It is now widely believed, in leading medical/scientific organizations across the world, that processed (and, particularly, ultraprocessed foods) represent one of the major health dangers of our time.

Ultraprocessed foods are metabolic disruptors that act to increase adiposity, reduce mitochondrial efficiency, drive insulin resistance, alter growth, and contribute significantly to human morbidity and mortality. The number of high-incidence and often chronic disease states that have greatly increased in scope and severity due to higher consumption of such ultraprocessed foods is truly mind-boggling: diabetes, heart disease, obesity, kidney disease, liver diseases, dementias, and so many other disease states.

But what are processed and ultraprocessed foods? And which ones are the worst for your health? Here, we’ll explain what you need to know about processed foods, how they impact health and disease, and which dietary choices you can embrace to replace them and live longer and with fewer health problems.   

What is processed food, and how much do we consume?

In the broadest terms, processed food is a food that has been altered from its natural state, usually in the form of freezing, canning, baking, or drying, and often involving the addition of ingredients, preservatives, and other treatments to extend shelf life, enhance flavor, or improve texture. These foods can range from minimally processed items like pre-cut vegetables or roasted nuts to highly processed products (sometimes referred to as “ultraprocessed”) such as sugary snacks, frozen dinners, sauces and condiments, and sugary drinks. When foods are pumped with salt, sugars, fats, additives, preservatives, and artificial coloring, they move to the heavily processed or ultraprocessed category.

Processing can involve several techniques, such as:

Mechanical processing: Involves physical actions like cutting, grinding, or milling to change the texture or form of the food.

Chemical processing: Includes the addition of chemicals for various purposes, such as preservatives to extend shelf life, colorants to enhance appearance, and flavor enhancers to improve taste.

Heat treatment: Cooking, baking, frying, and other heat-related processes are used to alter the flavor, texture, and safety of foods.

Addition of additives: Additives like stabilizers, emulsifiers, and thickeners are used to modify the texture and consistency of foods.

Refining: This process often involves removing certain parts of whole foods to create products like white flour or refined sugars.

Consumption of ultraprocessed foods has risen substantially. Ultraprocessed foods account for more than 50% of daily caloric intake in several high-income countries, including the U.S. Shockingly, ultraprocessed foods account for 90% of the added sugars we consume, according to a separate study. Worse, ultraprocessed food consumption appears to have risen during the COVID19 pandemic and associated lockdowns.

Why isn’t processed food healthy?

While some level of processing is necessary for safety and convenience (e.g., pasteurization of dairy products or canning of vegetables), highly processed foods are rarely healthy because of:

Nutrient loss: Processing can lead to the loss of essential nutrients, such as vitamins, minerals, and fiber.

High levels of added sugars, salt, and unhealthy fats: Many processed foods are laden with added sugars, excessive salt (sodium), and unhealthy trans fats, which can contribute to various health issues such as obesity, diabetes, and heart disease.

Heat-altered proteins and lipids: The heat treatment so prevalent in modern food production (including the use of high temperatures, high pressure, dehydration, decompression, irradiation, salt, and preservatives to extend shelf life and palatability) significantly alters proteins and lipids, forming new substances that include detrimental advanced glycation end-products (AGEs).

Low satiety: Processed foods often lack the fiber and protein needed to provide a feeling of fullness, potentially leading to overeating.

Additives: Some food additives used in processing may have uncertain long-term health effects.

Low diet diversity: Relying heavily on processed foods can lead to a less varied diet, leading individuals to miss out on essential nutrients found in whole foods.

In all fairness, not all processed foods are unhealthy. Some minimally processed foods, such as frozen fruits and vegetables, typically retain much of their nutritional value and are convenient options for busy individuals. The key is to make informed choices by reading labels, understanding the ingredients, and striving for a balance between minimally processed and whole foods in your diet.

What diseases are linked to processed foods?

