Are processed foods bad for your gut health?

February 25, 2021

Is processed food really bad for your gut microbes and gut health? 

We are often told to avoid eating processed food, and experts have raised concerns about the link between ultra-processed foods and poor health.

The latest findings from our research also show a link between highly processed foods and ‘bad’ gut microbes that are associated with poorer health markers. 

But what exactly does processing do to our food? And is processed food really bad for your gut microbes and gut health? 

Let’s take a closer look.

The full scoop on processed foods and gut health

  • Foods are processed in many different ways to make them tasty, digestible, and safe to eat.
  • Ultra-processed foods often contain lots of added sugar, fat, salt as well as many other chemicals, preservatives, and emulsifiers, and are linked to metabolic changes and poorer health.
  • Our PREDICT study shows that eating a diet rich in minimally processed plant-based foods is associated with having more “good” gut microbes linked to better heart and metabolic health. Highly processed foods, whether from animals or plants, are associated with “bad” gut microbes linked to poorer health markers.
  • ZOE enables you to discover the unique mix of “good” and “bad” bugs living in your gut and get personalized recommendations to support your gut health.

What is food processing and why is it done?

Food processing is a very broad term, which covers any way that raw food is changed before we eat it.

Processing modifies food to make it more digestible, improve its flavor and appearance, remove harmful bugs or toxic substances, and make it last longer. 

In some cases, the processing is essential to make food safe to eat or to turn them into a state that we can digest. Cooking raw food is a form of processing, as is grinding wheat into flour or pasteurizing milk to kill harmful bacteria. 

Processed foods are often made by mixing more than one food or ingredient, for example, pork and salt in many cured types of meat or fruit and sugar in jams. Many common foods and ingredients, such as olive oil and vinegar, are also processed to some extent. 

We have been roasting, baking, broiling, boiling, freezing, chopping, grinding, drying, pressing, canning, smoking, salting, and sweetening our foods for a very long time.

But in the last few years, there has been a steep rise in what are known as ultra-processed foods, which often contain lots of fat, sugar, and salt.

Ultra-processed foods are made mostly or entirely from ingredients that have already been highly modified, like whey, isolated protein, or high-fructose corn syrup, together with additives such as preservatives, antioxidants, and stabilizers. This includes things like candies, cakes, cookies, and sodas, as well as many pre-prepared ready meals and snack foods. 

Are processed foods unhealthy?

Food processing often changes the structure of the food, known as the food matrix. These changes can alter the properties of the food and how it is used by the body. 

For example, grains like rice need to be cooked so they can be broken down in the gut, releasing carbohydrates and other nutrients. White bread is digested faster than less-processed wholegrain bread, potentially leading to spikes in blood sugar levels. And we can extract more calories out of ground almonds than the same amount of whole nuts

Not all processed foods are unhealthy, and many foods have to be processed in some way to make them digestible or safe to eat. But as a general rule, the more processed a food is, the less healthy it is for you.

Ultra-processed foods and drinks can contain high levels of refined carbohydrates, saturated fats, salt, and chemical additives. They often lack dietary fiber, good sources of protein, and healthy fats.

We are eating an increasing amount of ultra-processed foods, with more than half of our daily calories now coming from those types of foods

Eating a lot of ultra-processed food is associated with being overweight and having worse health outcomes, including conditions like heart disease, type 2 diabetes, irritable bowel syndrome, depression, asthma, and cancer.

Our findings suggest that ultra-processed foods might be less healthy for our gut microbes too.

How do processed foods affect your gut microbiome?

What you eat affects the trillions of microbes living in your gut, known as your microbiome, and both are linked to health.

The latest findings from our PREDICT study explored the links between diet, gut microbes, and markers of heart and metabolic health. We identified 15 “good” microbes linked to better health markers and a healthy, varied diet. And we also found 15 “bad” microbes associated with a worse diet and poorer health indicators.

Unsurprisingly, we found a strong association between eating a diet rich in minimally processed plant-based foods and having more species of "good" gut bugs. 

Interestingly, we found that diet quality - including the proportion of processed versus unprocessed foods - was just as important as the type of foods themselves.  

Processed animal-based foods like sausages, bacon, and creamy desserts were associated with having more "bad" microbes, as might be expected. 

But highly processed plant-based foods such as juices, sauces, and baked beans were also associated with "bad" microbes, highlighting how important food processing is for our microbiomes and our health.

Should I be eating processed foods?

Research shows a strong link between ultra-processed foods and worse long-term health. Our latest findings show that highly processed foods aren’t great for your gut bugs either.

We believe that no food should be completely off-limits. However, choosing more delicious and nutritious unprocessed or minimally processed foods and limiting ultra-processed foods will help to keep your gut microbes happy and well-fed.

We all have a unique gut microbiome, so there is no one 'best' way to eat that suits everybody. Importantly, there’s no one single food—or single microbe—that will make or break your microbiome. The microbiome is a complex community, and your regular dietary habits over time are what determines the mix.

Finding the foods that work best for your unique body and your community of gut bacteria starts with understanding which bugs are living in your gut right now, and which foods will help them thrive. 

Our ZOE at-home test reveals your unique mix of “good” and “bad” bugs and helps you find the foods that fit your body and your gut microbiome best, so you can take back control of your health and weight. Ready to discover the best way to eat for your unique body and gut?

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