Caffeine, green tea and tart cherries may guard against multiple sclerosis, cancer and cardiovascular troubles, respectively, new research suggests.
All three findings, which confirm the healthy properties of these foods, were presented this week at the Experimental Biology 2008 meeting in San Diego.
Caffeine appears to help ward off multiple sclerosis, at least in a preliminary animal study. Mice given caffeine were 75 percent less likely to develop the animal model of MS than those not given it, said study senior author Dr. Margaret Bynoe, an assistant professor of microbiology and immunology at Cornell University School of Veterinary Medicine, in Ithaca, N.Y.
MS is a debilitating autoimmune disease, and about 400,000 Americans are affected, according to the National Multiple Sclerosis Society. In MS, the immune system attacks the myelin, the fatty sheath that protects the nerve fibers in the central nervous system.
The myelin, as it is damaged, forms scar tissue that prevents or hinders nerve impulses from getting through, leading to a variety of symptoms such as numbness in the limbs or loss of vision. Treatments include medications, physical therapy and the use of assistive devices.
Why does caffeine help?
Caffeine is known to block a compound called adenosine. "Inhibiting adenosine prevents the infiltration of lymphocytes [a type of white blood cell involved in immune system response] into the central nervous system," Bynoe explained. "If the lymphocytes cannot get in, you cannot get the inflammation characteristic of MS. The inflammatory response is what causes the damage to the myelin covering the nerve cells."
Bynoe believes her team is the first to demonstrate this mechanism.
In the animals given caffeine, the equivalent of 6 to 8 cups of coffee a day for humans, "there was a reduction in the inflammation, the pathology, a reduction in the brain pathology," Bynoe said.
Adenosine plays a crucial role in many body processes, including energy transfer, the promotion of sleep and the suppression of arousal. On the cellular level, caffeine can bind to the same receptors as adenosine, preventing the adenosine from attaching to cells in the central nervous system.
The new finding is "certainly deserving of further study," said Dr. John Richert, executive vice president of research and clinical programs for the National Multiple Sclerosis Society.
But he had a caveat: "It's important to note that EAE [the animal model of MS] is not MS, and many potential treatments that have worked on EAE have not worked on MS."
In a second study, green tea extracts, already known for their antioxidant properties that help protect against cancer, had anticancer effects on cancer cell lines in the laboratory.
Scientists wanted to find out whether undigested extracts of black and green tea cancer-fighting compounds, known as catechins, would have more anticancer activity against the cancer cells than digested extracts, said study author Joshua Bomser, an associate professor of nutrition at Ohio State University.
"We set out to look at the effect of digestion, subjecting tea extracts to simulated digestion in the lab setting and looking for changes in biological activity between digested and undigested samples exposed to cancer cell lines," Bomser said.
In the laboratory study, they found that whether the extracts were digested or not and the type of tea affected the anticancer activity, as did the type of cancer cell.
"For the black tea, digestion didn't have much of an impact on colon cancer activity," he said. However, the anticancer effect of the green tea on the colon cancer cells was about 50 percent less when the extracts were digested. And the gastric cancer cells, overall, were less sensitive to the anticancer effects than were the colon cancer cells.
More study is needed, Bomser said, but, "If catechins [such as EGCG] are in fact the primary compounds responsible for anticancer activity rather than the breakdown products, you want to maintain and absorb as many catechins [as possible]," he said.
In a previous study, one researcher on the current team found that one way to protect the catechins from breaking down was to add lemon or vitamin C to tea.
The tea research is interesting, and the results not unexpected, said Tom Gasiewicz, chairman of the department of environmental medicine at the University of Rochester Medical Center, who has studied tea's health benefits extensively.
"To me, it's not unexpected that digestion would be accompanied by loss of [anticancer] activity," he said. "The bottom line is, we still don't know what concentrations are effective and have anticancer activity in other organs besides the GI tract."
Yet another team of researchers found in animal studies that tart cherries help reduce inflammation, in turn potentially reducing the risk of getting heart disease and type 2 diabetes. Inflammation is a normal process that fights infection or injury, but when it's chronic, it increases the risk for heart problems and diabetes.
The cherries contain antioxidants called anthocyanins, believed to give them their anti-inflammatory powers. The cherry study was funded by the Cherry Marketing Institute, but the institute had no other role in the study, conducted at the University of Michigan.
Compounds in the cherries, said Gasiewicz, may work in similar ways as the tea extracts.