Piles of a variety of healthy organic legumes.
Finger on the pulse: legumes are key to human health © Getty

Here’s a statistic that sticks in the throat: since the advent of agriculture, only 7,000 plant species out of a known 250,000 have been used by humans as food, according to UN biodiversity experts. Today, just 12 crops and five animal species make up 75 per cent of global calorie intake.

This is just one factor driving a new movement: sustainable healthy eating. It is a new aspiration in dietary circles for two reasons: unhealthy diets put more people at risk from death and disease than unsafe sex, alcohol, drug and tobacco use combined; and global food production is the biggest single driver of environmental degradation.

“Taken together, the outcome is dire,” noted a 2019 report by the EAT-Lancet Commission, an influential collective of 37 scientists from 16 countries, tasked with examining how the world should feed itself in the future. “A radical transformation of the global food system is urgently needed.”

There is one hitch: a healthy diet is subtly different from a sustainable one. Cutting down on red meat is not enough. To be a true adherent, you need to (almost) eliminate chicken, sidestep the salmon and diversify into nuts, seeds and legumes.

Demographics will drive the need for change on the world’s dinner table: there could be 10bn mouths to feed by 2050. Food production already accounts for about 30 per cent of greenhouse gas emissions and 40 per cent of land use. Around 70 per cent of freshwater drawn from lakes and rivers is to service agriculture. As less affluent nations emulate the diets of richer countries, the prospect of feeding a ballooning population looks gloomy. That is, at least if they are fed in the meat-rich manner to which they are becoming accustomed.


Maximum number of boiled eggs per week advocated by the ‘planetary health diet’

That is why scientists and policymakers are pressing people to make the “Great Food Transformation” to diets that are both nutritious and which preserve the environment sufficiently to feed future generations.

The UN Food and Agriculture Organization defines sustainable diets as those “with low environmental impacts which contribute to food and nutrition security and to healthy life for present and future generations . . . protective and respectful of biodiversity and ecosystems, culturally acceptable, accessible, economically fair and affordable; nutritionally adequate . . . while optimising natural and human resources.”

The reference to affordability is key: healthy diets, with the requisite five a day of fruit and veg, can be costly, but local and seasonal fare is cheaper. The EAT-Lancet Commission scientists spent two years devising the “planetary health diet” and dished up their findings in January.

The top line was clear: less meat and dairy foods, fewer spuds, more plants. If you were to represent a day’s intake on a plate, half the space would be taken up by fruits, vegetables and nuts. The rest would be whole grains, plant proteins such as beans and lentils, unsaturated plant oils, small amounts of meat and dairy, a little bit of added sugars and starchy vegetables.

Apportioning food groups on a daily basis, nuts and legumes far outweigh chicken or fish. A daily glass of milk covers the dairy requirements. Interestingly, it is an omnivorous — rather than vegetarian or vegan — diet.

Corinna Hawkes, director of the Centre for Food Policy at City University of London, is a commission member. “The healthy diet was based on scientific principles, not sustainability criteria,” she says.

“Then, in a separate process, we looked at how that diet could be achieved within planetary boundaries.”

Prof Hawkes says this factors in factors such as greenhouse gas emissions, water use and biodiversity, and found that it’s not always the foods that are the problem but rather the way they’re produced.

She says: “When it comes to meat production and greenhouse gases, people often think of farting cows but you also get a lot of emissions in the production of chicken feed.”

And when it comes to fish production, around 60 per cent of the world’s fish stocks are either fully fished or overfished.

Prof Hawkes thinks that the food industry should be helping consumers with the shift: “It is true that consumers vote with their forks but it cannot be right that they bear the entire responsibility for saving the planet.”

Sustainability also means cutting food waste. A third of the food produced globally for human consumption ends up lost before it reaches the shelves or thrown away after. To avoid this, I now buy daily on the school run, rather than weekly (easier in the city, I admit). I am a big fan of my local supermarket’s “wonky” range of cheaper, imperfect produce and I laugh — nay sniff — in the face of expiration dates.

Lunch is leftovers, except when it’s a boiled egg. which the planetary health diet limits to about one a week.

This sustainable healthy eating revolution? I’ll try my best but I’m not nuts about it.

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