Thursday, 13 February 2020 10:34

Headlines don’t match the research

Written by  Dr Jacqueline Rowarth
Jacqueline Rowarth. Jacqueline Rowarth.

OPINION: Diet-shaming appears to be the new trend and virtue-signaling by ‘celebrities’ is rife.

They’re doing it for their children. Only the cynical would wonder whether their on-line profile needed a boost.

The claim is that animal protein damages the environment more than plant protein, so we should be eating the latter rather than the former. Whether this is true or not very much depends upon which production systems are being compared and the basis for the calculations. 

The latest report hitting the headlines is from the University of Otago. It attempts to make dietary recommendations for the New Zealand context, but states overtly that UK data were used. Further, the base for the dietary calculations was 2,130 kilocalories. It wasn’t protein to provide essential amino acids.

The authors are clear; the media headlines are not.

Step one might be to wonder what greenhouse gas (GHG) savings there might be in New Zealand if everybody moved to a 2,130-kilocalorie intake. Over 30% of our population is classed as obese. They suffer greater ill-health and die at a younger age than if they were not overweight. Clearly, reductions in GHGs are not the only benefit of weight loss.

If calorie restriction occurs, diets need optimising for protein and vitamins as well as fibre.

Dr Graeme Coles, Canterbury-based nutrition scientist, suggests that everybody can contribute to mitigating the effects of climate change by eating a balanced diet. 

“A factor often forgotten,” he says, “is that humans combine amino acids from their diet to make protein. If an amino acid is limiting, the other amino acids are wasted – they’re used for energy and the nitrogen is excreted. Human-accessible protein is also not the same as total protein in a food.” 

Dr Coles has calculated that the wasted amino acids in a vegan diet are equivalent to two return flights a year to the UK from New Zealand, in comparison with an optimised diet. 

Another concern with vegan diets is simply health. It is challenging to obtain enough protein to build or maintain muscle without supplements (which are not included in the calculations on GHG; nor are the GHG-associated with leather and wool replacements, many of which come from the petro-chemical industry). Implications for immunity, and for reproduction, including for the second generation, are also beginning to emerge.

There are other issues – as well – in moving away from animals. Including basic soil, topography, climate and resource inputs needed to produce plant-based food. There is not enough suitable land in the world to feed its population solely from plants. Understanding the limitations of land use is why New Zealand produces animal protein with less environmental impact than other countries. And we do it without government subsidies…

The Ministry of Education new classroom resource on climate change did not suggest to children that they become vegan. It did suggest reducing consumption of meat and milk. Some children can do this without compromising health and some probably could do with greater consumption – starting point is key.
The latest paper from Otago did not promote veganism. It recommended eating patterns emphasizing the consumption of whole, plant-based foods. 

And last year’s Intergovernmental Panel on Climate Change did not say become vegan. It said: “Balanced diets, featuring plant-based foods, such as those based on coarse grains, sustainable legumes, fruits and vegetables, nuts and seeds, and animal-sourced food in resilient, sustainable and low GHG emission systems, present major opportunities for adaptation and mitigation while generating significant co-benefits in terms of human health.”

New Zealand’s animal-sourced food fits the bill.

A New Year’s resolution that everybody can embrace is optimising diet rather than eliminating a nutrient source. The ever-increasing number of studies available have raised awareness, and personal responsibility, thereby avoiding diet-shaming, can do the rest.

• Dr Jacqueline Rowarth is a soil scientist with a PhD in nutrient cycling. She has been vegetarian for 45 years.

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