Evaluating Nutrition Information

1. Sources of Nutrition Information• Government (Dietary Guidelines/ MyPlate)• Diet and health books• Internet websites• Food packaging• Family and Friends• Media (TV, newspapers, magazines)• Published findings of scientific studies• Classes• Nutritionists/dieticians

2. Sorting Fact from Fallacies• People tend to believe what they hear repeatedly• To increase number of viewers (and make more money),

media sensationalizes and over simplifies nutrition topics• Reports on studies’ findings often over state or distort

information or lack important details

• Be alert to the influences of your food choices• Recognize preconceived ideas about nutrition• Keep an open mind to current scientific evidence• Think critically

3. The Science of Nutrition• Scientific studies are the cornerstone to reliable nutrition

information• Antidotal evidence (reports of people’s individual experiences)

can also be useful

4. Scientific Process• Researchers test hypotheses (educated guesses) that arise

from observations of a phenomena• Hypotheses are tested by researchers conducting a “study”

(an experiment or doing research)

5. Types of Nutrition Studies

EPIDEMIOLOGICAL• Compares disease rates among population groups and

attempts to identify related conditions/behaviors (ex. Diet and exercise)

• Examples:- observation of scurry in sailors’- observation of low rate of breast cancer in Japanese

• Shows correlation (relationships between diet and disease) but not causation (the actual reason for the observation)

Types of Nutrition Studies

ANIMAL STUDIES• Used as a starting point to help explain a hypotheses• Used because human studies are difficult to conduct

and expensive• Must be followed-up with cell or human studies to

verify findings because animals are differently physically and mental than humans

Types of Nutrition Studies

CELL CULTURE STUDIES• Specific human body cells are isolated and grown in a

laboratory• Study the effects of nutrients on cell processes• Nutrigenomics

- The science of how genes, diet and disease interact to create health problems

- Certain genes determine susceptibility to disease- Certain foods turn disease susceptibility genes on or off - Knowing family genetic tendencies helps determine best diet for

the individual- Part of biochemical individuality

Types of Nutrition Studies

HUMAN STUDIES• Case Control Studies

Small-scale epidemiological study 2 closely-matching groups (age, gender, race) One group has the health condition (ex. Diabetes) being

examined, the other does not Identify the factors (ex. Vegetable consumption) that differ

between the groups Provides clues about cause and prevention of disease

Types of Nutrition Studies

HUMAN STUDIES• Clinical Trials

Researchers make a change (ex. Diet or exercise) and study the effects

Two subject groups: Experimental (people are given or make the change) and Control (similar people are not given or make the change)

Health and disease differences are measured between the two groups

Types of Nutrition Studies

First Clinical Trial• Sailors on long ocean voyages in 1747• Given oranges and lemons and did not develop scurvy (a

condition of joint pain, skin sores and bleeding gums)• Something in the oranges/lemons prevented the disease• 40 years later – common practice to provide sailors with citrus

fruit (limes, lemons, oranges) on long sea voyages to prevent scurvy – “Limeys”

• 200 years later (1930’s) vitamin C is discovered as the “something” in citrus that prevented scurvy

6. Reducing Errors (Bias) inHuman Studies• Groups as randomly assigned• Blind studies - Use of placebos (treatment or pill that only

looks like the actual treatment of pill)• Double-blind study – Both the subjects and the researchers

do not know who is or is not receiving the actual treatment/pill or a placebo

• Expectation of treatment/pill effect (even when receiving the placebo) can alter study results. (Ex. Bulimia)

7. Understanding Published Nutrition InformationA) Why is nutrition information confusing and often contradictory? Nutrition science is constantly changing with new findings

from studies Some studies are flawed (contain bias or errors)

Understanding Published Nutrition InformationB) How is nutrition information disseminated (spread)? Researchers publish their study findings in professional

scientific journals Before reliable study findings are published, they are peer-

reviewed (judged/critiqued by other researchers) Professional scientific journals are not commonly read by the

general public

Understanding Published Nutrition InformationC) What are the types (sources) of published nutrition information? Primary – Professional scientific journals Secondary – Scientific magazines/articles/books based on

primary source Science writing – General magazine, newspaper articles or

books written by science writers Mass media – Nightly news reports and internet

websites/blogs

Every time findings from the original research is summarized and restated, inaccuracies in interpretation of the information is possible

8. Evaluating Internet Information• There are no rules for posting on the Internet• Consider the source

Who are the authors or sponsors of the site? Is the information presented cited or documented? Is the site up-to-date?What are the qualifications of the author/sponsor? .edu, .gov, and .org sites are more creditable than .com sites.What is the motivation for the site? (education or selling products)When studies are cited, consider their quality and purpose.

Just because it is in print does not mean it is true.