What are ultra-processed foods and are they bad for our health?

You hear it all the time: the advice to “eat less processed food.” But what is processed food? For that matter, what is minimally processed food or ultra-processed food? And how does processed food affect our health?

What are processed and ultra-processed foods?

Unprocessed or minimally processed foods are whole foods in which the vitamins and nutrients are still intact. The food is in its natural (or nearly natural) state. These foods may be minimally altered by removal of inedible parts, drying, crushing, roasting, boiling, freezing, or pasteurization, to make them suitable to store and safe to consume. Unprocessed or minimally processed foods would include carrots, apples, raw chicken, melon, and raw, unsalted nuts.

Processing changes a food from its natural state. Processed foods are essentially made by adding salt, oil, sugar, or other substances. Examples include canned fish or canned vegetables, fruits in syrup, and freshly made breads. Most processed foods have two or three ingredients.

Some foods are highly processed or ultra-processed. They most likely have many added ingredients such as sugar, salt, fat, and artificial colors or preservatives. Ultra-processed foods are made mostly from substances extracted from foods, such as fats, starches, added sugars, and hydrogenated fats. They may also contain additives like artificial colors and flavors or stabilizers. Examples of these foods are frozen meals, soft drinks, hot dogs and cold cuts, fast food, packaged cookies, cakes, and salty snacks.

According to a study published in The BMJ, ultra-processed foods are the main source (nearly 58%) of calories eaten in the US, and contribute almost 90% of the energy we get from added sugars.

How do processed foods affect our health?

A recent study published in the journal Cell Metabolism compared the effects of an ultra-processed diet to the effects of an unprocessed diet on calorie intake and weight gain. The study involved 20 heathy, overweight adults staying at a medical facility. Each study participant received an ultra-processed diet and an unprocessed diet for 14 days each. During each diet phase, the study subjects were presented with three daily meals and were instructed to consume as much or as little as desired. Up to 60 minutes was allotted to consume each meal, with snacks (either ultra-processed or unprocessed, depending on the study phase) available throughout the day.

The meals were matched across the diets for total calories, fat, carbohydrate, protein, fiber, sugars, and sodium. The big difference was the source of calories: in the ultra-processed diet phase, 83.5% of calories came from ultra-processed food; in the unprocessed diet phase, 83.3% of calories came from unprocessed foods.

The researchers found that study subjects consumed about 500 more calories per day on the ultra-processed diet versus the unprocessed diet. The ultra-processed diet period was marked by an increased intake of carbohydrate and fat, but not protein. Participants gained on average two pounds during the ultra-processed diet phase, and lost two pounds during the unprocessed diet phase. The authors concluded that limiting ultra-processed foods may be an effective strategy for preventing and treating obesity.

The study did have several limitations. For one thing, with only 20 participants, this was a very small study. For another, there was significant variation in individual responses to the two diets. Eleven people gained extreme weight on the ultra-processed diet — as much as 13 pounds over 14 days — while a few participants saw no weight gain. It’s also unclear how generalizable the results are to a wider population, because the study did not include people with chronic diseases such as heart disease or diabetes. In addition, the study was done in a clinical research setting, which could have affected their eating behavior (the study subjects may have been more isolated and bored than in their natural environments).

Another study, this one published in The BMJ, examined representative dietary records of more than 100,000 French adults over a five-year period. They found that those who consumed more ultra-processed foods had higher risks of cardiovascular disease, coronary heart disease, and cerebrovascular disease. These results remained statistically significant even after the researchers adjusted for the nutritional quality of the diet (considering factors such as the amount saturated fat, sodium, sugar, and dietary fiber in the diets). Although large observational studies do not prove cause and effect, the research does suggest an association between ultra-processed diets and heart disease.

Learn to identify processed foods

Whenever possible, try to avoid or limit ultra-processed foods. Consider the examples in this table to help you quickly determine if a food is minimally processed, processed, or ultra-processed.

Minimally processedProcessedUltra-processed
CornCanned cornCorn chips
AppleApple juiceApple pie
PotatoBaked potatoFrench fries
CarrotCarrot juiceCarrot cake
WheatFlourCookies

Comments:

  1. Mac.

    Although primarily meant to educate/elucidate the public at large between a healthy vs unhealthy (health-wise, questionable) dietary choices in general, unfortunately, it seems to fail in its primary mission.
    Minimally it lacks the following components.
    Fails to address:
    why some choices are clearly/mechanistically, healthy/unhealthy/less than optimal.
    pros and cons of each choice
    Good/healthy alternatives

    Has indeed left a big/grand canyon gap addressing the optimal vs less than optimal vs poor choices, even in common dietary varieties preparations/styles

  2. Michael Bernhardt

    I agree with your article, but I disagree strongly with your examples. A baked potato is not processed, it is only cooked. Canned corn cannot be considered processed in my opinion. Apple juice is more processed than the apples in apple pie. Carrot juice is more processed than the carrots in carrot cake. Added sugar is a whole other matter.

