Zinc deficiency in elderly people can lead to multiple
diseases
Researchers have suggested that it's important for
elderly people to get adequate dietary intake of zinc, since they may need more
of it at this life stage when their ability to absorb it is declining. Zinc can
be obtained in the diet from seafood and meats, but it's more difficult to
absorb from grains and vegetables - a particular concern for vegetarians.
Scientists in the Linus Pauling Institute at Oregon State
University and the OSU College of Public Health and Human Sciences have
outlined for the first time a biological mechanism by which zinc deficiency can
develop with age, leading to a decline of the immune system and increased
inflammation associated with many health problems, including cancer, heart
disease, autoimmune disease and diabetes.
The study was based on findings with laboratory animals.
It found that zinc transporters were significantly dysregulated in old animals.
They showed signs of zinc deficiency and had an enhanced inflammatory response
even though their diet supposedly contained adequate amounts of zinc.
When the animals were given about 10 times their dietary
requirement for zinc, the biomarkers of inflammation were restored to those of
young animals.
"We've previously shown in both animal and human
studies that zinc deficiency can cause DNA damage, and this new work shows how
it can help lead to systemic inflammation," said Emily Ho, an LPI
principal investigator and associate professor in OSU School of Biological and
Population Health Sciences.
"Some inflammation is normal, a part of immune
defense, wound healing and other functions," she said. "But in
excess, it's been associated with almost every degenerative disease you can
think of, including cancer and heart disease. It appears to be a significant
factor in the diseases that most people die from."
As a result of this and what is now know about zinc
absorption in the elderly, Ho said that she would recommend all senior citizens
take a dietary supplement that includes the full RDA for zinc, which is 11
milligrams a day for men and 8 milligrams for women.
"We found that the mechanisms to transport zinc are
disrupted by age-related epigenetic changes," said Carmen Wong, an OSU
research associate and co-author of this study.
"This can cause an increase in DNA methylation and
histone modifications that are related to disease processes, especially cancer.
Immune system cells are also particularly vulnerable to zinc deficiency,"
he stated.
Research at OSU and elsewhere has shown that zinc is
essential to protect against oxidative stress and help repair DNA damage. In
zinc deficiency, the risk of which has been shown to increase with age, the
body's ability to repair genetic damage may be decreasing even as the amount of
damage is going up.
Even though elderly people have less success in absorbing
zinc, the official RDA for them is the same as in younger adults. That issue
should be examined more closely, Ho said.
Levels of zinc intake above 40 milligrams per day should
be avoided, researchers said, because at very high levels they can interfere
with absorption of other necessary nutrients, including iron and copper. The
study was published in the Journal of Nutritional Biochemistry.
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