A Large Randomized Individual and Group Intervention Conducted by Registered Dietitians Increased Adherence to Mediterranean-Type Diets: The PREDIMED Study
Accepted 7 January 2008.
Abstract
Objective
To assess the effectiveness of an intervention aimed to increase adherence to a Mediterranean diet.
Design
A 12-month assessment of a randomized primary prevention trial.
Subjects/settings
One thousand five hundred fifty-one asymptomatic persons aged 55 to 80 years, with diabetes or ≥3 cardiovascular risk factors.
Intervention
Participants were randomly assigned to a control group or two Mediterranean diet groups. Those allocated to the two Mediterranean diet groups received individual motivational interviews every 3 months to negotiate nutrition goals, and group educational sessions on a quarterly basis. One Mediterranean diet group received free virgin olive oil (1 L/week), the other received free mixed nuts (30 g/day). Participants in the control group received verbal instructions and a leaflet recommending the National Cholesterol Education Program Adult Treatment Panel III dietary guidelines.
Main outcome measures
Changes in food and nutrient intake after 12 months.
Statistical analyses
Paired t tests (for within-group changes) and analysis of variance (for between-group changes) were conducted.
Results
Participants allocated to both Mediterranean diets increased their intake of virgin olive oil, nuts, vegetables, legumes, and fruits (P<0.05 for all within- and between-group differences). Participants in all three groups decreased their intake of meat and pastries, cakes, and sweets (P<0.05 for all). Fiber, monounsaturated fatty acid, and polyunsaturated fatty acid intake increased in the Mediterranean diet groups (P<0.005 for all). Favorable, although nonsignificant, changes in intake of other nutrients occurred only in the Mediterranean diet groups.
Conclusions
A 12-month behavioral intervention promoting the Mediterranean diet can favorably modify an individual's overall food pattern. The individual motivational interventions together with the group sessions and the free provision of high-fat and palatable key foods customary to the Mediterranean diet were effective in improving the dietary habits of participants in this trial.
Address correspondence to: Miguel A. Martinez-Gonzalez, MD, PhD, Department of Preventive Medicine and Public Health, University of Navarra, C/ Irunlarrea s/n 31080, Pamplona, Navarra, Spain.
ABSTRACT
A Large Randomized Individual and Group Intervention Conducted by Registered Dietitians Increased Adherence to Mediterranean-Type Diets: The PREDIMED Study