This statement summarizes the current U.S. Preventive Services Task Force (USPSTF) recommendations on counseling to promote a healthy diet in primary care patients and the supporting scientific evidence, and it updates the 1996 recommendations contained in the Guide to Clinical Preventive Services, second edition.1 Explanations of the ratings and of the strength of overall evidence are given in Tables 1 and 2, respectively. The complete information on which this statement is based, including evidence tables and references, is available in the Systematic Evidence Review2 on this topic, which can be obtained through the USPSTF Web site (www.uspreventiveservicestaskforce.org) and through the National Guideline Clearing-house (www.guideline.gov). The summary of the evidence and the recommendation statement are also available in print through the Agency for Healthcare Research and Quality Publications Clearinghouse (telephone: 1-800-358-9295; e-mail: email@example.com).
To address whether to recommend counseling to promote a healthy diet among primary care patients, the USPSTF reviewed the evidence on nutritional and behavioral counseling by a variety of practitioners (e.g., physicians, nurses, nutritionists, dietitians, health educators) and in a variety of clinical settings (e.g., primary care practices, specialty clinics). In updating its recommendations, the USPSTF did not reevaluate the benefits of a healthy diet, which are detailed in many other reports. Instead, it focused on new controlled studies of the efficacy of counseling for changing dietary behavior in patients similar to those found in primary care practices. The review did not include studies of dietary interventions for specific chronic illnesses (e.g., heart disease, diabetes, renal failure) but included studies enrolling patients with common risk factors such as elevated cholesterol, hypertension, obesity, or family history of heart disease. Counseling interventions with a primary focus on weight loss, weight management, and/or the treatment of obesity are covered in a separate review3 and are outside the scope of this recommendation. Studies of diet interventions focusing on lowering cholesterol levels in patients with elevated cholesterol or other lipid abnormalities are addressed in a separate USPSTF report titled “Screening for Lipid Disorders in Adults.”4 Studies of breastfeeding also will be addressed in a future USPSTF report. All published reports are available on the USPSTF Web site at: http://www.uspreventiveservicestaskforce.org/recommendations.htm.
|The USPSTF grades its recommendations according to one of five classifications (A, B, C, D, or I) reflecting the strength of evidence and magnitude of net benefit (benefits minus harms).|
|A.||The USPSTF strongly recommends that clinicians routinely provide [the service] to eligible patients. The USPSTF found good evidence that [the service] improves important health outcomes and concludes that benefits substantially outweigh harms.|
|B.||The USPSTF recommends that clinicians routinely provide [the service] to eligible patients. The USPSTF found at least fair evidence that [the service] improves important health outcomes and concludes that benefits outweigh harms.|
|C.||The USPSTF makes no recommendation for or against routine provision of [the service]. The USPSTF found at least fair evidence that [the service] can improve health outcomes but concludes that the balance of benefits and harms is too close to justify a general recommendation.|
|D.||The USPSTF recommends against routinely providing [the service] to asymptomatic patients. The USPSTF found at least fair evidence that [the service] is ineffective or that harms outweigh benefits.|
|I.||The USPSTF concludes that the evidence is insufficient to recommend for or against routinely providing [the service]. Evidence that [the service] is effective is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined.|
|The USPSTF grades the quality of the overall evidence for a service on a three point scale (good, fair, or poor).|
|Good:||Evidence includes consistent results from well-designed, well-conducted studies in representative populations that directly assess effects on health outcomes.|
|Fair:||Evidence is sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality, or consistency of the individual studies; generalizability to routine practice; or indirect nature of the evidence on health outcomes.|
|Poor:||Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, important flaws in their design or conduct, gaps in the chain of evidence, or lack of information on important health outcomes.|
These recommendations were first published in Am J Prev Med 2003;24:93–100.
Summary of Recommendations
The USPSTF concludes that the evidence is insufficient to recommend for or against routine behavioral counseling to promote a healthy diet in unselected patients in primary care settings. I recommendation.
The USPSTF found fair evidence that brief, low- to medium-intensity behavioral dietary counseling in the primary care setting can produce small to medium changes in average daily intake of core components of an overall healthy diet (especially saturated fat, fruit, and vegetables) in unselected patients. The strength of this evidence, however, is limited by reliance on self-reported diet outcomes, limited use of measures corroborating reported changes in diet, limited follow-up data beyond six to 12 months, and enrollment of study participants who may not be fully representative of primary care patients. In addition, there is limited evidence to assess possible harms (see “Clinical Considerations”). As a result, the USPSTF concluded that there is insufficient evidence to determine the significance and magnitude of the benefit of routine counseling to promote a healthy diet in adults. Although community-based studies have evaluated measures to reduce dietary fat intake in children, no controlled trials of routine behavioral dietary counseling for children or adolescents in the primary care setting were identified.
The USPSTF recommends intensive behavioral dietary counseling for adult patients with hyperlipidemia and other known risk factors for cardiovascular and diet-related chronic disease. Intensive counseling can be delivered by primary care clinicians or by referral to other specialists, such as nutritionists or dietitians. B recommendation.
