MINNEAPOLIS, MN — Eating a diet rich in fruits and vegetables as a young adult may help lower coronary artery calcium (CAC), a known predictor of CV events, up to two decades later, suggests new research.
Analysis of a cohort of more than 2000 participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study showed that, after adjustment for factors such as age, body-mass index (BMI), and smoking status, those who consumed seven to nine daily servings of fruits and vegetables at baseline (when they were a mean age of 25.3 years) were 26% less likely to have CAC 20 years later vs those who consumed only two to four servings of these items per day.
However, when stratified by sex, this association remained significant only in women, with those in the top tertile of fruit and vegetable intake 45% less likely to have CAC vs those in the bottom tertile.
CAC, "a direct marker of coronary atherosclerosis, is . . . a powerful CVD risk stratification tool," note the investigators, led by Dr Michael D Miedema (Minneapolis Heart Institute, MN). However, Miedema told heartwire from Medscape that most of the past nutritional research has looked only at middle-aged populations.
"We frequently tell younger people 'what you eat matters,' but really we don't have any good evidence that it has an impact on their risk of heart disease down the road," he said. "So the point of this study was to look at a younger population to see: is it okay to wait until your 50s to eat healthily? Or does what you do in your 20s and 30s actually matter?"
The findings were published online October 26, 2015 in Circulation.
"The dietary pattern and lifestyle pattern exhibited by the high consumers . . . is consistent with what has been historically and is currently recommended to reduce [CVD] risk," Dr Alice H Lichtenstein (Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA) writes in an accompanying editorial.
However, she notes that a remaining question is whether the inverse association with CAC score found in this study is actually directly attributable to high intake of fruits and vegetables or to "a constellation of factors."
CAC and Diet
The CARDIA study was created in 1985–1986 to assess CVD risk factors in 5115 young adults from four sites in the US.
For this analysis, the investigators assessed 2506 CARDIA participants (63% women) who were interviewed about past-month dietary consumption at baseline and also underwent computed tomography between 2005 and 2006 to measure CAC.
"CAC has been shown to predict mortality independent of age, and even minimal amounts of coronary calcification (CAC score 1–10) have been associated with a substantial increase in mortality," write the investigators.
Women in the top tertile of fruit and vegetable intake consumed 8.9 servings per day vs 3.3 servings/day for those in the bottom tertile. For men, the mean intake was 7.2 and 2.6 servings/day for the top and bottom tertiles, respectively.
The overall group with the highest tertile of fruit and vegetable intake at baseline had a significantly lower prevalence of CAC at follow-up compared with the group who had the lowest intake (adjusted odds ratio [OR] 0.74, 95% CI 0.56–0.99; P for trend <0.001).
The trend remained significant even after further adjustment for other dietary variables,such as intake of fried potatoes, cakes/cookies/doughnuts, soft drinks, and fast food (OR 0.92, 95% CI 0.67–1.26; P=0.002). It also stayed significant after adjustment for systolic blood pressure, LDL and HDL cholesterol, and fasting blood sugar levels (OR 0.78, 95% CI 0.58–1.03, P<0.001).
More Protective for Women?
Women-only assessment showed that those who had the highest intake of fruits and vegetables had an OR of 0.55 (95% CI 0.35–0.87) for prevalent CAC vs those in the lowest-intake group (P=0.01). Those who were in the middle tertile (mean 5.4 servings/day) were also significantly less likely to have CAC vs the lowest tertile (OR 0.73, 95% CI 0.48–1.10). However, the association wasn't significant for the men.
This latter result "may be due to a lack of power, as our study included only 935 male participants," write the investigators. "However, a less significant association between CVD and [fruits and vegetables] intake in men has been seen in other studies."
"Potentially, women have the capacity to protect themselves a little bit more, but that doesn't mean that men don't have the capacity," said Miedema. "It's important for men to follow a healthy diet as well. It's just that male gender is a risk factor for heart disease."
Although the investigators note that "our results reinforce the importance of establishing a high intake of [fruits and vegetables] as part of a healthy dietary pattern early in life," Miedema added that that doesn't mean those who start eating healthily later in life can't see any benefit.
"It's very clear that cardiovascular disease is a lifelong process. So the more healthy things we do throughout the lifespan, the more likely it is that we'll lower our risk."
Say No to Banana Splits
Lichtenstein notes in her editorial that the new findings support the beneficial effects of a diet high in fruits and vegetables and applauded that the study "had an impressive retention rate of 72%."
However, she writes that "it is somewhat puzzling" that the associations were not significant for the male participants. In addition to the possible reasons for this listed by the investigators, Lichtenstein points out that the women with higher intake also had significantly lower BMI, LDL-C, and energy intake and higher HDL-C.
She also points out that because there were 48 different options under the fruits and vegetables heading, "it is highly unlikely that a single nutrient was the putative factor linking intake and the outcome of coronary artery calcification."
So what was the cause? "Could it be attributable to what the high consumers . . . were not eating and behaviors they were or were not engaging in?"
Lichtenstein writes that current dietary recommendations for CVD risk reduction is to consume veggies, fruits, whole grains, low-fat dairy products, poultry, fish, and nuts and to limit the consumption of red meat and sweetened beverages.
"I suspect the message we don't want to send is that by changing one's dessert order from a hot fudge sundae to a banana split, thereby adding a serving of fruit, it will translate to a lower [CAC] score," notes Lichtenstein.
"Perhaps we should stop focusing on individual components of the diet . . . and start focusing on dietary patterns."
The CARDIA study is funded by the National Heart, Lung, and Blood Institute in collaboration with the University of Alabama at Birmingham, Northwestern University, University of Minnesota, Kaiser Foundation Research Institute, and Johns Hopkins University School of Medicine and has received partial support from the Intramural Research Program of the National Institute on Aging. The study authors and Lichtenstein report no relevant financial relationships.
Heartwire from Medscape © 2015 Medscape, LLC
Cite this: Early Fruit and Veggie Intake May Lower Later Calcium Scores, Suggests Study - Medscape - Oct 26, 2015.