November 2, 2015 | Erin Bluvas, bluvase@sc.edu 

Over the past 10 years, researchers at the Arnold School of Public Health’s Cancer Prevention and Control Program (CPCP) have been studying the effects of chronic inflammation on the human body. During this time, they have amassed a large body of evidence that demonstrates how inflammation impacts our health (i.e., leads to early onset of chronic diseases, disability and premature death) and developed their copyrighted dietary inflammatory index (DII), which ranks foods and macronutrients according to their inflammatory properties. CPCP is even in the process of working with a new start-up company, Connecting Health Innovations LLC to convert the DII into a comprehensive set of clinical tools for use by medical professionals and their patients.

But they haven’t stopped there. Now that CPCP researchers have established clear relationships among diet, chronic inflammation and chronic diseases, they have drilled down even further to look at how these three factors are tied to telomere length. “Like the plastic tips on the ends of shoelaces, telomeres are the protective caps on the ends of DNA and protein that prevent them from fraying,” explains Nitin Shivappa, a CPCP researcher and research faculty member in the Department of Epidemiology and Biostatistics. “They protect the genetic data, which is important to ensure that cells can continue to divide normally.”

It’s not enough for telomeres to exist, they must maintain an adequate length in order to protect individuals from abnormal or inadequate cell division and, subsequently, adverse health consequences. “Telomeres naturally shorten over the human lifespan; however, there is considerable variability in how quickly they shorten,” says CPCP director and Health Sciences Distinguished Professor James R. Hébert. “Shorter telomeres have been associated with coronary heart disease, stroke, diabetes, dementia, osteoporosis and many types of cancer. Some studies have linked shorter telomeres with early death.”

Using data from one of the largest prevention studies in the world, the PREvención con DIeta MEDiterránea- NAVARRA trial (PREDIMED-NAVARRA), Shivappa and Hébert worked with Spanish colleagues to examine whether diet-related inflammation, measured using DII, could alter the rate of telomere erosion (i.e., shortening) in adults who were at high risk of cardiovascular disease. The study, published in the American Journal of Clinical Nutrition, measured the telomere lengths of the 520 participants, ages 60 to 80, and then measured them again after following the anti-inflammatory Mediterranean diet for five years.

The research team found that participants with the highest DII scores, indicating a strongly pro-inflammatory diet, had a risk of accelerated telomere shortening that was almost two times greater than those with the lowest anti-inflammatory diet scores (i.e., indicating a strongly anti-inflammatory diet). “These findings suggest diet-related inflammation hastens telomere shortening, which in turn leads to shortening of life span, and that an anti-inflammatory diet puts the brakes on telomere erosion,” says Shivappa. “A pro-inflammatory diet, characterized by high intake of meat, refined (white) grains, added sugars and foods rich in saturated and trans fats, increases the risk of telomere shortening, which eventually leads to earlier death.”

With these results in mind, clinicians should encourage their patients to adopt diets that are rich in anti-inflammatory components. By revealing inflammatory properties through rankings, DII can help determine which diets are pro-inflammatory and which ones are anti-inflammatory. “We know from other studies that pro-inflammatory diets lead to increased disability from a variety of chronic conditions, including diabetes,” says Hébert. Although they advocate anti-inflammatory diets, the researchers aren’t pushing any one particular diet. “There are many examples of good diets with strong anti-inflammatory properties,” Hébert says. “Apparently, the Mediterranean diet is one of these.”

Naturally, the researchers’ investigations into the applications of their powerful DII do not stop here. As a next step in their telomere length research, they are interested in seeing if they would find similar results in other populations eating diets that are healthful. “Like the Mediterranean diet, cuisines from East, Southeast and South Asia would be rich in anti-inflammatory components, such as vegetables, fruit, whole grains, nuts and seeds, healthy oils and fish,” Shivappa says. Hébert agrees: “Additional research in this area would not only confirm what we saw in the Spanish cohort, but it also would allow us to look at the effects of the DII in other populations eating a variety of other healthy diets.”