Busy lifestyles have made ultra-processed foods (UPFs) a regular part of many people’s diets. Foods such as sugary drinks, crisps, ready meals and sweetened breakfast cereals are convenient, affordable and widely available.
In recent years, researchers have begun exploring how diets high in ultra-processed foods may affect mental health disorders. Evidence suggests they may negatively affect wellbeing through inflammation, blood sugar disruption and changes to the gut-brain axis.
In this article we’ll explore what ultra processed foods are, how they may affect the brain and mood, what the current research says, and practical ways to build a more balanced diet.
Table of Contents
What Are Ultra-Processed Foods?
Ultra-processed foods have undergone multiple processes and have had many different ingredients added to enhance the product’s flavour, texture, appearance, or shelf life. Colours, flavours, emulsifiers and other additives can all be added to the food to produce a final product. Typically, ultra-processed foods require little to no preparation, making them very appealing to people with busy schedules. This category of processing has been defined in the NOVA food classification.
The NOVA Food Classification Explained Simply
As processed foods have developed over time and become more common, a system was made to divide them into four primary categories, depending on their extent of processing. The NOVA system categorises food into:
1. Unprocessed or Minimally Processed Foods
These foods only undergo essential processing such as pasteurising or drying, no chemicals are added to the product. This category includes fresh produce like fruits and vegetables, meats, fish, nuts eggs and dairy products like milk. The processing of these products make sure they are safe to eat and help improve shelf life.
2. Processed Culinary Ingredients
These ingredients are commonly used in cooking, seasoning and preparing meals from the products in group 1. The ingredients are processed through methods like refining and grinding. The foods produced in this category include salt, sugar, butter, and cooking oils. The reason for this category is to help with the preparation of foods found in category 1 and enhance their flavour.
3. Processed Foods
The processed foods in this category are made by adding group 2 products like salt or oil to group 1 products like meat or cheese. The processing done to these foods enhance the flavour, texture and appearance of these products and prolongs their shelf life. Examples of the foods produced are cured meats, salted nuts or canned vegetables, fruits, legumes and more.
4. Ultra-Processed Food and Drink Products
The foods in this category usually contain little components of foods from group 1; however, they aim to mimic the products in taste and texture, like sweeteners instead of sugar. The main reason for these foods is to create ready-to-eat, convenient foods and drinks. Industrial techniques are needed to produce these types of foods like extrusion to create attractive foods and drinks.
Common Examples of Ultra Processed Foods and Drinks
- Sugary Drinks
- Crackers and Crisps
- Ready-to-eat Frozen Meals like Pizzas and Chicken nuggets
- Chocolate and Sweets
- Breakfast Cereals
- Prepackaged sliced Hams and Meats
Processed vs Ultra-Processed: What’s the Difference
When you think of processed foods, you might picture packaged snacks with long lists of unfamiliar ingredients. But most foods are processed in some way, and some methods help make them safe to eat. However, processed and ultra-processed foods are different, and understanding that difference is important. Simple steps like pasteurizing milk or washing and freezing vegetables count as food processing. This doesn’t make these foods unhealthy. These methods can help keep food safe or make it last longer without adding extra ingredients. Ultra-processed foods usually have more than 5 ingredients and have gone through multiple processes to reach their final product. These foods have added fats, sugars, salt and preservatives. Eating too many of these foods can have a negative effect on your health and may be associated with high blood pressure, weight gain, type 2 diabetes and coronary heart disease due to the high amounts of added ingredients like salt and fats. These types of ultra-processed foods should be limited in your diet where possible.
What Does the Research Say About Ultra-Processed Foods and Mental Health?
In recent years, there has been a growing concern that ultra-processed foods are also affecting people’s mental health and not just their physical health. Studies have shown that habitual consumption of UPFs (Ultra-Processed foods) maybe associated with deteriorating mental well-being over time.
UPFs and Depression
Eating a diet that is high in ultra-processed foods such as packaged snacks and artificial drinks may be linked to a significantly higher risk of depression. This Is due to the high sugar, unhealthy fats, and artificial flavourings and preservatives that have been added to the foods. They can disrupt normal body functions triggering inflammation and disrupting proper gut function.
