Junk food link to early-onset bowel cancer firms in new study

An international study has linked the consumption of ultra-processed foods to the rising rate of bowel cancer in people under 50.

In recent decades the global and Australian incidence of early-onset bowel cancer has increased.

So, too, has global consumption of ultra-processed food and new research, published in JAMA Oncology, is pointing the finger at diet as a likely cause of early-onset colorectal (bowel) cancer (EOCRC).

Ultra-processed foods are often quick, easy and ready-to-eat, but they often contain high levels of sugar, salt, saturated fat and food additives.

It’s junk food, in other words, and the science is showing that it’s definitely not good for us.

“The increased risk seems to be fairly linear, meaning that the more ultra-processed foods you eat, the more potential that it could lead to colon polyps,” said Dr Andrew Chan, a gastroenterologist at the Mass General Brigham Cancer Institute in Boston, who led the study.

For almost two and half decades, Chan and his team tracked and analysed the diets and endoscopy results of almost 30,000 female nurses in their 20s, 30s and 40s and found that participants who reported consuming the highest levels of ultra-processed foods had a 45 per cent higher risk of developing adenomas, which can be precursors of cancer.

“Our study isn’t cause and effect, so we can’t say that this is definitive,” Chan told US media. “But it does serve as some clues that what we eat may play a role.

“So, as we move forward, I think it’s helpful to think about where it is that we can potentially limit our intake and lay the groundwork for future studies for us to be able to identify, more specifically, the mechanisms and the specific foods.”

Researchers have known for some time that EOCRC often occurs in individuals without family history or an identifiable genetic predisposition, meaning that modifiable environmental and lifestyle factors play a part.

This new study is the first to directly link ultra-processed foods with EOCRC, although the study authors noted that junk foods alone were not wholly responsible for the rise is diagnoses.

“Diet isn’t a complete explanation for why we’re seeing this trend – we see many individuals in our clinic with early-onset colon cancer who eat very healthy diets,” says Chan.

He says that further study into identifying other risk factors is still required, in addition to working on ways to better categorise ultra-processed foods, since some foods in this category might be more harmful than others.