The modified diet was found to be twice as effective in promoting proximal de-stiffening of the aorta, the largest artery in the body responsible for carrying oxygenated blood throughout the body.
Polyphenols, naturally occurring compounds, are abundant in fruits such as grapes, apples, pears, cherries, and berries, as well as in vegetables, cereals, and beverages like coffee and green tea. Certain fruits contain up to 200 to 300 milligrams of polyphenols per 100 grams of fresh weight.
The body's tissues are safeguarded against oxidative stress and its associated pathologies, including inflammation, coronary heart disease, and cancers, by polyphenols, which are reducing agents. Vitamin C, vitamin E, carotenoids, and other dietary reducing agents, also known as antioxidants, work in conjunction with polyphenols to provide protection.
However, it is important not to overestimate their benefits, as animal studies have shown that high doses of polyphenol supplements can lead to an imbalance in thyroid levels, kidney damage, and tumors. In humans, they may increase the risk of stroke and premature death.
The research team of the DIRECT PLUS trial was the first to introduce the concept of a green-Mediterranean, high polyphenols diet. This modified Mediterranean diet differs from the traditional one in that it contains higher levels of dietary polyphenols and lower amounts of red or processed meat. In addition to consuming 28 grams of walnuts daily, the green-Mediterranean dieters drank three to four cups of green tea and one cup of Wolffia-globosa (mankai) plant green shake made from duckweed every day for a year and a half. The aquatic green plant mankai is high in bioavailable iron, B12, 200 kinds of polyphenols, and protein and can thus serve as a good substitute for meat.
The "green Mediterranean-high polyphenols" diet has been shown to significantly reverse proximal aortic stiffness (PAS), which is a marker of vascular aging and increased cardiovascular risk. In the DIRECT PLUS clinical intervention trial, the green Mediterranean diet was compared to the healthy Mediterranean diet and a healthy guideline-recommended control diet.
Results showed that the green Mediterranean diet led to a 15% regression in proximal aortic stiffness, while the Mediterranean diet resulted in a 7.3% regression, and the healthy guideline-directed diet resulted in a 4.8% regression. The study, titled "Effect of Lifestyle Modification and Green Mediterranean Diet on Proximal Aortic Stiffness," was published in the prestigious Journal of the American College of Cardiology.
For the first time, the study demonstrated the significant impact of diet on age-related proximal aortic stiffness. The DIRECT PLUS trial was a long-term clinical study conducted over 18 months with 300 participants, using MRI scans to measure aortic stiffness. MRI scans are the most accurate non-invasive method of assessing the elasticity of the blood vessel wall, which is compromised when the elastic fibers within the arterial wall (elastin) begin to fray due to mechanical stress.
Proximal aortic stiffness (PAS) is an indicator of aortic stiffness in the section of the aorta from the ascending to the proximal-descending thoracic aorta. PAS is a specific marker of vascular aging and is an independent risk factor for predicting morbidity and mortality due to cardiovascular disease.
The first and most commonly used intervention to treat obesity and its metabolic complications is changing to a healthier lifestyle. Although intense exercise can reduce PAS, the effect of weight loss interventions on PAS is still unclear. The Mediterranean diet is the most well-established dietary intervention for reducing cardiometabolic risk and preventing cardiovascular disease.
In protecting the heart and other vital organs, the Green Mediterranean/high polyphenols diet is superior to the Mediterranean diet. However, the effects of the Mediterranean diet on PAS are not well-understood. Recently, it was reported that a hypocaloric-green Mediterranean diet enriched with plant-based polyphenols and less meat and simple carbohydrates may offer benefits beyond the hypocaloric-Mediterranean and healthy dietary guidelines for improving cardiometabolic risk.
The study was headed by Prof. Iris Shai, who is affiliated with Ben-Gurion University of the Negev in Beersheba, Israel, as well as the Harvard School of Public Health and the University of Leipzig, Germany, where she holds adjunct and honorary professor positions, respectively. Dr. Gal Tsaban, a cardiologist from Soroka-University Medical Center, and researchers from Harvard and Leipzig universities were also part of the research team.
The team's previous studies have demonstrated that the green Mediterranean, high polyphenols diet has several beneficial effects, such as altering the microbiome, halting brain atrophy, and regressing hepatosteatosis intrahepatic and visceral adiposity.
According to Shai, "A healthy lifestyle is the cornerstone of improving cardiometabolic health. Our study results show that the quality of the diet plays a critical role in reducing atherogenic adipose tissue, lowering cardiometabolic risk, and improving one's lipid profile. The consumption of dietary polyphenols while replacing red meat with an equivalent amount of plant-based protein can significantly enhance human health in various ways."
According to Shai, "Despite this, there is currently no evidence to suggest that any dietary interventions can affect vascular aging physiology. To our knowledge, this study is the first to demonstrate that maintaining a healthy lifestyle can regress PAS, a predictor of reduced cardiovascular disease risk. Compared to other Mediterranean diets, the Green-Mediterranean diet may have a greater impact on the regression of PAS. Although maintaining a healthy diet alone is associated with PAS regression, the Green-Mediterranean diet can achieve a dramatic 15% reduction in PAS through simple and achievable dietary and lifestyle changes."
Tsaban added, "Our study's findings emphasize that not all diets are created equal, and that the Green-Mediterranean diet may have beneficial effects on vascular health."
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