Ultra-processed foods

The NOVA classification, developed by researchers at the University of São Paulo, categorizes foods into four groups based on the extent and purpose of industrial processing. Group 1 comprises unprocessed or minimally processed foods (e.g., fresh fruits, vegetables, milk). Group 2 includes processed culinary ingredients (e.g., salt, sugar, oils). Group 3 covers processed foods (e.g., canned vegetables, cheeses, breads) made by adding Group 2 ingredients to Group 1 foods. Group 4, ultra-processed foods, are industrial formulations made mostly from substances extracted from foods, such as hydrogenated oils, high-fructose corn syrup, and protein isolates, with little or no whole food content. They often contain cosmetic additives like emulsifiers, thickeners, and artificial colors, and are designed to be durable, convenient, and hyper-palatable. Examples include soft drinks, packaged snacks, instant noodles, and reconstituted meat products.

Numerous prospective cohort studies and meta-analyses have linked high consumption of ultra-processed foods with increased risks of obesity, type 2 diabetes, cardiovascular disease, and all-cause mortality. A 2019 cohort study in the BMJ found that each 10% increase in the proportion of ultra-processed foods in the diet was associated with a 12% higher risk of cardiovascular disease. A 2020 systematic review and meta-analysis in the American Journal of Clinical Nutrition reported a 29% higher risk of all-cause mortality for the highest versus lowest consumers. Potential mechanisms include high energy density, low fiber content, rapid digestion, and the presence of additives that may disrupt the gut microbiome, increase inflammation, or interfere with satiety signaling. However, most evidence is observational, and residual confounding remains a concern; randomized controlled trials are limited but have shown that ultra-processed diets lead to greater energy intake and weight gain compared to unprocessed diets.

Ultra-processed foods now dominate food supplies in many countries. In the United States, they contribute about 58% of total energy intake, and in the United Kingdom, about 50%. Sales are growing rapidly in low- and middle-income countries, where they are often cheaper and more accessible than fresh foods. In response, several governments have implemented policies to reduce consumption. Mexico and Chile have introduced front-of-package warning labels for products high in sugar, sodium, or saturated fat. Brazil's dietary guidelines explicitly recommend avoiding ultra-processed foods. The Pan American Health Organization has called for regulatory measures, including taxation and marketing restrictions, particularly to protect children. The World Health Organization has recognized the importance of limiting free sugars and processed foods, though it has not formally adopted the NOVA classification.

Beyond the well-known health risks, ultra-processed foods have subtle and surprising effects. For instance, they often contain additives that are not required to be listed individually if they are part of a flavoring or processing aid. Some emulsifiers, such as carboxymethylcellulose and polysorbate 80, have been shown in animal studies to alter the gut microbiota and promote intestinal inflammation. The concept of 'ultra-processing' also extends to plant-based meat alternatives, which are often classified as ultra-processed despite being marketed as healthy. In addition, the NOVA classification has been criticized for grouping foods with very different nutritional profiles, such as whole-grain bread and sugary cereals, into the same category. The term 'ultra-processed' was coined by Brazilian researcher Carlos Monteiro in 2009, and the classification has since been adopted by many researchers and public health bodies, though it remains a topic of debate in food science.

NOVA classification

A food classification system that groups foods into four categories based on the extent and purpose of industrial processing.

Hyper-palatable

Foods engineered to be highly rewarding to the palate, often through combinations of sugar, fat, and salt.

Emulsifiers

Additives that help mix ingredients that normally separate, such as oil and water, often used in processed foods.