Why This Registered Dietitian Eats Processed Foods
The topic of processed foods is far more nuanced than the headlines suggest.
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“Eating Processed Foods Tied to Shorter Life”
“The Link Between Highly Processed Foods and Brain Health”
“Ultraprocessed Foods Linked to Heart Disease, Diabetes, Mental Disorders, and Early Death, Study Finds”
You may have seen these headlines in the New York Times or on CNN. If you missed them, I’m sure you’ve seen others to the same effect. Much is made about the dangers of food processing and ultraprocessed foods (UPF) in particular.
To a degree, the concern is warranted. After all, many highly processed foods have limited nutritional value. Research links UPF to obesity, heart disease, cancer, and other chronic conditions. In the U.S., we consume about 60% of our calories from UPF, which can be problematic. But when you take a closer look, you’ll find that the headlines tell just a small part of the story.
The Pros and Cons of Food Processing
Most of the food we eat is processed in one way or another, which means it’s been cooked, crushed, canned, milled, pasteurized, frozen, or dried, has additives such as vitamins, minerals, fiber, sweeteners, or food coloring, or has been altered in other ways. Olive oil, canned tuna fish, and salted peanuts all qualify as processed foods, and so do soft drinks, orange cheese puffs, and packaged cookies.
Processing has many advantages. It makes food more palatable, and it helps reduce food insecurity by ensuring a steady supply of convenient, shelf-stable food. Processing can turn nutritious but hard-to-digest foods, such as dairy milk, into lactose-free versions that everyone can enjoy. Processed gluten-free grain products are a boon to those with celiac disease. And, through the addition of vitamins and minerals to relatively low-cost foods such as milk, bread, and breakfast cereal, processing provides greater access to nutrients that support overall health.
Let’s not overlook the time-saving perks of processed foods, such as jarred marina sauce, breaded chicken cutlets, and frozen vegetables, which I especially appreciated when I was feeding a family of five every day and still value in midlife. Thanks largely to processing, adults spent an average of just 51 minutes a day preparing food in 2019– far less time than your grandmother toiled in the kitchen on a daily basis.
Of course, processing has its pitfalls. Many UPF tend to offer fewer favorable nutrients, including fiber, and more added sugar, salt, and saturated fat. Many less-nutritious UPF are drinkable (soda, energy drinks, etc.) or have a soft or crunchy texture that makes it easier to consume excess calories. Highly processed foods may also contain additives that negatively influence health. More on that in a minute.
What Are Processed Foods?
When assessing the relationship between UPF and health, researchers tend to rely on a classification system called NOVA. (NOVA is not an acronym, it’s the actual name.) NOVA has been used in nearly all scientific studies to date on processed food.
NOVA consists of four categories ranging from least- to most-processed. Category 1 contains unprocessed or minimally processed items while category 4 foods have been altered the most. For example, unsalted peanuts are in category one, but salted peanuts fall into category 4. Olives are a category 1 food, while olive oil falls into category 2. Canned tuna fish is in category 3 but if it has added salt, it goes in category 4.
While all of this sounds logical and orderly, NOVA is surprisingly subjective, and the system confuses both researchers and consumers. In addition, NOVA fails to account for the nutrient composition of foods, and therein lies a major problem. Many common foods that I eat regularly and suggest as a registered dietitian, such as tofu, packaged whole wheat bread, and enriched breakfast cereal, fall into category 4, where they are lumped in with sugary drinks, ready-to-eat meals, potato chips, and candy. Here are some other nutrient-rich category 4 foods:
•Unsweetened soy milk
•Peanut butter (not the natural kind)
•Tofu
•Seltzer water
•Plant-based burgers, such as soy burgers
•Infant formula
•Protein powder
•Ultrafiltered milk and lactose-reduced milk
Research Relates Processed Foods to Health Problems
There’s no shortage of news about research linking UPF to health problems. However, it’s important to note that, with the exception of just one study that I am aware of, nearly all of that research is observational in nature. Observational research is not designed to prove a cause-and-effect relationship so it can’t place blame squarely on UPF.
