For the last few decades, the nutrient content of our crops has been declining. In the late 1990s, the US Department of Agriculture found the vitamin C content of lemons had decreased by almost a third over the previous 22 years. Calcium in carrots had reduced by more than a quarter, vitamin A in bananas was down by 57%, and the mineral content of wheat has declined by between 20-30% since the 1960s.
Causes of nutrient decline
A number of reasons have been suggested, ranging from new crop varieties bred to grow quicker and bigger to higher carbon dioxide levels causing plants to produce more sugars and starches, leading to faster growth but fewer nutrients. Proposed fixes include GM crops, synthetic soil amendments, or underground farms.
Regenerative agriculture as a solution
One group of agricultural researchers argues that the answer may be regenerative agriculture, which focuses on building organic matter and ecosystems in the soil. Francesca Brkic, working with the University of Lincoln, explored how regenerative agriculture affects nutrient density. Sampling found iron in kale up to 22 times higher, selenium in dried peas eight times higher, and folate in carrots up to 20,000 times greater compared with conventional farms.
Brkic says: “Organic had to be our minimum baseline, because regen doesn’t have a certifiable standard. But while organic as a concept focuses on not doing harmful things, it doesn’t specify that you are doing positive things.” Regenerative farms were defined by using cover crops and grazing animals, while abstaining from ploughing and using insecticides or other pesticides.
Soil health and mycorrhizal networks
The way soil is treated by modern farming may be part of the problem. Ploughing and heavy use of chemicals disturb or destroy the soil’s mycorrhizal networks, which allow plants to pull in nutrients. Dr David Montgomery, a US geologist and co-author of What Your Food Ate, says regenerative agriculture can right the wrongs of “degenerative” farming.
“It was the microbial truckers and miners in our soils that got put off the job by conventional agriculture,” he says. “Regenerative practices that treat soil as an ecosystem can return those miners and truckers to the job.” Montgomery and his wife, Anne Biklé, conducted a 2022 study noting correlation between regenerative agriculture and higher nutrient density in US food crops.
Other studies and conflicting evidence
A large literature review by Newcastle University in 2015 found that eating organic fruit, vegetables, and cereals would provide additional antioxidants equivalent to one to two extra portions of fruit and vegetables a day. The Bionutrient Institute multi-year study found the strongest positive correlation for high nutritional value was biological activity and overall soil health.
However, other research has not reached similar conclusions. Reviews by UK and French food standard agencies found small differences, and a large-scale review by Stanford University found results highly variable and sometimes insignificant.
Criticisms of regenerative agriculture
Regenerative agriculture has critics. It is less reliant on mechanisation and agrochemicals, requiring more human labour and often considered less cost-effective. It is also susceptible to greenwashing. Physician Dr Naheed Ali notes “dietary displacement,” where individuals perceive food to have more nutritional value due to sustainable claims, potentially leading to inadequate intake of important nutrients.
Some soil scientists, like Prof Ken Giller and his colleagues, think it is “unlikely” that regenerative agriculture can reliably feed the world’s 8.3 billion people while reaping environmental benefits. Montgomery disagrees, saying it can scale because it depends on a philosophy of building soil health.
“Just imagine what we could do,” says Brkic, “if we made a few tweaks to our soil and agriculture practices and the impact that that would have on us.”
