Smetana S, Mathys A, Knoch A, Heinz V. Meat alternatives: life cycle assessment of most known meat substitutes. The International Journal of Life Cycle Assessment. 2015 2015/09/01;20(9):1254-67.
This article compares the environmental impacts of different meat substitutes. Multiple environmental impacts were measured, and assessed by weight (kilograms), energy (kilojoules) and protein (grams). The authors estimated impacts from the stage of raw resources to (including) consumer use.
Bottom line for nutrition practice:
One of the key objectives of meat substitutes is to lower environmental impact compared to that of livestock. Across all three measures, lab grown meat and myco-protein based foods (fungus/ mushroom) had the highest impacts. After this, results depended on the unit of measurement (weight, energy, protein). The authors report that the best performers were insect and soya-based substitutes and chicken (although chicken ranked more poorly when measured by weight).
|Environmental Impacts||Weight (kilo)||Energy (kilojoule)||Protein (gram)|
|Medium||Dairy/ gluten||Soya/ insect||Gluten/ dairy|
|Best||Insect/ soya||Chicken/ Dairy/ gluten||Soya/ insect/ chicken|
Purpose: Food production is among the highest human environmental impacting activities. Agriculture itself accounts for 70-85 % of the water footprint and 30 % of world greenhouse gas emissions (2.5 times more than global transport). Food production’s projected increase of 70 % by 2050 highlights the importance of environmental impacts connected with meat production. The production of various meat substitutes (plant-based, mycoprotein-based, dairy-based, and animal-based substitutes) aims to reduce the environmental impact caused by livestock. This article outlined the comparative analysis of meat substitutes’ environmental performance in order to estimate the most promising options.
Methods: The study considered ‘cradle-to-plate’ meal life cycle with the application of ReCiPe and IMPACT 2002+ methods. Inventory was based on literature and field data. Functional unit (FU) was 1 kg of a ready-to-eat meal at a consumer. The study evaluated alternative FU (the equivalent of 3.75 MJ energy content of fried chicken lean meat and 0.3 kg of digested dry matter protein content) as a part of sensitivity analysis.
Results and discussion: Results showed the highest impacts for lab-grown meat and mycoprotein-based analogues (high demand for energy for medium cultivation), medium impacts for chicken (local feed), and dairy-based and gluten-based meat substitutes, and the lowest impact for insect-based and soy meal-based substitutes (by-products allocated). Alternative FU confirmed the worst performance of lab-grown and mycoprotein-based analogues. The best performing products were insect-based and soy meal-based substitutes and chicken. The other substitutes had medium level impacts. The results were very sensitive to the changes of FU. Midpoint impact category results were the same order of magnitude as a previously published work, although wide ranges of possible results and system boundaries made the comparison with literature data not reliable.
Conclusions and recommendations: The results of the comparison were highly dependable on selected FU. Therefore, the proposed comparison with different integrative FU indicated the lowest impact of soy meal-based and insect-based substitutes (with given technology level development). Insect-based meat substitute has a potential to be more sustainable with the use of more advanced cultivation and processing techniques. The same is applicable to lab-grown meat and in a minor degree to gluten, dairy, and mycoprotein-based substitutes.
Details of results:
The study compared seven products: chicken; dairy based; lab grown; insect based; mycoprotein based; gluten based and soy based products. The authors chose an environmental assessment method that was one of the most comprehensive at the time of the study (ReCiPe V1.08). It allowed for an overall single score for each product to be determined, analyzing factors such as climate change, ozone layer depletion, human toxicity, acidification, ecotoxicity, land occupation, metal and fossil fuel depletion. Impacts for each product was assessed from cradle (raw resources production) to plate (consumer use).
In explaining the results, the authors note that lab grown meat is at an early stage of development, and will benefit from advances (although this study is now 7 years old, so progress has likely been made – see Editor’s comments for results from a recent study regarding lab meat). The lab grown meat had the highest impacts in most categories, and most of the impacts resulted from inorganic emissions, energy consumption used for the medium cultivation and from growing the meat. Mycoprotein production was also associated with high energy demand and also as a result of the production of the egg protein and fertilizer components. The biggest impact from the chicken came from the production of the chicken feed, from growing the chickens, and from the consumer frying the food at home. Chicken had the highest impact on terrestrial and freshwater ecotoxicity compared to the other alternatives (in part resulting from the use of grains and protein feed). When looking specifically at factors related to human health, lab grown meat also had the highest impact, followed by chicken and mycoprotein.
Dairy and gluten-based products had higher demands for transportation and energy for processing the products. Gluten based alternatives also had the highest impact on agricultural land occupation (for wheat grain production), and the authors also note their impact on metal depletion, human health, and terrestrial toxicity. Dairy based products had high impacts on ozone layer depletion, terrestrial acidification, and agricultural land occupation.
The low impact from insect based and soya-based alternatives was associated with the use of effective processing and growing technologies, and also because these technologies use by-products or side stream use from other processes (e.g., molasses from sugar beets). Insect-based products had high impacts on terrestrial and freshwater ecotoxicity. While land use change impacts were not included in this study, when the authors accounted for them – only soya had a substantial change (>25%). The authors argue however, that this still leaves soya as one of the most sustainable alternatives.
The impact from frying foods by the consumer was similar for each alternative. However, as each alternative had different overall impacts, frying accounted for a higher portion of environmental impacts for low-impact meat substitutes whereas it had a minor role with the higher impact alternatives.
The authors suggest that environmental impacts could be decreased by improving technology for lab, dairy, mycoprotein, soy, and gluten products and producing soya products closer to soya growing area. They also note the emergence of other alternatives (algae based, egg based, etc.) which may have less environmental impacts.
Of additional interest:
While this study is older, it was included as a more recent study was not found. However, results line up with a recent study which illustrated that lab grown meat is not necessarily more environmentally friendly than beef (and beef has a much greater impact on the environment than chicken, which was used in this study). Lynch J, Pierrehumbert R. Climate Impacts of Cultured Meat and Beef Cattle. Frontiers in Sustainable Food Systems. 2019 2019-February-19;3(5).
As some producers have argued, it does seem more reasonable to measure the impacts of food by
energy or protein, as compared to weight. The 2017 Clark and Tilman meta-analysis (synopsis included on this website) “Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice” did find, however, that plant-based foods still had the lowest environmental impacts - even when analyzed per kilocalorie of food produced. This aligns with this studies findings that soy-based meat alternatives are top performers overall. Differences of impact between units of measurement is an important aspect to watch for in future research on sustainable food systems.
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