Neurological Implications of the Ultra-Processed Modern Diet
By Austin Perlmutter, MD
There’s no debating that our modern-day diets have dramatically departed from the foods our ancestors consumed. Changes in our food production systems and subsequently, the food we eat have had several effects, some of them positive. However, it has become abundantly clear that the highly processed form of food we consume throughout the day is a major risk factor for the development of most diseases. As it relates to the brain, this includes conditions like depression and dementia. In this article, we’re unpacking the neuroscience of how an ultra-processed diet is affecting our brains. We’ll explore mechanisms including metabolic impacts, inflammation, and the impact on the gut-brain connection. We’ll cover the latest research, and I’ll be sure to give you lots of information on what to do about it.
Background
Over the last decades, as the population in America grew, there was a strong desire to produce cheap, shelf-stable, calorically dense, ready-to-eat and highly palatable foods. Coupled with advances in industrial technologies, food companies began to create new products to meet a growing demand from the public. These new foods replaced the previous foods at a rapid clip, and they have now become the mainstay of our diet.
Data from a 2009-2010 survey of over 9000 people in the United States found ultra-processed foods make up about 60% of our calorie consumption and over 90% of our added sugar intake. This trend is international and affects all age demographics. For example, in a 2024 analysis of toddlers in the United Kingdom published in the European Journal of Nutrition, it was found that ultra-processed foods made up about 47% of calorie intake at 21 months, a number that increased to nearly 60% by age 7. These trends are also on the rise. Comparing data from 1999 to 2018 in the United States for youth, energy intake from ultra-processed food rose from 61 to 67%.
When we consider that our brains and bodies are made of the molecules in the food we consume, we recognize that we are increasingly made from ultra-processed food.
What is an ultra-processed food?
Definitions of ultra-processed foods (UPFs) vary somewhat, but by and large these are foods that can’t be made in the typical kitchen, as they’re highly refined, made using industrial processes and contain additives and other ingredients that enhance shelf stability and palatability. They tend to be rich in sugar, salt, protein isolates and fats, as well as colorings, emulsifiers and flavorings. Popular examples include breakfast cereals, most snack foods, processed meats and frozen meals. Additionally, sugar-sweetened beverages (like energy drinks, soda and coffee drinks) are considered UPFs.
What do ultra-processed foods do to general health?
A higher consumption of ultra-processed foods has been linked to excess weight gain, obesity, type-2 diabetes, high blood pressure, stroke, heart disease, cancer, early death and much more. In a telling 2024 umbrella review published in the journal BMJ, eating more UPFs was associated with a 21% increased risk of dying early of any cause, and a 66% increased risk for dying of heart disease.
What brain-specific conditions are linked to consumption of UPFs?
Eating more UPFs has been deemed a key risk factor for the development of a host of brain-specific issues. For example, a May 2024 publication entitled “Associations Between Ultra-Processed Food Consumption and Adverse Brain Health Outcomes” in the journal Neurology found that higher consumption of UPFs correlated with higher risk of cognitive impairment and stroke, while people eating the opposite (a diet low in UPFs) were at a lower risk for each of these outcomes. In a cohort study published in the journal JAMA Neurology in 2023, it was found that people eating more UPFs had a 28% faster rate of cognitive decline as the aged, and a 25% faster rate of loss of higher-level thinking.
In addition to more rapid cognitive decline, stroke and overt dementia, eating more UPFs appears to negatively impact mood. A 2024 systematic review from Brazil looked at nearly 16.000 people for roughly 1.5 years and found that every 10% increase in UPFs was linked to a 10% increase in depressive symptoms. They also found that those with the highest versus the lowest exposure to UPFs were at a 32% increased risk for having depressive symptoms.
The effects of UPFs on brain metabolic health
Despite weighing only 2-3 pounds, the brain uses an astonishing 20% of our body’s energy in the form of primarily glucose. A host of studies over the last decades have revealed strong links between impairments in brain energy access and risk for cognitive decline and dementia. This helps explain the higher risk for dementia in those with poorly controlled diabetes. Eating UPFs appears to have a direct correlation with risk for development of type 2 diabetes and ensuing metabolic dysfunction. In research published in 2024 in The Lancet, those with higher UPF consumption were at a 50% higher risk for developing diabetes, and every 10% increase in UPF increased risk for developing diabetes by 12% in a linear fashion. Important new animal data from 2024 published in Molecular Metabolism shows that a UPF diet leads to changes in brain metabolism. This suggests that dietary UPF consumption links to worse brain health by damaging overall metabolic health and damaging healthy brain metabolism.
