Ultra-processed foods

Ultra-processed foods, a.k.a. energy-dense nutrient-poor foods, discretionary choices or junk foods dominate modern supermarkets. They represent a large proportion of the average dietary intake in developed countries and, not surprisingly, are linked with poor health outcomes.

What are ultra-processed foods?

The term “ultra-processed” foods refers to the NOVA classification and it’s based on the degree of processing of foods. This classification has 4 categories:

unprocessed or minimally processed (such as grains, meat, fish, milk, eggs, vegetables, fruit, nuts and seeds)
processed culinary ingredients (such as sugar, oils and butter)
processed foods
ultra-processed foods (1, 2)

Processed vs ultra-processed foods

Have you ever met someone that tries to justify their junk food intake with the argument that “everything is processed”? Well, the term “ultra-processed” can clear things up.

Processed foods include processed breads, cheese, canned foods (fruit, fish, vegetables) and traditionally cured meats (e.g. salted and smoked) (1, 2). In other words, these are minimally processed foods made using processes that have existed for centuries.

On the other hand, ultra-processed foods are made using multiple physical, biological and/or chemical processes which may include hydrogenation, hydrolysis, extruding, pre-frying (2, 3), moulding and reshaping (3). They are made to be highly palatable (or hyperpalatable), convenient (2, 3, 4), affordable, packaged in large portion sizes (4). A lot of money goes into marketing these products (2, 3, 4); this includes misleading nutrition and health claims (see more on my article How to read food labels) and misuse of a limited The Health Star Rating System (2).

Examples of ultra-processed foods

The following foods are considered ultra-prooessed:

sweet or savoury packaged snacks (3)
sugar-sweetened beverages (2, 3)
instant noodles and soups (2, 3)
many breakfast cereals (2)
fast food dishes (2)
industrial packaged breads and buns (3)
confectionery and desserts (3)
reconstituted meat and fish products that contain preservatives other than salt (e.g. nitrites), such as meatballs and nuggets (3)
ready meals (3)
food products made mostly from sugar, oils and fats and industrially made substances such as hydrogenated oils, modified starches and protein isolates and/or that contain additives such as flavours, colours, emulsifiers, humectants and sweeteners to imitate “real food” characteristics (2, 3)

Ultra-processed foods have more free sugars, sodium and energy, and less potassium and fibre than less processed foods. Total and saturated fat is also slightly higher in ultra-processed foods (2, 4).

In an audit of 230 packaged breakfast cereals, snacks, confectionery, beverages, condiments and liquid breakfast meal replacements found that 94% of them fell into the ultra-processed category. 95% of them contained added sugars in multiple forms (see my previous article on sugar-containing ingredients) and 62% contained added fats (5).

How much are we eating?

Ultra-processed foods represent 57.9% of the average energy intake in the US, 56.7% in the UK and 47.7% in Canada. In Australia, this percentage in 2011-2012 was 42% for people 2 years old and above. In less developed countries such as Chile, Brazil and Mexico, this percentage is lower: 20-30% (2).

In terms of nutrient contribution (i.e. where your nutrients come from), a study found that in Nordic and central European countries, people are getting between 50 and 90% of most nutrients (except for vitamin C and beta-carotene) from highly processed foods (1).

What are we eating?

In Australia, the top consumed ultra-processed food types were mass-produced packaged breads, frozen and shelf stable ready meals, fast food dishes, pastries, buns and cakes (2).

Health issues

Overweight and obesity

Several studies have found that people who eat more ultra-processed foods have a higher chance of being overweight or obese (2, 4, 5) and having higher fasting glucose. This is observed independently of the actual composition of the foods, suggesting that is the level of processing and not the nutrition composition of foods which is to blame for negative effects (4).

Ultra-processed foods can lead to obesity because they are usually more energy dense, produce a higher glycaemic response and are less satiating (3, 4).

Inflammation and metabolic disease

The impact of highly processed foods on the composition and abundance of the gut microbiome can lead to inflammation and metabolic syndrome (6), which are at the root of many modern chronic conditions.

Cardiovascular risk

Ultra-processed food consumption has also been associated with low HDL cholesterol, high LDL and total cholesterol and hypertension. Again, this is independent of the nutrient composition of the foods (4).

Cancer

An internet-based study on a large French cohort found that higher intakes of ultra-processed foods were associated with increased risk of overall cancer and postmenopausal breast cancer. The associations were significant for fats and sauces, sugary products and drinks for overall cancer, and sugary products for breast cancer. Interestingly, there were no significant associations between consumption of ultra-processed foods and prostate and colorectal cancer. However, this may be due to the fact that 78.3% of the participants were women (3).

There are a few things that could make ultra-processed foods carcinogenic:

components formed during processing, such as acrymalamide, heterocyclic amines and polycyclic aromatic hydrocarbons (3) (note these also occur during some forms of cooking)
components in the packaging, such as BPA (bisphenol A)
food additives such as sodium nitrate and titanium dioxide (3)

Other factors that can link ultra-processed foods to cancer are:

as seen before, ultra-processed food consumption can lead to obesity and obesity is a risk factor for some cancers (3)
most ultra-processed foods are high in salt, which may increase the risk of gastric cancer (3)
ultra-processed foods are low in fibre, which protects against colorectal cancer and may reduce the risk of breast cancer (3)

Summary and recommendations

Ultra-processed foods tend to be energy-dense, nutrient-poor and less satiating than whole foods. They are associated with obesity, inflammation, metabolic syndrome, cardiovascular risk and cancer, among other detrimental effects.

While it is true that some less processed foods such as homemade meals may be less healthy than ultra-processed foods (4), it is likely that most highly processed foods will have a detrimental effect in our health if they represent a large proportion of our dietary intake.

References

Gibney MJ. Ultra-Processed Foods: Definitions and Policy Issues. Current developments in nutrition. 2019;3(2):nzy077.
Machado PP, Steele EM, Levy RB, Sui Z, Rangan A, Woods J, et al. Ultra-processed foods and recommended intake levels of nutrients linked to non-communicable diseases in Australia: evidence from a nationally representative cross-sectional study. BMJ Open. 2019;9(8):e029544.
Fiolet T, Srour B, Sellem L, Kesse-Guyot E, Alles B, Mejean C, et al. Consumption of ultra-processed foods and cancer risk: results from NutriNet-Sante prospective cohort. Bmj. 2018;360:k322.
Poti JM, Braga B, Qin B. Ultra-processed Food Intake and Obesity: What Really Matters for Health-Processing or Nutrient Content? Current obesity reports. 2017;6(4):420-31.
Pulker CE, Scott JA, Pollard CM. Ultra-processed family foods in Australia: nutrition claims, health claims and marketing techniques. Public Health Nutr. 2018;21(1):38-48.
Zinocker MK, Lindseth IA. The Western Diet-Microbiome-Host Interaction and Its Role in Metabolic Disease. Nutrients. 2018;10(3).

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