Ultra-Processed Foods: A Stealthy Killer

Large studies and overwhelming data link these cheap, easy, and tasty foods to disease and early death

Most fast-food restaurants sell ultra-processed food like french fries. (Flotsam/Shutterstock）

In recent decades, ultra-processed foods (such as fast-food hamburgers, instant noodles, cakes, potato chips, etc.) have entered nearly every household. They taste good and are convenient and affordable. However, research shows that ultra-processed foods may cause serious health problems, and excessive consumption can increase the risk of death.

Excessive Consumption Increases the Risk of Early Death

Data show up to 71 percent of packaged foods sold in the United States are considered ultra-processed. Although there are differences based on education and income levels, the intake of ultra-processed foods is generally high across all socioeconomic levels.

Study findings published in the British Medical Journal in May 2019 showed that consuming large amounts of ultra-processed foods (more than four servings per day) increased overall mortality by 62 percent over the maximum 15-year follow-up period. For every additional daily serving of ultra-processed food consumed, overall mortality increased by 18 percent. This study followed 19,899 participants (7,786 men and 12,113 women) with an average age of 37.6 years for a median duration of 10.4 years between 1999 and 2014.

The researchers pointed out that this study is observational and can’t establish causality, though several other studies have revealed specific mechanisms of action that link key ingredients in processed foods to disease-causing cellular processes such as insulin resistance and systemic inflammation. Unmeasured confounding factors may also influence some observed risks. Nevertheless, these and other findings support studies linking ultra-processed foods with adverse health conditions.

The research team stated that policies must be developed to limit the proportion of ultra-processed foods in diets and promote the consumption of unprocessed or minimally processed foods to improve global public health.

Higher Consumption Raises Certain Cancer Rates

The term “ultra-processed foods” comes from the NOVA food classification system (pdf) developed by researchers at the University of São Paulo in Brazil. The system categorizes foods into four groups based on their degree of processing during production:

1. Unprocessed or minimally processed foods: Fruits, vegetables, milk, fish, beans, eggs, and nuts that have not had any ingredients added and have undergone minimal changes compared to their natural state
2. Processed ingredients: Foods added to other foods and not consumed alone, such as salt, sugar, and oil
3. Processed foods: Made from the first two food groups and can be changed in various ways (examples: jams, pickles, canned fruits, homemade bread, cheeses)
4. Ultra-processed foods: Usually contain five or more ingredients with a long shelf life and often contain many industrial additives such as preservatives, emulsifiers, sweeteners, and artificial colors and flavors.

A study published in February in the eClinicalMedicine journal found that consuming large amounts of ultra-processed foods is associated with an increased risk of cancer, particularly ovarian and brain cancer. In addition, the study found that high consumption of ultra-processed foods is associated with an increased risk of mortality from cancer, especially ovarian and breast cancer.

The study found that for every 10 percent increase in ultra-processed food intake in the diet, there was a 2 percent increase in cancer rates and a 19 percent increase in ovarian cancer rates. For every 10 percent increase in ultra-processed food consumption, there was a 6 percent increase in overall cancer mortality rates, a 16 percent increase in breast cancer mortality rates, and a 30 percent increase in ovarian cancer mortality rates.

This is the most comprehensive assessment of the association between ultra-processed foods and cancer risk to date.

“This study adds to a growing body of evidence suggesting that ultra-processed foods may have negative health effects, including an increased risk of cancer,” said Eszter Vamos, the study’s lead senior author and senior clinical lecturer in public health medicine at Imperial College London.

Ultra-Processed Foods Linked to Various Diseases

A study published in JAMA Neurology in December 2022 found that limiting the intake of ultra-processed foods may help reduce cognitive decline in middle-aged and older people.

The research team from the School of Medicine at the University of São Paulo in Brazil recruited 10,775 participants ages 35 to 74. It divided them into four groups based on the percentage of ultra-processed foods that they consumed as part of their overall diet. The participants were followed for a median of eight years.

The statistics showed that compared with the group that consumed the least amount of ultra-processed foods, middle-aged people who consumed the highest percentage (three-quarters of their diet) experienced a 28 percent faster decline in cognitive ability and a 25 percent faster decline in “executive function,” which is necessary for learning, working, and daily life, over the course of the study.

In a different study, published in May 2019 in the British Medical Journal, researchers from France and Brazil evaluated the association between ultra-processed food intake and cardiovascular disease (CVD) risk, including heart disease and stroke.

They divided 105,159 participants (21,912 men and 83,247 women) with an average age of 42.7 years into groups based on the processing level of the foods in their diets. They also measured disease incidence during a follow-up period of up to 10 years (2009 to 2018).

Researchers found that when the absolute proportion of ultra-processed foods in the diet increased by 10 percent, there was a corresponding increase in overall CVD incidence rates by 12 percent, with the rate of heart disease increasing by 13 percent, and the rate of stroke increasing by 11 percent.

Ultra-Processed Foods and Teens

The latest evidence suggests that teenagers who consume more ultra-processed foods are likelier to make unhealthy dietary choices than those who consume less. Study results released at the American Heart Association’s Hypertension Scientific Sessions held in September 2022 found a link between poor dietary habits and certain ultra-processed foods, such as pastries, candy, and frozen desserts.

In a two-month experiment, more than 300 teenagers completed a dietary survey detailing their ultra-processed food intake. The results showed an increase in the frequency of frozen dessert consumption was associated with an 11 percent increase in all other ultra-processed food consumption; an increase in the frequency of pastry consumption was associated with a 12 percent increase in all other ultra-processed food consumption; and an increase in the frequency of candy consumption was associated with a 31 percent increase in all other ultra-processed food consumption.

Maria Balhara, the study’s lead researcher and a student at the David Brautman College in Florida, said: “Ultra-processed foods are designed to be very tasty or designed to be as addictive as possible. They are cheap and convenient, making them difficult to resist. Most people eat too much of these foods without realizing it.”