Is a plant-based diet healthier and more environmentally friendly than a meat one? File photo / NZME
Opinion:
Claims that plant-based and cultured food diets are better for health and the environment deserve further investigation, Dr Jacqueline Rowarth writes.
Science advances all the time. Data are gathered, interpretation occurs and debate follows. A basic tenet of science is that the evidence can be discussed and perspectives considered as part of the refereeing process - and then rejected or incorporated.
Frequently a discussion leads to another hypothesis and subsequent testing.
The refereeing process enables scientists independent of the research to consider the data de novo – to do their own interpretations and then see if their interpretations align. When they don’t, the debate can be heated.
At the moment, however, it seems to be marketers and the believers that have become heated about food production, not the agricultural scientists.
While the latter create food production systems that are ever more precise and feed ever more people as the global population expands, marketers are urging the adoption of plant-based and cultured food.
Plant-based and precision fermentation are the future for healthier people and the planet, they say. The believers believe because the story sounds ok and signals good intent... but the data don’t stack up.
Investigation reveals that both require crops for ingredients and energy. Crops require land, cultivation, agrichemicals and processing.
Processing is in preservation and in making plants edible – soaking, cooking, for instance.
Plants have evolved many ways of protecting themselves from predators and the lengthy process of preparation, which used to occupy a huge amount of time for hunter-gatherer societies, is part of ensuring the food is digestible.
The problem with plants, however, is that they do not contain high-quality protein for humans – the essential amino acids (EAA) that make up the protein are not in the ratios that humans need.
In order to obtain nutritional requirements for plants, more energy (calories/kilojoules) must be consumed than if an omnivore diet is followed, and more nitrogen is excreted following the breakdown of consumed but unrequired amino acids.
Extra energy is associated with extra land and extra excreted nitrogen is associated with increased greenhouse gases in the sewage system.
Similarly, recent calculations around precision fermentation have indicated that all is not as good as had been thought.
The 2021, the Good Food Institute report revealed that costs were 10,000 to 100 times higher than comparable conventional meat products, depending on the ingredients and efficiency of their use.
To bring costs down, they suggested reductions were required in production costs and use of medium ingredients (particularly growth factors and recombinant proteins), reduction in costs of infrastructure, and government investment through subsidies to enable commercially orientated companies to get going.
The authors also recommended being more energy efficient to reduce environmental impacts and costs, including switching to renewable energy away from fossil fuel.
This year a life cycle assessment on cultured meat pointed to more challenges in terms of environmental impact.
The more refined the growth medium, the more impact there is.
Authors from The University of California concluded that contrary to popular belief, the environmental impact of cultured meat is likely to be higher by orders of magnitude than conventional beef production if a highly refined growth medium is involved.
The paper is still in review but warns “that investment dollars have specifically been allocated to this sector with the thesis that this product will be more environmentally friendly than beef.”
Models used to compare, predict and conclude are always subject to assumptions and constraints, including the starting points and choice of parameters modelled.
They can be used to compare outcomes under different scenarios and the outcomes can then be re-examined, by a different method.
Triangulation - coming at a problem from three different ways - can lead to increased confidence or a new set of parameters and investigations.
Listen to Jamie Mackay interview Dr Jacqueline Rowarth on The Country below:
Major conflicts and uncertainties should lead to questions being asked on the path to follow, as is the case with plant-based and precision fermentation.
For some people, reducing the consumption of animal protein, or consumption overall, will be a good idea. For others it won’t be - iron is deficient in the diet of approximately 10 per cent of women in New Zealand and 1 per cent of men.
Globally the percentage is much higher.
The extraordinary nature of modern-day food is its variety and the remarkable choices we have in eating in the way that suits us.
Certainly, it is more expensive than it was as the costs of production have escalated, but the environmental impact has reduced (per mouthful) with the development of precision agriculture.
There is no such thing as carbon-neutral food; claims to the contrary are using offsetting (e.g., planting trees) to make the calculation, which, as the Parliamentary Commissioner for the Environment, and Climate Change Commissioner have explained is not a long-term solution.
At this stage the research has not achieved the wizardry of the Star Trek replicator, able to synthesise food on demand apparently out of nowhere. The energy source might have been the warp drive... or not. And it is energy that remains at the heart of this globe’s issues for food production.
The good thing about animals is that they harvest the grass that has grown from the energy from the sun and turn it into human-accessible protein with EAA in the needed proportions.
New Zealand farmers are leaders in managing the process.
- Dr Jacqueline Rowarth, Adjunct Professor Lincoln University, is a member of the Science Advisory Council of the World Farmers’ Organisation and on the Board of Directors of several agricultural organisations. The thoughts and analysis presented here are her own jsrowarth@gmail.com
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