Zinc, an important mineral in human health, appears to affect how the immune system responds to stimulation, especially inflammation, research from Oregon State University shows.
Zinc deficiency could play a role in chronic diseases such as cardiovascular disease, cancer and diabetes that involve inflammation. Such diseases often show up in older adults, who are more at risk for zinc deficiency.
"When you take away zinc, the cells that control inflammation appear to activate and respond differently; this causes the cells to promote more inflammation," said the lead author of the study.
Zinc is required for many biological processes, including growth and development, neurological function and immunity. It is naturally found in protein-rich foods such as meat and shellfish, with oysters among the highest in zinc content.
Approximately 12 percent of people in the U.S. do not consume enough zinc in their diets. Of those 65 and older, closer to 40 percent have an inadequate zinc intake. Older adults tend to eat fewer zinc-rich foods and their bodies don’t use or absorb zinc as well, making them very susceptible to zinc deficiency.
In the study, researchers set out to better understand the relationship between zinc deficiency and inflammation. They conducted experiments that indicated zinc deficiency induced an increase in inflammatory response in cells. The researchers were able to show, for the first time, that reducing zinc caused improper immune cell activation and dysregulation of a specific protein that affects inflammation in the cell.
Researchers also compared zinc levels in living mice, young and old. The older mice had low zinc levels that corresponded with increased chronic inflammation.
Together, the studies suggest a potential link between zinc deficiency and increased inflammation that can occur with age.
Understanding the role of zinc in the body is important to determining whether dietary guidelines for zinc need to be adjusted. The recommended daily intake of zinc for adults is 8 milligrams for women and 11 milligrams for men, regardless of age. The guidelines may need to be adjusted for older adults to ensure they are getting enough zinc, the researchers said.
There is no good clinical biomarker test to determine if people are getting enough zinc, so identifying zinc deficiency can be difficult. In addition, the body does not have much ability to store zinc, so regular intake is important. Getting too much zinc can cause other problems, including interfering with other minerals. The upper limit for zinc is 40 milligrams per day.
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