Ultra-processed foods and cancer: study rethinks prevailing concerns

Ultra-processed foods have in recent years raised widespread concerns due to their possible association with a number of chronic diseases, including colorectal cancer.

However, a large US study involving more than 460,000 people reached results that may prompt a reconsideration of some of these assumptions, according to ScienceDaily.

The study showed that consuming larger amounts of ultra-processed foods is not associated with an increased risk of colorectal cancer overall. In contrast, the results revealed that the effects of these foods vary according to their type and ingredients: some were linked to lower rates of the disease, while others were linked to higher rates.

Ingredients more important than degree of processing

The study was led by researcher Erika Loftfield from the National Cancer Institute, and its results were published in PLOS Medicine. The findings indicate that the health effects of ultra-processed foods do not necessarily depend on their "ultra-processed" status, but on their nutritional value and actual ingredients.

These foods make up more than half of the calories consumed by adults in the United States, yet this category includes extremely diverse products, which makes assessing their health effects collectively complicated.

(Illustrative, iStock)

Clear difference between types of foods

The study indicated that some ultra-processed products, such as whole-grain products and some dairy products, were associated with a lower risk of colorectal cancer. In contrast, consumption of processed meats was associated with a higher risk of the disease.

These results highlight that processing level alone may not be a sufficient indicator to judge the potential health effects of different foods.

Follow-up of more than 460,000 people

The researchers based their work on dietary and health data of 461,682 Americans aged between 50 and 71 when they joined the NIH-AARP Diet and Health Study during 1995 and 1996.

Over a follow-up period of about 19 years, the research team found no overall relationship between total consumption of ultra-processed foods and colorectal cancer incidence. In other words, incidence rates did not increase among people who consumed larger amounts of these foods compared with others.

Whole grains and dairy may offer protection

When analyzing specific food categories separately, it was found that increased consumption of whole grains, fiber, dairy products, and calcium from ultra-processed sources was associated with lower rates of colorectal cancer.

By contrast, ultra-processed meats showed the opposite trend, with high consumption associated with increased rates of the disease.

Dairy products (iStock)

Replacing foods reduces risk

The researchers also examined the effect of replacing part of ultra-processed foods with less processed alternatives. The analysis showed that replacing 10% of these foods, by weight, with less-processed foods was associated with a 2% reduction in colorectal cancer risk.

What do the results mean?

The study suggests that the nutritional characteristics of each product may be more important than its classification as ultra-processed. Foods included in this category are not alike in their health effects and may differ significantly in their relationship to cancer risk.

Existing dietary recommendations

These findings support an approach that focuses on food quality and nutritional composition instead of treating all ultra-processed foods the same. They also align with current dietary recommendations for colorectal cancer prevention, which encourage consuming whole grains, fiber, dairy products, and calcium-rich foods, while limiting processed meat consumption.