Study tallies the payback for humans and planet of eating more plants and less meat

If the world increased its consumption of fruits and vegetables and maxed out its average weekly red meat consumption at just over 10 ounces, about 5.1 million premature deaths would be averted annually, and projected greenhouse gas emissions in 2050 would be pared 29%, new research has concluded.

The resulting savings in healthcare costs would amount to $735 billion per year, and planetary economic costs associated with climate change would drop by about $234 billion per year, said a study published Monday in the journal PNAS.

All told, the savings could range from $1 trillion to $31 trillion, or as much as 13% of global gross domestic product by the year 2050, a group of Oxford researcher reckoned.

The planetary tally is among the first to look at the economic and environmental effects of dietary changes, and to parse out those effects region by region. It found that developing countries, particularly in East Asia and Latin America, would realize the greatest savings in lives by adopting a more healthful diet. Those countries would also realize the greatest reductions in greenhouse gas emissions with the global dietary shift.

The “healthy global diet� that would occasion these planetary improvements would put most of the world on a regimen of increased fruits, vegetables and legumes and drive down red meat consumption -- and hence production -- by a global average of 57%. The idealized diet would increase daily consumption of fruits and vegetables by 25% globally and limit average daily sugar intake to less than 50 grams (the equivalent of less than a can of sweetened soda, or about 21 sugar cubes). Intakes of 2,200 to 2,300 calories daily would be the worldwide norm.

“Large changes in the food system would be necessary to achieve the dietary patterns considered here,� the authors acknowledged.

To reach weekly limits of about 10.2 ounces of red meat (a McDonald’s Big Mac has 7.5 ounces of beef), average global consumption would have to decline 56%. But that average obscures the deep cuts it would make in countries that are affluent or growing: High-income Western countries would be in for red-meat reductions of 78%, and middle-income countries that have greatly accelerated their meat intake in recent years would need to pare it back by 69%. East Asia and Latin America would have to reduce their red meat consumption 74% and 72%, respectively.

But the planetary payback would be substantial. Researchers attributed close to half of the savings in lives to reduced rates of heart disease, about a quarter to reduced stroke rates, and 16% to 18% to lower cancer deaths.

For South Asia and sub-Saharan Africa, increased consumption of fruits and vegetables would drive health improvements. In East Asia, Western high- and middle-income countries and Latin America, the decline in red meat consumption improved health. And the health benefits of weight loss and obesity prevention would save the most lives in the eastern Mediterranean region, Latin America and the high-income Western countries.

Meanwhile, the agricultural shifts that would attend such a reduction in red meat consumption would have a powerful effect on the emissions causing climate change. About a quarter of all greenhouse gas emissions are the result of food production, and red meat production is a substantial contributor to those emissions.

Widespread adoption of the healthy global diet would hold the growth of food-related greenhouse gas emissions over 2005-07 levels to 7% by the year 2050 -- down from a projected growth, in the absence of the recommended dietary changes, of 51%. That estimated decline in projected 2050 greenhouse gas emissions is likely conservative, the authors wrote, because it did not take into account the beneficial effects of avoiding deforestation as land is cleared for the grazing of livestock.

The same study also found that worldwide adoption of far more radical dietary changes would bring steeper reductions in premature deaths and greenhouse gas emissions. Vegetarian diet would avert 7.3 million deaths yearly, and worldwide adoption of a vegan diet would avert 8.1 million early deaths per year. Projected 2050 greenhouse gas emissions would be 45% to 55% lower if the world adopted a vegetarian diet and 63% to 70% if a vegan diet became ubiquitous.

The authors expressed hope that their estimates would help world leaders identify “targeted, region-specific interventions� that would have the dual benefit of improving the health of the planet and its human inhabitants.

Follow me on Twitter @LATMelissaHealy and “like� Los Angeles Times Science & Health on Facebook.