Heart-healthy diet additive to drug benefits in secondary prevention of CVD

December 03, 2012

Hamilton, ON - A high-quality, heart-healthy diet is associated with a lower risk of recurrent cardiovascular events in patients who already have cardiovascular disease or diabetes, a new analysis of the ONTARGET and TRANSCEND studies shows[1]. These findings applied globally, across the 40 countries involved in the trials, and showed that the benefits of good nutrition were additive to the protective effects of medication.

"Our main finding was that a heart-healthy diet—rich in fruits, vegetables, nuts, whole grains, and fish—significantly reduced the chance of a second heart attack or stroke or death," lead author Dr Mahsid Dehghan (McMaster University, Hamilton, ON) told heart wire . Consumption of such a diet reduced the relative risk of cardiovascular death by 35%, MI by 14%, stroke by 19%, and congestive heart failure (CHF) by 28%, compared with those eating the poorest diet, she noted.

 
Our main finding was that a heart-healthy diet—rich in fruits, vegetables, nuts, wholegrains, and fish—significantly reduced the chance of a second heart attack or stroke or death.
 

"This is a very big impact of diet as a protective factor. Sometimes people who have a history of CVD take medication and they think that things are being taken care of by the medication. But even if you are taking medication, you will benefit from eating healthily. It will protect you more," Dehghan stressed. It's also important that doctors understand and impart this message to their patients, she says. "These people are high risk. Physicians should encourage high-risk patients to improve their diet. People will take this more seriously if it comes from their doctor."

Asked to comment on the findings, Dr Robert Eckel (University of Colorado, Denver), who was not involved in this research, told heart wire : "This is the kind of evidence we need; it's incredibly encouraging. I've been in the clinic today and I can't tell you how many times I've emphasized a heart-healthy diet to patients. It's important to document what we have all believed for a long time, and we can use this to impress the cardiology community and beyond, including primary-care physicians. A physician should spend three minutes with a patient assessing lifestyle, and this new research adds credibility to that recommendation."

Eckel also stressed, however, that the study was not specifically designed to address this question: "It's a retrospective analysis, with all of the limitations associated with that, but nevertheless I'm really pleased with the results."

Gaynor Bussell, a spokesperson for the British Dietetic Association, agrees. "This wasn't a surprise to me. It backs up what we already know and reaffirms what we have been saying—it's never too late to make improvements to diet and lifestyle, whether you have preexisting conditions or whether you are in your 80s or 90s."

First report of protective effect of good diet in secondary prevention

Dehghan and colleagues assessed the diets of 31 546 men and women, with an average age of 67, enrolled in two parallel, multinational, double-blind randomized trials evaluating the effects of the antihypertensive agents telmisartan, ramipril, or their combination (ONTARGET) or telmisartan vs placebo (TRANSCEND) in 733 centers in 40 middle- and high-income countries.

In this nutritional analysis, diets were assessed at baseline, using the short form of the food frequency questionnaire (FFQ), which entails 20 questions about eating habits over the past 12 months. A "healthy" diet consisted of a high intake of fruits, vegetables, whole grains, nuts, and fish relative to meat and eggs. Dehghan acknowledges that this is "a rough measure" of food intake, but "we believe people do not change their diet often, and the FFQ has been well validated," she noted.

They then used two indexes to assess dietary quality based on the FFQs: the Diet Risk Score and the modified Alternative Healthy Eating Index (AHEI). The association between dietary quality and the primary composite outcome of CV death, MI, stroke, or CHF was assessed using Cox proportional hazard regression, adjusted for age, sex, trial-enrollment allocation, region, and other known confounders.

Patients in the healthier quintiles of modified AHEI had a significantly lower risk of CVD (hazard ratio 0.78, highest vs lowest quintile).

"The protective association was consistent regardless of whether patients were receiving proven drugs," Dehghan and colleagues observe.

"As far as we are aware, this is the first study to report the protective impact of healthy eating on CV death, new MI, stroke, and CHF events in patients taking secondary preventive drugs," they add. And while they acknowledge the limitations of this kind of analysis, "These data suggest that at least 20% recurrence of CVD could be avoided by adhering to a healthy diet," they observe.

Key finding that effects are additive to medication

 
This shows the Mediterranean-type diet comes up trumps.
 

Bussell said the magnitude of the additive effect of diet on top of medication is a key finding of this new research. "Patients were already on optimal medication, and yet they were still getting this added protection. I see a lot of people who are on statins who say, 'I don't need to worry about the butter and the cream, the tablets are doing it for me.' This has given us evidence to show that you can make a further difference, so for me it was quite pleasing."

And Dehghan stresses that the benefit of a high-quality diet was documented in countries in all regions of the world; she and her colleagues are now working on customizing healthy eating plans for different populations in different countries.

Bussell says this is a good idea. "Most countries are moving toward the Western-type diet, unfortunately. This shows the Mediterranean-type diet comes up trumps."

Dehghan reports no conflicts of interest . Disclosures for the coauthors are listed in the paper. The ONTARGET and TRANSCEND trials were funded by Boehringer Ingelheim. Eckel has no disclosures .

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