The risk of hospitalisation or death from heart disease is 32% lower in vegetarians than people who eat meat and fish, according to a new study from the University of Oxford.
Heart disease is the single largest cause of death in developed countries, and is responsible for 65,000 deaths each year in the UK alone. The new findings, published in the American Journal of Clinical Nutrition, suggest that a vegetarian diet could significantly reduce people's risk of heart disease.
'Most of the difference in risk is probably caused by effects on cholesterol and blood pressure, and shows the important role of diet in the prevention of heart disease,' explains Dr Francesca Crowe, lead author of the study at the Cancer Epidemiology Unit, University of Oxford.
This is the largest study ever conducted in the UK comparing rates of heart disease between vegetarians and non-vegetarians.
The analysis looked at almost 45,000 volunteers from England and Scotland enrolled in the European Prospective Investigation into Cancer and Nutrition (EPIC)-Oxford study, of whom 34% were vegetarian. Such a significant representation of vegetarians is rare in studies of this type, and allowed researchers to make more precise estimates of the relative risks between the two groups.
The EPIC-Oxford cohort study was funded by Cancer Research UK and the Medical Research Council and carried out by the Cancer Epidemiology Unit at the University of Oxford.
Professor Tim Key, co-author of the study and deputy director of the Cancer Epidemiology Unit, University of Oxford, said: 'The results clearly show that the risk of heart disease in vegetarians is about a third lower than in comparable non-vegetarians.'
The Oxford researchers arrived at the figure of 32% risk reduction after accounting for factors such as age, smoking, alcohol intake, physical activity, educational level and socioeconomic background.
Participants were recruited to the study throughout the 1990s, and completed questionnaires regarding their health and lifestyle when they joined. These included detailed questions on diet and exercise as well as other factors affecting health such as smoking and alcohol consumption. Almost 20,000 participants also had their blood pressures recorded, and gave blood samples for cholesterol testing.
The volunteers were tracked until 2009, during which time researchers identified 1235 cases of heart disease. This comprised 169 deaths and 1066 hospital diagnoses, identified through linkage with hospital records and death certificates. Heart disease cases were validated using data from the Myocardial Ischaemia National Audit Project (MINAP).
The researchers found that vegetarians had lower blood pressures and cholesterol levels than non-vegetarians, which is thought to be the main reason behind their reduced risk of heart disease.
Vegetarians typically had lower body mass indices (BMI) and fewer cases of diabetes as a result of their diets, although these were not found to significantly affect the results. If the results are adjusted to exclude the effects of BMI, vegetarians remain 28% less likely to develop heart disease.
The findings reinforce the idea that diet is central to prevention of heart disease, and build on previous work looking at the influence of vegetarian diets, the researchers say.
Notes to Editors
* The Cancer Epidemiology Unit is funded by Cancer Research UK and by a programme grant from the Medical Research Council, and is part of the Nuffield Department of Clinical Medicine of the Medical Sciences Division at the University of Oxford.
The main emphasis of research in the Cancer Epidemiology Unit is on providing large-scale reliable evidence on the relationship between common exposures (such as diet, reproductive factors, and the use of oral contraceptives and hormone replacement therapy) and common conditions of public health importance such as breast, prostate, and cervical cancers, cardiovascular disease and fractures.
* MINAP is a national clinical audit of all acute coronary syndromes and is overseen by a Steering Group representing key stakeholders, including professional bodies, national government and patient representatives – in collaboration with the British Cardiovascular Society. MINAP is commissioned by the Healthcare Quality Improvement Partnership (HQIP). Data are collected by nurses and clinical audit staff and entered in a dedicated data application. An academic group, which reports to the Steering Group, has been established to facilitate research use of the data.
MINAP is one of 6 national cardiac clinical audits that are managed by the National Institute for Cardiovascular Outcomes Research (NICOR), which is part of the Institute of Cardiovascular Science at University College London (UCL). NICOR is a partnership of clinicians, IT experts, statisticians, academics and managers which manages six cardiovascular clinical audits and several new technology registries. Its mission is to provide information to improve heart disease patients' quality of care, outcomes and help to reduce inequity in care.
* Oxford University's Medical Sciences Division is one of the largest biomedical research centres in Europe, with over 2,500 people involved in research and more than 2,800 students. The University is rated the best in the world for medicine, and it is home to the UK's top-ranked medical school.
From the genetic and molecular basis of disease to the latest advances in neuroscience, Oxford is at the forefront of medical research. It has one of the largest clinical trial portfolios in the UK and great expertise in taking discoveries from the lab into the clinic. Partnerships with the local NHS Trusts enable patients to benefit from close links between medical research and healthcare delivery.
A great strength of Oxford medicine is its long-standing network of clinical research units in Asia and Africa, enabling world-leading research on the most pressing global health challenges such as malaria, TB, HIV/AIDS and flu. Oxford is also renowned for its large-scale studies which examine the role of factors such as smoking, alcohol and diet on cancer, heart disease and other conditions.
* Over the past century, The Medical Research Council has been at the forefront of scientific discovery to improve human health. Founded in 1913 to tackle tuberculosis, the MRC now invests taxpayers' money in some of the best medical research in the world across every area of health. Twenty-nine MRC-funded researchers have won Nobel prizes in a wide range of disciplines, and MRC scientists have been behind such diverse discoveries as vitamins, the structure of DNA and the link between smoking and cancer, as well as achievements such as pioneering the use of randomised controlled trials, the invention of MRI scanning, and the development of a group of antibodies used in the making of some of the most successful drugs ever developed.
Today, MRC-funded scientists tackle some of the greatest health problems facing humanity in the 21st century, from the rising tide of chronic diseases associated with ageing to the threats posed by rapidly mutating micro-organisms. www.mrc.ac.uk
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American Journal of Clinical Nutrition