Processed Foods
A more nuanced approach to the emerging research on this topic.
The conversation surrounding processed and ultra-processed foods (UPFs) is constantly evolving. As with most things, the topic of food processing and its impact on our health has become quite polarizing. Some claim that processed foods are squarely responsible for an increase in obesity, cardiovascular problems, and even cancer. While others (including some of us) have said they pose no threat to human health. In reality, the “truth” lies somewhere in the middle. In this newsletter, we will unpack some of the latest research and help you make informed decisions for a balanced dietary approach. While occasionally eating processed (and even ultra-processed foods) is totally fine, processed foods should not comprise the majority of our diets. This conversation is complicated by many factors including access to nutrient-dense foods which must be considered (processed foods tend to be less expensive and easier to access for many people), as well as undue guilt and shame which can lead to food anxiety and even disordered eating. We hope you appreciate this reframed, more nuanced approach to the conversation surrounding processed foods.
Main takeaway: Research on processed and ultra-processed foods is continuously ongoing. Current evidence is largely based on observational studies and self-reported data that are prone to bias and likely do not properly control for confounding variables (i.e. an unmeasured variable(s) that influences both the supposed cause and effect). The reality is that this is a nuanced discussion as it's important to understand what foods are considered UPFs, why many people are over-consuming UPFs, to balance the reality of personal/family finances, and to ensure we do not further fuel disordered eating. Unfortunately, many studies are being taken out of context and picked up by major media outlets to spread fear, guilt, and shame. Processed foods are not inherently harmful, but there are important considerations including hyperpalatability (they are delicious to eat), the ease for which overeating can occur with UPFs, the caloric density of UPFs, the reduced calorie thermic effort* to digest UPFs (processed food is easier to digest than whole food calorically), and the proportion of UPFs in our diet overall.
Note: An experimental study showed a 50% reduction in postprandial energy expenditure following consumption of ultra-processed foods, compared with unprocessed iso-caloric foods, though it is worth noting that a meta-analysis found no association between satiety (the sensation of fullness) and thermic efforts. More research is needed on this potential mechanism of action.
Unprocessed, Minimally Process, Processed vs. Ultra-Processed: What's the Difference?
The Nova Food Classification System created by a group of scientists in Brazil, is a commonly used way to organize foods according to the extent and purpose of the processing they undergo. Food processing as identified by NOVA involves physical, biological, and chemical processes that occur after foods are separated from nature, and before they are consumed or used in the preparation of dishes and meals”.
Group 1:
Unprocessed foods are obtained directly from plants or animals and do not undergo any alteration following their removal from nature (e.g. fruit, vegetables, eggs, meat, milk, etc.)
Minimally processed foods are natural foods that have been submitted to cleaning, removal of inedible or unwanted parts, fractioning, grinding, drying, fermentation, pasteurization, cooling, freezing, or other processes that may subtract part of the food, but which do not add oils, fats, sugar, salt or other substances to the original food.
Group 2:
Foods processed in the kitchen or culinary food ingredients are products extracted from natural foods or from nature by processes such as pressing, grinding, crushing, pulverizing, and refining. They are used in homes and restaurants to season and cook food and thus create varied and delicious dishes and meals of all types, including broths and soups, salads, pies, breads, cakes, sweets, and preserves. Uses oils, fats, salt, and sugar in small amounts for seasoning and cooking foods and to create culinary preparations. As long as they are used in moderation in culinary preparations based on natural or minimally processed foods, oils, fats, salt, and sugar contribute to diverse and delicious diets without rendering them nutritionally unbalanced.
Group 3:
Processed foods are the foods obtained by combining foods of groups 1 and 2 to obtain the many food products for domestic use (bread, jams, etc.) made up of a few ingredients. These are products manufactured by industry with the use of salt, sugar, oil, or other substances (Group 2) added to natural or minimally processed foods (Group 1) to preserve or to make them more palatable. They are derived directly from foods and are recognized as versions of the original foods. They are usually consumed as a part of or as a side dish in culinary preparations made using natural or minimally processed foods. Most processed foods have two or three ingredients.
Group 4:
Ultra-processed foods are industrial formulations made entirely or mostly from substances extracted from foods (oils, fats, sugar, starch, and proteins), derived from food constituents (hydrogenated fats and modified starch), or synthesized in laboratories from food substrates or other organic sources (flavor enhancers, colors, and several food additives used to make the product hyper-palatable or able to be stored for a long time). Manufacturing techniques include extrusion, moulding, and preprocessing by frying. Beverages may be ultra-processed. Group 1 foods are a small proportion of, or are even absent from, ultra-processed products.
