The research, published in the European Heart Journal, analysed data from the European Prospective Investigation into Cancer and Nutrition (EPIC) Heart study, finding that people consuming at least eight portions of fruit and vegetables a day have a 22 percent lower risk of dying from ischaemic heart disease (IHD) than those who consuming fewer than three portions a day.
“This study involved over 300,000 people in eight different European countries, with 1,636 deaths from IHD. It shows a 4 percent reduced risk of dying from IHD for each additional portion of fruit and vegetables consumed above the lowest intake of two portions,” said the lead author of the study Dr Francesca Crowe, from the University of Oxford, UK.
“The main message … is that in this study, people who consume more fruits and vegetables have lower risk of dying from IHD. However, we need to be cautious in our interpretation of the results because we are unsure whether the association between fruit and vegetable intake and risk of IHD is due to some other component of diet or lifestyle,” added Dr Crowe.
Ischaemic heart disease (IHD) is characterised by reduced blood supply to the heart. People suffering from IHD can develop angina, chest pains and have a heart attack. It is the leading cause of death for both men and women in Europe, the US, and other industrialized countries.
The results from many observational studies have suggested that a high fruit and vegetable intake reduces the risk of heart disease.
In 2003, the World Health Organization (WHO) concluded that there was convincing evidence that fruits and vegetables lower the risk of CHD and recommended an intake of 400–500 g/day— the equivalent to five or six portions of about 80 grams each.
“For developing effective public health strategies, it is essential to clarify the possible relation between fruit and vegetable consumption with CHD mortality, so that dietary advice and government policies can target the most important factors for reducing the rate of this major cause of death,” said the authors.
The new study investigated the links between ischaemic heart disease and vegetable intake using data from the EPIC study. For the analysis of IHD deaths, data from population cohorts in eight countries for people aged between 40 and 85 were used.
The researchers said that data from two of the original EPIC cohorts – France and Norway – were excluded from the analysis because the number of cardiovascular deaths was too small.
The results of the analysis showed that people consuming at least eight portions (of 80 g each) of fruits and vegetables a day had a 22 percent lower risk of fatal IHD compared with those consuming fewer than three portions a day.
After calibration of fruit and vegetable intake to account for differences in dietary assessment between the participating centres, the researchers found that a one portion (80 g) increment in fruit and vegetable intake was associated with a 4 percent lower risk of fatal heart disease.
“Although we have known for some time that eating five portions a day can help to lower our risk of heart disease, it has been less clear whether eating more than this will have an even better effect,” said Victoria Taylor, senior dietitian at the British Heart Foundation.
In an accompanying editorial, Professor Sir Michael Marmot, from University College London, UK, said that it is difficult to reach firm conclusions about causation from the current study.
“Commonly, one hears the clinical line of argument: if fruit and vegetables are protective why not isolate the protective nutrient, put it in a pill, and thereby dispense with worry about diet,”
“That approach has not proved useful. Trials of antioxidant vitamins have not led to reductions in either cancer or cardiovascular disease. That may be because antioxidant vitamins were not the crucial protective components; or it is the foods and, indeed, dietary patterns that are important, not specific micronutrients,” he said.
“We still don’t know exactly why we see this relationship between fruit and vegetables and heart disease. It may be something in the fruit and vegetables itself, but equally it could be something in the lifestyles of people who tend to eat more fruit and vegetables …There’s still work to be done by researchers to answer these questions,” said Taylor.
Prof Marmot added that obesity is seen as a major risk factor for CVD and many types of cancers.
“If it turns out that higher fruit and vegetable consumption goes along with lower intake of energy dense or fast foods, there could be an indirect protective effect,” he said.
“If we could understand, by means of well-designed intervention studies, the biological mechanisms that could underlie the association between fruits and vegetables and IHD, this might help to determine whether or not the relation between fruit and vegetables with IHD risk is causal,” said Dr. Crowe.
Source: European Heart Journal
Published online ahead of print, doi:10.1093/eurheartj/ehq465
“Fruit and vegetable intake and mortality from ischaemic heart disease: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Heart study”
Authors: F.L. Crowe, A.W. Roddam, T.J. Key, P.N. Appleby, K. Overvad, M.U. Jakobsen et al