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 do these foods affect our health?

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 the removal of inedible parts, drying, crushing, roasting, boiling, freezing, or pasteurization. These make them them suitable for storage and safe to eat. Examples of unprocessed or minimally processed foods 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 percent -- of calories eaten in the United States, and contribute almost 90 percent of the energy we get from added sugars.

How do processed foods affect 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 healthy, 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 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 limitations in that it was very small and done in a clinical research setting. But another study that examined the dietary records of more than 100,000 French adults over five years found that those who consumed more ultra-processed foods had higher risks of cardiovascular disease, coronary heart disease, and cerebrovascular disease.

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

Source: Harvard University Medical School: health.harvard.edu