Packaged baked goods, snacks, fizzy drinks, sugary cookie, cereals, instant noodles are often clubbed under 'ultra-processed foods'. These foods often contain high levels of sugar, fat, and salt, and lack in essential vitamins and fibre. Fortunately or unfortunately, they account for up to 50% of total daily energy intake in several developed countries.
For the study, the French based researchers examined the potential associations between ultra-processed food intake and risk of overall cancer, as well as that of breast, prostate, and bowel (colorectal) cancers.
A total of 104,980 healthy French adults (22% men; 78% women) with an average age of 43 years were examined. They were made to answer at least two 24-hour online dietary questionnaires, designed to measure usual intake of 3,300 different food items (NutriNet-Sante cohort study).
For the study, foods were classified according to degree of processing. Incidences of cancer were identified from participants' and the declarations were validated by medical records and national databases over an average of five years.
In addition to this, several well known risk factors for cancer such as age, sex, educational level, family history of cancer, smoking status and physical activity levels, were also taken into account.
The findings showed that a 10% increase in the proportion of ultra-processed foods in the diet increased 12% in the risk of overall cancer and 11% in the risk of breast cancer. However, no significant associations were found for prostate and colorectal cancers. Association between less processed foods (such as canned vegetables, cheeses and freshly made unpackaged bread) and risk of cancer were also not found to be that prevalent. On the other hand, consumption of fresh or minimally processed foods (fruits, vegetables, pulses, rice, pasta, eggs, meat, fish and milk) was associated with lower risks of overall cancer and breast cancer.
One has to take into account the limitations of the study too. For instance, one cannot rule out some misclassification of foods or guarantee detection of every new cancer case. The scientists also stressed that further work is needed to better understand the effects of the various stages of processing, on community level too public campaigns are needed to target healthy eating.