Alessandra C. Grasso, Margreet R. Olthof, Corné van Dooren, Roline Broekema, Marjolein Visser, Ingeborg A. Brouwer

The Journal of Nutrition

Eating more dietary protein than what is currently recommended is suggested to improve physical functioning and well-being in older adults. However, increasing protein intake is likely to have adverse consequences for the climate if the level of greenhouse gas emissions (GHGE) associated with various protein sources is not considered. Therefore, there is a need to identify changes in the diet of older adults that can increase their protein intake while reducing their diet’s GHGE.

In this study we used diet optimization techniques to identify dietary changes that simultaneously increase protein intake in older adults and reduce their diet’s GHGE. We used dietary data on 1,354 community-dwelling older adults (56-101 y) from the Longitudinal Aging Study Amsterdam cohort to calculate the average intake of 254 food items (e.g. chicken breast) and 25 food groups (e.g. poultry). Starting from this average diet, we modelled several diets by applying nutritional, environmental, and acceptability conditions such as ‘the modelled diet’s GHGE needs to be 50% lower than that of the average diet’. Then we calculated the differences in intakes between the modelled diets and the average diet to determine what and how much change in food intake is needed.

We found that achieving a high-protein diet without considering GHGE resulted in a 5-12% increase in GHGE in men and 9-14% increase in women. To achieve a high-protein diet with a moderate GHGE reduction, meat intake needed to be reduced to the amount recommended by the national food-based dietary guidelines for men but no change in total meat intake was needed for women. Further, a replacement of beef/lamb and processed meat with poultry and pork was needed, as well as increases in whole grains, nuts, and meat/dairy alternatives and decreases in discretionary food products like sweets for both men and women.

In conclusion, meeting the protein requirement of the growing older population with reduced GHGE requires a change in meat type (and quantity for men), an increase in consumption of a variety of plant-proteins, and a reduction in consumption of discretionary food products.

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