The language used to describe the foods we eat can have a big effect on how we perceive them: the “organic,” “artisanal,” “homemade,” and “selected” sound a little more tempting than the “canned,” “rehydrated,” or “freeze-dried” prosaic.
Another adjective that can whet our appetite is “natural,” while we tend to associate “processed” with products with a long list of unreasonable ingredients.
But when it comes to our health, is the natural always better than the processed?
In reality, naturalness does not automatically mean that a food is healthy, says Christina Sadler, manager of the European Food Information Council and a researcher at the University of Surrey in the UK.
In fact, natural foods can contain toxins and minimal processing can make them safer.
Beans, for example, contain lectins, which can cause vomiting and diarrhea. They are removed by soaking them overnight and then cooking them in boiling water.
Processing also makes the consumption of cow’s milk safe.
Milk has been pasteurized since the late nineteenth century to kill harmful bacteria. Before this time it was distributed locally because there was no good refrigeration in the houses.
“Cows were milked every day and people brought milk to their neighborhoods to sell,” says John Lucey, a professor of food science at the University of Wisconsin-Madison in the United States.
“But the cities got bigger, the milk moved away and took longer to reach the consumer, which meant the pathogens could multiply.”
Growing evidence suggesting that some organisms in milk could be harmful led to the development of heating devices for milk and the invention of pasteurization, which was soon adopted in Europe and later in the US.
“It’s one of the most important public health success stories of the last century,” Lucey says.
“Just before World War II, about a quarter of all food- and water-borne diseases came from milk. Now it’s less than 1%.”
Processing can also help retain nutrients from what we eat.
For example, freezing, which is classified as minimal processing, allows fruits and vegetables to retain nutrients that might otherwise degrade while in the refrigerator.
“Vegetables often freeze shortly after harvest, rather than being picked, transported, and then deposited on the shelves, losing nutrients,” Sadler says.
In 2017, a group of researchers bought fresh vegetables at different grocery stores and analyzed their levels of nutrients, including vitamin C and folic acid, on the day they bought them and within five days of making them and having them in the refrigerator.
They saw that they had comparable levels of nutrients. And in some cases, the study found that frozen ones had higher levels than those stored in the refrigerator.
“There’s a misconception that frozen products aren’t as good as fresh ones, but that’s really inaccurate,” says Ronald Pegg, a professor of food science and technology at the University of Georgia, also in the US.
© Getty Images Canned tomatoes are a good example of healthy processed food.
Processing also allows vitamins and minerals, such as vitamin D, calcium, and folic acid, to be added to certain processed foods, including bread and cereals.
Such efforts have helped reduce several nutrient deficiencies among the general public.
However, this does not necessarily make the food nutritionally balanced.
Processing can also help preserve food and make it more accessible.
Fermentation makes the cheese stay stable for longer and, in some cases, reduces the amount of lactose, making it more digestible for those with a mild intolerance to it.
In the past, the main reason food was processed was to increase its shelf life.
For a long time, preserving foods by adding ingredients like sugar or salt was crucial for people to survive the winter, says Gunter Kuhnle, a professor of food and nutritional sciences at the University of Reading.
“The processing allowed us to be where we are today because it prevented us from starving,” he explains.
“Many foods need to be processed to be consumed, such as bread. We couldn’t survive on grains alone.”
Adding heat, also a minimal process makes many foods edible, such as potatoes and mushrooms.
© Getty Images Fresh vegetables can sometimes lose many of their benefits if kept in the refrigerator for a long time.
“Canned tomatoes are a classic example that processed foods are better than their fresh versions,” kuhnle says.
“They can be collected much later when the product is much more mature, and they can be processed in a much smoother way.”
And while some processes can cause food to be less nutritious, they can still make food more accessible.
Bacon, for example, does not improve health, but it gives more people access to meat by preventing food from spoiling.
Processed ones also tend to be cheaper, as they can be produced at lower costs.
Not the ultra-processed ones
Various research has concluded that healthier foods are three times more expensive than those high in salt, sugar, and fat, which are most highly processed.
But these highly processed products, which are made from food-derived substances and additives, are generally not good for us.
Studies have shown that food additives can alter our gut bacteria and cause inflammation in our bodies, which is linked to an increased risk of heart disease.
In addition, research shows that people tend to overeat ultra-processed foods.
Studies have shown that people who eat ultra-processed foods consume more calories overall and gain more weight, and have an increased risk of developing heart disease.
A small 2019 study found that participants, in the two weeks they had a diet rich in ultra-processed products, consumed 500 more calories a day than during the weeks they ate whole foods.
They also gained an average of almost a kilo with the ultra-processed diet.
© Getty Images Processed foods can have high levels of fat, salt, and sugar.
However, the mechanisms behind why need to be better understood, the researchers say.
More generally, there seems to be a consensus that more research is needed into the effects that processed foods have on our health.
For example, it is still unknown how flavonoids and polyphenols (micronutrients found in some plants and have been linked to many health benefits) in fruits are affected by processing, Kuhnle says.
“There’s not much information on how processing limits health benefits. A lot of research focuses on a single food, but people don’t just eat apples, their diet consists of apples, smoothies, cakes” and so on.
While minimal processing has many benefits, the same cannot be said for what classification systems call “ultra-processed” foods.
But there is a debate among scientists regarding the definitions and terminology surrounding what constitutes minimal and “ultra” processing.
Earlier this year, Sadler analyzed numerous systems that seek to classify processed foods.
It found no consensus on what factors determine the level of processing and claims that the classification criteria are “ambiguous” and “inconsistent.”
Nova is one of the most well-known classification systems used in food research.
The classification includes unprocessed or minimally processed, processed culinary ingredients, processed foods, and ultra-processed foods.
According to Nova, ultra-processed foods are composed of fractional ingredients and contain few or no whole foods.
But definitions of ultra-processed foods vary between publications and there is an ongoing debate about these definitions.
“There is no good definition of processing. The public has the idea, when they hear the word ‘processing,’ that all the food is disassembled and reassembled, but it could be as simple as heating or cooling,” Lucey says.
© Getty Images Food processing is a broad term that describes many types of foods.
There is a debate about whether public health nutrition policies should focus more on the degree of food processing than on food nutrient profiles.
But is there anything inherently wrong with processing?
A group of scientists wrote in a 2017 paper: “As far as we know, no arguments have been offered as to how, or whether, food processing in any way constitutes a risk to consumer health from possible adverse nutrient intake or chemical or microbiological hazards.”
However, it is worth noting that the lead author sits on the scientific committees of food producers Nestlé and Cereal Partners Worldwide.
While ultra-processed foods typically contain fewer nutrients than minimally processed foods, fortified foods, to which micronutrients are added during production to improve public health, play an important role in public health, they argue.
While some studies show that ultra-processed foods fill us less and leave us with the need to eat more, the authors of the article argue that some processing is also used to reduce the number of calories in some foods, such as semi-skimmed milk and low-fat margarine.
Some ultra-processed foods may be associated with poor health outcomes, but not all processed foods are cut with the same pattern.
Frozen vegetables, pasteurized milk, or boiled potatoes, for example, maybe better for us than their raw counterparts.
But here’s the key: all those foods also look a lot like their natural form, and this is what we need to keep in mind.
As long as we can recognize that processed food is close to its natural form, including it in our diet can even be good for us.