Processed and ultraprocessed foods have been linked to a range of adverse health effects such as overeating, higher body fat percentage, excessive production of advanced glycation end-products (AGEs) leading to inflammation and oxidative stress, gut dysbiosis, and hemodynamic and metabolic dysfunction, including poor glucose regulation. These impacts correlate strongly with the incidence, development of and exacerbation of a host of diseases and disorders, most notably: 

Diabetes: A five-year study involving more than 20,000 participants showed that an increase in ultraprocessed foods is associated with a significant increase in risk of developing type 2 diabetes (T2D). While the exact mechanisms are still being studied, it appears that processed foods amp up the body’s glycation process, which then produces abnormally high levels of advanced glycation end-products (AGEs), substances that promote oxidative stress and inflammation by binding with cell surface receptors or cross-linking with body proteins, altering their structure and function. Detrimental impacts included elevated blood glucose (hyperglycemia), hyperlipidemia, and reduced insulin sensitivity — the hallmarks of diabetes risk, incidence and progression to a whole host of diabetic complications.

Cardiovascular and other chronic non-communicable diseases: As in the case of diabetes, AGE production — elevated by consumption of ultraprocessed foods — appears to be one of the major causes of the formation of areas of calcification and the formation of blood clots in the walls of the arteries. In this way, AGEs are involved in the aging of blood vessels and their numerous damages. This mechanism, along with others, links the high consumption of processed foods to a bevy of cardiovascular abnormalities, including atherosclerosis, hypertension, and dyslipidemia (elevated triglycerides and an unfavorable balance between “bad” and “good” LDL/HDL cholesterol levels), all of which contribute to cardiovascular disease (CVD), stroke, and many other chronic, degenerative diseases, including kidney diseases. 

Neurodegenerative diseases: Akin to what occurs in the development of diabetes and cardiovascular disorders, the risk for vascular dementia appears to rise significantly from diets characterized by high consumption of ultraprocessed foods, in part because of the link to chronically high blood pressure, which causes arteries to stay narrow and restricts the brain’s blood supply. The mechanisms behind this action are still being elucidated, but groundbreaking research out of the UK (August 2023, PNAS) has shed much light on the process. Complementing these findings are the growing number of studies, including one published in May 2023, that have demonstrated that diets low in such processed foods and higher in “green leafy vegetable intake” (e.g., the MIND and Mediterranean diets) are associated with less postmortem Alzheimer’s disease pathology, primarily β-amyloid load. The risks for Alzheimer’s disease, ALS and Parkinson's all appear to rise with ultraprocessed food intake, possibly related to detrimental impacts of elevated AGE levels and the latter’s tendency to promote oxidative stress and inflammation. 

Obesity: Many prospective cohort studies have demonstrated strong linkage between higher consumption of ultraprocessed foods and greater risk of overweight and obesity. These findings are supported by a recent clinical trial which found that ultraprocessed food consumption causes excessive energy intake and weight gain.

Digestive disorders: A 2023 review declares that AGEs, which are elevated by consumption of a high-processed-foods diet, markedly alter gut structure, “leading to increased intestinal permeability and reduced expression of enteric neurons, as well as to reshaping the microbiota composition.” Researchers further postulate that inflammatory bowel disease (IBD), an umbrella term that encompasses both ulcerative colitis and Crohn’s disease, is one of the major gut disorders that is likely exacerbated (if not directly caused by) the direct effects of AGEs, although IBD’s causes are likely multifactorial. 

Certain cancers: A 2023 study published in Lancet detailed results of a large UK-based cohort study, which found that higher consumption of ultraprocessed foods is strongly linked to an increased burden and mortality for several cancers, especially ovarian cancer in women and, to a lesser but still significant extent, breast cancer.

The above list isn’t even comprehensive. Ultraprocessed food consumption has also been linked to non-alcoholic fatty liver disease (NAFL), polycystic ovarian disease, osteoporosis, osteoarthritis, depression and other mental illnesses, and even infertility.

The worst processed foods bad for your health

You can probably rattle off some clearly processed foods: examples include candy bars, cookies, and anything on a drive-thru menu. But frozen carrots, whole wheat bread, and canned beans — all things we’d file in the “healthy” category — are also highly processed. The only foods that are truly unprocessed are those eaten straight from the ground, with little to no manipulation by the time it ends up on your plate.

Any food that’s cooked, canned, frozen, or packaged is technically considered processed. That said, the level of processing matters. Minimally processed foods, like a bag of spinach or frozen blueberries, should still be part of a healthy diet because they aren’t loaded with sugar, salt, or fat.  