Image adapted from the Nova Food Classification System.
Generally, researchers and academics agree on which foods belong in which category, based on their degree of processing. Building this type of consensus is an important step within the research process, but does it translate into the real world? Not necessarily.
Take, for example, Group 4. Within this classification of “ultra-processed” we find distilled spirits (alcohol), which most would probably agree doesn’t offer much in the way of nutrition. Alcohol is one of the few things we know is associated with negative health outcomes, including certain types of cancer. However, Group 4 also includes infant formula, something many parents rely on to adequately feed and nourish their children when breastfeeding is, for any reason, not an option. Proper nutrition in the “First 100 Days” of life is a key predictor for future health outcomes and preventing malnutrition, stunting, and cognitive developmental delays.
There’s also an important caveat for Group 4 foods: exceptions exist for the fortification of certain foods, such as flour, with nutrients such as iron (ferrous sulfate), and B vitamins like folic acid, and thiamine. If these nutrients are added alone, the classification changes to “minimally processed foods” and instead belongs in Group 1 per the NOVA criteria. This “fortification” is a very important part of public health measures as they provide sources of elements and vitamins critical to human health, but are not necessarily prevalent in our foods to the degree necessary to meet our daily recommended allowances or to support health conditions like pregnancy.
The Bottom Line: the NOVA classification system indicates the degree of processing a food undergoes, not how nutritious it is or isn’t. In other words, we shouldn’t consider it a proxy for how “healthy” a food may be.
Why should I care about whether food is processed or not?
Health Concerns and Hype
Growing research links diets high in ultra-processed foods with potential health risks like obesity, increased risk of cardiovascular disease, renal disease, type 2 diabetes, cancers, impaired gut health, poorer mental health, cognitive impairment, and other chronic diseases.
It's important to remember: that it's not just the presence of processed foods but the overall pattern of your diet that matters.
A recent study published about the connection between ultra-processed foods and negative health effects has received a lot of attention. The study examined people who consumed more ultra-processed foods and the health issues they experienced.
What did the study show?
This is the largest meta-analysis to date evaluating the link between ultra-processed foods and health outcomes. The review looked at 32 health outcomes, 13 of which included both a dose-response analysis and comparing high versus low intake (the remaining 19 only included comparing high versus low intake).
For 9 of the 32 outcomes, there was strong evidence (which the authors grade as highly suggestive or convincing) of a link to high ultra-processed food intake, including the risk of all-cause mortality, cardiovascular disease-related mortality, heart disease-related mortality, type 2 diabetes, anxiety, depression, common mental disorders, sleep problems and wheezing (Figure 1).
For 10 of the 32 outcomes, there was no link with ultra-processed food intake, including cancer mortality, breast cancer, central nervous system cancer, chronic lymphocytic leukemia, prostate cancer, pancreatic cancer, asthma, high serum triglycerides, ulcerative colitis, and hyperglycemia.
For the remaining 13 outcomes, there was weak evidence of a link, including cancer overall, colorectal cancer, cardiovascular disease events, cardiovascular disease morbidity, high blood pressure, low HDL cholesterol, Crohn’s disease, abdominal obesity, metabolic syndrome, non-alcoholic fatty liver disease, obesity, overweight, and overweight+obesity (Figure 1).
Figure 1: Overall adverse outcomes evidence for many of the studies analyzed by evidence quality & credibility. Overall, found that 32 of the 45 pooled analyses (71%) noted higher risks of adverse health outcomes with higher dietary exposure to ultra-processed foods.
Recreated from: Lane M M, Gamage E, Du S, Ashtree D N, McGuinness A J, Gauci S et al. Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses BMJ 2024; 384:e077310 (Copyrights April 2024). Studies found to have no evidence of the impact of UPFs on adverse outcomes are not included.
Key: CVD = cardiovascular disease, HTN = hypertension, HDL = high-density lipoprotein
Limitations
Observational Design: This study is observational, meaning it can only establish associations, not direct cause-and-effect. There may be other factors (confounding variables) that researchers could not account for that could explain the observed link between ultra-processed foods and health outcomes.
