Veganuary: Can veganism save the planet?

From stuff.co.nz

By Jacqueline Rowarth

OPINION: Whether you enjoyed your festive dinner with gusto, defiance, guilt, or smugness in the knowledge that you chose non-animal food, you can make a resolution to embrace a more environmentally friendly diet for the future.

You’ll be able to do this by eating food in moderation to meet the needs of your body and mind.

Extreme diets, over-eating and simply the number of people doing the eating are the main causes of environmental impacts associated with food, not animals per se.

This doesn’t fit with the message from activists to save the planet by becoming vegan, but the science doesn’t fit the message either.

The science says that from insect to ruminant, the primary aim in food ingestion is to meet nutritional targets which change according to maturity and activity. The factors driving food selection are complex because the many nutrients obtained from foods interact in their effects on animals.

Professor David Raubenheimer (University of Sydney and author of Eat Like the Animals), has used fundamental biology and nutritional ecology to show that animals can reach their intake target of nutrients by eating a single food that is nutritionally balanced, or by eating complementary foods.

However, when an animal is restricted to a nutritionally imbalanced food, without access to a complementary food, it must reach a compromise between over-ingesting some food components and under-ingesting others. This could be the cause of obesity in humans – a dominant protein appetite has interacted with a reduction over time in dietary protein concentration (burgers versus steak), resulting in excessive intake of energy as protein needs are met.

Extreme diets, over-eating and simply the number of people doing the eating are the main causes of environmental impacts associated with food, not animals per se

Dr Graeme Coles, Canterbury-based nutrition scientist, has explained that a comparison of diets using identical twins will show that the twin on an omnivorous diet with sufficient essential amino acids to meet requirements will excrete less nitrogen than the other twin on a plant-diet with sufficient essential amino acids.

In fact, the plant (vegan) twin will excrete twice as much nitrogen as the omnivore twin because to overcome poor protein quality and gain all the essential amino acids needed, the vegan twin will need to eat twice as much protein. The surplus non-essential amino acids will be broken down for energy within the liver and the excess nitrogen will be eliminated as urea. That urea contributes to nitrous oxide, a potent, long-lived greenhouse gas, in the sewerage system.

In contrast, the well-known flatulence associated with plant-based diets contributes little of significance to greenhouse gases.

Coles also urges people to consider the bioavailability of protein (the protein quality) when comparing diets. Plants have evolved a myriad of mechanisms to protect their proteins from predation. These are termed “anti-nutritional factors” – the nutrients appear to be present but can’t be accessed by the digestive system. Humans apply external treatments to overcome the factors, including fractionation, soaking, heating, acidification, fermentation and pulverisation.

Treatment takes time and energy, and causes losses, which increases the greenhouse gas emissions associated with the food. Soybeans, which are generally considered to be the best large-scale plant-protein source, have high concentrations of dietary trypsin inhibitors, oestrogen mimics and tannins. They are all natural, but they do mean that processing is required. And even with the processing, only approximately 73 per cent of soybean protein is digestible in comparison with 80-100 per cent from animal proteins. In terms of processing GHG, a good steak is three minutes on each side – or no cooking at all for steak tartare.

The argument that animals eat food that humans could be eating doesn’t stack up either.

Research from the Food and Agriculture Organisation (FAO) reported in 2017 that 86 per cent of livestock feed globally is not human edible, nor does it displace other food production. Only 7 to 13 per cent of beef production comes from feed lot systems, where a large proportion of the diet is waste from distilleries – alcohol and biofuel. Of further interest is that “out of the 2.5 billion hectares needed for animal production, 77 per cent are grasslands, with a large share of pastures that could not be converted to croplands and could therefore only be used for grazing animals”.

Dr Anne Mottet, livestock development officer at the FAO, and co-authors showed that grazing livestock contribute directly to global food security by producing a greater amount of highly valuable nutrients for humans, such as high-quality proteins, than they consume.

In New Zealand, these grasslands support considerable soil carbon and biodiversity – not as much of the latter as native forests, but certainly more of both than arable areas where soil disturbance is part of production. But arable land is often used to produce grazeable biomass between crops, and during fallow periods needed to restore soil structure and allow weed management – indicating a role for animals.

This month is Veganuary. If you are trying it, remember to check whether you need supplements like iron and B12. They are available in plant sources but you have to eat a very big plate of spinach to equate to a small steak.

Dr Jacqueline Rowarth, adjunct professor at Lincoln University, is a farmer-elected director of DairyNZ and Ravensdown. Dr Coles is omnivore; Jacqueline has been vegetarian for almost five decades.The analysis and conclusions above are her own.

https://www.stuff.co.nz/business/farming/opinion/300493046/veganuary-can-veganism-save-the-planet