First, butter is the enemy. Then solid margarine is on the forbidden list.
Next, beta-carotene supplements are thought to prevent cancer, until they are found to increase the risk of lung cancer in smokers.
Later, tomatoes are the darlings of the prostate-cancer prevention community, until broccoli, cabbage and other crucifers take center stage.
As incremental advances in scientific knowledge cause shifts and reversals in diet and health messages, what are confused, frustrated consumers to do?
Some appear to respond by tuning out the conflicting advice and eating less healthful diets, according to a recent Hutch study.
The results of this National Cancer Institute-funded study, led by Dr. Ruth Patterson of the Hutchinson Center's Public Health Sciences Division, appear in the January issue of the Journal of the American Dietetic Association.
Negative = fat-laden
"The more negative and confused people feel about dietary recommendations, the more likely they are to eat a fat-laden diet that skimps on fruits and vegetables," Patterson said.
"It seems as if all of a sudden big steakhouses are 'it.' And they're not just serving steak. They're serving a 1-pound steak, and everything is drenched in butter and bleu cheese."
Patterson's was the first population-based study of its kind to track the existence and extent of nutrition backlash.
She and collaborators from the Hutch and University of Washington conducted a cancer-risk behavior survey that included questions regarding attitudes toward dietary recommendations. The random survey, which involved 1,751 adults in the state of Washington (60 percent women; 90 percent white; mean age 44), asked also about consumption of fat, fruits and vegetables.
The results found evidence both for and against nutrition backlash, defined as negative feelings about dietary recommendations, such as anger, skepticism, helplessness, worry and cynicism.
About 70 percent felt that Americans are obsessed with fat in their diet and the government should not tell people what to eat. Also, more than a quarter agreed that eating low-fat foods takes the pleasure out of eating and more than 40 percent stated that they were tired of hearing about what foods they should or should not eat.
Those who scored highest on the backlash scale were young men (age 18 to 35), the elderly (age 60 and older) and people of lower socioeconomic status, as measured by education or income.
Consumers who reported the greatest degree of backlash had diets that about 4 percentage points higher in percent energy from fat compared to those at the opposite end of the spectrum - "a substantive difference," Patterson said.
"If we assume that on average, Americans eat diets with 34 percent of energy from fat, we could hypothesize that individuals with high backlash chose diets with 36 to 38 percent energy from fat."
Nutrition experts advise that consumers get 30 percent or less of their daily calories from fat.
The survey results were not all bad news, however. More than 90 percent felt nutrition research will help them live longer, and three-quarters backed warning labels on high-fat foods.
"The majority of the public still cares about diet and health, but some subgroups definitely have just plain had it," said Patterson, also a research associate professor of epidemiology in the UW School of Public Health and Community Medicine.
The high public interest in nutrition information can be a double-edged sword, Patterson said.
"Interest in new scientific findings presents the opportunity to improve the nation's health by providing information that helps consumers adopt healthy diets," she said. "However, perceptions that the diet/health message is constantly changing or that dietary recommendations are conflicting could undermine the credibility of future nutrition-education efforts."
To counter the barrage of inconsistent diet and health messages, Patterson calls for collaboration among health organizations, government agencies, the food industry and the media.
"Such a partnership could work to ensure the development and dissemination of consistent, positive messages that promote wise food choices," she said.
In the meantime, Patterson suggests that Americans adopt a more European attitude about food, citing the first recommendation of the French Dietary Guidelines: "Enjoy your food."
"We need to celebrate the fact that we have a wonderful, diverse food supply and that there are all kinds of ways to have a good, healthy diet while still eating many enjoyable foods."
Collaborators from PHS were Drs. Alan Kristal, Marian Neuhouser and Jessie Satia. Also involved was Dr. Adam Drewnowski, director of the Nutritional Sciences Program in the UW School of Public Health and Community Medicine, who holds a joint membership in PHS.