chapter 2 evaluating nutrition information nutrition-chapter 21

Chapter 2

Evaluating Nutrition InformationNutrition-Chapter 2 1

Introduction• Early 1900’s the disease

pellagra was widely spread in southern states.

• Symptoms: – diarrhea– skin rash – mental confusion

• Seen in prisons, orphanages, and mental health institutions

Nutrition-Chapter 2 2

Introduction• Initially people believed it was

an infectious disease. But in 1914 Dr. J Goldberger suggested that diet played a role because all those effected had a diet of:– Corn Bread– Hominy grits– Molasses– Potatoes– Cabbage– Rice

• ***Higher income individuals also ate things like meat, milk, and fresh vegetables!***


Introduction• Tested his hypothesis by adding

missing nutritents to diet and saw complete remission of symptoms…still wasn’t supported.

• Did a “filth party” swabbed nose and throats of sick people and then applied them to healthy people…Result: no disease transfer!...No one believed him!

• Wasn’t until 1937 (8 yrs after Goldberger’s death) that another scientist (Elvehjem) discovered niocin (vitamin) in liver extract.


Introduction• More recent example of a

medical hypothesis involved stomach ulcers

• Warren and Marshall in 1982 hypothesized it was not stress but bacteria that caused ulcers after isolating the bacteria Helicobacter pylori from patients

• No one believed them they believed bland diet and antacids were the only treatment while W&M were suggesting antibiotics!


Helicobacter pylori

• To prove it Marshall actually ingested the bacteria and proved it by developing ulcers.

• They were awarded the Nobel Prize in Medicine in 2005


2.1 Understanding the Scientific Method• In the past, nutrition

facts and dietary practices were based on:

• Intuition• Common sense• “Conventional

wisdom”• Anecdotes

• Today, nutrition experts rely on the scientific method to base nutrition recommendations.


Today nutrition facts and dietary practices use:


Key Terms related to the Scientific Method

• Hypothesis– Possible explanation about an observation

that guides scientific research

• Anecdote– Reports of personal experiences

• Variable– Personal characteristic or other factor that

changes and can influence an outcome


Laboratory Experiments

• An experiment is a systematic way of testing a hypothesis.

• Experiments are often tested on cells or small animals.

• Experiments may be conducted humans.


Experimentation

Most experiments have two groups:– Treatment group:

receives treatment – Control group: does

not receive treatment; human subjects may receive a placebo

What is a placebo? A fake treatment, such

as a sham pill, injection, or medical procedure


Experiments

• In vitro:– “Test tube”

experimenting on parts derived from living organism, such as cells

• In vivo:– Testing on whole living

organisms, such as lab rodents


Human Research:Epidemiological Studies

• Epidemiology is the study of occurrence, distribution, and causes of health problems in populations.

• Two types of epidemiological studies:

– Experimental (intervention)

– Observational


Experimental (Intervention) Epidemiological Studies

• Experimental epidemiological studies can obtain information about health conditions that may have resulted from specific dietary practices.

• Human subjects divided into two groups:– Experimental (receive

treatment)– Control (no treatment—

typically receive placebo)


What Is the Placebo Effect?

• The placebo effect occurs when a person reports a positive (or negative) reaction to a treatment even though he or she received the placebo.


Observational Epidemiological Studies

• Most human epidemiological research is observational.– Case-control study:

individuals who have a health condition are compared with individuals with similar characteristics who do not have the condition.

– Cohort study: study that measures variables in a group of people over time


Epidemiological studies may be:

1. 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

2. Retrospective◦ Means “to look back”◦ Examines people’s past

exposures to explain why some people are affected by a condition and not others


Epidemiological Studies

18Nutrition-Chapter 2

Limitations of Epidemiological Studies

• Cannot establish causation, that is, whether a practice is responsible for an effect.

• When two events or observations occur simultaneously within a population, it is not necessarily an indication that one is related to each other.


Correlations

What is a correlation? A relationship between variables Occurs when two variables change over

the same period◦ Important to understand that some changes

could be coincidences and not the result of “cause and effect” relationships


Examples of Direct and Inverse Correlations


Elements of an Experimental Epidemiological Study

1. Reviewing scientific literature

2. Developing a hypothesis

3. Designing the study – Double-blind studies– Reviewing human subjects research designs

4. Conducting human research

5. Analyzing data, drawing conclusions, and reporting findings– Research bias

6. Spreading the news

7. Following up with more research


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 wary of ads for nutrition-related products

that rely on testimonials and anecdotes.


Be Skeptical of Claims

• Do not assume that information in popular media is reliable.

• First Amendment to U.S. Constitution guarantees freedom of speech.

• Consumers are responsible for questioning and researching accuracy of nutrition information.


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?


What Is Quackery?

Quackery is promoting useless medical treatments.

Practicing medicine without proper training is illegal.

BUT, providing nutrition information and advice without proper training is legal.


Look for Red Flags (Signs of Unreliable Nutrition Information)

Promises of quick and easy remediesPromises of quick and easy remedies

Claims that sound too good to be trueClaims that sound too good to be true

Scare tacticsScare tactics

Personal attacks on registered Personal attacks on registered dietitians or conventional scientistsdietitians or conventional scientists

Statements about the superiority of Statements about the superiority of natural dietary supplementsnatural dietary supplements


Look for Red Flags (cont.)

Testimonials and anecdotesTestimonials and anecdotes

Information that promotes a product’s Information that promotes a product’s benefits while overlooking its risksbenefits while overlooking its risks

Vague, meaningless, or scientific-Vague, meaningless, or scientific-sounding termssounding terms

Sensational statements without citing Sensational statements without citing references or sourcesreferences or sources


Look for Red Flags (cont.)

Recommendations based on a single Recommendations based on a single studystudyInformation concerning nutrients or Information concerning nutrients or human physiology that are not human physiology that are not supported by reliable scientific supported by reliable scientific evidenceevidenceDramatic generalizationsDramatic generalizationsDisclaimers, usually in small or Disclaimers, usually in small or difficult-to-read printdifficult-to-read print


Using the Internet Wisely

Be careful and consider sources of Internet information

Consider:◦Who or what organization sponsors site?◦ Is information intended to promote a product’s

sales?◦ Is there a comprehensive disclaimer such as

“not responsible or obligated to verify statements?”


Tips for Searching Nutrition Information on the Internet

1. Use multiple web sites, especially government sites.

2. Be wary of survey sites. 3. Rely on sites reviewed

or managed by health professionals.

4. Look for Health on the Net symbol.

5. Do not trust a site that does not indicate valid sources.

6. Do not trust a site that attacks medical or scientific establishment.7. Avoid sites that provide online diagnoses or treatments.8. Be wary of commercial sites (*.com) even those with links to reliable sites.9. Avoid providing your personal information.


Reliable Nutrition Experts

Where do you find factual answers about food or nutrition?◦ There is no standard legal definition for

“nutritionist” or “nutritionalist.”◦ Physicians generally do not have extensive

education in nutrition. Reliable sources of information: college or

university nutrition instructors or registered dietitians.


chapter 2 evaluating nutrition information nutrition-chapter 21

Documents

nutrition facts

nutrition experts

base nutrition recommendations

lab rodentsnutritionchapter

treatment group

fake treatment

treatment control group

treatment human subjects