UPFs and Anxiety
Similarly to depression and low moods high consumption of Ultra processed foods has been associated with increased symptoms of anxiety. The causes of this are relatively similar where chronic inflammation and disruption to gut health can affect mental health. This is because of the two-way communication known as the gut-brain axis.
What the Evidence Cannot Prove Yet
Most studies on the topic of ultra-processed food are observational, so they look at and follow patterns rather than cause and effect. Other factors may also influence mental health, such as lifestyle, exercise, and sleep, leading to bidirectional relationships, so if you are looking to reduce ultra-processed foods in your diet, you should also consider exercising regularly and getting enough sleep at night, ideally 7- 8 hours.
How Ultra-Processed Foods May Affect the Brain and Mood
Now we’ve looked at the effects that eating large amounts of ultra-processed foods can have on your mental health; let’s look at the science behind it.
Blood Sugar Spikes and Energy Crashes
Sweets can feel rewarding, but sugar does not reliably boost mood or energy levels. Sugary foods can raise blood glucose quickly, prompting the body to release insulin, which helps cells use glucose for energy. This normal response does not inevitably cause a “sugar rush”, anxiety or further cravings. Foods containing soluble fibre, such as oats, beans and apples, can slow digestion and help blood glucose rise more gradually.
Inflammation and Oxidative Stress
Many ultra-processed foods are low in vitamins and minerals that help protect our cells from damage. Relying heavily on these foods can leave less room for nutrient-rich options. Over time, a poor-quality diet may contribute to inflammation, which researchers are studying for its possible role in brain health and mood.
The Gut-Brain Axis
The gut-brain axis is a two-way communication network between your gut and your brain. It connects many parts of the body, including your nervous system, your immune system, and your gastrointestinal system. Because it works both ways, if one feels off, the other will be affected; for example, if you are nervous or stressed, it can lead to you feeling nauseous, and if you eat foods that are ultra-processed, it can affect your mood and behaviour. Most serotonin is produced in the gastrointestinal tract; this means it is highly influenced by what’s in your gut. When your gut is well lined with beneficial gut bacteria, it’s able to fight off toxins and harmful bacteria more easily, which can help protect nerves that connect your stomach to your brain, meaning if you fill your diet with good foods, you can protect your mental health. If you fill your diet with ultra-processed foods, there won’t be enough beneficial bacteria to fight off toxins and bad bacteria.
Are All Ultra-Processed Foods Equally Bad?
Why Context Matters
Not all ultra-processed foods possess the same health risks as each other. Drinks that are artificially sweetened or have high amounts of sugars and foods like processed meats are seen as bad for your health as they provide little to no nutrients, whereas foods like bread, cereals, or yogurt-based desserts, even though still classed under the NOVA classification as ultra-processed foods, are seen as more beneficial. They can contain nutrients such as fibre, calcium, and minerals. Because of this, they have less of a risk of causing harm to our bodies. It is important to limit the ultra-processed foods that contain a lot of artificial sweeteners and high levels of sugar, as these can be more harmful to your mental and physical health. However, nowadays, with busy day-to-day schedules, it can be difficult to completely avoid UPFs, so often a good rule of thumb to follow is the 80/20 diet, where 80% of your diet is whole foods, and the other 20% is ultra-processed foods or ‘treats’.
Better and Worse Choices Within Packaged Foods
Food processing can help make food safe to eat – for example, by pasteurizing milk. Processing alone does not make food unhealthy. Try to limit foods high in added sugar, saturated fat, or salt, rather than judging them only by whether they contain additives. A lot of people choose these foods because of their convenience as they are often ready out of the packet and no preparation is required; however, simple swaps can make big changes to your health.
- Instead of buying flavoured yogurts in the shop, you should opt for a natural Greek yogurt and add berries and honey. This will give the yogurt the same sweetness as the sweetened yogurts and give you added antioxidants and vitamins from the berries
- A similar swap can be made with sweetened breakfast cereals and trading them for cereals high in fibre or porridge oats by adding honey and berries to achieve a sweeter taste without the artificial sweeteners
- Instead of flavoured potato crisps, try nuts or even homemade popcorn, which can be seasoned with some sea salt; this is a good snack without all the unnecessary added ingredients
- Instead of processed deli meats, prepare some cooked meat at the beginning of the week and cut it up so it’s ready to use for lunches for the week
Omega-3 Sources
Omega-3 fatty acids are important for proper functioning of the brain, they have powerful anti-inflammatory functions, and research shows they may play an important role in preserving brain health throughout all life stages. Studies also show they may improve mild depression. Sources of omega-3 to include in your diet are oily fish, nuts, and seeds.
