May 17, 2004 (New Orleans) -- From fast food and soft drinks to green tea and black coffee, new research points to the powerful role foods and beverages play in our well-being.
"These studies are a first step in a long journey toward understanding the relationship between nutrition and our health," says Lee Kaplan, MD, PhD, director of the Obesity Research Center and director of the Massachusetts General Hospital Weight Center in Boston.
Understanding this relationship will allow scientists to develop appropriate preventive and therapeutic approaches for a variety of diseases, including cancer, [and] obesity, says Kaplan, who moderated a news conference to discuss the findings.
The studies were presented at an annual meeting of digestive disease experts. Among the research:
Java Slashes Risk of Liver Disease
In a study of nearly 6,000 adults who were at high risk for liver damage due to either excessive drinking, having hepatitis B or hepatitis C, obesity, or other problems that may affect the liver, the greater the consumption of caffeinated beverages, the lower the chance of having elevated liver blood tests that signal liver damage, says James E. Everhart, MD, MPH, chief medical officer of the Epidemiology and Clinical Trials Division of Digestive Diseases and Nutrition.
For example, people who drank more than two cups of coffee a day were about half as likely to have elevated liver enzyme blood tests compared with those who consumed less than a cup a day. And when divided into five groups according to the total amount of caffeine consumed, people in the highest group had about one-third the risk of liver damage than those in the lowest group.
Carbonated Beverages Raise Esophageal Cancer Risk
But before you reach for a caffeinated cola, take note: Other researchers found that carbonated soft drinks may raise the risk of cancer of the esophagus (the tube that connects the mouth to the stomach). Cancer of the esophagus is one of the fast growing cancers in the western world.
"Since many cancers are affected by what we eat and drink, we looked back at data from the U.S. Department of Agriculture to see what [changes in the diet] could explain the [more than fivefold] increase in esophageal cancer rates over the past 50 years," says Mohandas K. Mallath, MD, professor and head of the department of digestive diseases and clinical nutrition at Tata Memorial Hospital.
"What we found was a huge rise in intake of carbonated soft drinks," he tells WebMD. Per capita consumption of carbonated soft drinks rose by more than 450% during the past half-century, from 11 gallons in 1946 to 50 gallons in 2000 -- the equivalent of two cans of soft drinks per person per day, he says.
Since exposure to cancer-causing agents usually precedes the disease by about two decades, "an association seemed possible," Mallath says.
Searching the medical literature for evidence to bolster the theory, his team found a study offering a strong biological basis to explain the link, he says. The study showed that drinking carbonated beverages exposes the gastrointestinal tract to excess acid, the hallmark of acid reflux disease, or GERD, he says. And other studies show that GERD is a risk factor for esophageal cancer.
Also, countries in which people drink very few carbonated beverages, including Eastern Europe, Japan, China, Taiwan, Korea, and India, have had little increase in the incidence of esophageal cancer, Mallath notes.
Fast Foods Induce Persistent Tummy Aches
Still other research suggests that while drinking cola may be bad, using the soda to wash down fast food is even worse -- for kids.
Researchers at the Baylor College of Medicine in Houston report that children who eat daily in fast-food restaurants have about 50% more episodes of abdominal pain than those who eat fast food only once per week.
"The more fast food they ate, the greater the chance they suffered recurrent abdomen pain," says Hoda Malaty, MD, associate professor of medicine.
Eating fresh fruits, on the other hand, cuts the risk of recurrent abdominal pain in half, the study of 700 school children shows. Even eating two or fewer servings of fruits per week plays a protective role, Malaty tells WebMD.
For the study, the youngsters filled out a standardized questionnaire asking whether they had abdominal pain, how long it lasted, and how frequently it struck. Children were considered to have recurrent abdominal pain if they met four widely-accepted criteria: at least three attacks of pain; pain severe enough to affect activities; attacks occurring over a period of three months; and no known organic cause.
Green Tea May Lower Cancer Risk
It may be too late to do anything about all those colas you drank while growing up. But switching to green tea now may help to lower your risk of esophageal cancer, other research shows.
In a new study, a major antioxidant-like compound in green tea, epigallocatechin gallate (EGCG), inhibited the growth and reproduction of esophageal cancer cells, report researchers at Harvard Medical School and VA Boston Healthcare System.
In the lab study, esophageal cancer cells were treated with different concentrations of EGCG and monitored for cell growth. "What we found is that the compound essentially induces cell suicide so the cancer cells don't replicate," says Howard Yuan-Hui Chang, MD, an associate investigator at the VA Boston Healthcare System in West Roxbury, Mass.
The greater the concentration of EGCG, the higher the rate of cell suicide, he says. Also, there was no impact on healthy cells, "so it's selective for [killing] cancer cells."
Green tea has already been linked to a lowered risk of lung, skin, and prostate cancer, he tells WebMD. "These are exciting results that add to the growing body of knowledge on green tea's potential benefits as an anticancer therapy."
What to Do
So what should you do with all this new knowledge? The researchers note that while interesting, much of the research is still preliminary. Other than following government recommendations to consume a low-fat, high-fiber diet, it's too soon to be making definite recommendations, they say.
Also, "We have to learn to balance the potential beneficial effects of certain foods and beverages against the potential detrimental effects," Kaplan tells WebMD. "All of the findings have to be looked at in context of the total diet."