Writing in the Journal of Vascular Surgery, the Japanese research team reported that polyphenols from the nation's favourite drink, green tea, could offer benefits in preventing abdominal aneurysm expansion (AAA) – a serious condition characterised by destruction of the body’s main artery.
The life threatening condition, occurs when the main artery becomes overstretched and bloated – resulting in vasodilation and, if left untreated, a rupture that leads to death 50% of the time, noted the authors – led by Shuji Setozaki from Kyoto University.
"Abdominal aortic aneurysms often go unnoticed because there are no symptoms until they burst," commented study co-author Kenji Minakata. "If a patient is lucky and bloating is found before rupture, it needs to be treated surgically, such as by transplanting an artificial blood vessel or inserting a stent graft. At the moment there are no pharmacological treatments."
However, the new study from the Kyoto University team found that rats fed a green tea extract containing epigallocatechin-3-gallate (EGCG) developed AAA less frequently than rats that were not given the polyphenol.
"The type of polyphenol found in green tea [EGCG] has recently been shown to regenerate elastin, an essential protein that gives the artery its stretchy, yet sturdy, texture," explains Setozaki. "Considering that abdominal arterial aneurysms are caused by inflammation and the degradation of elastin components in the arterial wall, we thought drinking green tea may show promise for treatment."
The results confirmed that EGCG blocked AAA progression in the rat model by preserving the aortic thickness and elastin content through regeneration of elastin.
“Regular green tea consumption might be advantageous for patients with a small AAA or as a prophylactic strategy for AAA,” the team suggested.
Study co-author Hidetoshi Masumoto noted that 80% of the Japanese population – a population with the longest average lifespan in the world – drink green tea on a daily basis.
"We believe daily intake of green tea should be considered as a new preventative strategy for abdominal aortic aneurysm; the focus of future studies will be to investigate optimal doses,” he said.
To test the effects of EGCG on prevention of abdominal aortic aneurysm, Setozaki and colleagues treated rats given either the green tea extract or a control with enzymes that induce the condition.
They found that the condition developed less in rats that drank the green tea extract containing EGCG.
Consumption of the polyphenol also resulted in less inflammation and more elastin production, said the team – noting that these mechanisms likely protected the artery from rupture.
“Abdominal aortic diameter was significantly smaller in the EGCG group than in the control group on day 28,” the team noted – adding that medial layer wall thickness and elastin content were also significantly greater in the EGCG group than in the control group on day.
“Daily green tea intake should be considered as a potential novel preventive strategy for AAA,” they concluded.
Source: Journal of Vascular Surgery
Published online ahead of print, doi: 10.1016/j.jvs.2016.06.003
“Prevention of abdominal aortic aneurysm progression by oral administration of green tea polyphenol in a rat model”
Authors: Shuji Setozaki, et al