"Is 'All Ultra-Processed Foods Are Bad' on Hold? A Study of 460,000 People Reveals an Unexpected Relationship with Colorectal Cancer"

Picking up a bag of bread at the supermarket, you might wonder, "Is this bad for my health because it's processed food?" Even though you've just chosen a convenient breakfast, you might feel a bit guilty.

A new perspective on such food selection dilemmas has been provided by recent research.

A large-scale follow-up study involving over 460,000 people in the United States found no clear link between the total intake of "ultra-processed foods" and the incidence of colorectal cancer.

However, interpreting this as "all ultra-processed foods are safe" would overlook an important part of the study. When examining different types of foods within the same category, the association with cancer incidence varied.

The study raises the question of whether it's appropriate to judge the quality of food solely based on how processed it is.

Differences between the "overall" and the "breakdown" observed over about 19 years of follow-up

The research was conducted by scientists from the U.S. National Cancer Institute and others, and was published in the medical journal "PLOS Medicine" on October 15, 2026. ScienceDaily introduced it on October 21.

The subjects were 461,682 people aged 50 to 71 who participated in the "NIH-AARP Diet and Health Study" in 1995-1996. Participants answered a dietary frequency questionnaire at the start of the study, and the research team estimated the intake of ultra-processed foods from this information.

The follow-up continued until 2018, with a median follow-up period of 18.8 years.

As a result, no overall association was found between higher consumption of ultra-processed foods and a higher likelihood of developing colorectal cancer. However, different trends emerged when analyzing by food groups and nutritional components.

Higher intake of whole grains, dietary fiber, dairy products, and calcium from ultra-processed foods was associated with a lower incidence of colorectal cancer. On the other hand, higher intake of meat from ultra-processed foods was associated with a higher incidence.

In other words, differences that were not apparent when looking at the total amount became visible when breaking down the contents.

Not all "ultra-processed foods" are the same

Some people might only think of snacks, soft drinks, and instant foods when they hear the term "ultra-processed foods."

However, the categories covered in the study are broad. Depending on the manufacturing process and composition, products using whole grains or dairy products may also be included.

This highlights the difficulty of classification.

Grouping foods that provide whole grains and dietary fiber with those centered on processed meats and comparing the total intake of that group can dilute the differences seen in individual foods.

The results of this study indicate that just because foods share the commonality of being processed does not mean they have the same nutritional composition.

However, this does not mean that "any product with whole grains is good" or "anything containing dairy is healthy." The associations found in the food groups studied cannot be directly translated to evaluations of individual products on store shelves.

"No association found" is not the same as "proven safe"

The most important thing to note in this news is the term "no association."

What the study showed is that with the subjects and methods used, no clear association between the total intake of ultra-processed foods and the incidence of colorectal cancer could be confirmed. This does not mean that all ultra-processed foods have been cleared of any health impacts.

This was an observational study of participants' eating habits, not a trial where researchers assigned diets for comparison, so it cannot be concluded that a particular food directly increased or prevented cancer.

Moreover, the subjects were primarily older white Americans. The same results may not apply directly to Japanese eating habits or younger generations.

It is also important to note that the dietary survey was conducted only once at the start of the study. Over about 20 years, both personal eating habits and the types and compositions of products available in the market could change, and these changes may not have been fully captured.

While the large number of "460,000" is a strength of the study, it does not eliminate the limitations of measurement methods and the study population.

The challenge of measuring diets, as noted by experts

In expert comments submitted to the UK's Science Media Centre, both the diversity of foods and the methods of investigation were points of discussion.

Rosie Red-Brownson-Smith, a nutrition researcher at King's College London, evaluated that ultra-processed foods should not be treated as a uniform group, while also pointing out that the initial questionnaire alone makes it difficult to fully grasp the degree of processing and differences in individual products.

For example, even foods with similar names can have different compositions depending on the manufacturer and product. It is difficult to accurately estimate exposure to individual additives from general dietary frequency responses.

