A green adaptation to the traditional Mediterranean diet improves proximal aortic stiffness (PAS), a distinct marker of vascular aging and increased cardiovascular risk, according to an exploratory post hoc analysis of the DIRECT-PLUS randomized clinical trial.
The green Mediterranean diet is distinct from the traditional Mediterranean diet because of its more abundant dietary polyphenols, from green tea and a Wolffia globosa (Mankai) plant green shake, and lower intake of red or processed meat.
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Independent of weight loss, the modified green Mediterranean diet regressed PAS by 15%, the traditional Mediterranean diet by 7.3%, and the healthy dietary guideline–based diet by 4.8%, the study team observed.
“The DIRECT-PLUS trial research team was the first to introduce the concept of the green-Mediterranean/high polyphenols diet,” lead researcher Iris Shai, RD, PhD, with Ben-Gurion University of the Negev, Be’er-Sheva, Israel, told this news organization.
This diet promoted “dramatic proximal aortic de-stiffening” as assessed by MRI over 18 months in roughly 300 participants with abdominal obesity/dyslipidemia. “To date, no dietary strategies have been shown to impact vascular aging physiology,” Dr. Shai said.
The analysis was published online in the Journal of the American College of Cardiology.
Not all healthy diets are equal
Of the 294 participants, 281 had valid PAS measurements at baseline. The baseline PAS (6.1 m/s) was similar across intervention groups (P = .20). Increased PAS was associated with aging, hypertension, dyslipidemia, diabetes, and visceral adiposity (P < .05).
After 18 months’ intervention (retention rate 89.8%), all diet groups showed significant PAS reductions: –0.05 m/s with the standard healthy diet (4.8%), –0.08 m/s with the traditional Mediterranean diet (7.3%) and –0.15 the green Mediterranean diet (15%).
In the multivariable model, the green Mediterranean dieters had greater PAS reduction than did the healthy-diet and Mediterranean dieters (P = .003 and P = .032, respectively).
The researchers caution that DIRECT-PLUS had multiple endpoints and this exploratory post hoc analysis might be sensitive to type I statistical error and should be considered “hypothesis-generating.”
High-quality study, believable results
Reached for comment on the study, Deepak L. Bhatt, MD, MPH, director of Mount Sinai Heart in New York, said, “There is not a lot of high-quality research on diet, and I would call this high-quality research in as much as they used randomization which most dietary studies don’t do.
“The greener Mediterranean diet seemed to be the best one on the surrogate marker of MRI-defined aortic stiffness,” Dr. Bhatt, professor of cardiovascular medicine, Icahn School of Medicine at Mount Sinai, who wasn’t involved in the study, told this news organization.
“It makes sense that a diet that has more green in it, more polyphenols, would be healthier. This has been shown in some other studies, that these plant-based polyphenols might have various cardiovascular protective aspects to them,” Dr. Bhatt said.
Overall, he said the results are “quite believable, with the caveat that it would be nice to see the results reproduced in a more diverse and larger sample.”
“There is emerging evidence that diets that are higher in fresh fruits and vegetables and whole grains and lower in overall caloric intake, in general, seem to be good diets to reduce cardiovascular risk factors and maybe even reduce actual cardiovascular risk,” Dr. Bhatt added.
The study was funded by grants from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), the Rosetrees Trust, Israel Ministry of Health, Israel Ministry of Science and Technology, and the California Walnuts Commission. Dr. Shai and Dr. Bhatt have no relevant conflicts of interest.
A version of this article first appeared on Medscape.com.