After reviewing 35 years' worth of diet counseling studies, the U.S. Preventive Services Task Force concludes that intensive diet counseling can help at-risk adult patients eat less fat and more fruits and vegetables, concluding that this counseling can be delivered by primary care clinicians or by referral to other specialists, such as nutritionists or dietitians. The review and the task force's recommendations are published in the January issue of the American Journal of Preventive Medicine.
Effective counseling for at-risk patients typically involved multiple individual or group sessions and stressed techniques to boost patients' skills, motivation and social supports and personal involvement in goal setting. Because patients at risk for chronic diseases such as high blood pressure or cholesterol problems may have greater motivation to change their diet, counseling can contribute to positive results, say Michael P. Pignone, M.D., M.P.H., and Alice Ammerman, Ph.D., of the University of North Carolina School of Medicine and colleagues.
Studies of average-risk patients showed mixed results, and in cases where counseling did improve the patients' diets, the study did not reveal sufficient evidence of greater health benefits.
Most of the evidence on counseling's effectiveness comes from patients' reports of how their eating habits have changed, which might not be the most reliable measure of diet change, the task force also noted.
Pignone and colleagues analyzed 21 different studies where adult patients were counseled to eat less saturated fat or overall fat, eat more fruits or vegetables or eat more fiber each day. They ranked the success of the counseling based on the overall drop in saturated fat intake or increase in fruit and vegetable or fiber intake.
The researchers also noted factors such as where the counseling took place, how often and how long the sessions lasted, what types of techniques were used and whether interactive materials such as telephone calls and computer messages were part of the study.
Patients who received multiple types of counseling, such as a personal evaluation of their diet or group counseling, made bigger changes to their diet than less intensively counseled individuals. A combination of interactive materials and brief face-to-face advice also helped patients make larger changes to their diet, say the researchers.
The task force cited a lack of controlled studies of routine diet counseling in children and teens and a lack of good information on the possible harms of diet counseling as reasons not to recommend routine clinical counseling for those age groups.
One of the biggest questions remaining is whether small diet changes can lead to better health, Pignone and the task force say, although previous research suggests that moderate or large diet changes are associated with lower rates of heart disease and some types of cancer.
"Because we also have little direct evidence about the effect of small dietary changes on the risk of important health outcomes, we cannot determine with certainty whether these small changes in dietary behavior will translate into changes in the incidence of chronic disease," Pignone and colleagues say.
The study was funded by the Agency for Healthcare Research and Quality, a U.S. Department of Health and Human Services agency.
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