Regenerative Agriculture

This Antioxidant May Provide a Key Link Between Regenerative Agriculture and Human Health

Published by
Katherine Kornei

It’s a question that Laura Stewart has heard many times: “What’s the white stuff?” Stewart and her husband, Ches, sell mushroom-growing kits, and dense networks of hair-like strands—mycelium—shoot through the bags of compressed sawdust and soybean hulls in a matter of days. “You can just watch it run,” said Stewart, co-owner of Haw River Mushrooms in Saxapahaw, North Carolina.

Researchers now believe that those fungal threads play a key role in establishing healthy soils, which then go on to produce crops that contain higher levels of a compound shown to promote health. Demonstrating such a connection between soil, crops, and human health has long been a holy grail of the food and agriculture community.

“We’ve done a good job of linking soil health to plant health, but never have really done a good job of linking soil health to human health.”

Lore has it that J.I. Rodale, an early pioneer of organic farming and the founder of the Rodale Institute, wrote “Healthy Soil = Healthy Food = Healthy People” on a chalkboard over half a century ago. That’s an appealing—and logical—statement, said David Montgomery, a geomorphologist at the University of Washington and author of the forthcoming book What Your Food Ate (which he co-wrote with his wife, Anne Biklé) and other books on soil. But investigations into its veracity conducted in the 20th century often lacked scientific underpinning, he said. That’s in part because microbial ecology wasn’t well understood, Montgomery maintains. “In some ways, science has been catching up to the idea.”

Researchers have just begun to show recently that soils managed according to the principles of regenerative agriculture—minimal tillage, crop rotation, and the use of cover crops—yield more nutritious harvests. In one case, for instance, Montgomery and Biklé studied nine pairs of regenerative and conventional farms and found that crops grown on the regenerative operations contained higher levels of certain vitamins, minerals, and phytochemicals.

That connection between healthy soil and healthy food is important, but it’s not the complete equation, admits Andrew Smith, Rodale’s chief operating officer and chief scientist. “We’ve done a good job of linking soil health to plant health, but never have really done a good job of linking soil health to human health.”

Enter ergothioneine.

Discovered in 1909, ergothioneine is an amalgam of carbon, hydrogen, oxygen, nitrogen, and sulfur. It’s an amino acid, which means that it’s a building block of proteins. Ergothioneine is believed to confer health benefits—it’s been shown to be an antioxidant, meaning that it counteracts processes that trigger cell damage, and it’s also been associated with a decreased risk of cardiovascular disease and mortality. Deficiencies in ergothioneine have furthermore been linked to an increased incidence of cognitive decline. In light of these findings, a researcher recently proposed that ergothioneine be classified as a “longevity vitamin.”

However, despite the fact that it is found in human tissue, our bodies don’t produce ergothioneine. It’s made exclusively by fungi, blue-green algae, and some bacteria and yeast. Ergothioneine enters our bodies through the food we eat, said Douglas Kell, a biochemist at the University of Liverpool. “We take this molecule into our bodies from our diet.”

Research has shown that mushrooms are far and away the leading dietary source of ergothioneine. Varieties such as shitake, oyster, and maitake are particularly rich in it—they contain up to four-fold higher levels than button mushrooms and portabellas. And yet, many people don’t eat mushrooms, but everyone has ergothioneine in their blood, said Robert Beelman, a food scientist at Penn State University who studies the amino acid. “Where are they getting it?”

That quandary led Beelman and his collaborators to consider mycelium, the same stuff that occasionally befuddles Laura Stewart’s customers.

Riding the Biological Highway

Fungi are characterized by vast networks of underground growth: mycelium transports nutrients and water, and dense mats of the stuff have been shown to stretch for miles. (Mushrooms, on the other hand, are a fungus’ fruiting bodies, which are just the tip of the proverbial fungal iceberg.)

Perhaps ergothioneine is riding that biological highway of mycelium toward plants, Beelman and his colleagues hypothesized. Any substance produced by fungi and distributed through its mycelium could plausibly be taken up by nearby plant roots and incorporated into plant tissues, the scientists surmised. “Maybe it’s the fungi in the soil that pass it on to plants,” said Beelman.