Therefore, the results of this study cannot be read as confirming the safety of specific additives.

The comments from experts suggest the necessity of discerning "what can be understood with this method" rather than simply affirming or denying the study.

Debate on SNS about "too broad a classification" and "misleading headlines"

This study also became a topic of discussion in the science community of the overseas bulletin board-style SNS "Reddit." Posts that could be confirmed showed two major points of contention.

One was the question of the broadness of the classification of ultra-processed foods.

Opinions suggested that since the content of processing varies by food, the relationship with health should not be uniform. Some posts focused on dietary fiber, expressing discomfort with evaluating foods based solely on the presence or absence of processing.

The other was criticism of the headline "no association with colorectal cancer."

It was pointed out that emphasizing only the overall results, when different associations were shown by food group, could be misleading. Some posts introduced the conclusions of the paper, interpreting that the results do not significantly contradict traditional dietary advice.

These are reactions from some users and do not represent the entire public opinion. Nonetheless, it is clear that the same study can be seen as both "news that alleviates concerns about ultra-processed foods" and "news that cannot be judged by the headline alone."

Looking beyond "processed or not" at the Japanese dining table

So, what perspective should be taken when selecting food in Japan?

What can be learned from this study is not a blanket approval of "it's okay to eat ultra-processed foods," but rather the idea of not narrowing down the criteria for judgment to just one.

For example, when choosing bread, don't judge solely based on whether it's in a bag; also look at the ingredients, the use of whole grains, and dietary fiber. For the entire breakfast, consider whether you're consistently consuming processed meats or if the combination of foods is unbalanced.

However, this is just one example of applying the study's perspective to daily life and is not a result of measuring the risk of specific products in Japan.

Additionally, the focus of this study is colorectal cancer. The health considerations in food selection are not limited to this, and this study alone does not eliminate the need to consider salt, sugar, and calorie intake.

Dividing foods into "homemade is unconditionally good" and "store-bought is uniformly bad" does not capture the reality of daily meals. It is necessary to look at the types of products, the amount consumed, the frequency, and the overall composition of the diet.

To look a little more specifically at what's in your shopping basket

Labeling food as "good" or "bad" makes judgment easier. However, the simpler the classification, the more information is lost.

This large-scale study does not put an end to the debate over ultra-processed foods. Rather, it indicates the need to examine the differences within the same category more carefully.

Should foods containing whole grains and processed meats be evaluated the same way just because they share the commonality of being processed? Conversely, is it acceptable to think that attention to individual foods is unnecessary just because no overall association was seen?

Neither of these is the reading encouraged by this study.

The useful question when shopping is not just "Is this a processed food?" but also "What is it made of?" "What can I get from it?" "How much do I usually eat?" Adding one more question like this can lead to food choices that are not swayed by sensational headlines.

Sources

1. ScienceDaily: Research introduction dated October 21, 2026. Confirmed subject numbers, follow-up period, results by food group, and study limitations.
   https://www.sciencedaily.com/releases/2026/10/261020085014.htmScienceDaily

2. PLOS Medicine: Original paper published on October 15, 2026. Confirmed research methods, results, and conclusions analyzing the association between ultra-processed foods and colorectal cancer.
   https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1005251PLOS Medicine

3. Science Media Centre: Expert comments on the study. Referenced issues of food classification, limitations of dietary assessment by questionnaire, and points to avoid overinterpretation of results.
   https://www.sciencemediacentre.org/expert-reaction-to-us-study-looking-at-total-ultra-processed-food-intake-and-colorectal-cancer-incidence/Science Media Centre

4. Reddit "r/science": Public thread on this study. Summarized reactions regarding the broadness of food classification and the interpretation of headlines. The content of posts is introduced as opinions on SNS, not scientific evidence.
   https://www.reddit.com/r/science/comments/1x7r07e/large_study_finds_no_link_between_ultraprocessed/