Common ultra-processed foods to avoid at all cost

You’ve heard the saying, “Shop near the edges of the grocery store” … and for the most part, that’s the easiest way to avoid ultraprocessed foods. 

Disturbingly, more than half of what we eat is ultraprocessed. Even still, there’s more discerning to do. Whole wheat bread has added sugar and salt (and coloring to make it brown!), for instance, but it’s still a way better option than white bread, which is loaded up with even more sugar and salt.

Examples of ultra-processed foods that are the least healthy:

• White bread
• Sugar-sweetened beverages (like Coke)
• Sugar-sweetened breakfast cereals
• Hot dogs
• Potato chips
• Packaged cookies
• Bottled sauces such as ketchup

How to limit your processed foods consumption

If you want to limit the amount of highly processed foods in your diet, it’s going to take some work. Here are some strategies to make it easier:

• Up your consumption of whole foods, especially those that are plant-based: The science shows that if you increase your consumption of fruits, vegetables, whole grains, legumes and nuts, you will not only reap the health rewards associated with their beneficial fibers (including prebiotic fibers), polyphenols and other nutrients, but you will also likely lower your consumption of highly processed foods. 
  
  
• Instead of counting carbs, assess their quality: Whether you are an individual with diabetes, or a relatively healthy teen or adult hoping to lose weight or just best maintain health, you may have heard or been told that you should limit your intake of carbohydrates. While carb-counting remains a distinct feature of many recommended dietary strategies, especially for those with diabetes (and endorsed by the American Diabetes Association), newer research points to the greater benefit of assessing the quality, rather than the quantity, of carbohydrates consumed. In fact, it has been shown that total carbohydrate intake is not associated with CVD outcomes. Rather, it is higher free sugar intake that is associated with higher CVD incidence and higher triglyceride concentrations within all lipoproteins. And where does free sugar come from, largely? Processed foods, and to a lesser extent pure sugars (agave, honey, table sugar). Conversely, “higher fiber intake and replacement of refined grain starch and free sugars with whole grain starch and non-free sugars, respectively, may be protective for incident CVD.”

• Cook more at home: When you make your own meals, you control how much sugar, fat and salt gets added to a dish. By starting with mostly healthy ingredients, like fresh veggies and minimally processed grains, your meal will most likely be healthier than if you ate out. Restaurant meals are often much larger than a normal serving and are often loaded with sugar, salt, and fat. When you do eat out, you’ll never fully know how much has been added to a meal, but aim to have more veggies on your plate and foods that are baked, not fried.
  
  
• Watch out for gimmicks: Many foods labeled “healthy” or “natural” might in fact be heavily processed. Why? The FDA doesn’t strictly police how brands can use these words on their packaging, so you could be thinking you’re making a smart choice when, in fact, it’s not as healthy as you think.
  
  
• Learn to read labels: You can get around gimmicky packaging by understanding how to read food labels. You can start by looking at how much sodium and added sugar a food has. That’s often your first clue that a food is more processed. Most adults should limit sodium to less than 2,300 mg per day. For sugar, aim for less than 100 calories (or 24 grams) per day for women and less than 150 calories (36 grams) for men. For those with diabetes, you should always check with your healthcare professional to make sure you have the right targets for you.
  
  
• Look at the ingredient list: Beyond just reading labels, look at the ingredients in packaged foods. Anything ending in “-ose” is a dead giveaway for sugars such as fructose, sucrose, glucose, maltose, etc. Those are all sneaky names for added sugar.  

Key takeaways

Many foods are processed these days, but you can aim to consume more minimally processed foods while avoiding most ultraprocessed foods high in added sugars, salt, and unhealthy fats. Instead, focus consumption on lean proteins, fruits and veggies, legumes, whole grains, and healthy fats such as those from plant foods (e.g., avocadoes, nuts) and fatty fish (such as salmon). By adjusting your diet in this way, you will be in a better position to lower your blood sugar levels, improve your lipid levels, and reduce the effects of oxidative stress and inflammation so increasingly implicated in diseases such as diabetes, heart disease, kidney and liver diseases, obesity, digestive disorders, ovarian and breast cancers, neurological disorders (such as Alzheimer’s), and more.