Lying about your vegetables

"Approval bias" dogs research efforts to find out what people really eat. How much more do people in the f/v business overestimate their produce consumption? This insightful NYT blog entry looks at the topic. From the post:

It’s long been known that people claim to eat far less than they really do. Some studies suggest people underreport their caloric intake by 30 percent or more.
But when it comes to fruits and vegetables, it appears people lie in the other direction — vowing that they consume far more than they really do. The finding, reported in the current Nutrition Journal, suggests the data the health community has collected on fruit and vegetable consumption are tainted by “approval bias.” We know we are expected to eat five or more servings of fruits and vegetables a day, so that’s what we say when we are asked, and we may even really believe it


Researchers from the University of Colorado in Denver randomly selected 163 women who were recruited by telephone and told they would be taking part in a general health survey. Half the women were sent a letter describing the survey as a study of fruit and vegetable intake. The letter included a brief statement of the benefits of fruits and vegetables, a Five-A-Day sticker and a Five-a-Day refrigerator magnet. The rest of the group received a general letter, without mention of fruits, vegetables, stickers or magnets.


Within 10 days of receiving the letters, the study subjects answered a food frequency questionnaire and were asked to recall how many fruits and vegetables they had eaten in the past 24 hours.
Because the two groups were randomly selected, average fruit and vegetable consumption should have been similar. However, the group that had seen the five-a-day promotional material reported far higher consumption, 5.2 servings per day, compared to 3.7 per day in the other group. And 61 percent of the five-a-day group reported eating fruits and vegetables on three or more occasions the prior day, compared to just 32 percent in the other group.




TK: Lesson to the industry; don't trust research results when consumers surveyed readily know that the questions are being asked on behalf of a produce group.