  3. Sam Bolton

    I always wonder where home cooked/prepared food fits into this, and e.g. a smoothie or muffin. These can still be healthy, depending on the ingredients but are they still considered ultra-processed? What about hummus? Again, probably ultra-processed, but if you make your own, then it can be all healthy ingredients.

  4. Abdullah khan

    the past ages people were strong , healthy, and have long lives, because they do not eat process foods. Every things were in the natural forms, thanks to Harvard they giving awareness to the world.

  5. Celine

    I feel the distinction between processed and ultra processed is not completely clear in this article. Surely its particular ingredients that exist in ultra processed foods (like sulphite in sausages) that are the problem or particular kinds of processes- e.g. white flour has less fibre than wholemeal. The article is very fuzzy. You can’t simply say a cookie is ultra processed and therefore bad to eat.

  6. Lindsey

    Does this mean whenever we cook food, like chicken or broccoli then it becomes processed? How is a baked potato Considered processed?

  7. Lawrence Odili

    This is good , more on this topic.

  8. Davis

    I think your table of examples needs some serious rework. A baked potato is not much more processed than a potato. Are you suggesting potatoes should best be eaten raw? As another example, flour is processed for certain, but most everything except for gravy with flour in it is a baked product. So really, those are processed foods. The flour is pretty much irrelevant because nobody eats flour by itself.

  9. Susan

    What about foods like cheese and tofu or kombucha (fermented)? They are ultra-processed in a sense.

  10. Yuli Kornblum

    This may be a transient response to the new food. It is just possible that after some time the system will be used to the new food. Also the mention of the bread in the ultra-processed food. Can we eat the bread ingredients without baking them? It is just possible that eating a doughnut from time to time is beneficial as it makes the person eating them happy.

  11. Wendy

    The ultra-processed apple pie listing – is that commercially purchased apple pie or one baked from scratch at home?

  12. Frey

    I noticed that steaming foods (veggies) was not listed as a means of minimally processing. Isn’t it?

  13. Sylvain

    Canned sardines (perhaps other fishes as well) are often recommended in healthy-eating diets. Yet, according to this article, they are ultra-processed food (and, indeed, few brands are relatively less salty – excepting such a brand as BRUNSWICK that can be purchased at Price Shopper in NY). My question is: are canned fish or, in general, canned seafood healthy at all?

  14. Michael Corbett

    Baking the potato makes it processed? Does anyone really eat potatoes uncooked???

  15. Juliana

    I always thought processed food are food like sausageds, deli meat, store bought frozen food that are mass produced.
    Is home cooked dish considered ‘ultra processed food’? I am confused about how they are defined here.

  16. Jim McRae

    Why are snacks offered between meals in dietary studies?
    With increasing evidence that it may be “ better” to eat in a 10 hour window the time between three meals around 3 hours and snacks should not be necessary. Many snacks are highly processed and calorie bombs.

  17. Andrew

    Highly processed foods often contain highly processed ingredients like modified food starch that enhance product stability, flavor and mouth feel. Also, there is a long list of food additive preservatives that may be on the GRAS list but are found in many of these processed foods resulting in greater consumption than is considered safe. And then, what about ultra-processed food safety among young and old people?

  18. Dave Glass

    I would guess that wine would have to be an ultra processed food that is generally considered healthy. If fermentation is OK, then how about black tea?

  19. sarah

    These are honestly terrible descriptions of processed, ultra processed, etc.

    Baking a potato makes it processed? Wouldn’t that be minimally processed? Cookies are ultra processed even if you made them at home? These are crazy generalizations and this table at the end makes me doubt everything. French fries – from a fast food restaurant, ultra processed for sure. If I make them at home – they are cut and cooked, that’s minimally processed. Flour is processed? We eating whole wheat berries now? White flour, sure. But flour in and of itself would be minimally processed, wouldn’t it?

  20. azure

    Tofu is a processed food (fairly heavily processed) that perhaps is an except to the rule.

    Would sauerkraut and kimchi also be considered to be “processed” foods?

    • steven j

      No, tofu is not heavily processed as it retains it’s nutrients and vitamins. Sauerkraut is fermented and is minimally processed. And in fact is much better than raw cabbage. Just about everything life has exceptions. Not sure you get this

    • SM

      I don’t believe fermenting is considered processing. Fermentation doesn’t strip away vitamins or minerals…it actually adds important things like pre and pro biotics

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