Scientists in Sweden and in the United States have found out that overweight or obese teenagers have a higher risk of developing bowel cancer when they reach middle age compared to slimmer teenagers.

In the study, researchers from the Orebro University Hospital in Sweden and the Harvard School of Public Health in Massachusetts analyzed records of 240,000 Swedish men, who underwent a conscription assessment for the military when they reached their late teens, for 35 years.

During their conscription, most of the participants had normal weight. Men who were overweight accounted for 6.5 percent and those who were obese were about 1 percent.

People who have a body mass index (BMI) of about 25 or higher are considered overweight and those who have a BMI of 30 or more fall under obesity.

The researchers checked the health of the participants again over the average 35 years of follow-up and discovered that 885 of them had developed colorectal cancer, including 501 who had colon cancers and 384 who had rectal cancers.

The men who were overweight during their teenage years had twice the chance to develop colorectal cancer (2.08-fold higher risk), while obese teenagers had a much higher potential to have the illness (2.38-fold higher risk).

"Late adolescence marks the transition from childhood to adulthood and is a period of accelerated growth, especially among men, thus this period may represent a critical window," the researchers said.

"It is important that we understand the role of exposures in childhood and adolescence in the development of colorectal cancer."

The research team added that the study was able to show a strong connection between adolescent obesity and colorectal cancer. Combined with the increasing numbers of teenage obesity, these factors can help provide a better understanding on how bowel cancer incidences continue to rise among young adults.

According to Rachel Thompson of the World Cancer Research Fund, the evidence provided in the research highlights the risk factor of obesity for colorectal cancer.

Thompson pointed out that the lifestyle habits of an individual could influence the chance of developing bowel cancer.

She said that while research involving the potential connection between obesity and cancer risk is still in its infancy, it will be interesting to find out if subsequent studies could help bolster the findings of the Swedish and American research.

The Orebro University Hospital and Harvard School of Public Health study was published in the journal Gut.

Photo: Gaulsstin | Flickr