A study by researchers at the University of Michigan has found that high levels of cadmium — a heavy metal found in cigarettes, environmental pollutants, and certain foods — can spike the risk of death from respiratory viral infections, which could possibly include COVID-19.
“Our study suggests the public in general, both smokers and nonsmokers, could benefit from reduced exposure to cadmium,” commented lead author Sung Kyun Park, professor of epidemiology and environmental health sciences.
Cadmium exposure can, over time, threaten the integrity of our respiratory immune systems. Those with high levels of the chemical are particularly susceptible. While cigarette smoke is a potent source of cadmium intake, certain foods can be dietary sources of cadmium, including rice, cereals, and soybeans. Previous studies have found that the consumption of tofu can lead to elevated cadmium levels in nonsmokers.
“Unfortunately, the human body finds it much more difficult to excrete cadmium than other toxic metals, and its presence in many nutritious foods means it is critical to continue reducing sources of environmental pollution that contribute to its presence in the air, soil, and water,” explained senior author, Howard Hu.
The team took a deep dive into data collected as part of the US National Health and Nutrition Examination Survey from 1988-1994 and 1999-2006, which held insights into the health and nutrition of the US population. In total, there were almost 16,000 participants in these studies, in which samples of blood and urine were taken to measure cadmium levels.
After adjusting for factors such as age, sex, and body mass index, the researchers found that those with the highest levels of cadmium were 15 percent more likely to die of influenza or pneumonia.
“We couldn’t directly look at cadmium body burden among COVID-19 patients in the early pandemic,” said Park. “Our motivation was to find a modifiable risk factor that can predispose people with COVID-19 infection to develop a severe complication and die of COVID-19."
“COVID-19 may not be a one-time event. Our findings suggest that the public can benefit from reduced cadmium exposure when the next pandemic occurs. This cannot be done suddenly and takes time through policy changes.”
No, you don’t need to start avoiding tofu like the plague, says Hu. “This isn’t a recommendation for a draconian change in lifestyle, since many of these foods are typical staples of a balanced, nutritious diet, and their overall contribution to cadmium burden is likely modest.”
“Rather, the suggestion is to consider some shifts in choices.”
In the meantime, the team calls for epidemiologists to take a closer look at potential sources of cadmium exposure within the general population and for environmental crusaders to continue to limit cadmium pollution.