Scientific evidence and daily food for a better life: Milan, 19 June 2015

- Basing nutrient guidelines solely on observational evidence may risk generating ineffective public health advice.
- Energy intake is more important than macronutrient balance in relation to weight management.
- A whole-diet rather than a single-nutrient approach may be more effective for chronic disease reduction.

This paper presents a report of a nutrition conference held at EXPO 2015 in Milan. Over the course of a day, seven speakers from four continents discussed the evidence and scientific processes that underpin the development of dietary guidelines, highlighting issues and challenges at each stage. These include the quality of studies associating disease outcomes with diet, specifically a reliance on observational studies, short duration of intervention trials, low statistical power and lack of follow-up. Concerns were raised over the oversimplification of dietary messages which promote carbohydrates in general without evidence of benefit, while restricting fats when meta-analyses suggests that different fatty acids have different effects on disease risk. The merits of food-based dietary guidelines and holistic dietary patterns were described, whereas the impact of increasing or reducing consumption of individual food groups or macronutrients remains unclear. The meeting ended with a restatement of the importance of dietary guidelines, and associated education, to improve public health, but a plea was made to ensure that the process of setting guidelines is evidence based, responsive and considers the impact of the whole diet.