Processed foods: Your questions answered

We recently asked our community to send us their burning questions about processed foods. 

From the feedback we received, we picked out the six most common questions. We'll answer them here.

At ZOE, we know that a diverse diet rich in fresh produce is the healthiest diet. But it’s not always easy to know which foods are best when rushing around a grocery store. 

To add to the confusion, the food industry has flooded the market with delicious, cheap, convenient, and non-nutritious ultra-processed foods (more on these later). With aggressive marketing and gaudy packaging, navigating the grocery store can be challenging.

With the ZOE program, no food is off the table, but there are some that we recommend you only eat occasionally. If you’d like to learn more about how ZOE can provide tailored nutrition advice to suit your unique body, take our free quiz today.

So, without further ado, let’s dive into your questions.

1. What does ‘processed’ mean?

In short, processed foods are altered in some way before they reach your plate. For instance, they might be frozen, canned, baked, or dried. 

Processed foods include cheese, fresh bread, smoked and cured meats, salted nuts, frozen vegetables, tinned fruit, beer, and wine. In other words, most foods people eat regularly are processed to some degree.

But there are different degrees of processing. For instance, fresh spinach in a bag or chopped nuts are considered “minimally processed.” 

Sometimes, processing might mean adding salt, sugar, or preservatives, which can make the food less healthy. Other times, the processing might be beneficial for health. For instance, when manufacturers pasteurize milk, it makes it safer.

Similarly, extra virgin olive oil is classed as a processed culinary ingredient because olive oil producers have to extract it from olives. However, it’s still a healthy addition to a salad.

At the other end of the scale, we have ultra-processed foods. These tend to contain ingredients you wouldn’t use at home. Manufacturers create ultra-processed foods from compounds extracted from other foods. They often add stabilizers, artificial colors, and flavorings.

For a more detailed explanation of the different levels of processing, read ZOE’s article on ultra-processed foods.

2. Are all processed foods bad for you?

In a word, no. Minimally processed and processed foods can be healthy. 

For instance, freezing vegetables doesn’t make them less nutritious. Similarly, a chopped nut is likely to give you a similar nutritional boost to a whole nut.

Indeed, some foods, such as pulses, need to be processed before we can eat them.

When it comes to ultra-processed foods, though, the story is different. There is growing evidence that a diet high in ultra-processed foods can increase the risk of various health conditions, including high cholesterol and cardiovascular disease. 

In short, processed and minimally processed foods are generally fine as part of a diverse diet, whereas you should limit your intake of ultra-processed foods. This leads to our next question.

3. How can you tell if food is processed?

It's relatively easy to tell if a food item is processed: If it’s canned, bagged, frozen, or in any way different from the raw ingredients, it has been processed. But, as we now know, that’s not necessarily a bad thing.

To know whether a food is ultra-processed, here’s a rough guide. If the answer to any of the following questions is “yes,” then it’s likely to be ultra-processed:

  • Is the list of ingredients long?

  • Do the ingredients include unrecognizable names?

  • Does the product contain high levels of fat, salt, and sugar?

  • Does the product have a long shelf life?

One caveat to the final point on this list is UHT, or long-life milk, which is normally classed as minimally processed. 

Foods with a longer shelf life generally contain preservatives. However, to produce UHT milk, manufacturers subject the milk to high temperatures. This kills off bugs and gives it a longer shelf life without needing preservatives. 

4. Are plant-based meat substitutes processed?

As many people reduce or eliminate animal products from their diet, plant-based meat and milk substitutes have become more popular. 

If you’ve read this far, you might already have guessed that these products are processed. 

But are they ultra-processed? Often, the answer is “yes.” We asked Mark Hall, one of ZOE’s nutrition coaches to weigh in.

He says that it’s “very much brand dependent.” Looking at plant-based burgers, specifically, he explains that they’re often “heavily processed, contain similar levels of saturated fats to their meat equivalents, and contain significantly higher amounts of sodium.”

Although there is great variety, using our rough four-point guide above will help you gauge whether an individual product is ultra-processed. As with any food, it’s worth checking the salt, sugar, and fat levels before you buy.

5. Do food additives impact gut bacteria?

Your gut microbiome consists of trillions of microorganisms. Scientists now know that the health and diversity of this community are vital for good health. So, understanding whether food additives impact them is an important question.

However, to date, there has been little research into the effects of additives on the human microbiome. 

Because manufacturers use some additives to prevent bacteria from growing, it wouldn’t be surprising if they influenced gut bacteria in some way. 

Some animal studies do show that certain additives cause short-term disruption of the gut microbiome. We asked Emily Leeming — a registered dietician and head of programs at ZOE — for her take on research so far; she explains:

“Most of the studies on food additives’ impact on our gut microbes were done in rat and mice models — usually in far greater quantities equivalent to body size than we would consume as humans. So, it can be hard to translate to how we eat day to day.”

Because humans in industrialized countries often consume a cocktail of these chemicals daily, further research is warranted. 

Emily continues, “our gut microbes love fiber-rich and polyphenol-rich foods. The important focus for your gut microbiota is getting enough of these types of plant foods — adding more in, rather than cutting things out.”

Understanding the full effect of food additives on the gut microbiome will take time. Scientists will need to conduct studies on a wide range of additives and combinations of additives. 

If you want to know what bacteria are living in your gut, start today by taking our free quiz.

6. How can I avoid processed foods?

In truth, unless you have a great deal of spare time and money, avoiding all processed foods is nearly impossible. And even if you cook everything from scratch using fresh ingredients, as you chop and heat them, by definition, you’re processing them.

As we’ve learned, avoiding all processed foods is not necessary for good health. Many processed foods can be a valuable part of a healthy diet.

As for avoiding ultra-processed foods, that can also be challenging. Manufacturers design these products to be delicious and convenient, and they are marketed aggressively. 

There is no need to eliminate them from your diet entirely, but replacing them with products that are less processed may benefit your health in the long run. Here are a few suggested swaps to get you started:

  • swap cold cuts for white meat or fish

  • swap cheese slices for minimally processed cheeses like cheddar

  • swap soda for water with fresh fruit, tea, or coffee

  • swap breakfast cereal for oatmeal

  • swap candy for trail mix

At ZOE, we know that everyone responds differently to food. For instance, a food that causes a large increase in blood sugar or blood fats for one person might hardly affect another. This is why personalized nutrition is important.

With the ZOE program, we provide nutritional advice tailored to your unique body, including personalized swap suggestions to help you replace ultra-processed foods with foods that better suit your body. 

To find out more, take our free quiz today.


Consumption of ultra-processed foods and health status: a systematic review and meta-analysis. British Journal of Nutrition. (2020).

Food-grade cationic antimicrobial ε-polylysine transiently alters the gut microbial community and predicted metagenome function in CD-1 mice. NPJ Science of Food. (2017).

Impact of food additives on gut homeostasis. Nutrients. (2019).

Methods for processing pulses to optimize nutritional functionality and maximize amino acid availability in foods and feeds. Cereal Foods World. (2020).

Mineral, fiber, and total phenolic retention in eight fruits and vegetables: a comparison of refrigerated and frozen storage. Journal of Agricultural and Food Chemistry. (2015).