Diet Advice, and Change in Body Weight and CVD Risk
Does dietary advice and providing food improve body weight and cardiovascular disease (CVD) risk factors?
This was a randomized controlled trial of healthy overweight adults (209 men and 710 women), with a mean age 44.7 years, and body mass index (BMI) of 32.4 kg/m2. Randomization occurred between November 2005 and August 2009. The control group received Health Canada’s food guide advice (n = 486). The intervention groups received: 1) dietary advice consistent with both Dietary Approaches to Stop Hypertension (DASH) and dietary portfolio principles (n = 145), 2) weekly food provision reflecting this advice (n = 148), or 3) food delivery plus advice (n = 140). Interventions lasted 6 months with 12-month follow-up. Semiquantitative food frequency questionnaires and fasting blood, anthropometric, and blood pressure measures were obtained at baseline, 6 months, and 18 months.
A total of 919 participants were enrolled and randomized to one of four arms. Both the intervention arms and the control arm demonstrated reductions in body weight (-0.8 to -1.2 kg), and waist circumference (-1.1 to -1.9 cm). Retention of participants was higher among the arms in which food was provided compared with the arms in which food was not provided (p < 0.001). Significant reductions in diastolic blood pressure and mean arterial blood pressure were observed in the control group only. Although small reductions in the Framingham coronary heart disease risk score were observed for all four groups, the within-group changes were not statistically significant.
The authors concluded that provision of foods increased retention, but only modestly increased intake of recommended foods. Current dietary recommendations showed small overall benefits in coronary heart disease risk factors. Additional dietary strategies to maximize these benefits are required.
This study demonstrated the challenges of conducting a clinical study of dietary interventions. Understanding factors related to participants who responded or did not respond will assist the investigators in future research.
Keywords: Blood Pressure, Body Mass Index, Body Weight, Coronary Disease, Diet, Hypertension, Overweight, Primary Prevention, Risk Factors, Waist Circumference, Weight Loss
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