ou've read news reports of nutrition studies. But what do all the terms mean?
Bias. Problems in the study design that affect the reliability of the results; perhaps the subjects weren't chosen right.
Blind (single or double) study. Study (single blind) where the subjects don't know if they're in the experimental or placebo group until after the study's over; study (double blind) where the researchers don't know either, so they can't influence the outcome.
Clinical trial. Studies done to directly show the effectiveness and the safety of a supplement, medication, or treatment with a selected group of people.
Confounding variable. A "hidden" and related variable (perhaps an unknown phytonutrient) that the researcher attributes to something different.
Control group. The study group that doesn't have the treatment. A control group is used to know if a treatment has an effect.
Correlation. An association between two research variables, such as eating lycopene and reduced risk for prostate cancer. A correlation does not prove cause and effect, but may suggest further study.
Epidemiological study. Study of the incidence and prevalence of a health condition among a specific group of people, such as neural tube defects among newborns.
In vitro study. Laboratory study with cells or tissue samples, usually done before an in vivo study.
In vivo study. Study with living subjects, either animal or human research.
Meta-analysis. A way to pool quantitative data from many studies to see what overall conclusions can be drawn, such as the pooling of more than forty studies on oats and more than twenty-five studies on soy protein to show their links to cholesterol-lowering.
Observational study. Study that identifies a link between a health condition and behavior, such as overweight and TV-watching, but doesn't prove cause and effect.
Placebo. A "fake" treatment, perhaps a sugar pill, that appears to be the same as the treatment under study. It's used to remove bias when study subjects don't know which treatment they have.
Placebo effect. Positive results among subjects who think they're getting the real treatment.
Prevalence. How many existing cases of a disease or a health condition as of a specific date, for a defined population.
Prospective study. Study that poses the research questions, then follows groups of people, often for decades.
Random sample. A way to choose study subjects whereby anyone from a target population has an equal chance to be picked. In that way the results can be more easily generalized to a larger group.
Reliability. Describes research that is carefully controlled so the data can be reproduced. In other words, the researcher would get the same result with the same study subject several times.
Retrospective study. Study that uses recorded data or recall of the past. Because the study relies on memory or some variables that can't be easily controlled, this type of research has limitations.
Risk factor. A factor that's statistically linked to the incidence of disease, such as a high BMI as a risk factor for heart disease. Again, it doesn't necessarily mean cause and effect.
Adapted from source: Reprinted with permission of the International
"Well" Connected Links
Search engines list legitimate and less reliable Web sites side-by-side; you need skills to sort them out. That's why it's wise to tap health-related resources that indicate high standards:
. . . how to judge food scares that circulate through e-mail? Being 100 percent sure about these food scares takes research. What appears in your e-mail is likely a hoax (1) if it wasn't written by the e-mail sender, (2) if you're asked to forward the e-mail, (3) if it claims not to be a hoax or an urban legend, (4) if it appeals to your emotions, and (5) if it doesn't cite a legitimate source or a credible Web site. Read critically for obvious false claims, poor logic, and lack of common sense. If you're still not sure, you might want to check Web sites such as www.quackwatch.com or www.urbanlegends.com that debunk food myths.
provides online, consumer-focused health information (www.webmd.com). These sites voluntarily comply with a code of conduct for health and medical Web sites. HON is an honor symbol and system, so still be a careful online consumer.
• Ask a nutrition expert, such as an RD or a DTR, who has a quick ability to see nuances of Web site bias and inaccuracy. If you find news of interest on the Internet, such as about a phytonutrient link to health, or a dietary supplement, print the information with the name and address of the Web site; take it to your healthcare provider or a nutrition expert for a perspective.
To find reliable nutrition and health Web sites, see "Resources You Can Use" at the back of this book.
E-Nutrition Advice: Just for You
With a few mouse clicks, you can calculate your BMI, assess your food choices, even tie in to online weight control counseling. But consider this:
As you surf the Internet, keep track of your path. You may be unaware when you pass from a reliable to an unreliable source of information.
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