For decades they have been working underground, establishing mycorrhizal-like networks of commerce and influence, taking root in academia and institutions, and even extending their tendrils into supranational governance. Their goal is to transform the diets of people across the world, to spark a revolution in food production and consumption. They call themselves the leguminati. “When you rediscover beans, it’s something we’ve all taken for granted, and then you realise – oh my God – these are really great, it’s like a secret,” says Steve Sando, the founder of the California-based bean company, Rancho Gordo, who is, for many, the godfather of this cult. “The secret’s been revealed to them and they tend not to be able to shut up about it, because they feel they’ve discovered the world.” Beans are enjoying a culinary renaissance and, say their advocates, it is not a moment too soon. Long thought of as bland, fiddly to cook, or poverty food, in recent years there has been growing recognition that beans are not only delicious, but that eating more of them could help solve a host of planetary and human health problems. Food production is a big cause of climate breakdown, amounting to about a quarter of the world’s greenhouse gas emissions. Three-fifths of those emissions come from meat production, leading many to argue for a shift towards a plant-based diet. But that does not take plants off the hook entirely. The “green revolution” of the 20th century led to an exponential increase in agricultural output, but it was via the widespread use of nitrogen-based fertilisers, a byproduct of the petrochemical industry that emit nitrous oxide, a greenhouse gas with a heating effect 300 times that of carbon dioxide. Added to that, poorly applied fertiliser runs off into rivers and waterways leading to pollution and algal blooms that kill fish and other wildlife. It was issues such as these that Josiah Meldrum, the cofounder with Nick Saltmarsh of the UK bean company Hodmedod’s, had in mind in the early 2000s when he was asked by climate campaigners in Norwich how a city such as theirs, with a population of about 122,000 then (144,000 now), could feed itself without exceeding planetary boundaries. “It was that climate project that led us to realise quite how fantastic pulses are,” he says. “The impact of synthetic nitrogen fertilisers on global climate is massive, because they’re about 2.5-4.5% of global manmade emissions. “So if we could move away from some of those inputs and produce those field-scale crops in a low-input way, we could really make a difference, we could really start to transform things. That’s really when we began getting interested broadly in leguminous plants.” Pulses, which include beans and also lentils and chickpeas, are the dried seeds of the legume family of plants, which also counts among its members oil-seeds, such as peanuts and soya beans, and varieties more commonly eaten fresh, such as broad beans, green peas and snap peas. From a food production perspective, legumes have some remarkable properties. Perhaps most crucially, they can produce their own nitrogen. “Because of a symbiotic relationship that bacteria in the root nodules have with the plants, they are able to take atmospheric nitrogen and convert it into plant-usable form,” says Chelsea Didinger, a beans researcher. That nitrogen is not just taken up and exploited by the plants themselves, they also leave a significant amount behind, meaning that including legumes in a rotation significantly reduces the amount of fertiliser needed for subsequent crops. “That crop rotation is really important because by not growing the same crop on the same ground every year, you’re also breaking any cycles for pests or disease,” says Didinger. Importantly, in a world adapting to changing climate conditions that are leading to droughts in many areas, they also have a low water footprint compared with many other crops, and certainly compared with meat. On average it takes 15,400 litres of water to make 1kg of beef, but about 5,000 litres for the same amount of beans. But are they really comparable? No, and yes. “When we’re talking about nutrition they are really unique, because they are high in protein [and] people love protein, protein is very hot these days,” says Didinger. “If you’re looking for a source of protein coming from plants, they are one of the best, they’re packed with protein. But it doesn’t stop there. They are also super rich in fibre, they are basically the richest natural source of dietary fibre that there is.” But all these beany benefits are for nought if no one can be persuaded to eat the things, and consumption of this miracle crop has been in long-term decline, particularly in the global north, but increasingly in developing countries where, as people become more affluent, they want to imitate western diets. The UN reports declines in bean consumption in countries that traditionally have pulse-rich diets, such as India and Mexico. “We hardly eat any in the UK,” says Meldrum. “We’re really low global per capita consumers of pulses, and yet we have a really good climate for growing particularly peas, which historically would have been a subsistence food. They would have been really core to our diet.” Things are slowly changing. Over the past two decades, Sando has almost singlehandedly repopularised beans in the US, building Rancho Gordo from a small farmer’s market stall to a multimillion-dollar business. His beans are not like the pale, soggy things you tip out of a tin and rinse off in a colander. They are heirloom beans, native to the Americas, the kind the Mayans and Aztecs would have built their empires on, but which had all but fallen off the food map. Now top chefs are queueing up to include them in their recipes, and Sando’s own recipe book has been on the NYT bestseller list. “They’ve been bred for flavour, and often for the way they look, whereas modern beans are bred for convenience for industrial farming,” says Sando. Meldrum is trying to do a similar job in the UK, but with beans generally needing a warmer climate than soggy Norfolk, he has had to be experimental. “We knew that the pulse crops – the beans, peas, chickpeas and lentils that people wanted to eat – were all imported and they were varieties that don’t grow well here,” he says. “So the first thing we realised is that we needed to encourage people to eat what could be grown here, which is peas and fava beans, which are small, dried broad beans.” They have some heavy-hitters on their side. Paul Newnham, the executive director of the UN Sustainability Goal 2 advocacy hub for ending hunger, writes in a recent report: “Beans are not just nutritious, affordable and delicious, they are a force for good, a symbol of hope, a catalyst for change.” Yes, like all good global food conspiracies, the leguminati is backed by the UN. But unlike intermittent calls over the years to include more insects in our diets, this one is rather more appetising.