17 March 2022

Soil health and Covid-19 immune response could be linked, scientists say


A Chinese-British research identifies a statistical correlation between the concentration of zinc, iron, copper and selenium in soil and the outcome of Covid-19 cases: the lower the concentration, the higher the fatality rate. The investigation suggests a link between the two events. But further studies will be needed

by Matteo Cavallito


The scarcity of zinc and other elements in the soil and, consequently, in the human body seem to be correlated to a higher mortality rate from Covid-19, a study has cautiously suggested. Resarchers from Xi’an Jiaotong-Liverpool University, a Sino-British academic joint venture, investigated the concentrations of several key elements – including iron, copper and selenium – in the United States. The survey involved 3,057 U.S. counties (98% of the total) comparing data collected with the percentage of fatal disease outcomes between Oct. 8, 2020, and March 25, 2021.

“The lower the concentration of zinc in surface soils, the higher the case fatality rate of Covid-19,” said Ying Chen, a researcher at the Wisdom Lake Academy of Pharmacy and co-author of the study with colleagues Zheng Feei Ma and Linxi Yuan of the Suzhou-based university’s Department of Health and Environmental Sciences.”Our results,” he added, “indicate that zinc, among the four trace elements tested, has the highest chance of impacting Covid-19 case fatality rate.”

The lower the concentration, the higher the Covid-19 fatality rate

19.3 million cases in 24 weeks with a total of 338 thousand deaths have been registered in the surveyed counties. The mortality rate, in other words, amounts to 1.75%. “In the south-east region where concentrations of Se, Zn, Fe and Cu are relatively low,” the study says, “the case fatality rate of COVID-19 is relatively high (i.e., 1.74 to 3.84%, according to the survey infographic, ed.), whereas in the west coast area where Zn, Fe and Cu are high, the case fatality rate is low (from 0 to 1,27%, ed.), suggesting an overall pattern of inverse association, especially for Zn, Fe and Cu.”

The statistical correlation could be explained by the importance of these elements in human health. Zinc, in particular, “as a component of various metal enzymes and activator of certain enzymes, can enhance physical immunity”, says Linxi Yuan. While “A lack of iron and copper intake may increase the risk of some viral infections”

But the assumption still needs to be verified

The authors, however, express some caution. The hypothesis that zinc deficiency increases the risk of death in Covid patients still has to be verified. Moreover, further investigation is needed the mechanismto better undasses how the transmission of some elements from the soil to the human body takes place. These dynamics are mainly related to nutrition, but their effective extent is not completely clear yet.

For now, the analysis helps to highlight once again the importance of ecosystem interactions. “Trace elements come from the environment we live in, including the soil, water, and atmosphere,” co-author Zheng Feei Ma said. “They affect human health through food chains and environmental flow, and their importance lies not only in the maintenance of human health but also in the health of other organisms in ecosystem.”

The role of micronutrients

At the heart of the link between soil balance and human health, there have always been micronutrients such as iron, zinc, folate, vitamins and more. Today, according to estimates, 30% of the world’s population, more than 2 billion people, do not get enough of them. This is as much a consequence of undiversified diets as it is of soil degradation.

When soil health declines, the loss of nutrients from its crops follows. To deal with this problem, the world has been using so-called crop biofortification strategies. Which consist alternatively in the selection of the richest crops, in the use of specific fertilizers or in the adoption of genetic engineering. Even if the ultimate solution to the problem, perhaps, could be specifically provided by soil preservation.