Dose-Response Analysis Was Not Performed: Several prospective studies looking at ultra-processed food intake have shown a cusp for negative health impact at about 4 servings of ultra-processed foods per day, or at about 20% of total calories. Because this meta-analysis did not include a dose-response evaluation, it’s not possible to state at what level of intake ultra-processed foods pose no risk to health.
Self-Reported Data: Participants self-reported their dietary intake, which can be subject to inaccuracies and underreporting.
Definition & Classification of Ultra-Processed Foods: There's some variation in how ultra-processed foods are defined and classified, which could impact the consistency of results across studies.
Potential Confounding Factors: While the study adjusted for certain factors like socioeconomic status and physical activity, other unmeasured lifestyle habits or health conditions might also play a role and could not be completely ruled out (e.g. smoking, alcohol intake, sleeping patterns, etc).
Long-Term Effects: This systematic umbrella review of existing meta-analyses provides data on specific time periods as captured in the various studies that were included for analysis, but might not fully capture the potential long-term effects of a diet high in ultra-processed foods. Extrapolation of such varied study periods might be difficult to do definitively.
Conclusion
The researchers recommended that more studies are needed to fully understand how ultra-processed foods impact health and highlighted the need to better illuminate the mechanisms by which UPFs directly impact humans.
Beyond the Label: Hyperpalatability & Diet Composition
Ultra-processed foods are often engineered to be super delicious and convenient, making it easy to overeat them and more readily available so that we can grab and go at any time in our hectic lives. When advising patients on realistic and sustainable dietary goals, one should ideally limit the proportion of ultra-processed foods in their diet while prioritizing whole, minimally processed foods. In reality, we all live very busy lives and have varying access (both financially and physically) to unprocessed or minimally processed foods and as such adding some processed food(s) will be an essential part of any food pattern and can still be nutritionally adequate.
A linear programming analysis showed that while foods that fall into the NOVA ultra-processed foods category were indeed principal sources of added sugar, sodium, and fat, they were also major contributors of vitamin E, thiamin, niacin, folate, and calcium, and the main contributors of plant protein. The objective of this study was to illustrate how to minimize the cost associated with obtaining food and satisfying the specific nutritional requirements we need in our diets to live healthfully. Plant proteins for example are provided by grain-based products, which fall into the ultra-processed category, but can be critical to optimal health. What is key to take away, is that we are all balancing as best we can the nutritional needs we have with not only access to healthy, whole food options but also the realistic budgets we have to spend on our overall diet - while still achieving the healthiest constellation for ourselves and our families within those constraints.
Many of us opt for supplements or “green powders” to enrich our diets, but we have to remember that those are processed foods as well, and may have limited value as their effects are not always quantified, and are not regulated by the FDA. Therefore, the actual amounts of the vitamins, minerals or other substances may not be validated or consistent. It is better to opt for whole foods when possible, but more nuanced studies are needed to understand the contribution of fortified foods and the differing types of UPFs on our overall health.
Addressing Challenges: Cost, Access, and Food Anxiety
We recognize that healthy eating can be impacted by budgets and limited access to fresh foods. Fear-mongering about processed foods is not only unhelpful in changing the behaviors of many people, but it can be in fact harmful as this can lead to unnecessary shame and anxiety around food choices. A disproportionate focus on processed food has the potential to meet the criteria for disordered eating and/or clinical eating disorders. While diagnostically undefined, orthorexia is commonly recognized as an unhealthy obsession with healthy eating.
According to a 2023 analysis, 73 percent of the U.S. food supply is ultra-processed (other studies have shown similar and/or lower numbers); and, on average, those ultra-processed foods are 52 percent cheaper than their minimally-processed counterparts. In a time when people are working hard to provide for their families and have limited time to prepare meals and limited financial resources to buy food - governments, scientists, and healthcare professionals cannot continue to provide such confused, conflicting, and shameful guidance.
Currently, the topic of UPFs is under review by the 2025 Dietary Guidelines Advisory Committee. Without a more objective conversation about the safety of processed foods and their role in human health, it is possible that some nutrient-dense foods may be discouraged if processing levels are incorporated into updated dietary guidelines without careful consideration and discussion. For instance, the following foods are classified as “ultra-processed” according to NOVA criteria but may be allowable under food assistance programs such as Women Infant and Children (WIC) and Supplemental Nutrition Assistance Program (SNAP): fruit-flavored yogurt with low or no added sugar, ultrafiltered milk, soymilk, canned fruits and vegetables with preservatives, packaged whole wheat bread, peanut butter, and tofu.
