Busting the plant-based diet myth

One might have thought that a sustainable healthy diet would be exactly what people would want to eat and promote to others ... but one would be wrong.

The outrage greeting the use of the term "sustainable healthy diet" by the Intergovernmental Panel on Climate Change (IPCC) in its greenhouse gas emission report made it clear.

Some were appalled to find that, in places, including the Summary for Policymakers, the term "plant-based diet" was replaced with "sustainable healthy diet".

Greenpeace described the action as sabotage: "The New Zealand delegation, joined by India and Kenya, proposed changing the language from ‘plant-based foods' to ‘healthy diets'. This change was accepted, despite clear scientific evidence that meat and dairy is responsible for significantly more emissions than a plant-based diet."

What Greenpeace, and all other groups promoting plant-based diets, overlook is the impact of the diet that meets human nutritional requirements, not just energy or protein.

Research has been done.

For the US, modelling indicates plants-only agriculture produces more food (+23%) but the food does not meet the essential nutrient requirement of the population.

Authors from Virginia Tech and the US Department of Agriculture found people would need to eat more (resulting in an excess of calories) and would have nutrient deficiencies. "Overall," wrote the authors, "the removal of animals resulted in diets that are nonviable in the long or short term to support the nutritional needs of the US population without nutrient supplementation."

What constitutes a sustainable and healthy diet has also been investigated by the CSIRO, Australia's equivalent to Crown Research Institutes.

Researchers calculated that discretionary foods (anything that isn't an essential part of healthy dietary patterns) contributed almost 30 per cent of the greenhouse gases (GHG) of an average Australian diet.

Discretionary foods anything fatty, salty or sugary and alcohol. The average Australian eats 6.2 servings a day. A serving is one can of fizzy drink, 400ml beer, 100ml wine, 25g chocolate, one tablespoon of jam or honey, or 12 hot chips. One snack-size pack of chippies would be two servings.

The CSIRO researchers suggested reducing discretionary food intake would allow for small increases in emissions from core foods, particularly vegetables, dairy (a recommended increase from 1.5 to 2.5 servings, one serving being 250ml milk, 200g yoghurt or 40 g cheese), and grains.

The nutritional benefit would be achieved at a 3.6 per cent increase in GHG, which the authors described as "small".

Naturally, the NGOs will say anything is too much - but again the bigger picture should be considered.

The use of water and cropland has also been analysed in terms of the average Australian diet.

Again, reduced discretionary foods were recommended and dairy was increased - and specifically mentioned was an increase in red meat (beef and lamb) from 0.66 servings a day to 0.81 (about 81g raw meat). Using precision agriculture, as available in NZ, reduced the average footprint by almost 20 per cent.

In Ireland, similar recommendations on protein have been made for ageing people to maintain muscle mass. "Healthy older adults should eat a more protein-dense diet than the general adult population. Foods such as meat, poultry, fish, dairy products, and eggs, and, to a lesser extent, beans, peas, lentils and nuts, should be consumed in at least two meals a day."

This is supported by researchers at the National University of Singapore who found that animal protein is more beneficial for lean muscle mass than plant protein, especially in younger adults (anybody under 50). Given all the scientific research on diet, animal protein clearly plays an important part in achieving "healthy".

By focusing on need rather than want (by removing discretionary foods) the environmental impact can be reduced as well. This is what the IPCC report was trying to achieve.

The Working Group III report that resulted in outrage and conspiracy theories, highlighted the need for diets that feature coarse grains, legumes, fruits and vegetables, nuts and seeds, and animal-sourced food produced in resilient, sustainable and low-GHG emission systems. The sort of animal protein NZ produces.

The IPCC said "sustainable healthy diets" promote all dimensions of individuals' health and wellbeing; have low environmental pressure and impact; are accessible, affordable, safe and equitable.

People make food choices for all sorts of reasons, but avoiding animal protein to save the planet should not be one of them.

Despite the claims, New Zealand's policy input to the IPCC was not about sabotaging global efforts to reduce global emissions, it was about helping sense to prevail.

The government officials involved should be commended for enabling science to overcome ideology.