The impact of UPFs on gut health and brain inflammation
Chronic inflammation in the body is a top driver of death and disability around the world. This is because health states associated with chronic inflammation range from diabetes to cardiovascular disease, cancer, obesity and far more. As it relates to the brain, chronic inflammation is believed to contribute to dementia, mood disorders, neurodevelopmental disorders and premature aging of the brain, along with stroke.
Key to our understanding of how chronic inflammation develops in the brain and the body is the state of our gut health, as this is a principal site where our immune system is exposed to microbes and the outside world. Research suggests that UPF may trigger chronic brain inflammation through metabolic dysfunction as well as through alterations in the gut. This appears to be a reflection of both the unhealthy ingredients in UPF (for example, added sugar, artificial sweeteners, colorants and preservatives) as well as the lack of gut and immunity-supporting nutrients that are typically missing in UPF (healthy fats, vitamins, minerals and polyphenols). An unhealthy diet rich in UPFs is may contribute to a more “leaky” gut membrane and increased inflammation within the gut. This may lead to a more “leaky” blood brain barrier which could promote brain inflammation, helping to explain the correlations between mental and cognitive issues and UPF consumption.
How to fight back against UPFs to protect your brain
Whether it’s through metabolism, inflammation, gut-brain dysfunction or other pathways, the bottom line is that UPFs are a bad choice for brain health. Yet so much of our modern world is designed to make UPFs the default option and therefore challenging to avoid. The good news is that we can each take steps to decrease our consumption of UPFs and increase consumption of foods that can stabilize metabolism, decrease chronic inflammation and repair the health of the gut-brain connection. Here are 4 central tools to aid in this process.
Read the ingredient list and nutrition facts.
Reading ingredient lists is an invaluable practice for reducing the consumption of ultra-processed foods and making healthier choices. By understanding what goes into your food, you can better avoid items laden with additives, artificial flavors, preservatives, and excess sugars or fats. Opting for products with shorter, recognizable ingredient lists often means choosing foods closer to their natural state. To make the most of this habit, aim to prioritize foods with whole, minimally processed ingredients and steer clear of items with lengthy lists or unpronounceable components. Developing this practice not only enhances your food literacy but also supports mindful eating and healthier habits. In addition, be sure to check out the nutrition facts on the back of your food and try to avoid anything with added sugar. Added sugars can come in the form of high fructose corn syrup, dextrose, sucrose, cane juice and more, so it’s often easier to simply decrease or eliminate foods with any added sugar.
Make/supply your own food
One of the most powerful methods of fighting back against consumption of UPFs is as simple as cooking more. Preparing meals from scratch allows greater control over ingredients, ensuring that more whole foods like fresh vegetables, fruits, whole grains, lean proteins, and healthy fats make it onto the plate. This approach not only promotes better health but also helps to cultivate mindful eating habits. To make home cooking easier, plan meals ahead of time, batch-cook for busy days, and stock your kitchen with versatile ingredients like dried herbs, legumes, and frozen produce. Preparing simple dishes like stir-fries, soups, and sheet-pan meals can make nutritious home-cooked meals more accessible and enjoyable. A pressure cooker is also a highly efficient way to improve access to quick, healthy food. Finally, bringing healthy snacks with you to places you might otherwise buy and eat UPFs is an amazing way to decrease reliance on less healthy options.
Adopt a Mediterranean or minimally processed diet
Adopting a Mediterranean or minimally processed diet can significantly boost cognitive health and reduce the risk of neurodegenerative diseases. The Mediterranean diet emphasizes abundant fruits, vegetables, whole grains, lean proteins such as fish, and healthy fats like olive oil and nuts. These nutrient-dense foods contain key brain-active polyphenols, omega-3 fatty acids, and essential vitamins and minerals that help reduce inflammation metabolic dysfunction, two key factors associated with cognitive decline. Incorporating more whole, minimally processed foods into your diet while limiting refined sugars and unhealthy fats supports brain function, memory, and overall well-being. If you’re not sold on adopting any specific diet, it can be helpful to simply move towards eating more single ingredient foods and away from packaged foods.
Say no to the worst ultra-processed foods
Eating one unhealthy meal is unlikely to have any major impact on your long-term brain health. But over time, UPFs start damaging metabolism, negatively impacting the gut-brain axis and promoting chronic inflammation. This means if you occasionally eat some UPFs, it’s probably not a big deal, but if they become a major part of your diet (as they are for most Americans) you are setting yourself up for issues. Within the category of UPFs, some are worse than others. To this end, here are some UPFs exceptionally worthy of targeted removal from your diet:
Sweetened beverages like soda, energy drinks and fruit drinks (especially with added sugar, but also look out for artificial sweeteners)
Breakfast cereals
Packaged baked goods
Fast foods
Processed meat products
Most processed snack foods (chips, cookies, etc)
Candy
Artificially sweetened foods