In a 2019 Cell Metabolism randomized control trial, which can show causation, people ate either 80% of their calories from UPF or followed a minimally processed diet. On the UPF diet, people ate about 500 more calories daily and gained about two pounds. The study concluded that eating UPF caused weight gain. However, it lasted just two weeks, which makes it difficult to determine the long term effects of eating UPF.
As I mentioned earlier, NOVA lumps all UPF foods together, regardless of their nutrient content. That means studies that use NOVA tend to do the same. But when you take a closer look, it’s clear that food groups exert different effects on health outcomes.
A 2022 study in The British Medical Journal found no association between overall UPF intake and risk of colorectal cancer in women. However, upon further investigation, eating more ready-to-eat/mixed dishes was associated with a greater likelihood of colon cancer in women, while sweetened yogurt and dairy-based desserts, also considered UPF foods, was associated with a decreased likelihood.
Research published in 2023 in Diabetes Care observed that people who ate the most UPF were about 50% more likely to develop type 2 diabetes. Animal-based products, particularly processed meats, were linked to the greatest risk for type 2 diabetes, followed by ready-to-eat/mixed dishes. But the data also showed that packaged whole grain breads, enriched breakfast cereals, and yogurt and dairy-based desserts – all considered UPF by NOVA - reduced the risk for type 2 diabetes. Surprisingly, packaged sweets and desserts and packaged savory snacks were also considered protective.
In addition to the varying effects of UPF on chronic conditions, men and women may differ in their response to eating them. A 2023 Nutrients study that used NOVA found an association between greater UPF intake and depression in females but not in males, even after controlling for age, body mass index, alcohol intake, smoking, education, high blood pressure, diabetes, and level of physical activity. The study didn’t consider diet quality, however. It’s worth nothing that individuals with a high UPF intake may also lack adequate amounts of fruits, vegetables, low-fat dairy foods, whole grains, and lean protein sources, which can contribute to mental wellbeing.
Food Additives and Your Health
It’s possible that certain food additives in UPF, including emulsifiers, preservatives, and artificial sweeteners, play a role in the risk for illness.
Nitrates, used as preservatives in hot dogs, bacon, and smoked fish, may produce cancer-causing compounds in the body. One recent observational study found a relationship between nitrate consumption and breast cancer risk.
Emulsifiers are added to processed foods such as peanut butter, mayonnaise, and creamy sauces. Emulsifiers prevent the separation of oil and water in foods, provide a smoother texture, and increase shelf life. Cellulose gum (carboxymethylcellulose), polysorbate, and carrageenens are among the most common food emulsifiers.
A 2021 Microbiome study found that carboxymethylcellulose and polysorbate 80 increase the risk for intestinal inflammation. While this wasn’t a human study, the results suggest that these emulsifiers may create an environment in the gut that promotes inflammation in people. A 2017 review reported that studies conducted with animals showed emulsifiers can alter the gut environment to the point of promoting inflammatory bowel disease and metabolic syndrome. More human research is needed to determine the true effects of emulsifiers on gut health and overall wellbeing.
People often turn to artificially sweetened drinks (ASB) to reduce sugar and caloric intake, but higher intakes of regular soft drinks or ASB are been linked to a greater risk for cardiovascular disease. According to one study, saccharin, sucralose, and stevia change the composition of the gut microbiota, which plays a role in heart health.
Should You Be Concerned About Ultraprocessed Foods?
There’s no reason to dismiss UPF out of hand because many of them are good for you. I’m not suggesting a steady intake of Diet Coke, Twinkies, and fast-food burgers, of course. But instead of thinking of foods as good or bad based on processing, consider their nutritional merits.
A balanced eating pattern that’s low in saturated fat, sodium, and added sugar is the best policy in midlife and beyond. Most of the time, choose foods that are nutrient-rich, affordable, and figure in with your cultural preferences and dietary needs. If you desire, avoid or limit products with emulsifiers, nitrates, and artificial sweeteners. That’s the way I roll.
Questions? Comments? Let me know!