Dietary Intervention to Reverse Carotid Atherosclerosis
Background— It is currently unknown whether dietary weight loss interventions can induce regression of carotid atherosclerosis.
Methods and Results— In a 2-year Dietary Intervention Randomized Controlled Trial–Carotid (DIRECT-Carotid) study, participants were randomized to low-fat, Mediterranean, or low-carbohydrate diets and were followed for changes in carotid artery intima-media thickness, measured with standard B-mode ultrasound, and carotid vessel wall volume (VWV), measured with carotid 3D ultrasound. Of 140 complete images of participants (aged 51 years; body mass index, 30 kg/m2; 88% men), higher baseline carotid VWV was associated with increased intima-media thickness, age, male sex, baseline weight, blood pressure, and insulin levels (P<0.05 for all). After 2 years of dietary intervention, we observed a significant 5% regression in mean carotid VWV (−58.1 mm3; 95% confidence interval, −81.0 to −35.1 mm3; P<0.001), with no differences in the low-fat, Mediterranean, or low-carbohydrate groups (−60.69 mm3, −37.69 mm3, −84.33 mm3, respectively; P=0.28). Mean change in intima-media thickness was −1.1% (P=0.18). A reduction in the ratio of apolipoprotein B100 to apolipoprotein A1 was observed in the low-carbohydrate compared with the low-fat group (P=0.001). Participants who exhibited carotid VWV regression (mean decrease, −128.0 mm3; 95% confidence interval, −148.1 to −107.9 mm3) compared with participants who exhibited progression (mean increase, +89.6 mm3; 95% confidence interval, +66.6 to +112.6 mm3) had achieved greater weight loss (−5.3 versus −3.2 kg; P=0.03), greater decreases in systolic blood pressure (−6.8 versus −1.1 mm Hg; P=0.009) and total homocysteine (−0.06 versus +1.44 μmol/L; P=0.04), and a higher increase of apolipoprotein A1 (+0.05 versus −0.00 g/L; P=0.06). In multivariate regression models, only the decrease in systolic blood pressure remained a significant independent modifiable predictor of subsequent greater regression in both carotid VWV (β=0.23; P=0.01) and intima-media thickness (β=0.28; P=0.008) levels.
Conclusions— Two-year weight loss diets can induce a significant regression of measurable carotid VWV. The effect is similar in low-fat, Mediterranean, or low-carbohydrate strategies and appears to be mediated mainly by the weight loss–induced decline in blood pressure.
Clinical Trial Registration— http://www.clinicaltrials.gov. Unique Identifier: NCT00160108.
Received May 11, 2009; accepted December 28, 2009.