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Ultra-processed foods and cancer

by A. Manolova | 21 November 2023

Ultra-processed foods, cancer, nutrition, health, science

Over the past few decades, the global food landscape has been radically transformed by the explosion in consumption of ultra-processed foods. These foods, which include a wide range of products such as soft drinks, packaged snacks, reconstituted meat products and ready-to-heat meals, are characterized by high levels of additives and preservatives, and contain little or no whole foods. They are often high in calories, carbohydrates and fat, low in fiber and high in salt. These foods have been shown to encourage over-consumption, as the satiety effect is less than with unprocessed foods (read our article on the subject). Ultra-processed foods are said to account for over half of the total calorie intake in many Western diets, with countries like the USA and the UK leading the way. This shift towards highly processed foods is not just a dietary trend, but a fundamental change in the way we eat, driven by the demands of a fast-paced, convenience-driven lifestyle.

The health consequences of this change in diet are alarming. Numerous studies have linked high consumption of these foods to a range of chronic diseases, including obesity, heart disease, diabetes and hypertension. For example, a notable study published in 2019 examined the association between the consumption of ultra-processed foods and the risk of various health problems. The results revealed that a 10% increase in the proportion of ultra-processed foods in the diet was associated with significantly higher rates of cardiovascular, coronary and cerebrovascular diseases. Another study showed that people who consumed more than 4 servings a day of these foods were 50% more likely to die than those who did not (read our article on the subject).

Despite the established links between this type of food and various chronic diseases, their relationship with cancer risk is less clear-cut. Although cardiovascular disease remains the leading cause of mortality worldwide, cancer now outstrips it in high-income countries. Worldwide, cancer is responsible for one in six deaths. It is estimated that around 30-50% of cancers could be prevented through lifestyle changes, including dietary adjustments. However, knowledge of the specific impact of ultra-processed foods on cancer development and mortality remains limited. In addition to very poor nutritional quality and caloric hyperdensity, ultra-processed food could be linked to cancers via certain contaminants that are formed during industrial processes, and by certain additives and materials used for packaging that could possess carcinogenic properties and/or be endocrine disruptors. As cancer rates continue to climb worldwide, it's vital to understand the potential role of ultra-processed foods on our health. Faced with the ease and appeal of ultra-processed foods, what is the risk of developing serious health problems such as cancer? And what's the risk of dying from them?

The Study

To answer these questions, researchers carried out a large-scale prospective study based on data from the UK Biobank. Initiated between 2006 and 2010, the UK Biobank is a vast biomedical database and research resource containing detailed genetic and health information on over 500,000 participants in the UK. Researchers determined the proportion of ultra-processed foods in the diet, and investigated the link between consumption of these foods and cancer risk, as well as cancer mortality.

The study involved a cohort of 197 426 UK Biobank participants (54.6% women), aged between 40 and 69, who were followed from their first 24-hour dietary assessments (5 in total) between 2009 and 2012 until January 31, 2021. These participants' diets were analyzed using the NOVA food classification system, which classifies foods according to their level of processing. In addition, for the analysis, the researchers took into account numerous variables, such as socio-demographic characteristics, smoking, level of physical activity, body mass index, alcohol consumption and total energy intake.

Results & Analyzes

The main results of this study show a significant increase in overall cancer risk correlated with the consumption of ultra-processed foods. Specifically, for every 10% increase in ultra-processed foods relative to total dietary intake, a 2% increase in overall cancer incidence was observed. Ultra-processed foods made up a significant proportion of participants' diets, averaging 22.9%. The study went further, identifying specific types of cancer that showed a significant association with consumption of this type of food. Ovarian cancer stood out, with a 19% (8-30%) increased risk for every 10% increase in ultra-processed food consumption.

Beyond cancer incidence, the study also highlighted the impact of ultra-processed food consumption on cancer mortality, with a 6% increase in overall cancer mortality for every 10% increase in consumption of this type of food. Ovarian and breast cancer mortality rates were significantly higher, with respective increases of 30% and 16% for each 10% increase in ultra-processed food consumption. All these findings persisted even when the results were adjusted for different socio-economic, behavioral and dietary factors.

The authors suggest several mechanisms that could explain the observed associations between ultra-processed food consumption and an increased risk of cancer and cancer-related mortality. First and most obvious is the inferior nutritional quality of ultra-processed foods, which are thought to alter food matrices, leading to a deterioration in nutrient bioavailability and bioaccessibility. Secondly, ultra-processed foods are said to promote obesity and type 2 diabetes, both of which are risk factors for many types of cancer, including those of the digestive tract and certain hormone-related cancers in women. What's more, ultra-processed foods often contain controversial food additives, neo-formed contaminants from ultra-processing and toxic substances that can migrate from food packaging. For example, the NutriNet-Santé cohort reported that higher consumption of artificial sweeteners, commonly found in these foods, was associated with an increased risk of overall cancer, breast cancer and obesity-related cancer. Similarly, increased consumption of nitrates and nitrites from food additives was associated with a higher risk of breast and prostate cancer. Finally, these foods are associated with greater exposure to endocrine-disrupting chemicals such as phthalates and bisphenols, found in food packaging materials. These chemicals have been linked to a variety of adverse health effects, including potential impacts on the endocrine system, cancer risks and neurological and immunological damage.

Practical Applications

This study highlights the importance of paying attention to the amount of ultra-processed foods on our plates. Given the established link between consumption of these products and increased risk of cancer and mortality, particularly for ovarian and breast cancers, there is a clear incentive to adopt diets rich in low-processed or unprocessed foods. All the more so, as the results of this study show a proportion equal to 22.9% between 2009 and 2012. Ten years later, some studies point to a share of over 30% in ultra-processed foods...

From a public health point of view, it is necessary to develop guidelines and public policies that would encourage the production and consumption of low-processed or unprocessed foods, with the aim of improving the general health of the population. Because ultra-processed products are less expensive and benefit from very aggressive marketing, which encourages their excessive consumption and contributes to the increase in non-communicable diseases such as obesity and cardiovascular disease.

References

  1. Chang K, Gunter MJ, Rauber F, Levy RB, Huybrechts I, Kliemann N, Millet C and Vamos EP. Ultra-processed food consumption, cancer risk and cancer mortality: a large-scale prospective analysis within the UK Biobank. eClinicalMedicine 56 : 1011840, 2023.
  2. Srour B, Fezeu LK, Kesse-Guyot E, Allès B, Méjean C, Andrianasolo RM, Chazelas E, Deschasaux M, Fiolet T, Hercberg S and Touvier M. Ultra-processed food intake and risk of cardiovascular disease: prospective cohort study (NutriNet-Santé). Br Med J 365 : l1451, 2019.

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