The USPSTF found good evidence that medium- to high-intensity counseling interventions can produce medium to large changes in average daily intake of core components of a healthy diet (including saturated fat, fiber, fruit, and vegetables) among adult patients at increased risk for diet-related chronic disease. Intensive counseling interventions that have been examined in controlled trials among at-risk adult patients have combined nutrition education with behavioral dietary counseling provided by a nutritionist, dietitian, or specially trained primary care clinician (e.g., physician, nurse, nurse practitioner). The USPSTF concluded that such counseling is likely to improve important health outcomes and that benefits outweigh potential harms. No controlled trials of intensive counseling in children or adolescents that measured diet were identified.5,6
Several brief dietary assessment questionnaires have been validated for use in the primary care setting.7,8 These instruments can identify dietary counseling needs, guide interventions, and monitor changes in patients' dietary patterns. However, these instruments are susceptible to the bias of the respondent. Therefore, when used to evaluate the efficacy of counseling, efforts to verify self-reported information are recommended since patients receiving dietary interventions may be more likely to report positive changes in dietary behavior than control patients.9–12
Effective interventions combine nutrition education with behavior-oriented counseling to help patients acquire the skills, motivation, and support needed to alter their daily eating patterns and food preparation practices. Examples of behavior-oriented counseling interventions include teaching self-monitoring, training to overcome common barriers to selecting a healthy diet, helping patients to set their own goals, providing guidance in shopping and food preparation, role playing, and arranging for intra-treatment social support. In general, these interventions can be described with reference to the 5-A behavioral counseling framework13: Assess dietary practices and related risk factors, Advise to change dietary practices, Agree on individual diet change goals, Assist to change dietary practices or address motivational barriers, and Arrange regular follow-up and support or refer to more intensive behavioral nutritional counseling (e.g., medical nutrition therapy) if needed.
Two approaches appear promising for the general population of adult patients in primary care settings: (1) medium-intensity face-to-face dietary counseling (two or three group or individual sessions) delivered by a dietitian or nutritionist or by a specially trained primary care physician or nurse practitioner, and (2) lower-intensity interventions that involve five minutes or less of primary care provider counseling supplemented by patient self-help materials, telephone counseling, or other interactive health communications. However, more research is needed to assess the long-term efficacy of these treatments and the balance of benefits and harms.
The largest effect of dietary counseling in asymptomatic adults has been observed with more intensive interventions (multiple sessions lasting 30 minutes or longer) among patients with hyperlipidemia or hypertension, and among others at increased risk for diet-related chronic disease. Effective interventions include individual or group counseling delivered by nutritionists, dietitians, or specially trained primary care practitioners or health educators in the primary care setting or in other clinical settings by referral. Most studies of these interventions have enrolled selected patients, many of whom had known diet-related risk factors such as hyperlipidemia or hypertension. Similar approaches may be effective with unselected adult patients, but adherence to dietary advice may be lower, and health benefits smaller, than in patients who have been told they are at higher risk for diet-related chronic disease.14
Possible harms of dietary counseling have not been well defined or measured. Some have raised concerns that if patients focus only on reducing total fat intake without attention to reducing caloric intake, an increase in carbohydrate intake (e.g., reduced-fat or low-fat food products) may lead to weight gain, elevated triglyceride levels, or insulin resistance. Nationally, obesity rates have increased despite declining fat consumption, but studies did not consistently examine effects of counseling on outcomes such as caloric intake and weight.
Little is known about effective dietary counseling for children or adolescents in the primary care setting. Most studies of nutritional interventions for children and adolescents have focused on nonclinical settings (such as schools) or have used physiologic outcomes such as cholesterol levels or weight rather than more comprehensive measures of a healthy diet.5,6
The brief review of evidence that is normally included in USPSTF recommendation statements is available in the complete Recommendation and Rationale statement on the USPSTF Web site (http://www.uspreventiveservicestaskforce.org/recommendations.htm).
Recommendations of Others
Dietary guidelines for the general population have been issued by the U.S. Department of Agriculture18 and the Department of Health and Human Services; specific dietary objectives for the nation are outlined in Healthy People 2010.19 Guidelines from the American Heart Association and the American Cancer Society address diets that will lower the risk for heart disease and cancer, respectively.20,21 These guidelines generally agree in recommending a diet that includes a variety of fruits, vegetables, and grain products; is low in saturated fat and cholesterol, and moderate in total fat; and balances calories with physical activity to maintain a healthy weight.
A variety of groups have recommended nutritional counseling or dietary advice for patients at average risk for chronic disease, including the American College of Preventive Medicine, American Academy of Family Physicians, American Academy of Pediatrics, and the American College of Obstetricians and Gynecologists.22–25 These recommendations are based primarily on the benefits of a healthy diet rather than on evaluations of the efficacy of counseling. The Canadian Task Force on Preventive Health Care concluded in 1994 that there was fair evidence to provide general dietary advice to all patients, based on a limited number of trials of counseling.26
Recommendations on nutritional counseling for patients at risk (e.g., those who have hypertension or hyperlipidemia) have been issued by the American Dietetic Association (ADA) and two panels sponsored by the National Institutes of Health National Heart, Lung, and Blood Institute. The ADA recommends that primary care providers screen for nutrition-related illnesses, prescribe diets, provide preliminary counseling on specific nutritional needs, follow up with patients, and refer patients to appropriate dietetic professionals when necessary.27 Similarly, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends that dietary assessments be included as part of routine medical history and that physicians counsel patients on lifestyle modifications for the prevention and treatment of high blood pressure (e.g., lose weight if overweight, limit alcohol intake, reduce sodium intake, reduce saturated fat and cholesterol intake).28 The National Cholesterol Education Program recommends that individuals with elevated levels of low density lipoprotein limit their intake of fats, particularly saturated fats, and cholesterol and increase dietary fiber.29