A study published today in Circulation has found that eating red and processed meat may increase the risk of developing ischaemic heart disease (IHD); the risk was 19% higher for every 100 g of meat eaten per day. The researchers found no significant link between the risk of IHD and consumption of poultry, white fish, or milk, and found that intakes of fatty fish, cheese, yoghurt and eggs had a modest effect on reducing IHD risk.
Ischaemic heart disease, also known as coronary heart disease, is when coronary arteries become narrowed by a gradual build-up of fatty material within their walls.
The positive association between red and processed meat and the risk of IHD may be related to the saturated fat content of these foods. In the UK meat and meat products contribute 24% of saturated fat intake in adults. Although dairy products are also relatively rich in saturated fats, the finding that intake of dairy products was not positively related to IHD risk might suggest that different food sources of saturated fat and/or different proportions of individual saturated fatty acids in meat and dairy foods may differ in their impact on risk of IHD.
Over 400,000 men and women in nine countries took part in the study, supported in part by the Wellcome-funded LEAP programme, based at the Oxford Martin School, University of Oxford. The participants, part of the ongoing pan-European EPIC investigation into the impact of diet on health, completed diet questionnaires and were followed up for twelve years. Researchers measured blood pressure and lipid levels in a sample of the group and collected data on smoking, alcohol intake, physical activity, education level and self-reported histories of diabetes, hypertension and hyperlipidemia. Diagnosis of ischaemic heart disease was confirmed in just over 7,000 participants.
To assess whether associations might be due to changes in diet in the years shortly before diagnosis, further analyses were conducted in which results from the first four years of follow-up were excluded. The positive association of risk with red and processed meat remained significant, whereas the modest inverse associations between yoghurt, cheese and eggs and risk were no longer significant, suggesting that these weaker associations may simply reflect changes in diet due to early signs of disease.
Participants with the highest consumption of red and processed meat were found to have higher cholesterol levels and systolic blood pressure.
In statistical analyses which estimated replacing 100 kcal/day of red and processed meat with 100 kcal/day of fatty fish, yoghurt, cheese or eggs, risk of ischaemic heart disease was approximately 20% lower.
Lead author Tim Key, Professor of Epidemiology and Deputy Director of the Cancer Epidemiology Unit in the Nuffield Department of Population Health, said: ’The results suggest that substituting other foods for red and processed meat may reduce the risk of ischaemic heart disease.’
Although the researchers adjusted results for major risk factors for IHD including smoking, obesity and socio-economic factors, the relatively modest associations observed may have been influenced by these or other unmeasured factors.
Co-author John Danesh, Professor of Epidemiology and Medicine, Director of Department of Public Health and Primary Care at the University of Cambridge said ‘This large prospective study showed a moderate positive association between consumption of red and processed meat and risk of ischaemic heart disease. It is not clear whether these associations reflect causality, but they were consistent with the associations of these foods with LDL cholesterol and for systolic blood pressure which could mediate such effects.’