Journal paper on food, protein efficiency and GHG emissions

This paper, the authors of which include several FCRN mailing list members, examines 'Protein efficiency per unit energy and per unit greenhouse gas emissions: Potential contribution of diet choices to climate change mitigation'. (González A D, Frostell B and Carlsson-Kanyama A (2011) Protein efficiency per unit energy and per unit greenhouse gas emissions: Potential contribution of diet choices to climate change mitigation, Food Policy doi:10.1016/j.foodpol.2011.07.003). Reference, abstract and conclusions copied as follows:

The production, transport and processing of food products have significant environmental impacts, some of them related to climate change. This study examined the energy use and greenhouse gas emissions associated with the production and transport to a port in Sweden (wholesale point) of 84 common food items of animal and vegetable origin. Energy use and greenhouse gas (GHG) emissions for food items produced in different countries and using various means of production were compared. The results confirmed that animal-based foods are associated with higher energy use and GHG emissions than plant-based foods, with the exception of vegetables produced in heated greenhouses. Analyses of the nutritional value of the foods to assess the amount of protein delivered to the wholesale point per unit energy used or GHG emitted (protein delivery efficiency) showed that the efficiency was much  higher for plant-based foods than for animal-based. Remarkably, the efficiency of delivering plant-based protein increased as the amount of protein in the food increased, while the efficiency of delivering animal-based protein decreased. These results have implications for policies encouraging diets with lower environmental impacts for a growing world population.

Conclusions

Protein is a limiting nutrient that is essential for good nutrition and protein deficiency is known to cause a variety of health problems. This study examined the energy use and GHG emissions involved in producing and transporting protein in foods (locally produced and imported) to a wholesale point in Gothenburg, Sweden. Life cycle inventories from previous works were reviewed and new calculations were made for food groups including meats, legumes, cereals, field-grown vegetables, greenhouse-grown vegetables and fruit. Using data on the protein content of these foods we assessed the energy use and GHG emissions efficiency of delivering protein, i.e., the number of grams of protein delivered to the wholesale point per unit energy used and per unit GHG emitted in production and transport.

Whether in terms of energy spent or emissions of GHGs, this study showed that the efficiency of delivering protein to an entry port in Sweden was much higher for plant-based foods than for animal-based. In addition, plant-based protein had the specific attribute of increasing efficiency with increasing protein content of the food. Therefore, strategies aimed at feeding a growing world population and reducing contributions to climate change should include measures to encourage a more vegetarian diet with the focus on consuming vegetable products with high protein content, such as legumes, nuts and grains. These results could encourage industry and entrepreneurs to produce an attractive variety of convenience foods with a low environmental impact.

This is an interesting paper although it is worth noting that its main nutritional focus is on protein. The authors do note that meat and dairy foods provide much more than protein (iron, zinc, calcium, vit B12 etc) and cite research suggesting that plant based sources can also provide these micronutrients and minerals – but their analysis is somewhat brief.  For a more detailed analysis of the positive and negative contribution that animal source foods make to the diet  (focusing largely on the developed world perspective), you may want to have a look at this paper by Millward and Garnett here.  In addition, the China workshop summary report here  includes a useful summary, by Joe Millward, of the latest evidence on the role of meat and dairy foods in the diet- you may also want to go through his powerpoint slides.

It’s also important to emphasise that the authors are by no means arguing for meat/dairy free diets – they “do not suggest complete elimination of animal products but rather a partial change to other food groups.”

One other observation about this paper is that it doesn’t look at land use and plant protein.  The FCRN-WWF-UK report, published in 2010 – points out that a shift to tofu and quorn based products could lead to an increase in land use requirements overseas – see pages 60-62.

If you don’t have subscription access, contact Alejandro Gonzalez and he may be able to send you a copy.