Many large studies, conducted over long periods of time, have shown that a diet rich in ultra-processed foods increases the risk of obesity, type 2 diabetes, hypertension, cardiovascular disease, depression and premature death.
Most of these ultra-processed foods, such as soft drinks, sweet and savory packaged snacks, margarine, mass-produced bread, instant noodles (soups in bags), sausages, hot dogs, pre-cooked / ready-to-heat meals, ice cream, cakes , pastries, mixes for desserts, sugary yogurt, are rich in calories, unhealthy fats, added sugars and sodium, while being low in fiber, vitamins and minerals, which the body needs.
Now, a recent study, published in the British Medical Journal, links high consumption of ultra-processed foods to a higher risk of colorectal cancer in men.
Minimally processed, processed and ultra-processed foods
The NOVA food classification system classifies all foods in four groups, depending on their degree of processing. The first group includes “unprocessed (natural) and minimally processed foods”, which are natural foods modified by natural processes such as drying, crushing, filtration, roasting, fermentation, pasteurization and freezing.
Foods in the second group are “processed food ingredients,” including oils, lard, sugar and salt.
The third group are “processed foods”, such as canned vegetables, canned fruit in syrup, canned fish in oil, some processed animal foods (ham, bacon, pastrami, smoked fish) and natural cheeses with the addition of salt. These foods are obtained by adding processed culinary ingredients to unprocessed and minimally processed foods.
The fourth group, “ultra-processed foods”, are formulations of ingredients, usually created through a series of industrial techniques. They are obtained by “breaking up” whole foods, altering them and then recombining them with additives to make them convenient, attractive and super tasty.
What the latest study shows on more than 200,000 people over 28 years
For this study, researchers at Harvard University and Tufts University looked at the association between ultra-processed foods and colorectal cancer risk among 206,248 men and women whose food choices and health status were monitored. for 28 years.
Participants completed diet questionnaires every four years and provided health and lifestyle information every two years. The researchers assigned the foods the participants consumed to a NOVA food group.
During the study, 3,216 cases of colorectal cancer occurred.
Overall, men whose diets contained the most processed foods had a 29% higher risk of developing colorectal cancer than those whose diets contained the least amount. There was no link between ultra-processed foods and cancer risk in women.
The researchers analyzed subgroups of ultra-processed foods and found that ready-to-eat meat, poultry and seafood foods, as well as sugary drinks, were linked to an increased risk of colorectal cancer in men.
It is unclear why an association between ultra-processed foods and colon cancer risk in women has not been observed. It is possible that women make different ultra-processed food choices than men. Sex hormones may also play a role.
Colorectal cancer risk attributed to ultra-processed foods was largely independent of risk factors such as body mass index and poor diet quality, suggesting that other aspects of ultra-processed foods are responsible for development colon cancer.
Ultra-processed foods: zero-value input for the body
Ultra-processed foods contain additives such as emulsifiers and artificial sweeteners, some of which can alter the composition of the gut microbiome in a direction that promotes inflammation.
Potential carcinogens can also form during food processing. Acrylamide (a chemical), for example, can be produced when foods are heated to high temperatures (e.g. French fries, potato chips, cereal products) and has been associated with increased oxidative stress and inflammation in the body.
Ultra-processed foods can also contain contaminants that transfer from their plastic packaging, such as bisphenol A. So, during processing, these foods are deprived of the protective phytochemicals and nutrients found in whole foods.
What to do
The latest findings add to a growing body of research showing that both nutritional quality and degree of food processing should be taken into consideration when evaluating the relationship between diet and health and when reviewing diet. Some progress has been made in some countries. The Canadian Food Guide, for example, updated in 2019, recommends limiting your intake of highly processed foods.
It is recommended that you make a list of the ultra-processed foods that you consume on a regular basis. Implement strategies to buy them less often and replace them with healthy and tasty foods.
Then, you can choose to make at home what you usually buy at the store: salad dressing (you need olive oil, lemon juice, some Dijon mustard and a sweet syrup like date or agave – put them in a jar and mix vigorously), pancakes, baked vegetables / meat instead of the pan with oil, etc.
Last but not least, choose whole, lightly processed snacks, such as popcorn, whole, unsweetened dried fruit, nuts, and plain yogurt. As often as possible, choose foods with ingredients that you would find in your cupboard and refrigerator.