The consumption of ultra-processed foods can increase the risk of colorectal cancer, a new study shows.
The study, published this week in the medical journal The BMJ, analyzed the diets of over 46,000 men and 150,00 women to trace the correlation between what they ate and cases of colorectal cancer. After 24-28 years of participant follow-ups, researchers found a link between ultra-processed foods and colorectal cancer in men, but not women.
"Men who consumed ultra-processed foods in the highest fifth had a 29% higher risk of developing colorectal cancer than did those in the lowest fifth," the study detailed. For women, however, no "significant association" was calculated.
"Reasons for such a sex difference are still unknown, but may involve the different roles that obesity, sex hormones, and metabolic hormones play in men versus women," said co-senior author and cancer epidemiologist Fang Fang Zhang to CNN Health.
Colorectal cancer is also referred to as colon or rectal cancer, depending on where the disease starts, according to the American Cancer Society. It occurs when cells in the body start to grow out of control in the colon or the rectum. Excluding skin cancer, colorectal cancer is the third most common cancer in the U.S. and the second leading cause of death from cancer worldwide.
However, the rate of people being diagnosed with this form of cancer has dropped each year since the mid-1980s, the American Cancer Society stated. The decrease is attributed to more people getting screened and changing their lifestyle-related risk factors, including diet.
According to the study, diet is as an "important modifiable risk factor for colorectal cancer."
Ultra-processed foods include "prepackaged soups, sauces, frozen pizza, ready-to-eat meals and pleasure foods such as hot dogs, sausages, french fries, sodas, store-bought cookies, cakes, candies, doughnuts, ice cream" and more.
These foods make up 57% of total daily calories consumed in the U.S., researchers noted. Diets high in ultra-processed foods are also usually low in nutrients and bioactive compounds that are beneficial in preventing cancer, such as fiber, calcium, and vitamin D.
The study also looked into the subgroups of ultra-processed foods and found a positive association between colorectal cancer and higher consumption of meat, poultry and seafood based ready-to-eat products and sugar sweetened beverage among men and for higher consumption of ready-to-eat/heat mixed dishes among women (like frozen pizza).
In addition, the consumption of yogurt and dairy based desserts was negatively associated with the risk of colorectal cancer among women, meaning some healthier ultra-processed foods can have a positive effect in preventing the disease.
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The study also recognized that diet in not the only factor causing cancer. In the highest fifth of ultra-processed food consumption, people reported other unhealthy habits including smoking and lower levels of physical activity.
"We should consider substituting the ultra-processed foods with unprocessed or minimally processed foods in our diet for cancer prevention and prevention of obesity and cardiovascular diseases," concluded Zhang to CNN Health.