Tackling hidden hunger by fortifying microgreens with zinc

Two new research papers on agronomic zinc biofortification for microgreens position these edible plants as a solution to global hunger. The Penn State researchers say microgreens are ideal because they grow quickly, are nutrient-dense, and contain low levels of anti-nutrients.

One publication in the Journal of Agricultural and Food Chemistry reveals that high light intensity increases antioxidants, such as vitamin C, flavonoids, and phenolic acids. These are essential for plant defense, growth, and color while also being beneficial for humans.

“We provided zinc in fertigation — applying nutrients via irrigation — and analyzed the metabolomic profiles — comprehensive analyses of the molecules involved in the metabolism process in plant tissues — of pea and radish microgreens in response to light intensity and zinc fertilization inputs,” comments lead author and team leader Francesco Di Gioia, associate professor of vegetable crop science in the College of Agricultural Sciences.

Answer to hidden hunger

High-light intensity was seen to decrease amino acids and glucosinolates — plant defense compounds, explains first author Pradip Poudel, postdoctoral scholar at Penn State. Enriching the plants with zinc led to higher specific antioxidant levels and more amino acids.

Adding zinc altered the plant’s metabolic pathways (phenylpropanoid metabolism), which are related to its antioxidants and nitrogen metabolism. These pathways support protein development and energy production, increasing adenosine triphosphate levels, which indicates a boost in cellular energy linked to photosynthesis and cellular respiration.

“The research shows how adjusting zinc levels and light exposure can help grow nutrient-rich, functional foods like radish microgreens that may support better health,” says Di Gioia. 

Microgreen growth and nutrition was boosted by high light intensity and zinc supplementation.“It’s a step forward in fighting micronutrient deficiencies globally. Often called ‘hidden hunger,’ micronutrient malnutrition is a form of chronic undernutrition where people lack essential vitamins and minerals, despite consuming enough calories.”

Both studies were components of Poudel’s doctoral thesis, which was part of a larger research project.

Second experiment

The second publication in Food Chemistry examined pea microgreens exposed to different zinc sulfate concentrations in irrigation solutions and various light intensity regimes.

Researchers found that higher light intensity increased the production of flavonoids and phenolic acids, which have antioxidant effects. Meanwhile, zinc enrichment raised levels of vitamins B1, B6, and C, as well as sulfur-containing amino acids. 

These nutrients are important for plant function and the health of its consumers. Zinc also increased oxalic acid levels, helping plants detoxify excess metals, adds Poudel.

“This suggests that optimizing light is critical for improving the nutritional and functional quality of zinc-enriched microgreens,” he notes. 

“These studies help inform better growing strategies for producing microgreens aimed at reducing zinc deficiency. They’re excellent candidates for targeted zinc enrichment because they have a short growth cycle — harvested in seven to 21 days — they are low in phytic acid, which blocks zinc absorption, and are popular as functional foods.”

Nutrition Insight recently met with Colleen Delaney, Ph.D., registered dietitian nutritionist, and technical adviser of US programs at Vitamin Angels, to examine causes of hidden hunger and how to reverse this trend. 

A previous study confirmed that a fast-growing floating fern is free of harmful cyanotoxins and also holds potential as a sustainable food source to tackle global food insecurity.

Another study suggested that microgreens can help reduce global malnutrition by increasing nutrition and diversifying diets. Researchers analyzed and profiled microgreens from broccoli, black radish, red beet, pea, sunflower, and bean, which exhibited high macro-, micro-, and antioxidant capacity.