Coffee, soft drinks not linked to colon cancer risk

A new study published online May 7 in the Journal of the National Cancer Institute suggests drinking even large amounts of coffee and sugar-sweetened, carbonated soft drinks does not increase risk of colon cancer.

On the other hand, the study led by Xuehong Zhang, M.D., Sc.D., and colleagues at the Harvard School of Public Health suggests that eating lots of tea may boost the risk.

This is contradictory to some of previous research, which suggested coffee and tea may lower the risk of cancer while sugar-laced soft-drinks may increase the risk.

For the study, Dr. Zhang and colleagues meta-analyzed data from 13 studies conducted in North America and Europe involving 731,441 participants of whom 5,604 were diagnosed with colon cancer.

Those who drank more than six 8-oz cups of coffee a day were no more likely than those who drank less to develop colon cancer, the researchers found.

Similarly, those who drank more than 18 oz daily of sugar-sweetened, carbonated beverages did not have higher risk of colon cancer.

The researchers cautioned that caution needs to be exercised when interpreting the results as only 2 percent of the study participants drank more than 18 oz of these beverages daily.

It is not immediately clear if those who drank coffee and sugar-sweetened soft drinks in moderation were at risk of the cancer.

It may be a surprise to many that the researchers found a moderate association between drinking high amounts of non-herbal tea (more than four 8-oz cups a day) and the colon cancer risk.  

Again, few people drank that much tea and therefore the link may be due to chance.

A health observer suggested that readers should understand the study is observational and the results may be biased.

Tea, particularly green tea, is well known for its anti-cancer activity.  Rutgers University researchers and many others have researched the effect of green tea and found EGCG, a major component in the plant leaves, prompts apoptosis, a process that causes death of cancer cells.

Sugar has been linked to increased risk of other cancers to say the least.  One recent study led by researchers at the University of Minnesota suggests that using two or more soft drinks may increase risk of pancreatic cancer by 87 percent compared to those who did not.

Sugar sweetened beverages have been linked to obesity and diabetes, which have been further associated with increased risk of cancer, according to other studies.

Colon cancer is diagnosed in about 106,000 men and women in the United States each year and the disease and rectal cancer kill about 50,000 annually in the country, according to the National Institute of Cancer.

Colon cancer symptoms include changes in bowel habits, constipation, diarrhea, bright red or dark red blood in stools, thinner than normal stools, and abdominal discomfort, bloating, frequent gas pains or cramps.

David Liu