'Green' Mediterranean Diet Linked to Aortic Stiffness Reversal

Aortic stiffness regressed in overweight or dyslipidemic individuals who started a healthy diet, with the biggest benefit from a low-calorie "green" Mediterranean diet, post hoc analysis of a randomized trial showed.

The diet enriched with plant polyphenols and lower in red or processed meat and simple carbohydrates was better than a typical hypocaloric Mediterranean diet or following conventional healthy diet guidelines with regard to proximal aortic stenosis (PAS), reported Iris Shai, RD, PhD, of Ben-Gurion University of the Negev in Beer-Sheva, Israel, and colleagues.

After adjusting for other factors, PAS dropped by 15% over baseline with the green Mediterranean diet compared with 7.3% on the regular healthy Mediterranean diet and 4.8% with the guideline-based diet (-0.15 vs -0.08 and -0.05 raw natural logarithmic m/s, P=0.003 and P=0.032, respectively).

"This study, to our knowledge, is the first to show that PAS might be regressed by maintaining a healthy lifestyle," Shai's group wrote in a research letter in the Journal of the American College of Cardiology.

Beyond just weight loss, the green Mediterranean diet may have greater influence on PAS, which as a measure of "the aortic stiffness from the ascending to the proximal descending thoracic aorta, is a distinct marker of vascular aging and a sensitive early predictor of cardiovascular morbidity and mortality risk," they added. "Beyond aging, and similarly to atherosclerosis, PAS is sensitive to obesity-related metabolic conditions, specifically metabolic syndrome."

While lifestyle changes are the first line of treatment for obesity and metabolic syndrome, the prior data supporting its impact on PAS regression has rested on studies of intense physical activity.

Prior analyses of the group's DIRECT-PLUS trial, showed greater success of the "green" Mediterranean diet for the primary endpoints of reductions in abdominal fat, hepatic fat, and waist circumference over 18 months although the weight loss was similar to the regular Mediterranean diet (-3.9% and -2.7% over baseline).

The researchers thus analyzed the impact on PAS in the 281 participants with a valid baseline PAS. The overall trial included 294 adults age 30 and older with abdominal obesity or dyslipidemia (average age 51, BMI 31.3, 88% men) randomized to 18 months following healthy dietary guidelines, a hypocaloric Mediterranean diet, or hypocaloric "green" Mediterranean diet.

The two Mediterranean diets were to total the same 1,500-1,800 kcal/day for men and 1,200-1,400 kcal/day for women and to include 28 g of walnuts daily. The "green" version of the Mediterranean diet added consumption of 3-4 cups of green tea and a shake made of Wolffia globosa (Mankai, a high-protein aquatic plant also known as duckweed) each day, along with avoidance of processed red meat. All three groups got free gym memberships and instructions for moderate-intensity, largely aerobic physical activity.

PAS started out statistically similar between groups. Between-group differences in change in PAS were adjusted for age, sex, natural log of baseline PAS, change in weight, hypertension, dyslipidemia, diabetes, and baseline and change in mean arterial pressures.

The trial excluded people treated with warfarin because of the high level of vitamin K in the green plant-based shake that would interact with it.

Limitations of the trial included the post hoc exploratory nature of the analysis in a modest-sized trial with three primary and numerous secondary endpoints, which could have led to type I statistical error. The researchers acknowledged that the findings should be considered hypothesis-generating.

Another limitation was the largely male population studied, which the researchers attributed to the "unique" environment for the study. It was conducted among workers at an isolated nuclear research facility in Israel, where a monitored lunch was provided and which had a medical department where most of the clinical and medical measurements and lifestyle-intervention sessions were performed.

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