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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Aspirin `delays memory loss in elderly`

Daily low dose aspirin could slow the decline in brain power among elderly women at high risk of heart disease, a new study has suggested.

The researchers based their findings on 681 women between the ages of 70 and 92, 601 of whom were at high risk of heart disease and stroke, defined as a 10 percent or greater risk on a validated risk scale.

All the women were subjected to a battery of tests to measure their physical health and intellectual capacity, including verbal fluency and memory speed, and dementia in 2000-1.

Their health was tracked over a period of five years, at the end of which the intellectual capacity of 489 women was assessed again.

Some 129 women were taking low dose aspirin (75 to 160 mg) every day to ward off a heart attack or stroke when the monitoring period started. A further 94 were taking various other non-steroidal anti-inflammatory drugs (NSAIDs).

The researchers found that the MMSE score fell, on average, across the whole group at the end of the five years, but this decline was considerably less in the 66 women who had taken aspirin every day over the entire period.

This result held true, even after taking account of age, genetic factors, the use of other NSAIDs and the cardiovascular risk score.

The researchers then divided the group into those who had taken aspirin for the entire five years (66), those who had stopped taking it by 2005-6 (18), those who were taking it by 2005-6 (67), and those who hadn’t taken the drug at any point (338).

Compared with women who had not taken aspirin at all, those who had done so for all five years, increased their MMSE score, while those who had taken aspirin at some point, registered only insignificant falls in MMSE score.

The test results for verbal fluency and memory speed indicated similar patterns, although the findings weren’t statistically significant.

There were no differences, however, in the rate at which the women developed dementia.

The researchers then looked only at the women with a Framingham risk score of more than 10 percent.

Again, similar patterns were evident.

The fall in MMSE score was less among those taking aspirin than those who weren’t, and there was no difference between those taking other NSAIDs and those who weren’t.

The same was true of the verbal and memory tests, although the differences were not statistically significant.

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Smoking may lead to cataract in elderly

In a new study, researchers have found new evidence that smoking may also increase the risk of age-related cataract, which is the leading cause of blindness and vision loss in the world.

The new findings are the result of a meta-analysis conducted by a team of researchers from China.

“Although cataracts can be removed surgically to restore sight, many people remain blind from cataracts due to inadequate surgical services and high surgery expenses,” author Juan Ye, MD from Zhejiang University in China said.

“Identifying modifiable risk factors for cataracts may help establish preventive measures and reduce the financial as well as clinical burden caused by the disease,” Ye said.

The team performed the analysis using 12 cohorts and eight case-control studies from Africa, Asia, Australia, Europe and North America, to compare the prevalence of age-related cataract in individuals who ever smoked cigarettes to those who have never smoked.

Further subgroup analyses were performed based on the subjects’ status as a past or current smoker and the three subtypes of age-related cataract.

The results showed that every individual that ever smoked cigarettes was associated with an increased risk of age-related cataract, with a higher risk of incidence in current smokers.

In the subgroup analysis, former and current smokers showed a positive association with two of the subtypes - nuclear cataract, when the clouding is in the central nucleus of the eye, and subscapular cataract, when the clouding is in the rear of the lens capsule.

The analysis found no association between smoking and cortical cataract, in which the cloudiness affects the cortex of the lens.

While the overall analysis suggests that smoking cigarettes may increase the risk of age-related cataracts, the researchers point out that further effort should be made to clarify the underlying mechanisms.

“We think our analysis may inspire more high-quality epidemiological studies,” Ye said.

“Our analysis shows that association between smoking and the risk of age-related cataract differ by subtypes, suggesting that pathophysiologic processes may differ in the different cataract types,” Ye added.

The study has been published in Investigative Ophthalmology and Visual Science.

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