People with heart disease could lower their risk of heart attack and stroke by eating a diet rich in fruit, vegetables, fish and unrefined foods, a big international study led by a New Zealander indicates.
The study of more than 15,000 people with stable heart-artery disease in 39 countries also found that eating larger amounts of healthy food was more important than avoiding unhealthy foods.
Published in the European Heart Journal, the study, led by Auckland City Hospital cardiologist Professor Ralph Stewart, found that for every 100 people eating the highest proportion of healthy foods - key ingredients of the so-called Mediterranean diet - there were three fewer heart attacks, strokes or deaths compared with 100 people eating the smallest quantities of healthy foods.
The participants were trialling a potential new heart drug and had answered questions on how often they ate servings of various food groups.
A "Mediterranean diet score" was calculated for increasing consumption of whole grains, fruits, vegetables, legumes, fish and alcohol, and for less meat.
A "Western diet score" was calculated for increasing intake of refined grains, sweets and desserts, sugary drinks and deep-fried foods.
After 3.7 years' follow-up, a heart attack, stroke or death - termed a major adverse cardiac event - had occurred in 10.1 per cent of the participants. Such events occurred in 7.3 per cent of the people in the highest Mediterranean-diet bracket, 10.5 per cent in the next bracket down and 10.8 per cent in those who ate smaller quantities of the healthier foods.
"After adjusting for other factors that might affect the results we found that every one unit increase in the Mediterranean diet score was associated with a 7 per cent reduction in the risk of heart attacks, strokes or death from cardiovascular or other causes in patients with existing heart disease," Mr Stewart said.
"In contrast, greater consumption of foods thought to be less healthy and more typical of Western diets, was not associated with an increase in these adverse events, which we had not expected.
"The research suggests we should place more emphasis on encouraging people with heart disease to eat more healthy foods, and perhaps focus less on avoiding unhealthy foods."
But this was not a licence to eat unhealthy foods, he warned.
Some foods, particularly fruit and vegetables, seemed to lower the risk of heart attacks and strokes, and this benefit was not explained by risk factors such as good and bad cholesterol or blood pressure.
"If you eat more of these foods, in preference to others, you may lower your risk."
Auckland University heart disease researcher, Professor Rod Jackson noted that the authors did not report on saturated fat consumption or fat consumption at all because they stated it had not been recorded reliably.
"However, the findings are quite consistent with the standard diet-heart hypothesis. A Mediterranean diet is low in saturated fat and was associated with lower risk of CHD [coronary heart disease].
"The Western diet score was based on consumption of refined carbohydrates, sweets and desserts, sugared drinks and deep-fried food. None of these foods except deep-fried foods, and only if the fat was saturated, are associated with CHD. They are associated with overweight/obesity and diabetes but the pro-fat lobby have always confused the issue by wrongly lumping obesity and diabetes with CHD.
" ... they are very different conditions and are trending in opposite directions."