The study, published in the journal Nutrition , also provides the latest clue to a powerful link between chronic inflammation and poor health, according to Mark Reynolds, DDS, PhD, associate professor at the Dental School, part of UMB.

Chronic inflammation appears to be an important factor underlying aging and many age-related disorders, and dietary restriction has been shown to reduce the risk for chronic disease and promote longevity in multiple animal models, says Reynolds, who is chair of the Department of periodontics at the School.

The study, of 81 rhesus monkeys at the National Institutes of Health, showed that males fed a diet of 30 percent fewer calories for 13 to 17 years had significantly lower levels of a gum-damaging condition known as periodontal pocketing, less immune response to invading bacteria, and higher inflammatory molecules than males fed a normal diet. Periodontal inflammation and disease start from bacteria. Also, for the monkeys not fed the reduced-calorie diet, males showed significantly greater periodontal breakdown than females. Consistent with previous studies of humans, the monkeys in the study showed an increasing degree of gum problems as they aged. Aging and obesity are associated with increased biological signs of overall inflammation and periodontal disease in humans, says Reynolds. Although about one-third of adults aged 30 to 90 have periodontitis, attempts to study humans directly have been hampered by the environmental complexities of oral diseases and factors such as smoking. Non-human primates, such as rhesus monkeys, are an important model for studying inflammatory gum disease and oral infections in humans, says Reynolds.

Reynolds studies the role of inflammation in periodontal disease, including modifiable risk factors such as nutrition. Periodontal disease is one of the few inflammatory conditions that can be readily seen and studied in humans and other animals.

Reynolds was at the National Institute on Aging (NIA) before joining the faculty at the Dental School in 1999. Continuing research verified that the monkeys develop visible gum disease, and the NIA awarded John Novak, BDS, LDS, RCS, MS, at the University of Kentucky; Reynolds; and others a five-year grant for their study.

Men develop higher rates of periodontal and coronary heart disease than do women on the whole, says Reynolds. A major question has been: how much do modifiable risk factors, such as smoking, physical inactivity, and obesity, contribute to the male-female gap? Or, is this difference in risk a natural occurrence between males and females? The monkey study seems to point to a genetic basis for the difference in risk, he says, reflecting underlying differences in how males and females respond to injury and inflammation.

He adds, An understanding of such sex differences will become increasingly more important in the selection of treatments as we move toward personalized medicine based on individual genetic profiles.

The study appears in the Oct. 15 online issue of Nutrition , and will appear in the January hard copy. Along with Novak and Reynolds, the study team included other researchers from the Maryland Dental School and the University of Kentucky, as well as researchers at the Virginia Commonwealth University, the National Institute of Aging, and Louisiana State University.

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