Reporter 425, 19 October 1998
They may not give you the curly hair your mother promised but a major survey in the Nuffield Institute could reveal the true benefits of eating your greens
Previous research has suggested that diet may have an important role in the development of chronic diseases. A vegetarian diet is thought to protect against many of these diseases, including diabetes, gallstones and possibly breast cancer. However, it is currently not clear what aspect of the vegetarian diet may be beneficial, for example the absence of meat or the increased intake of vegetables.
Other related studies have suggested that green salad is associated with lower general mortality rates, and a high intake of fruit and vegetables is also thought to protect against colon cancer and lung cancer, independent of smoking. This project aims to analyse the effects of these specific food items on health, which could then be used to encourage more widespread healthy eating.
In the first stage of the research, 35,000 women between 35 and 69 have completed a detailed questionnaire. The survey includes information about the frequency of consumption of 217 different food items and questions about their lifestyle, such as levels of exercise and whether or not they smoke.
The survey also asked the women about other factors such as their medical history, alcohol consumption and education. The respondents have been broadly divided into meat eaters, fish eaters and vegetarians.
The initial questionnaire is now being followed up with a detailed four-day food diary, to confirm the initial results and ask more specific questions.
The final phase of the study will take place early in the next century when all participants will be contacted again, up to a decade after their initial response. This will allow the researchers to study changes in diet, but more importantly, the relationship between diet and health over time. To date, they have received notification from the NHS of 62 deaths and 696 cases of cancer in women taking part in the survey.
The pattern of food intake among survey participants was diverse, though most had high intakes of fruit and vegetables. 39% of the women described themselves as vegetarian and 55% take vitamins, minerals or food supplements. The survey also found that three quarters used low-fat milk and 15% added sugar to breakfast cereals or hot drinks.
Compared to the general population this is a fairly healthy group, said Dr Janet Cade, the projects co-ordinator. They seem to exercise more, drink about the same amount of alcohol and well over half do not smoke, she added. They also eat a lot of fresh fruit and vegetables and it will be interesting to see how this affects their future health.
The study is one of the largest studies of vegetarian diet carried out, and the first to consider the risk of disease to fish eaters. It is also the first to examine the possible impact of food phytochemicals on health, and may even test out some of the common food-related old wives tales. Some people believe that broccoli and Brussels sprouts can act as anti-cancer agents, said Dr Cade. If this is true, it is the type of healthy effect our research may pick up.
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