explain how to identify reliable nutrition
experts.

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Reliable Nutrition Experts
There is no standard definition for “nutritionist” or
“nutritionalist.”
Physicians generally do not have extensive
education in nutrition.
Reliable sources of information include nutrition
professors at colleges and universities with
nutrition and/or dietetics departments, registered
dietitians,* or registered dietitian nutritionists.*
* Legally protected credentials

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Becoming a Registered
Dietitian Nutritionist (RDN)
Three major professional divisions in
dietetics:
• Clinical dietetics
• Community nutrition
• Food systems management

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Becoming a Registered
Dietitian Nutritionist
1. Complete an accredited baccalaureate
degree program.
2. Complete a supervised professional
practice experience.
3. Pass the national registration
examination.

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Section 2.4 Nutrition Matters: What
Are Dietary Supplements?
Learning Outcomes
• Explain the difference between conventional
medicine and alternative health care, and
identify health care practices that are either
conventional or alternative.
• Explain how the FDA regulates medicines
differently than dietary supplements.
• Discuss the risks and benefits of taking dietary
supplements.

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What Are Dietary Supplements?1
According to the Dietary Supplement
Health and Education Act of 1994
(DSHEA), a dietary supplement:
• adds to a person’s dietary intake and contains
one or more dietary ingredients, including
nutrients or botanicals (herbs or other plant
materials);
• is taken by mouth; and
• is not promoted as a conventional food or the
only item of a meal or diet.

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What Are Dietary Supplements?2
Dietary supplements include:
• Nutrient pills,
• Protein powders,
• Herbal extracts, and
• Energy bars and drinks.
See Table 2.2 for information about some
popular dietary supplements.

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What is Alternative Health Care?
Alternative health care includes:
• Using supplements, such as herbal products, to
treat disease or promote good health;
• Chiropractic manipulations;
• Homeopathy and naturopathy;
• Massage therapy.
When alternative health care practices are used
along with conventional medical practices, the
combination is called “integrative” medicine.

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How are Dietary Supplements
Regulated?
Dietary supplements are regulated as foods
not as drugs.
Supplements bypass strict FDA regulations
imposed on drugs.
FDA regulates labels on supplements and
claims allowed on them.

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Using Dietary Supplements Wisely
When used properly, micronutrient
supplements are generally safe.
Herbal supplements may contain toxins.
Highly toxic or cancer-causing plants include
comfrey, pennyroyal, sassafras, kava,
lobelia, and ma huang.

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Considering the Use of Dietary
Supplements
If you are thinking about using dietary
supplements:
• determine if the supplement is necessary.
• consult a physician as soon as you develop
signs and symptoms of serious illness.
• be wary of claims made about a supplement’s
benefits and investigate by searching for
reliable information.