The research involved 44,561 people in England and Scotland who took part in the European Prospective Investigation into Cancer and Nutrition (EPIC) Oxford study. About one third of the participants, or 15,100, were vegetarians at the beginning of the research.
After a follow-up of 11.6 years, the data, analysed by scientists at the University of Oxford, showed that there had been 169 death cases and 1,066 cases of hospital admission related to heart disease among the participants.
According to the analysis, it was found that people on a vegetarian diet had a lower body mass index, a lower concentration of "bad" cholesterol and lower blood pressure. This was considered to be a likely reason for the lower incidence of heart disease compared to non-vegetarians.
Dr Francesca L Crowe, one of the authors of the study, said that vegetarians probably consumed less saturated fat than people eating meat and fish, hence the reduced risk of heart disease.
She added that the main conclusion of the study was that diet was an important factor for heart health.
According to the National Health Service, heart disease kills around one in five men and one in seven women in the UK. Causing 94,000 deaths in the country every year, it is the UK's biggest killer.