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Many Americans can’t get going in the morning without that jolt of caffeine. Others find that exercise helps them start the day off right. Now researchers have discovered that both these powerful stimulants when taken in combination have an even more dramatic impact on your health.
A team of scientists at Rutgers, The State University of New Jersey, led by Professor Allan Conney, showed that a combination of exercise and low to moderate amounts of caffeine protected against the effects of the sun’s ultraviolet-B (UVB) radiation, known to cause skin cancer. The caffeine and exercise mix kill off precancerous cells whose DNA has been damaged by UVB-rays.
The origins of this study go back over ten years, according to Professor Conney. “We studied the effects of green tea on Ultraviolet rays. We found that the green tea was active, meaning that it inhibited ultraviolet-induced skin cancer in mice. We then studied decaffeinated green tea, but it didn’t inhibit skin cancer.”
What the researchers also discovered in those early studies was that when caffeine was administered to the mice, it increased their locomotor activity. “It wasn’t exactly exercise,” says Professor Conney, “but they did move around more in their cages.”
This led to the researchers putting a running wheel in the cages so that the mice could voluntarily exercise. The mice embraced the running wheel with enthusiasm, running about two and a half miles a day on it. Even though the mice exercised, they maintained their normal body weight in spite of the fact that they were eating and drinking more. However, they did lose some tissue fat, changing their body composition.
The researchers decided that the effects of caffeine and exercise needed to be studied in more depth. So they took four groups of hairless mice, whose exposed skin was vulnerable to the sun’s UVB rays, and made them the test subjects in the latest experiments. The first group drank caffeinated water containing the human equivalent of about two cups of coffee a day. The second group voluntarily exercised on a running wheel, and the third group was given the caffeinated water and allowed to voluntarily exercise. A fourth group, which was the control, didn’t exercise and didn’t receive any caffeinated water. All of the mice were exposed to lamps that generated UVB radiation that damaged the DNA in their skin cells.
When the mice were examined, the researchers found that there was a certain degree of apoptosis, natural death of the DNA-damaged cells in all four groups. Apoptosis, one of the body’s defense mechanisms, occurs when a cell is damaged beyond repair. Apoptosis causes the cell to commit suicide, and then it removes the damaged cell, preventing the spread of disease. However, the scientists found that the caffeine drinkers and exercisers showed an increase in the amount of programmed cell death over the control group. The next step was to determine the extent of the increase.
Researchers used two methodologies to count the number of apoptotic cells and looked at them under the microscope. They stained caspase 3 enzymes with an antibody because this enzyme is involved in the killing of DNA-damaged cells. The differences between the four groups of mice in the formation of UVB-induced apoptotic cells were significant. Compared to the control group, the caffeine drinkers showed about a 95 percent increase in UVB-induced apoptosis, the exercisers showed a 120 percent increase, and the mice that were both drinking and exercising showed a nearly 400 percent increase.
The biggest question that remains unanswered is why caffeine and exercise work so well in combating the DNA-damaging effects of UVB rays on cells. The researchers suggested several mechanisms at the biochemical level that might be responsible for the protective effects of caffeine and exercise, but acknowledged that further study is necessary.
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