Am Fam Physician. 2006 May 1;73(9):1551.
Does dietary advice to patients achieve sustained dietary change or improvements in cardiovascular risk profile?
Dietary advice to lower fat and salt intake and increase intake of fruits, vegetables, and fiber produces modest improvements in cardiovascular risk factors. More intensive counseling yields greater effects.
Weight loss of 4 to 8 percent of body weight is associated with a decrease in blood pressure of 3 mm Hg (systolic and diastolic) and may decrease the need for medication in patients with hypertension.1 Salt reduction lowers blood pressure,2 and a low-fat diet can reduce cardiovascular risk.3 Obesity is associated with a variety of poor health outcomes. However, it is not clear whether dietary advice alone is enough to help patients make healthy eating choices that could prevent or delay the onset of disease.
Brunner and colleagues searched for randomized trials comparing dietary advice with no advice for the improvement of cardiovascular risk factors or for achieving sustained dietary changes in healthy adults. They found 23 trials with a total of 24,443 patients. The intervention arms consisted predominantly of individual counseling, group sessions, or written advice to lower fat and salt intake while increasing fruit, vegetable, and fiber intake. The least intensive interventions were single encounters. The most intensive included 50 hours of counseling over four years. Patients were followed for three months to four years with a median duration of nine months.
In the four trials that reported on blood pressure, dietary advice resulted in non-significant reductions of 2.1 mm Hg in systolic blood pressure and 1.6 mm Hg in diastolic blood pressure. Seven trials of dietary advice reported total blood cholesterol; these showed a statistically significant mean reduction in low-density lipoprotein cholesterol of 5 mg per dL (0.13 mmol per L) with no effect on high-density lipoprotein cholesterol or triglycerides. The 10 studies that measured dietary fat showed a mean reduction of 6 percent in the total dietary fat intake as a percentage of total calories. In eight studies, dietary advice increased patient intake of fruits and vegetables by 1.2 servings per day. Four studies showed that advising patients to increase dietary fiber led to a mean increase in fiber intake of 7.2 g per day. More intensive interventions tended to have greater effects. Based on their findings, the authors estimate that dietary advice may reduce the incidence of coronary heart disease by 12 percent.
The National Heart, Lung, and Blood Institute has a variety of resources for dietary advice available online. Patients who want to learn about healthy lifestyles can visithttp://www.nhlbi.nih.gov/health/index.htm#tools. Among the resources available at the Web site are a body mass index calculator, a Portion Distortion quiz, an interactive menu planner, recipes, and general and disease-specific dietary advice.
Brunner EJ, et al. Dietary advice for reducing cardiovascular risk. Cochrane Database Syst Rev. 2005;(4):CD002128.
1. Mulrow CD, Chiquette E, Angel L, Cornell J, Summer-bell C, Anagnostelis B, et al. Dieting to reduce body weight for controlling hypertension in adults. Cochrane Database Syst Rev. 1998;(4):CD000484.
2. He FJ, MacGregor GA. Effect of longer-term modest salt reduction on blood pressure. Cochrane Database Syst Rev. 2004;(1):CD004937.
3. Hooper L, Summerbell CD, Higgins JP, Thompson RL, Clements G, Capps N, et al. Reduced or modified dietary fat for preventing cardiovascular disease. Cochrane Database Syst Rev. 2000;(2):CD002137.
The series coordinator for AFP is Clarissa Kripke, M.D., Department of Family and Community Medicine, University of California, San Francisco.
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