Food fights

Nutrition seems to attract more heat and less light in debates than other areas of health. As Dariush Mozaffarian and Nita Forouhi write this week (doi:10.1136/bmj.k822), everyone seems to have an opinion on food, and the most extreme voices often drown out the well informed. The science doesn’t always help, often reliant as it is on observational studies or short term interventions and bedevilled by enormous vested interests, limited public funds, and methodologically weak guidelines.

So, is nutrition science up to the task? Mozaffarian and Forouhi say it is. They follow its evolution from a focus on single nutrients, deficiency diseases, calorie counting, and surrogate outcomes to today’s interest in foods, chronic diseases, diet quality for long term weight control, and complex biological pathways. The quality and quantity of research have improved, and we are getting better at integrating evidence from different study designs. “Comparison with other scientific fields suggests that the scope and pace of these discoveries, evolving priorities, and remaining uncertainties are not only natural and appropriate, but expected and reassuring,” they say.

Of course, the debates continue. One hotspot is dietary advice for people with type 2 diabetes. As Jane Feinmann reports (doi:10.1136/bmj.k1122), new evidence indicates that both very low calorie and low carbohydrate diets could markedly increase rates of diabetes remission. Carbohydrate restriction is recommended as one option for weight loss in patients with type 2 diabetes in Scotland but not yet in England and Wales—guidelines of the UK National Institute for Health and Care Excellence only go so far as to encourage restriction of carbohydrates with a high glycaemic index. But that’s ok, says GP David Unwin, as this effectively cuts out all breads and cereals. A consistent picture seems to be emerging from randomised trials, observational studies, and real world findings. National guidance should be revisited as a priority if large numbers of patients could be spared long term drug treatment for a potentially reversible condition.

Many fascinating nutritional questions and controversies remain. Which is why The BMJ is shortly to publish a major international series of articles on the science and politics of nutrition. Our aim is to promote good evidence and rational debate on what we know and what we need to learn in this crucial area of health and healthcare. The series will launch at a two day interactive conference in Zurich in June, co-hosted by The BMJ and the insurance group Swiss Re (http://institute.swissre.com/events/food_for_thought_bmj.html). Space at the conference is limited, but please do email me if you would like to attend.