“Ultra-processed” foods studies link overconsumption with heart disease and bowel cancer

01 Sep 2022 --- Two studies published by The BMJ have found a connection between high consumption of ultra-processed foods and increased risks of cardiovascular disease, bowel cancer and death. Meanwhile, an Italian study has analyzed the combined health impact of the Nutri-Score front-of-pack labeling system and the degree of food processing according to NOVA.

The findings add further evidence in support of policies that limit ultra-processed foods and instead promote eating unprocessed or minimally-processed foods to improve public health globally.

They also reinforce the opportunity to reformulate dietary guidelines worldwide by paying more attention to the degree of processing of foods along with nutrient-based recommendations.

Unhealthy foods spotlighted 
Ultra-processed foods include packaged baked goods and snacks, fizzy drinks, sugary cereals, and ready-to-eat or heat products, often containing high levels of added sugar, fat, and/or salt but lacking in vitamins and fiber.

The findings add evidence in support of policies that limit ultra-processed foods.Previously, few studies have assessed the association between ultra-processed food intake and colorectal cancer risk, and findings are mixed due to limitations in study design and sample sizes.

In the first study, researchers examined the association between the consumption of ultra-processed foods and the risk of colorectal cancer in US adults.

Their findings are based on three studies of US health professionals (46,341 men and 159,907 women) whose dietary intake was assessed every four years using food frequency questionnaires.

Foods were grouped by degree of processing, and rates of colorectal cancer were measured over 24 to 28 years, considering medical and lifestyle factors.

Results show that compared with those in the lowest fifth of ultra-processed food consumption, men in the highest fifth of consumption had a 29% higher risk of developing colorectal cancer.

No association was observed between overall ultra-processed food consumption and women’s risk of colorectal cancer. However, higher consumption of meat/poultry/seafood-based ready-to-eat products and sugar-sweetened beverages among men – and ready-to-eat/heat mixed dishes among women – was associated with an increased risk of colorectal cancer.

Further insights on heart disease and cancer 
In a separate study, researchers analyzed two food classification systems concerning mortality – the Food Standards Agency Nutrient Profiling System (FSAm-NPS), used to derive the color-coded Nutri-Score front-of-pack label, and the NOVA scale, which evaluates the degree of food processing.

Their findings are based on 22,895 Italian adults (average age 55 years; 48% men) from the Moli-sani Study, investigating genetic and environmental risk factors for heart diseases and cancer.

Both the quantity and quality of food and beverages consumed were assessed, and deaths were measured over 14 years (2005 to 2019), taking into account underlying medical conditions.

Those in the highest quarter of the FSAm-NPS index (least healthy diets) compared with the lowest quarter (healthiest diets) had a 19% higher risk of death from any cause and a 32% higher risk of death from cardiovascular disease.

Risks were similar when the two extreme categories of ultra-processed food intake on the NOVA scale were compared (19% and 27% higher for all-cause and cardiovascular mortality, respectively).

Mortality risks assessed
A higher degree of food processing explained a significant proportion of the excess mortality risk associated with a poor diet. In contrast, ultra-processed food intake remained associated with mortality even after the poor nutritional quality of the diet was accounted for.

Both studies are observational, so they can’t establish cause, and limitations include the possibility that some of the risks may be due to other unmeasured (confounding) factors. 

Nevertheless, both studies used reliable markers of dietary quality. They took account of well-known risk factors, and the findings back up other research linking highly processed food with poor health.

As such, both research teams say their findings support the public health importance of limiting certain types of ultra-processed foods for better health outcomes in the population. Results from the Italian study also reinforce the opportunity to reformulate dietary guidelines worldwide by paying more attention to the degree of processing of foods along with nutrient-based recommendations.

“Nobody wants foods that cause illness”
In a linked editorial, Brazilian researchers argue that” nobody sensible wants foods that cause illness.”

Therefore, the overall positive solution includes making supplies of fresh and minimally processed foods available, attractive and affordable. 

“Enacted, this will promote public health. It will also nourish families, society, economies and the environment,” they conclude.

Labeling alone is not enough 
Foods are characterized by their nutritional composition and the degree of processing, which is crucial to determining the overall food health potential. Therefore, its indication on the labels would help consumers choose with greater awareness.

These are the results of an Italian study by the Department of Epidemiology and Prevention at the IRCCS Neuromed of Pozzilli in collaboration with the University of Insubria in Varese and Como, the University of Catania and the Mediterranea Cardiocentro of Naples. 

A higher degree of food processing explained a significant proportion of the excess mortality risk associated with a poor diet.The researchers followed for 12 years more than 22,000 people participating in the Moli-sani Study, monitoring their health status and associating it with eating habits, taking into account both the nutritional composition of the diet and the degree of food processing.

“Our results – says Marialaura Bonaccio, epidemiologist of the Department of Epidemiology and Prevention at the IRCCS Neuromed of Pozzilli and first author of the study – confirm that the consumption of both nutrient-poor or ultra-processed foods independently increases the risk of mortality, in particular from cardiovascular diseases.”

However, when we considered both the overall nutritional composition of the diet and its degree of processing, it came out that the latter aspect was paramount in defining the risk of mortality. She explains that over 80% of the foods classified as unhealthy by the Nutri-Score are also ultra-processed. 

“This suggests that the increased risk of mortality is not due directly to the poor nutritional quality of some products, but rather to the fact that these foods are mostly ultra-processed.”

“It is estimated that one in five deaths in the world is due to unhealthy diets, for a total of 11 million deaths a year – recalls Augusto Di Castelnuovo, researcher at the Mediterranean Cardiocentro in Naples – This is why improving eating habits is at the top of the priority list of public health agencies and governments around the world.”

A proposal to help people make healthier food choices is to use a front-of-pack labeling system for commercial products. 

Already used voluntarily in some European countries, such as France and Spain, front-of-pack labels are now being examined by the European Commission to adopt a harmonized and mandatory nutrition labeling scheme in all Member States. 

But nutritional composition is not the only factor to consider when considering diet-health relationships. 

How much is too much?
Further, the NOVA classification looks at how much that product has been processed, mainly at the industrial level. 

NOVA identifies explicitly the so-called ultra-processed foods, i.e., those foods made in part or entirely with substances not routinely used in the kitchen (hydrolyzed proteins, maltodextrins, hydrogenated fats, etc.) and which generally contain various additives, such as dyes, preservatives, antioxidants, anti-caking agents, flavor enhancers and sweeteners.

This category includes the usual suspects: sugary and carbonated drinks, pre-packaged baked goods and spreads. But also, apparently innocent products must be regarded as ultra-processed. It is the case of rusks, some breakfast cereals, crackers and fruit yogurt.

According to the NOVA system, a slice of unprocessed meat is healthier than a vegan hamburger simply because the former has not undergone industrial manipulation and possibly does not contain food additives. At the same time, the latter results from articulated industrial processing at the end of which the percentage of whole food is negligible.

Edited by Elizabeth Green 

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