Objective: To find diets optimised on nutrition and environmental impact close to the current Dutch diet and to identify the most effective and acceptable options for mitigating environmental impact.
Design: Linear programming was used to optimise diets of Dutch men and women aged 9-69 years, divided into ten age-gender groups. The analysis included nutrient composition, a metric for popularity and life cycle assessments of 207 food products. Greenhouse gas emissions, fossil energy use and land occupation were used to calculate a weighted score for the overall environmental impact. Optimised diets were solutions that minimised changes to the current diet while satisfying all nutritional constraints, with stepwise reductions in environmental impact.
Setting: The Netherlands.
Subjects: Dutch children and adults aged 9-69 years.
Results: Meat was always reduced. Vegetable, fruit and dairy contents remained similar, while bread, fatty fish and legumes increased. The extent of changes depended on age and gender. Beverages were not heavily reduced. Nutrients critical for the outcome were α-linoleic acid, retinol, Ca, Na, Se, dietary fibre, SFA, thiamin and Fe (women of childbearing age). Total protein, essential amino acids and carbohydrates were not critical.
Conclusions: Reducing meat is the most effective option for lowering the environmental impact of diets in all age-gender groups. Reducing alcoholic and non-alcoholic beverages is another option. Leaving out fish and dairy products are not. The differences in nutritional requirements related to age and gender have a significant effect on the composition of the optimised diets.
Keywords: Fossil energy use; Greenhouse gas emissions; Land occupation; Linear programming; Minimal changes; Sustainable diets.