Fermented Foods
Fermented foods may support mental wellbeing by promoting a healthy gut microbiome, which communicates with the brain via the gut-brain axis. The gut and brain communicate in ways that may influence mood and stress. Researchers are still studying whether improving gut health can help reduce symptoms of anxiety. The easiest way to include fermented foods in your diet is by eating yogurt and making sure it has live active cultures; however, try to avoid yogurts with lots of added sugars. Other fermented foods include kefir, sauerkraut, and kombucha.
Protein at Each Meal
By incorporating protein at each meal, you are providing the building blocks, amino acids, for serotonin to be produced. Protein also helps to stabilize blood sugar as it slows the absorption of carbohydrates, leading to more stable energy. This can lead to more stable moods and a decrease of anxious feelings. Common sources of protein include meats, fish, eggs, peas, beans and lentils. These can all easily be incorporated into foods at each mealtime, ensuring you get enough protein throughout the day.
Polyphenol-Rich Foods
Polyphenol-Rich Foods are important for fighting inflammation and protecting gut health. They also help to fight free radicals, which is important, as free radicals can damage your cells. Damage to these cells, especially around the gut-brain axis, may lead to an increased risk of poor mental health. To ensure you’re eating enough polyphenol-rich foods, it’s important to ensure you’re ‘eating the rainbow’. Include brightly coloured fruits and vegetables along with nuts and seeds, spices and even dark chocolate; eating these will help reduce inflammation.
When to Seek Professional Support
Diet can support wellbeing; however, it should not be used as a substitute for medical care. If you are unable to carry out your usual daily activities because of how you’re feeling, you notice lasting changes to your usual eating and sleeping patterns over a long period of time, or you start to get feelings of panic and you are not able to calm down, you should seek help from your GP or a mental health professional.
Conclusion
Ultra-processed foods have become a common part of many people’s diets. They are often affordable and convenient, making them an easy choice for busy lifestyles. While not all processed foods pose the same risk to our health, regularly consuming large amounts of processed foods that are high in unhealthy fats, added sugars, and artificial additives may negatively impact both our physical and mental health.
However, it’s important to remember that other factors also influence mental health, including stress levels, exercise, sleep, and lifestyle habits.
Even though most foods nowadays are processed in some way and it is almost impossible to completely avoid them, making informed choices and trying to limit your intake can have positive long-term effects on both physical and mental health.
Frequently Asked Questions
Can ultra-processed foods cause depression?
Research has linked diets high in ultra-processed foods with depression, but this does not prove they cause it. Scientists are studying whether inflammation and changes in gut–brain communication could help explain this link.
What ultra-processed foods are worst for mental health?
There’s not one specific food that is the worst for your mental health. However, foods high in added sugars, salt, unhealthy fats and artificial additives may have the greatest negative impact. Examples include artificially sweetened drinks, instant meals and package snacks like potato crisps.
Is bread ultra-processed?
Pre-packaged bread that is mass-produced is considered an ultra-processed food as it has added sugars and artificial colours added to it. However, freshly baked bread is put into the processed food group, not the ultra-processed as it contains simple ingredients.
Are protein bars ultra-processed?
Proteins bars are considered an ultra-processed food, they often contain added sugar and extracted protein rather than natural protein. To increase their longevity, they usually have added ingredients such as added sugar, flavourings and stabilisers. Choosing bars with lower added sugar and shorter ingredient lists is a better option.
Can improving diet reduce anxiety?
A balanced diet may support mental wellbeing, although its effects on anxiety vary from person to person. Researchers are studying whether blood sugar regulation, inflammation, and nervous system function help explain the relationship between diet and anxiety.
What is the best diet for mental health?
The Mediterranean diet is often seen as a better diet for mental health. This is because it prioritizes whole, nutrient-dense foods which help reduce inflammation and balance blood sugars. This helps to support the gut-brain axis.
Co-authored by: Saoirse O’Donovan
You Might Also Be Interested in Reading: