Chapter 2 Evaluating Nutrition Information

Evaluating Nutrition Information Pellagra ● Pellagra was widespread in the U.S. in the early 1900s ● Symptoms were scaly skin sores, weakness, diarrhea, and mental confusion ● Joseph Goldberger was assigned by the U.S. Surgeon General to study pellagra Dr. Goldberger’s Hypothesis ● Dr. Goldberger developed the hypothesis that pellagra resulted from something lacking in people’s diets ○ Hypothesis - a possible explanation for an observation that guides scientific research ● He hypothesized the missing dietary factor was in meat, milk, and other foods eaten regularly by people with higher incomes Testing Dr. Goldberger’s Hypothesis ● To test his hypothesis, Dr. Goldberger gave these foods to people who had pellagra and they were cured of the disease ● To further support his hypothesis, he held “filth-parties” ○ Volunteers applied secretions taken from inside the nose and throat of a patient with pellagra to their noses and swallowed pills of flakes of skin from rashes of people with the disease ○ Goldberger and a colleague injected each other with the blood of a person with pellagra ○ None of the participants contracted pellagra Identification of the Missing Dietary Substance ● A team of scientists later discovered niacin ○ A vitamin from liver extracts ■ Found to be effective in treating pellagra ● It is now accepted that pellagra is a disease that resulted from a dietary deficiency ● This illustrates how researchers use scientific methods to solve medical mysteries relating to nutrition Source of Dietary Recommendations ● Previously, nutrition facts and dietary practices were based on intuition, common sense, tradition, or anecdotes ○ Anecdotes - personal reports concerning a treatment’s effectiveness ● Today, nutrition is based on scientific research Animal Research: Laboratory Experiments ● An experiment is a systematic way of testing a hypothesis ● Experiments are often conducted on animal models before performing research on humans ○ Mice and rats are often used ○ Government guidelines must be followed on the ethical care and treatment of laboratory animals Experimental Subjects ● In vivo describes experiments using whole living organisms ● In vitro describes experiments on cells or other components derived from living organisms ● A treatment group in a controlled study is a group that receives a treatment ● A control group in a controlled study is a group that does not receive a treatment Why is a Control Group Necessary? ● A control group allows scientists to compare results between two study groups ○ Helps determine whether treatment had any effect ● A variable is a factor that can change and influence a study’s outcome ○ Many variables influence the outcome of a study ○ Influence of variables needs to be controlled Human Research ● It may not be practical to conduct research on humans in laboratory settings, so scientists enroll “free-living” subjects ● Human subjects are randomly divided into treatment and control groups ○ Helps ensure groups have similar variables ● Only the treatment group is given the treatment ○ Placebo is given to members of the control group ■ Placebo - fake treatment Double-Blind Studies ● Human experimental studies are usually double-blind ○ Neither the investigators nor the subjects are aware of the subjects’ group assignment ○ This helps to avoid the placebo effect, the situation that occurs when a subject reports having positive results even though he or she is taking a placebo Epidemiological Studies ● Epidemiology - study of the occurrence, distribution, and causes of health problems in populations ○ Used by nutrition scientists to learn about the influence of diet on health ● Epidemiologists use: ○ Physical examinations to obtain health data ○ Surveys to collect information Collecting Nutrition-Related Information ● Epidemiologists and health care providers often rely on physical examinations of people to obtain health data NHANES ● The National Health and Nutrition Examination Survey (NHANES) uses interviews and physical examinations to assess the health and nutritional status of adults and children in the United States ○ Researchers use NHANES findings to determine the prevalence of major diseases and risk factors for diseases ○ Medical experts use the NHANES to establish national standards for assessing height, weight, and blood pressure Observational Studies ● Most nutrition research involving humans is observational ○ Case-control study - study in which individuals with a health condition are matched to persons with similar characteristics who do not have the condition ○ Cohort study - epidemiological study in which researchers collect and analyze various kinds of information about a large group of people over time ■ Retrospective ■ Prospective Retrospective versus Prospective Cohort Studies ● Retrospective cohort study - study in which researchers collect information about a group’s past exposures and identify current health outcomes ● 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 Correlations ● Scientists determine whether their hypothesis is supported by analyzing data ● Scientists look for correlations, or relationships, between variables ● Correlations can be: ○ Positive ■ The relationship that occurs between two variables increase or decrease in the same direction ○ Negative ■ The relationship that occurs when one variable increases and the other one decreases Outcomes of Nutrition-Related Studies ● Epidemiological studies cannot establish causation, a specific practice that is responsible for an effect ○ An outcome could be a coincidence ● When an experiment is complete, researchers summarize the findings and seek to publish articles in scientific journals ○ Must first undergo peer review, a critical analysis conducted by a group of peers Research Bias ● Expectation of researchers is to: ○ Avoid relying on personal attitudes and biases ○ Evaluate and report results objectively and honestly ● Peer-reviewed journals usually require authors to disclose their affiliations and sources of financial support Following Up with More Research ● Findings obtained from one research team must be supported by other studies ○ If same conclusions are found, findings are more likely to be accepted by other nutrition scientists ● Conflicting findings often result from differences in the ways various studies were designed and their results analyzed Not All Nutrition Information is Reliable ● Consumers are responsible for questioning and researching the accuracy of nutrition information ● The FDA can regulate nutrition- and health-related claims on product labels ○ Cannot prevent the spread of health and nutrition misinformation published in books or on the Internet or presented in television or radio programs Ask Questions ● To evaluate various sources of nutrition information, a person can ask: ○ What motivates the authors, promoters, or sponsors that provide the information? ○ Who is the source? ○ What is the source? Look for Red Flags ● Promises of quick and easy remedies ● Claims that sound too good to be true ● Scare tactics ● Attacks on conventional scientists and nutrition experts ● Testimonials and anecdotes ○ Personal endorsement of a product ● Promotes benefits while overlooking risks ● Vague, meaningless, or scientific-sounding terms ● Vague sources ● Pseudoscience ○ Presentation of information masquerading as factual or scientific ● Disclaimers Results Disclaimer ● This disclaimer may be a red flag indicating the product has limited effectiveness, despite its promoter’s claims Use the Internet Wisely ● Be wary of websites that: ○ Are authored or sponsored by one person ○ Promote or sell products for profit (.com) ● Some websites for reliable sources of nutrition information include: ○ Academy of Nutrition and Dietetics ○ National Osteoporosis Foundation ○ Centers for Disease Control and Prevention ○ Food and Drug Administration Scientific Nutrition-Related Literature ● Health care professionals refer to peer-reviewed scientific literature when searching for nutrition-related information ● To conduct an online review of scientific literature, visit the U.S. National Library of Medicine and National Institutes of Health “PubMed” website Reliable Experts ● A registered dietician (RD) or registered dietician nutritionist (RDN) is a collegetrained health care professional who has extensive knowledge of foods, nutrition, and dietetics, the application of nutrition and food information to achieve and maintain optimal health and to treat many health-related conditions Registered Dietician Nutritionists ● Clinical dieticians can work in hospitals and clinics as members of medical teams that include: ○ Physicians ○ Nurses ○ Physical therapists ● They help: ○ Evaluate the health status of a patient ○ Determine their dietary deficiencies and needs ○ Plan dietary treatments and meals Becoming a Registered Dietitian Nutritionist ● Specific educational and certification requirements must be met to become an RD or an RDN ○ Bachelor’s degree ○ Supervised practice program ○ National registration exam ● After becoming certified, continuing education requirements must be met to maintain certification