Stimulating theory: Combination of exercise, caffeine may prove useful in fighting skin cancers

October 1, 2008

A recent study shows that a daily low-to-moderate dose of caffeine and regular exercise may very well prevent skin cancers before they occur, in part by promoting the death of sunlight-damaged precancerous cells.

Key Points

Piscataway, N.J. - It has become a popular belief that caffeine - or at least excess amounts of it - can be detrimental to one's health, raising blood pressure and increasing the risk of coronary heart disease; however, this and many other effects of excessive caffeine intake are still being debated in the halls of medicine.

Coming to the defense of this central nervous system (CNS) stimulant, a recent study indicates that the combination of low-to-moderate amounts of caffeine, coupled with regular exercise, may actually be effective in preventing skin cancers before they occur.

Conspiracy theory

Murine study

Dr. Conney and a team of researchers conducted a study in four groups of hairless mice, analyzing the effects of voluntary exercise and caffeine on potentially cancerous cells.

One group drank caffeinated water, another exercised on a running wheel, a third group both drank and ran, and the fourth group did neither, serving as the control group.

The group of mice consumed caffeine in quantities equivalent to a couple cups of coffee a day for a human, and the exercising mice ran on exercise wheels for what would translate to about 2.5 miles per day. All four groups of mice were then exposed to UVB radiation that damaged the DNA in their skin cells.

Results

Results showed that the death of DNA-damaged cells - a process called apoptosis - in UVB-treated mice occurred to some degree in the skin cells of all four groups of mice.

The caffeine-drinking mice and the exercising group of mice showed 95 percent and 120 percent increased apoptosis, respectively.

However, the mice that were exposed to both caffeine and exercise showed a stunning nearly 400 percent increase in UVB-induced apoptosis, compared to the UVB-treated control group.

"If apoptosis takes place in a sun-damaged cell, its progress toward cancer will be aborted.

"The differences we noticed between the groups in the formation of UVB-induced apoptotic cells - those cells derailed from the track leading to skin cancer - were quite dramatic," Dr. Conney says.

Mechanisms of synergy

Dr. Conney says that these treatments likely work like two different mechanisms that seem to be synergistic in their effect on skin cells. The exact mechanism of this synergy is still unknown, but there are some theories to the apparent mystery.

"We believe that caffeine works by inhibiting the ATR/Chk1 pathway, which normally would shut down cell proliferation and allow time for DNA repair to occur. The caffeine seems to inhibit this pathway, which results in premature proliferation culminating in cell death," Dr. Conney tells Dermatology Times.

According to Dr. Conney, caffeine has received a bad rap because of its CNS stimulatory effect and also because of its tendency to raise blood pressure when given to people who are not ingesting caffeine.

However, epidemiological studies indicate that coffee has a protective effect against the formation of liver cancer, as well as a protective effect against the formation of breast cancer in people who have a BRCA1 or BRCA2 mutation.

Additional epidemiological studies suggest that coffee prevents Parkinson's disease and type II diabetes.

"You may not want to administer caffeine to people who have a high risk of blood pressure going up or cardiovascular disease. In my opinion, if a caffeine trial is successfully done in humans, then the benefits may outweigh the risks," Dr. Conney says.

Topical caffeine has both a sunscreen effect and enhances UV-induced apoptosis, Dr. Conney says. The next step would be to perform a similar trial in humans, possibly using topical caffeine coupled with exercise.

Dr. Conney also stresses that in no way should caffeine intake and exercise replace a sunscreen - at least not for the moment. The effect of caffeine and exercise needs to be proven first in humans, he says.