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Zinc Deficiency in Older Adults

By Lindsey Getz

A new study suggests that an elder’s zinc deficiency may produce serious health consequences.

While most of the research about zinc and infection points to zinc’s possible role in fighting the common cold, a study from Oregon State University’s Linus Pauling Institute and College of Public Health and Human Sciences suggests that zinc deficiency may lead to immune system decline and increased inflammation associated with many health problems, including cancer, heart disease, autoimmune disease, and diabetes. Because older patients tend to consume less zinc and also appear to absorb less of what they do consume, it’s important for older adults to pay closer attention to their zinc intake.

The study, published in the Journal of Nutritional Biochemistry, found that zinc transporters were significantly dysregulated in older animals. The animals showed signs of zinc deficiency and had an enhanced inflammatory response even though their diets supposedly contained adequate amounts of zinc. This could be significant for older adults.

“The elderly are the fastest growing population in the US and are highly vulnerable to zinc deficiency,” says Emily Ho, PhD, a principal investigator with the Linus Pauling Institute and an associate professor in Oregon State’s School of Biological and Population Health Sciences. “They don’t consume enough of this nutrient and don’t absorb it very well.”

Previous studies have shown that zinc deficiency can cause DNA damage. This new study is a step toward understanding how zinc deficiency also can lead to systemic inflammation, Ho explains. While some inflammation is a normal part of immune defense, excessive inflammation has been associated with various degenerative diseases from cancer to heart disease.

With zinc deficiency, the body’s ability to repair damage may also decrease, but Ho says these hypotheses remain under investigation. “We just don’t know precisely what’s going on,” she says. “We think that zinc has antioxidant and anti-inflammatory action that helps defend against the damage that inflammation causes in many chronic diseases, but this mechanism requires further research.”

Understanding Zinc
Zinc often fails to receive much attention in this country because severe nutrient deficiencies are uncommon. In third-world countries, zinc deficiency is a public health concern in which the resulting diarrhea and stunted growth in infants and small children can become quite severe, says Daniel H. Bessesen, MD, a professor of medicine at the University of Colorado School of Medicine.

But the elderly are at greater risk of developing a zinc deficiency than the general population. “Zinc is a micronutrient that has many effects on the body,” Bessesen explains. “It is key in the function of some transcription factors in making a normal immune response, in fighting oxidative stress, and as a cofactor for many enzymes. Deficiency can lead to a scaly red skin rash, especially around the mouth, on the hands, and in the groin. It can also lead to diarrhea, loss of appetite, and a risk for infections.”

Hair loss and poor wound healing also can be signs of a zinc deficiency, adds Rachel K. Johnson, PhD, MPH, RD, associate provost and a professor of nutrition at the University of Vermont in Burlington. “When healthcare providers note impaired immune function and the increasing likelihood of infections along with poor wound healing and poor appetite, they should consider checking the person’s zinc levels.”

Despite these potential warning signs of zinc deficiency, it’s not something that’s easy to detect. “Zinc is important for every cell in the body for a myriad of different functions,” says K. Michael Hambidge, MD, ScD, professor emeritus from the department of pediatrics and nutrition at the University of Colorado, Denver. “Perhaps because of this, symptoms of zinc deficiency are not specific, and it can easily go unnoticed unless it is very severe when a typical skin rash [would be] likely to occur.”

Identifying zinc deficiency is difficult, and there is no good test for it, adds Ho. “We currently use blood zinc levels, but it is well known that it does not do a good job as [the test is] not very reliable or sensitive,” she explains.

The zinc deficiency must be severe for tests to be conclusive, Hambidge adds. “There is no good test for a more mild or common case of zinc deficiency.”

Combating Deficiency
Ho says the best way for elder patients to combat the loss of zinc is to consume more of it—specifically 11 mg/day for men and 8 mg/day for women. “Lean meats and seafood are good sources, and oysters have the highest level of zinc from food,” Ho says. “Grains and other protein-rich plant sources like beans and legumes also have quite a bit of zinc. But if you are only consuming a plant-based diet, many of these foods also contain a compound that binds up zinc so you don’t absorb it well and would have to eat even more.”

For older patients who don’t eat a lot of meat and are at risk of not consuming enough zinc, Ho says a multivitamin containing zinc may be warranted, as long as patients are staying below the upper level recommendation of zinc, which is 40 mg/ per day. “It would seem reasonable for an older person who does not consume much meat, who has been getting infections, or who has diarrhea to use zinc supplements for a period of time and see if the diarrhea improves or if the frequency of infections goes down,” Bessesen notes.

Johnson notes that it’s important to remember that zinc can be toxic in large quantities, adding that patients should aim to stay below the upper level limit of 40 mg/day. Taking too many zinc supplements can lead to vomiting, diarrhea, cramps, and headaches. Zinc also can react with certain medications so it’s important for patients to inform their healthcare providers if they are starting any sort of supplement routine.

— Lindsey Getz is a freelance writer based in Royersford, Pennsylvania.