8/19/13
by Todd Neale
Senior Staff Writer, MedPage Today

A diet high in antioxidant-rich fruit may help protect against the development of an abdominal aortic aneurysm (AAA), a Swedish study suggested.

Through 13 years of follow-up, men and women who said they ate more than two servings of fruit a day had a 25% lower risk of developing AAA (HR 0.75, 95% CI 0.62-0.91) compared with those who ate less than 0.7 servings a day, according to Otto Stackelberg, MD, of the Karolinska Institute in Stockholm, and colleagues.

And those who ate the most fruit had a 43% lower risk of developing a ruptured AAA (HR 0.57, 95% 0.36-0.89), the researchers reported in the Aug. 20 issue of Circulation: Journal of the American Heart Association. There were no such associations with vegetable intake.

“A diet high in fruits may help to prevent many vascular diseases, and this study provides evidence that a lower risk of AAA will be among the benefits,” Stackelberg and colleagues wrote.

“Berries, especially blueberries and cranberries, are an amazing source of antioxidants which help reverse the oxidation process that results in cardiovascular disease,” commented Lori Mackstaller, MD, of the University of Arizona in Tucson.

“If people ate a balanced diet rich in fruits and vegetables — especially berries — it could help decrease inflammation,” she wrote in an email.

Established risk factors for AAA include older age, male sex, and smoking, but potential dietary risk factors have not been studied in depth.

“Growing evidence indicates that inflammation and oxidative stress may play an important role in AAA pathophysiology, and the redox balance facilitated by antioxidants has made them subject to speculation of having protective effects against AAA development,” the authors wrote. Thus, fruits and vegetables — which contain high levels of antioxidants — may be protective.

However, only one previous study has explored the association between fruit and vegetable intake and AAA risk. It showed thatincreased consumption of fruits and vegetables combined was associated with a lower risk of AAA, but it did not examine fruits and vegetables separately or look at the risk of ruptured AAA specifically.

Stackelberg and colleagues looked at data from two large Swedish cohort studies. The current analysis included 44,317 men and 36,109 women ages 46 to 84 at baseline who were followed from 1998 through 2010. All of the participants reported fruit and vegetable consumption at baseline using a 96-item food frequency questionnaire.

Through follow-up, there were 1,086 AAA cases, including 222 ruptured aneurysms. The majority of the cases (86%) and the ruptures (81.5%) occurred in men.

The risk of AAA decreased as consumption of fruit increased (P=0.003 for trend). The association between fruit consumption and AAA risk did not differ by sex.

In an analysis looking at specific types of fruit, no individual fruit was associated with the risk of developing AAA.

Smoking status was the largest confounder of the observed relationships, and in a stratified analysis eating more than two servings of fruit per day was associated with a reduced risk of ruptured AAA in past smokers (HR 0.42, 95% CI 0.19-0.94) and current smokers (HR 0.39, 95% CI 0.17-0.94), but not in those who never smoked (HR 1.02, 95% CI 0.39-2.70). The discrepancy is possibly related to the higher levels of oxidative stress induced by smoking.

Because it is biologically plausible that eating high levels of antioxidants could reduce the risk of developing AAA, it was unexpected that consumption of fruits but not vegetables was associated with AAA risk because both are rich in antioxidants.

“A possible explanation may be the different types of antioxidants found in fruits and vegetables that could have more or less effect on oxidative stress in the aortic wall,” the authors wrote.

They acknowledged some limitations of the study, including possible misclassification of dietary intake on the self-administered questionnaires, the possibility that diet could have changed over time, and the lack of routine screening of the aorta, limiting the ability to detect asymptomatic cases of AAA.

UPDATE: This article, originally published Aug. 19, 2013, at 4:00 p.m., was updated with new material (Aug. 19, 2013, at 8:08 p.m.).

From the American Heart Association:

• Antioxidant Vitamin Supplements and Cardiovascular Disease
• Implementing AHA Pediatric and Adult Nutrition Guidelines

• Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
• Download a complimentary source PDF.

last updated 08.20.2013