Vegetables are losing their nutrients. Can the decline be reversed?

In 2004, Donald Davis and fellow scientists at the University of Texas made an alarming discovery: 43 foods, mostly vegetables, showed a marked decrease in nutrients between the mid and late 20th century.

According to that research, the calcium in green beans dropped from 65 to 37mg. Vitamin A levels plummeted by almost half in asparagus. Broccoli stalks had less iron.

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Nutrient loss has continued since that study. More recent research has documented the declining nutrient value in some staple crops due to rising atmospheric carbon dioxide (CO₂) levels; a 2018 study that tested rice found that higher CO₂ levels reduced its protein, iron and zinc content.

While the climate crisis has only accelerated concerns about crops’ nutritional value, prompting the emergence of a process called biofortification as a strategy to replenish lost nutrients or those that foods never had in the first place.

Biofortification encompasses multiple technologies. One involves genetically modifying a crop to increase its nutritional contents, which allows for the rapid introduction of new traits. Another, agronomic biofortification, utilizes nutrient-rich fertilizers or soil amendments to concentrate particular minerals in plants. Lastly, selective plant breeding can produce new varieties, though it can take a decade or more to yield a single variety.

Biofortification is an alternative to fortification, which has been part of the US industrial food system since the 1920s, when the nation began boosting table salt with iodine to reduce conditions related to mineral deficiency, such as goiter. Biofortification puts nutrients directly into the seed, as opposed to fortification, which adds nutrients into food once it’s grown. On the global stage, international stakeholders such as the World Health Organization (WHO) and the Consultative Group on International Agricultural Research (CGIAR) have deemed the development of nutrient-enhanced biofortified crops as one of their leading goals in achieving food security.

Prateek Uniyal, program lead at the International Food Policy Research Institute (IFPRI), explained that “because of climate change, iron and zinc have been dipping by 30-40% due to excessive rainfall, cold and physical damage”.

HarvestPlus is an organization under IFPRI, and it provides global leadership on biofortification evidence and technology. It is currently working with governments in more than 30 countries, and its biofortified varieties have been planted by more than 10 million farmers across the world, predominantly in developing countries. By 2030, the organization estimates, 1 billion people will be benefiting from biofortified foods. “We’re about 20 years into a 40-year program,” said Jenny Walton, head of commercialization and scaling at HarvestPlus. “We’re trying to revolutionize staple food systems.”

While malnutrition demonstrates the urgent need to increase the nutrient density of crops globally, Benjamin Cohen, professor of environmental studies at Lafayette College, points to biofortification as a Band-Aid, rather than a solution to the problem.

“My concerns are about funders, based on policymakers, choosing to invest in biofortification instead of supporting more enduring smallholder models of farming that could be more efficient and resilient than large-scale systems,” said Cohen. “Promoting biofortification suggests solving a problem that should not exist if not for large-scale, capital-intensive agriculture. It’s likely that those same agricultural processes would only be further entrenched with biofortification.”

HarvestPlus sees plant breeding as the most sustainable way of biofortifying; it relies on existing plant genes. The organization works exclusively with staple crops and is developing them to contain higher amounts of vitamin A, iron and zinc, three micronutrients identified by the WHO to be the most deficient in diets globally. That approach means that in places such as Pakistan, where diets are wheat-heavy, fortifying that grain could make population-level change. HarvestPlus has already released 400 varieties of staple crop; none of them are patented.

But there are other concerns that nutrients are being lost at a broader scale than biofortification can replace.

Davis, who led the original University of Texas study demonstrating dwindling nutrient value in crops, said: “A limitation of biofortification is that it focuses on one or possibly two nutrients per plant, whereas nutrient decline tends to affect many nutrients simultaneously.”

And then there’s the hurdle of accessibility. Walton noted that there’s not yet a consistent supply of biofortified seeds. HarvestPlus also intends for its biofortified seeds to cost less than traditional seeds. But those lowered costs are the result of government subsidies. For example, India has partnered with HarvestPlus to make biofortified food available for children, in a country with a high rate of malnutrition stunting youth’s growth.

The government partnership model may pay off in low- to middle-income nations where malnutrition is common and businesses are working directly with the smallholder farmers growing biofortified varieties, rather than at industrial scale because the seed supply can’t yet reach that volume.

Cohen pointed out that while the need might be greatest in less industrialized countries, such countries may have fewer mechanisms to resist policies originating in better-resourced countries. They may have fewer regulations about genetically modified, biofortified crops, such as the controversial golden rice, which was altered to produce beta-carotene and, as a result, vitamin A. While golden rice was bred to help alleviate vitamin A deficiencies, Cohen has written that this strategy adopts “technical fixes to problems that could be addressed in ways less dependent on mono-cropped environments”. Essentially, if we plant diversified crops that have the vitamins a given population lacks, the same nutritional outcome could be achieved.

He said: “Powerful nations dictated the shape of food systems in other countries, left them in the position of more malnutrition, and now because those countries don’t have enough power to form their policies on a global market, the same powerful nations can now go back and intervene in their dietary systems.”

In addition, the industrial agriculture system also favors chemical fortification, said Peter Kelly, CEO of Grow Further, a philanthropic organization that invests in early-stage, scalable agricultural innovations in developing countries. He stated that “there’s not much interest in biofortification for the US domestic market. Some US food companies are supporting international work to improve nutrition. But it’s not really necessary in our current [US] food system because it can be done with chemical fortification.”

Kelly suggests pairing biofortification with other seed changes – perhaps breeding them to be more drought resistant – to further encourage stakeholders to invest in crops that better fit local growing conditions.

“All of our work is about adapting to climate change in some sense,” said Kelly. “Carbon dioxide levels can affect the nutrient levels in plants; we have to do this plant breeding just to keep up. Enhancing fruits, veggies and beans is one approach, but if that’s the only approach from the public policy perspective, it’s kind of idealistic.”