For older women, eating more vegetables may mean less atherosclerosis

Women 70 years and older who consumed an abundance of vegetables had lower measures of subclinical atherosclerosis in their carotid arteries than those who consumed few vegetables, Australian researchers found. Cruciferous vegetables—cabbage, Brussels sprouts, cauliflower, and broccoli—contributed the most benefit.

In an observational study of dietary patterns and common carotid artery intima-media thickness (CCA-IMT), older women who consumed at least three servings per day of vegetables had a 4.6% lower mean CCA-IMT and a 5% lower maximum CCA-IMT compared with the women who ate fewer than two servings, the researchers reported in Journal of the American Heart Association.

The 0.05-mm difference in maximum CCA-IMT found between the high-consumption group and low-consumption group “is likely to be clinically significant because a 0.1-mm decrease in carotid IMT is associated with a 10% to 18% decrease in risk of myocardial infarction and stroke,” wrote corresponding author Lauren C. Blekkenhorst, BHSc, research associate, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, and colleagues.

They studied epidemiologic determinants of CCA-IMT in participants initially enrolled in the Calcium Intake Fracture Outcome Study (CAIFOS). Begun in 1998, CAIFOS was a 5-year, double-blind, randomized, placebo-controlled trial of daily calcium supplementation to prevent osteoporotic fracture in woman aged 70 years and older. The current vegetable study, which included 954 women from the CAIFOS study population, was an ancillary investigation conceived in 2001.

Researchers ascertained food frequency via questionnaire at baseline. Vegetable types were broken down into cruciferous, allium (including onions, leek, and garlic), yellow/orange/red (tomato, capsicum, beetroot, carrot, pumpkin), leafy green (lettuce, salad greens, celery, silver beet, spinach), and legumes (peas, green beans, bean sprouts, alfalfa sprouts, soy beans, tofu, and other beans). One serving of vegetables was considered to be 75 g/day. The average number of daily vegetable servings per participant was 2.7 and the average total vegetable intake was 199.9 g/day. CCA-IMT and carotid focal plaque were assessed using high-resolution B-mode carotid ultrasonography.

Using linear regression, the researchers found that total vegetable intake was inversely associated with both mean and maximum CCA-IMT. For each additional serving of vegetables, mean CCA-IMT was 0.011 mm lower (1.4%, P=0.014) and maximum CCA-IMT was 0.016 mm lower (1.7%, P=0.002) after adjusting for lifestyle and cardiovascular risk factors.

Participants who consumed three or more servings of vegetables per day had about a 0.036 mm (4.6%) lower mean CCA-IMT and a 0.047 mm (5.0%) lower maximum CCA-IMT compared with those who consumed fewer than two servings.

When analyzed by vegetable type, intake of cruciferous vegetables was inversely associated with both mean and maximum CCA-IMT on linear regression analysis. For each additional 10 g/day intake of cruciferous vegetables, mean CCA-IMT was 0.006 mm lower (0.8%, P < 0.01) and maximum CCA-IMT was 0.007 mm lower (0.8%, P < 0.01). Intake of allium vegetables, yellow/orange/red vegetables, and leafy green vegetables were not significantly associated with mean or maximum CCA-IMT.

“Increasing vegetables within the diet with a focus on consuming cruciferous vegetables may protect against subclinical atherosclerosis in older adult women,” the authors concluded.

Vegetable intake was not associated with carotid plaque severity. Also, total fruit intake (per 150 g/day) was not associated with mean CCA-IMT and carotid plaque severity in adjusted models.

“If supported by other studies, dietary guidelines should highlight the importance of increasing consumption of cruciferous vegetables for protection from vascular disease,” the investigators wrote.

This study was funded by Healthway Western Australian Health Promotion Foundation and the National Health and Medical Research Council of Australia.