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Animals would eat those ergothioneine-laden plants, and creatures at the top of the food chain—humans—would accordingly ingest ergothioneine from both plant and animal sources. That would explain why the amino acid is present ubiquitously in the human population, Beelman said. “Everybody’s got it in their blood.”

Beelman and his colleagues found that oats grown on plots that were not tilled contained roughly one third more ergothioneine, on average, than oats grown on conventionally tilled land.

To test that hypothesis, Beelman and his collaborators teamed up with scientists at the Rodale Institute. The researchers measured ergothioneine levels in oats grown at Rodale’s 12-acre Farming Systems Trial site in Kutztown, Pennsylvania. They analyzed batches of oats grown on plots that differed in how intensively they had been tilled. Tillage, which involves physically turning the soil over to kill weeds and prepare a site for planting, is used extensively in modern-day agriculture. But it comes with a significant drawback: tillage reduces fungal biomass since it disrupts and destroys mycelium. By testing how the concentration of ergothioneine in crops varied as a function of soil management, Beelman and his colleagues hoped to prove Rodale’s statement in its entirety.

Beelman and his colleagues found that oats grown on plots that were not tilled contained roughly one third more ergothioneine, on average, than oats grown on conventionally tilled land. That’s not wholly a surprise, said Beelman. “I wonder if a lot of what we’re doing agriculturally is messing with the fungi in the soil,” he added.

Beelman and his colleagues have since expanded their investigation. Working at Penn State University’s Russell E. Larson Agricultural Research Center at Rock Springs, the researchers recently analyzed how three different approaches to tillage—intensive tilling, minimal tilling, and stopping tilling altogether, i.e., “no-till”—affected ergothioneine levels in corn, soybeans, and oats. Again, they found that the concentration of ergothioneine increased in each crop as the tillage intensity decreased.

“When you till the soil, you reduce the amount of ergothioneine that gets into the crop,” said Beelman. There’s now finally good evidence for cohesive links among soil health, crop health, and human health, he said. “Nobody had actually shown a specific connection. I think this does.”

The Challenges—and Necessity?—of No-Till Farming

There’s a slew of ecological reasons not to till farmland, and this new finding adds yet another one to the list. But tilling is used to control weeds, so eschewing the practice comes with its own challenges. That’s something that Elizabeth Kaiser, co-founder and co-owner of Singing Frogs Farm in Sebastopol, California (one of the farms Montgomery and Biklé included in their recent study), knows firsthand.

When Kaiser and her husband, Paul, first started growing crops on roughly three acres of their land in 2007, they chose to till. “Tillage allows you to have control over a large amount of space,” said Kaiser. “That’s just what you did.”

However, as Singing Frogs Farm began implementing regenerative practices such as boosting soil quality by applying compost and planting hedge rows to reduce erosion, it made sense to take the tractor out of the equation, too, said Kaiser. “We were building life on one side, and then literally two feet next to it, we were killing life. That dichotomy was too tremendous for us.”

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Since 2009, not a single row of crops has been tilled at Singing Frogs Farm. To transition from one crop to the next—beds are planted with between three and 10 crops over the course of a year—the Kaisers and their farm crew manually cut the prior crop at the soil surface, add fertilizer and compost, and simply plant again. “Ideally the soil isn’t disturbed except for [when] you’re literally sticking your hand in there to put the new plant in,” said Kaiser.

Singing Frogs Farm is known as one of the first small-scale vegetable farms to go completely no-till. It’s a choice that we willingly made, said Kaiser, but it’s still a commitment. “No till is a lot more labor.”

But perhaps that trade-off is one that’s worth embracing, said Beelman. In part because of aggressive tilling, agricultural soils are continuously degrading over time. And that’s not tenable over the long term, said Beelman. “Societies that destroy their soil, they eventually disappear.”

Katherine Kornei

Katherine Kornei is a science journalist whose work has appeared in Science, Scientific American, and The New York Times.

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Katherine Kornei

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