Finding Balance: A Practical Approach
Not all processed foods are created equal – some can be part of a healthy pattern. The key is moderation. The way you reach a nutritional goal is how you can sustain and keep it. If getting to a healthy outcome is impossible to sustain (e.g. excessive fasting, shakes as entire meals, ultra-restrictive diets), it will be impossible to maintain. If adding in some processed foods helps you eat your fruits and veggies, or it helps with providing a satisfying taste or experience and fulfills your nutrient and caloric needs, then it is a healthy option.
Working with a certified dietician, nutritionist, or other professional (Academy of Nutrition and Dietetics: eatright.org) who can provide balanced advice about your diet that also fits the reality of your budget is great (if you have access and can afford this). There are also many very reputable social media science communicators (including this newsletter’s co-authors!) and online programs that you can reference for free as well. Tips that are often given by reputable dietary advisors include planning your meals ahead of time, looking for budget-friendly whole-food recipes, and having diversity on your plates including a balance of protein, carbs, veggies, and fruits as part of your meals as much as possible, diversify and try new foods whether fresh, dried, frozen or even canned if it’s more affordable, avoiding extreme dieting programs (unless medically advised) as they simply are not sustainable, and prioritizing your overall well-being, not food labels and calorie counting.
Stopping the Shame and Guilt!
Occasionally indulging in ultra-processed foods like snacks or treats is perfectly fine. Don't feel guilty about enjoying them from time to time! The key to healthy eating is recognizing overall dietary patterns, not obsessing over individual food choices. A balanced diet allows for both nutritious choices and the occasional treat.
It has been shown in one study that it is possible to build a nutritionally adequate diet even if the majority of foods are UPFs. The study found that “healthy dietary patterns can include most of their energy from UPF, still receive a high diet quality score, and contain adequate amounts of most macro- and micronutrients.” We would not necessarily recommend this approach, but wanted to highlight that there are many different ways to achieve a healthy diet and it can meet the personal needs and budgets of each of us individually.
Key takeaways:
We all have differing food preferences, nutritional needs, financial budgets, and access to diverse types of foods. Instead of shaming or scaring people (which happens all too often on social media), it is better to seek out good nutritional communicators online and to talk to healthcare providers particularly nutritionists/dieticians who can help you find what works for you given the challenges you face.
Simply saying that ultra-processed foods are “bad for you” is not helpful nor is it accurate. Research is ongoing but while there is some evidence that diets high in UPFs may have negative impacts on your health, we do not need to panic if we occasionally consume them. It is also critical to note though, that UPFs are in fact an important part of a balanced diet from infancy and throughout adulthood.
Healthy eating is about finding balance. It's more important to focus on the overall quality of your diet than merely eliminating all processed foods, as this is very difficult for most people to achieve and maintain.
Contributing Authors:
Cara Harbstreet, MS RD LD is a registered dietitian and the owner of Street Smart Nutrition with nearly a decade of experience in the field. As an advocate for fearlessly nourishing meals, she promotes nutrition for the real world, not the ideal world, through frequent contributions to print and digital media and her active social media platforms: Instagram, TikTok, YouTube, and online at Street Smart Nutrition.
Michelle Bridenbaker, RN, BSN, MSDipTox, MBA has worked as a biologist, medical writer, pharmacy technician, advanced practice critical care/cardiac care nurse, diabetic educator, toxicologist, drug safety specialist, and medical information & communications expert in pharma/biotech. She has worked tirelessly to educate patients and healthcare professionals to improve patient care & overall health.
Dr. Sarah Ballantyne, PhD is the founder of Nutrivore.com and New York Times best-selling author of Nutrivore: The Radical New Science for Getting the Nutrients You Need from the Food You Eat. She creates educational resources to help people improve their day-to-day diet and lifestyle choices, empowered and informed by the most current evidence-based scientific research. With Nutrivore, Dr. Sarah has created a positive and inclusive approach to dietary guidance, based in science and devoid of dogma, using nutrient density and sufficiency as its basic principles: Nourishment, not judgment. Links to Dr. Ballantyne’s social media pages: TikTok, Threads, Instagram, and YouTube.
Additional Sources
https://www.sciencedirect.com/science/article/pii/S1551714424000016?via%3Dihub
https://www.nature.com/articles/s41575-024-00893-5
https://www.thelancet.com/action/showPdf?pii=S2589-5370%2824%2900063-4
https://www.tandfnline.com/doi/full/10.1080/0886022X.2024.2306224