A new review of studies on meat consumption around the world has found diets high in red meat are having serious consequences on our health.
The UK research, published in journal Science, shows while the meat is an important source of nutrients, it can increase the likelihood of developing cancer - particularly bowel and colorectal - and other diseases, including cardiovascular and type 2 diabetes.
"This Science article provides a state-of-the-art review of evidence regarding the increase in meat consumption worldwide as well as the impact of meat consumption on health and the environment," said Assoc Prof Taciano Milfont of Wellington's Victoria University.
The article makes it clear... that global meat consumption has major negative effects on human health and the environment, and this might not be sustainable in years to come.
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But the article also concludes it will be difficult to get people to stop eating so much meat, because the "existence of major vested interests and centres of power makes the political economy of diet change highly challenging".
Massey University professor Robert McLachlan said this is particularly the case in New Zealand, which has a strong farming background.
"But change is possible. In New Zealand, the consumption of red meat has fallen by 58 percent in just 10 years, and is now close to the average for rich nations, and close to recommended health limits on a population basis."
The review looked at data from 113 different countries, and found switching away from meat-heavy meals could reduce global mortality rates by up to 10 percent.
"It is possible for people to meet their nutritional needs without consuming meat and substantial reductions in meat intake would have a net positive impact on health," said Dr Cristina Cleghorn, senior research fellow at the University of Otago.
The World Cancer Research Fund recommends that people who eat red meat should consume less than 500g a week while the Global Burden of Disease project suggests people eat no more than 100g a week.
It's a challenge not restricted to wealthy countries like New Zealand however. People tend to eat more meat as their incomes rise, and consumption worldwide is fast outpacing population growth. It's estimated by mid-century, the world will be eating twice as much meat as it was in 2005.
While this could be good for New Zealand's exports in the short-term, experts are warning it can't go on forever.
"The consumption of meat, at least when viewed from the global perspective, is one of the most environmentally damaging day-to-day behaviours that humans perform," said Garrett Lentz, a University of Otago PhD candidate who is studying the environmental impacts of meat consumption.
"This is due to the vast range and severity of impacts tied to the raising of animals for food, including land and water degradation; habitat and biodiversity loss; and contribution to pollution, ocean dead zones, and climate change... Reduced meat consumption would result in a more efficient food system that could feed more people with fewer resources."
Dr Cleghorn said while New Zealand is "economically invested in the production of meat", the Government needs to encourage consumers to eat "plant-based meat alternatives" which could "start the shift away from animal-based agriculture".
"In order to generate health and climate co-benefits New Zealand could consider introducing an agricultural greenhouse gas tax, health and sustainability warning labels on meats and promotional campaigns to decrease meat consumption."
Is the review flawed?
Dr Mike Joy of Victoria University, who made headlines in 2011 when he criticised New Zealand's '100 percent pure' slogan, says the review does have a major hole - it doesn't examine the role fossil fuels have played in the agriculture boom of the last half-century.
"The huge population growth enabled by the so-called 'green revolution' was almost completely driven by fossil fuel-derived nitrogen fertilisers.
"Now the vast majority of humans on the planet are dependent on fossil fuel-derived fertilisers and meat production is a very inefficient way to transfer this fossil energy to humans. Thus, the omission of fossil energy is crucial because, notwithstanding the other issues in the paper, feeding 9 billion people with the meat-based diets anything like today will be impossible given fossil fuel declines."
Beef and Lamb NZ said the problem is people eating too much meat, and that when dietary recommendations are stuck to, the health and environmental impacts can be minimised.
"In New Zealand, this reinforces beef and lamb provide an efficient and sustainable source of essential nutrients to the diet, which can address nutrient intake needs and nutrient deficiencies including zinc, iron and vitamin B12," said Fiona Greig, head of nutrition.
"The body of evidence supports a moderate amount of lean red meat within a healthy diet, reinforced by the World Cancer Research Fund Report, which outlines overall dietary and exercise patterns are more important than individual foods."
The Science article concludes getting people to eat less meat will be difficult if the public doesn't understand the impact it's having on their health and the environment.