Chapter 2

SECTION 2.3 Nutrition Information: Fact or Fiction

-Testimonials and anecdotes are typically used to promote nutrition-related products, but consumers cannot be sure that this information is reliable or based on scientific facts. Anecdotal reports are not scientific evidence. -The media and the Internet are often unreliable sources of nutrition information. People who promote nutrition misinformation often take advantage of freedom of the press and freedom of speech to make their claims. Consumers need to be critical of various sources of nutrition information and ask questions to help determine its reliability.

double-blind

describes human studies in which neither the investigators nor the subjects are aware of the subjects' group assignments

inverse or negative correlation

describes the relationship that occurs when one variable increases and the other one decreases

direct or positive correlation

describes the relationship that occurs when two variables increase or decrease in the same direction

dietetics

application of nutrition and food information to achieve and maintain optimal health and to treat many health-related conditions

registered dietitian (RD) or registered dietitian nutritionist (RDN)

college-trained health care professional who has extensive knowledge of foods, nutrition, and dietetics

peer review

critical analysis of an article about a study submitted to a journal that is conducted by a group of investigators who were not part of the study but are experts involved in related

in vitro

describes experiments on cells or other components derived from living organisms

in vivo

describes experiments that use whole living organisms

cohort study

epidemiological study in which researchers collect and analyze various kinds of information about a large group of people over time

variable

factor that can change and influence an outcome of a study

placebo

fake treatment

control group

in a controlled study, group that does not receive a treatment

treatment (or experimental) group

in a controlled study, group that receives a treatment

placebo effect

in studies involving human subjects, the situation that occurs when a subject reports having positive results even study of the occurrence, distribution, and causes of health problems in populationsthough he or she is taking a placebo

anecdotes

personal reports concerning a treatment's effectiveness

correlation

relationship between variables

causation

specific practice that is responsible for an effect

prospective cohort study

study in which a group of initially healthy people are followed over a time period and any diseases that eventually develop are recorded

case-control study

study in which individuals with a health condition (cases) are matched to persons with similar characteristics who do not have the condition

retrospective cohort study

study in which researchers collect information about a group's past exposures and identify current health outcomes

epidemiology

study of the occurrence, distribution, and causes of health problems in populations

National Health and Nutrition Examination Survey (NHANES)

survey that uses interviews and physical examinations to assesses the health and nutritional status of adults and children in the United States

experiment

systematic way of testing a hypothesis

SECTION 2.1 Dr. Goldberger's Discovery

- In the early 1900s, Dr. Joseph Goldberger developed a dietary hypothesis for the cause of pellagra. Goldberger tested his hypotheses and determined that poor diet was the cause of the disease. The scientific community eventually accepted the notion that dietary deficiencies caused illnesses that could be deadly.

SECTION 2.4 Nutrition Experts: Registered Dietitians

A registered dietitian (RD) or a registered dietitian nutritionist (RDN) is a food and nutrition expert who has graduated from accredited degree programs in nutrition and dietetics, completed a supervised practice program, and passed a comprehensive national exam.

SECTION 2.2 Understanding the Scientific Method

- Nutrition research relies on generally accepted scientific methods. Other scientists can test the findings to confirm or reject them. Nutrition experts discard conventional beliefs, explanations, and practices when the results of current scientific research no longer support them. - In experimental studies, nutrition scientists can investigate whether a health condition results from a certain dietary practice. In human experimental studies, subjects are divided into treatment (intervention) and control groups. Members of the control group receive a placebo. Controls are important for comparing results. - Epidemiology is the study of the occurrence, distribution, and causes of health problems in populations. By conducting studies that explore differences in dietary practices and disease occurrences among populations, nutrition scientists may learn much about the influence of diet on health. - Observational research involves either case-control or cohort study designs. Cohort studies can be either retrospective or prospective. A correlation is a relationship between variables and can be direct (positive) or indirect (negative). Epidemiological studies cannot establish cause and effect, because the relationship between two variables could be a coincidence. - When a study is completed and the results analyzed, researchers summarize the findings and seek to publish articles about their investigations in scientific journals. Before articles are accepted for publication, they undergo peer review. Scientists generally do not accept a hypothesis or the results of a study until they are supported by considerable research evidence. - Conflicting findings often result because different teams of researchers use different study designs when investigating the same hypothesis. Furthermore, each team of scientists may analyze the results differently. Other factors, such as genetic and lifestyle differences, also can influence the results of nutrition research involving human subjects.