Processed foods have certainly gotten a bad rap over the past few years, but most of the food we eat is processed to some degree – that is, unless you choose fresh, whole foods and eat them straight away, they’ve been cooked or stored to last longer, like canned or frozen fruits and vegetables and packaged rice.
But different types of foods are processed to different degrees. The most highly processed foods are often called ultra-processed foods (UPF). These are foods that have multiple added ingredients added through industrial processes that can’t be replicated in a home kitchen. Or, according to researchers in a new study published in September 2024, Lancet For example, UPF is an edible product that contains ingredients that enhance palatability, profitability and shelf life.
When we think of ultra-processed foods, we think of processed meats (hot dogs, deli meats, chicken nuggets, etc.), packaged snacks, packaged baked goods, ice cream, soda, frozen meals, etc. Most of these foods contain large amounts of added sugar, salt, and fat. Some use artificial sweeteners to replace sugar. Many also contain artificial colors, flavors, preservatives, stabilizers, and emulsifiers to achieve a certain look, texture, and taste.
The researchers say many UPFs may also contain compounds created during manufacturing and packaging. These include bisphenol A, a compound used to make plastics, and advanced glycation end products (AGPs), which form when sugars interact with proteins and fats in the bloodstream, especially when foods are cooked at high temperatures. While AGPs are difficult to avoid entirely, UPFs tend to be a major source of them, and they’re associated with increased risk of inflammation and chronic disease.
However, some UPF foods are considered good for you. For example, packaged breads and breakfast cereals are considered UPF, but some contain more fiber and less added sugar, salt and fat, as well as certain vegetarian processed foods, such as veggie burgers and non-dairy milks like almond milk, oatmeal and soy milk.
UPF is widespread in our society, accounting for 57% of the energy intake of U.S. adults, so the researchers in this study wanted to know if people who consume more UPF have a higher risk of cardiovascular disease (CVD), coronary heart disease (CHD), and stroke compared to people who consume less UPF. Here’s what they found:
How was this study conducted and what does it suggest?
The study consisted of two parts. In the first part, the researchers analyzed data from three large cohorts to see if there was an association between higher UPF intake and CVD, CHD, and stroke. In the second part, they performed a meta-analysis of previous studies on the topic. The researchers wanted to compare the results of these studies with what they found in the first part.
Data for the first part of the study came from the Nurses’ Health Study (NHS), the Nurses’ Health Study II (NHS II) and the Health Professionals Follow-up Study (HPFS). All three of these studies were longitudinal studies that followed nurses and health professionals over several years.
The NHS involved 121,701 female nurses, aged 30–55 years, started in 1976 and followed for an average of 32 years. The NHS II involved 116,340 female nurses, aged 25–42 years, started in 1989 and followed for an average of 26 years. The HPFS involved 51,529 men (aged 40–75 years), started in 1986 and followed for an average of almost 30 years.
To take part in the study, participants had to meet certain criteria, such as completing all relevant questionnaires and not having any CVD or cancer at baseline. After reviewing that information, a total of 206,957 participants across the three cohorts were included in the study.
Demographic information was collected, including race, age, marital status, employment status, smoking, physical activity, sleep duration, medications, family history, weight, height, and medical examination.
Participants completed a food frequency questionnaire every 2–4 years. Foods were categorized into four main groups: unprocessed/minimally processed, processed cooking ingredients, processed foods, and ultra-processed foods.
The UPF was categorized into 10 mutually exclusive groups: breads and cereals (further divided into subgroups: breakfast cereals, dark/whole wheat breads, refined grain breads), sauces, spreads, and condiments, packaged sweet snacks and desserts, packaged savory snacks, sugar-sweetened beverages, processed red meat, poultry, and fish, ready-to-eat/heat-and-eat mixes, yogurt/dairy-based desserts, hard alcohol, and artificially sweetened beverages.
Diet quality was determined using validated assessment methods. Total daily energy intake and UPF intake were calculated. Researchers also reviewed participants’ medical records for death certificates and medical records, specifically for CVD, CHD, and stroke (cardiovascular disease is a general term for any type of disease that affects the heart; coronary heart disease is a specific type of CVD that can clog arteries and increase the risk of heart attack and stroke).
After conducting multiple statistical analyses, the researchers found that higher total UPF intake was associated with higher risk of CVD, CHD, and stroke. Specifically, compared to individuals with lower total UPF intakes, individuals with the highest UPF intakes had a 17% higher risk of CVD, a 23% higher risk of CHD, and a 9% higher risk of stroke.
Certain foods were also associated with increased or decreased risk. For example, higher intakes of sugary beverages and processed meats were associated with increased risk of CVD, CHD, and stroke, and higher intakes of artificially sweetened beverages were associated with increased risk of CVD and CHD.
However, ultra-processed savory snacks (e.g., popcorn), cold cereals, and yogurt and dairy-based desserts were inversely associated with and associated with reduced risk of CVD and CHD, and ultra-processed bread and cold cereals were associated with a reduced risk of stroke.
The second part of the study involved a review and meta-analysis of 19 previously published cohort studies, which included 1,261,040 adults from around the world. That said, the researchers found that some of their findings were consistent with many previous studies, especially those that split UPF into subgroups. They also felt that some of the previous studies had some flaws, such as combining all UPF into one category.
How does this apply to real life?
News headlines often lump UPFs together, and while it’s true that consuming many of them on a daily basis, such as processed meats and sugary or artificially sweetened drinks, increases your risk of disease, some foods considered UPF may actually help promote your health. These include high-fiber foods like whole grain breads, cereals, popcorn, and yogurt.
But it’s also important to eat these foods wisely and read labels carefully: Some whole grain foods contain high amounts of added sugar, fat and salt.
This also applies to yogurt. Whether you choose Greek or regular yogurt, plain yogurt is usually best. This way you can add your own sweeteners, like honey or fruit, and you know exactly what’s in it. If you choose low-fat or nonfat yogurt, be aware that it likely has some sort of thickener added. If you want to avoid that, choose yogurt made with whole milk.
If you normally drink carbonated drinks, try switching to carbonated water and flavouring it with herbs or fruit for a flavourful, bubbly drink. Start by replacing one bottle of carbonated water a day, then gradually increase the amount you replace, to make the transition smoother.
If you like sandwiches, you can opt for egg salad, tuna salad, nut butter, or use last night’s leftover chicken or steak in your sandwiches. But if you simply enjoy the taste and convenience of deli meats, choose healthier varieties that are low- or no-sodium, have no added sugar, and contain no nitrates or nitrites (usually labeled “raw”).
Conclusion
Based on their findings, the researchers recommend limiting or avoiding carbonated drinks and processed meats due to their negative association with CVD, CHD, and stroke, and also recommending caution with sodium content, saturated fat, added sugars, and unnecessary artificial chemicals in potentially healthy UPFs, such as whole grain breads, cereals, and savory snacks.
