Meeting health and environmental targets with minimum dietary change

It is well known that most people consume diets which deviate in some ways from the nutritional recommendations issued by the Scottish and UK governments.

Using data based on the diets of individuals collected by the National Diet and Nutrition Survey rolling programme, we have investigated the amount of change that is needed by different individuals in order for each to meet the nutritional recommendations, and what the impact might be of including a target on the greenhouse gas emissions (GHGE) associated with the revised diets.

The mathematical technique of linear programming is able to construct diets which optimise some criterion while meeting a set of constraints. These constraints can ensure the nutritional recommendations are met, but diets based only on these recommendations are unappealing. Additional constraints are also usually included. Here these were based on limiting change to current diets. Although our objective was to alter each person’s diet as little as possible, we found that substantial change was needed for the majority of people to satisfy the nutritional recommendations, usually involving increasing or reducing the amounts of some types of foods consumed by at least 50%. Moving to diets which meet nutritional targets will produce only small reductions in GHGE, and further change is needed to achieve significantly lower values in GHGE. This research also gave insight into the targets most demanding to achieve, which were an upper limit for sodium intake and a lower limit for dietary fibre.

image of a week's worth of food laid out on a table

 Illustration of a week’s diet constructed by linear programming to minimise greenhouse gas emissions whilst satisfying a wide range of dietary requirements.

Graham Horgan

Further details from: Graham Horgan