Naomi Allen - Diet and cancer by Cancer Research UK published on 2013/01/04 13:28:56 +0000 Cancer Research UK is helping to fund the UK arm of a massive study called EPIC, the European Prospective Investigation of Cancer. It’s the largest ever study looking at the links between diet and cancer. EPIC is a long-term study of more than 500,000 people in ten European countries. Around 90,000 are British men and women, including about 30,000 vegetarians, recruited by Cancer Research UK groups in Oxford and Norfolk. Paul Thorne spoke to EPIC researcher Dr Naomi Allen at the University of Oxford to find out more. He started by asking her to explain why such a large number of people were needed for the study. “Particularly for diet, we’re looking for small effects in relation to whether diet influences risk, so you need large numbers of individuals to specifically detect whether a small effect is real or not. And also when you’re looking at cancer, and particularly the rare forms of cancer, obviously the larger study you have, the more likely it is you’re going to detect small effects with these rare types of cancer. The other thing about EPIC was that we’ve included people from Norway all the way down to Greece. So we’ve got populations there with a Mediterranean-style diet, and those who are largely meat-eaters and fish-eaters. With such a broad range of dietary habits we can really identify which aspects of diet are important in trying to distinguish different rates of disease. We know both from EPIC and other epidemiological studies that dietary-related factors such as obesity and alcohol account for about 5 per cent of cancer in Western countries – that’s now well-established. So for bowel cancer, the cancer you might think for which diet is most strongly related to risk, the EPIC study has shown that meat – and in particular, processed meat – increases risk, as does high alcohol intake. And high fibre intake may lower the risk. But the evidence isn’t entirely consistent, as vegetarians don’t appear to have substantially lower rates of bowel cancer. But nonetheless, there is an emerging factor that meat may be a risk factor and fibre and fruit and vegetables may be protective. But for the two most common cancers – breast cancer in women and prostate cancer in men – there are no strong dietary links. The short answer is that there isn’t any one particular “superfood” to protect against cancer. After years of research we’re now realising that it’s highly unlikely that a single food or nutrient has a big effect on cancer risk. Up till now, we’ve take a rather reductionist approach, investigating single nutrients – usually focused on so-called superfoods that contain high amounts of antioxidants or vitamins – but these haven’t yielded any answers so far. Trials of vitamin supplementation have also failed to show any large benefit for cancer prevention. So I think it’s much more likely that sensible eating habits, avoiding excess weight gain, and limiting alcohol intake is much more likely to make a difference to cancer rates than focusing on single foods. The two most well-established dietary-related factors that we know cause cancer are obesity and alcohol, and the best advice is to maintain a normal weight and to lower or minimise alcohol intake – especially for women in relation to breast cancer risk.” That was Paul Thorne talking to Dr Naomi Allen. And you can find out more about EPIC, and watch a video about the study, on our News and Resources website.