Diet and nutrition

Diet is an important determinant of good health, but many questions remain about whether and how dietary and nutritional factors may affect a wide range of diseases. Our research is examining a number of prominent hypotheses in relation to diet and health. Diet has been measured in EPIC-Oxford and the Million Women Study, and we are also leading dietary analyses in the UK Biobank, for which we have developed the Oxford Web Q. We have assessed diet with traditional methods such as food frequency questionnaires, and we are now also using internet-based measures of diet as well as a range of biomarkers of nutritional status and metabolic profile. Current analyses include the role of diet in the aetiology of cancers of the prostate (see prostate section), breast and colorectum. We are also examining the long-term health of vegetarians (see vegetarian section).


Health of vegetarians

About 1.2 million people in the UK are vegetarians, but the long-term effects on health of a vegetarian diet are not well understood, and little is known about the health effects of a vegan diet. Previous research has demonstrated lower risks of ischaemic heart disease, stomach cancer and perhaps haematological cancers in vegetarians compared with non-vegetarians (Crowe et al 2013, Key et al 2009, 2014), but further research is needed to assess both the beneficial effects of a vegetarian diet, and possible hazards associated with low intakes of some nutrients, such as protein, long-chain n-3 fatty acids, vitamin B12, vitamin D and calcium (particularly in vegans). Recruitment into EPIC-Oxford was targeted at vegetarians and other people interested in diet and health, as well as the general population, and the participants comprise 34,000 meat eaters, 10,000 people who eat fish but not meat, 19,000 lacto-vegetarians and 2,500 vegans. Participants have been followed-up for 20 years by means of repeat questionnaires and linkage to NHS medical records. Analyses over the next five years will examine the risk of diseases of the cardiovascular system, bones and joints and gastro-intestinal tract in vegetarians, supported by a grant from the MRC.