Recent headlines have slammed plant-based fake meats, such as vegetarian sausages and textured plant proteins, as unhealthy, claiming that their consumption is linked to an increased risk of cardiovascular disease and death. But a closer look at the research underlying these claims reveals a more nuanced story.
According to the paper that sparked the headlines, the real culprit isn’t meat alternatives specifically, but ultra-processed, plant-based foods as a whole. But there’s an important caveat: “Plant-based” foods include some unexpected options, like chocolate-coated biscuits, frozen pizza, and soda. The study, published earlier this month, The Lancet Regional Health Europe, It has been suggested that ultra-processed plant-based foods may be linked to an increased risk of cardiovascular-related disease and death.
But plant-based meat made up only a small portion of the study participants’ overall food intake, and the study wasn’t designed to pinpoint which foods were most strongly associated with poor health. But critics say this confused interpretation shows how complicated nutrition research is, because the definitions of food scientists use don’t necessarily reflect what other people interpret as a plant-based diet.
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Foods are called ultra-processed when they’ve undergone industrial transformation, significantly altering their ingredients. These foods have a long journey to get to your plate. Pantry staples like instant noodles and store-bought cookies typically undergo several stages of processing that disentangle the inner workings of their ingredients. They’re then reformulated for convenience and taste, often with additives to improve appearance or extend shelf life. “Think of foods that you couldn’t prepare in your own kitchen,” because of their chemical composition or the industrial machinery required to prepare them, says nutritionist Evangeline Mantziolis, a researcher at the University of South Australia who wasn’t involved in the study.
In nutrition research, including this widely discussed paper, a framework called the NOVA classification system is used as a standard for classifying foods on a scale ranging from unprocessed to ultra-processed based on the degree to which they have been altered from their natural state. Most foods are intuitively classifiable: broccoli and beans would not be considered ultra-processed, but breakfast cereals and canned soups would. But other foods may not be obvious at first glance. For example, The Lancet Regional Health Europe The study cited beer and wine as examples of beverages that were not ultra-processed, while distilled spirits such as vodka were considered ultra-processed.
The idea behind using this framework in food research is that food processing can fundamentally change the way that food interacts with the body and affects health, says Fernanda Lauber, a nutritional epidemiologist at the University of São Paulo in Brazil and lead author of the new study. The health effects of food “do not simply result from the sum of its nutritional functions,” she says. “The way foods are combined, prepared and consumed in a meal also plays an important role in their health effects.”
In the study, Lauber and his colleagues linked what people ate per day to hospital and death records related to cardiovascular disease. The researchers used data from more than 100,000 adults from the UK Biobank, a large database that tracks the health, lifestyle, and genetic information of volunteers aged 40 to 69 in the UK.
The study’s plant-based category was in some ways a catch-all, says Gunter Kuhnle, a nutritional epidemiologist at the University of Reading who was not involved in the study. When he first read the paper’s title, Kuhnle thought it referred only to plant-based meat substitutes, plant-based beverages, and plant-based milk — in other words, replacements for animal-based products. “Reading the paper, it became pretty clear that this was not the case,” he says. The press release also reinforced that interpretation, specifically stating in the first paragraph that products “intended to replace foods of animal origin,” such as plant-based sausages, nuggets, and burgers, were associated with a higher risk of cardiovascular disease.
But there’s more to the story. Meat alternatives were rated alongside ultra-processed foods that aren’t intuitively “plant-based,” such as bread, cake, sugary soda, potato chips and ketchup. These foods don’t immediately spring to mind when thinking about a plant-based diet, Kuhnle says. Such broad categorizations “weren’t wrong,” he says, “just easily misunderstood.”
The study found that people who eat more ultra-processed foods are more likely to develop or die from heart disease, a finding that’s “not that surprising,” Kuhnle says, given that many dietary guidelines recommend eating “in moderation” of “plant-based” foods, such as sugary foods and drinks.
As a percentage of total energy intake, every 10% increase in consumption of ultra-processed plant-based foods – which includes tofu and tempeh as well as cookies and chocolate bars – was associated with a 5% increased risk of cardiovascular disease and a 12% increased chance of dying from that disease. The reverse was also true: every 10% increase in consumption of non-ultra-processed plant-based foods such as pasta, beans and potatoes was associated with a 7% lower risk of heart disease and a 13% lower chance of dying.
The problem is that this kind of analysis evaluates foods as a group, so it can’t show whether certain foods are worse than others. Moreover, tofu, tempeh and textured plant protein products, which are classified as ultra-processed, plant-based foods, only account for a small proportion of the total calories people ate, about 0.2% in total, compared with 10% for other foods such as packaged bread. “We can’t draw any specific conclusions related to this particular type of food,” Lauber said in response to the way the paper was covered in some media reports.
Still, the findings add to a growing body of evidence linking ultra-processed foods to adverse health effects. A recent review of multiple studies, including data from a total of nearly 10 million people, found that higher intakes of ultra-processed foods are associated with a range of health risks, including cardiovascular disease. The health effects of artificial meat products are less clear. One recent study showed that vegetarians and vegans consume more ultra-processed foods than meat eaters and prefer unhealthy plant-based foods over healthy alternatives, but the long-term effects of such dietary patterns on health have not been investigated. Meanwhile, ultra-processed meats such as sausages and salami themselves have been linked to increased overall mortality, particularly colorectal cancer.
It’s still unclear how ultra-processed foods cause health problems. Some studies point to the salt, sugar, and fat in these foods, but other studies suggest that the act of processing food — breaking down its natural structure and rebuilding it into a new one — may affect the body in ways we don’t yet understand. Chemical additives such as monosodium glutamate (MSG), a common flavor enhancer, and contaminants such as acrolein, which comes from frying, baking, and fermenting ultra-processed foods, may also affect appetite and health. Acrolein in particular has previously been linked to an increased risk of cardiovascular disease.
Lauber cautions that the study could not analyze causation. In reality, people’s eating habits are messy and they don’t usually follow strict rules for long periods of time, so it’s difficult to design a study that draws conclusions about whether a particular diet causes disease. But given the number of observational studies available, “there’s a huge amount of evidence that ultra-processed foods are probably not the best for our health,” Mantziolis says. Lauber’s study also takes into account other variables, such as the effects that family history, physical activity, and ethnicity may have on an individual’s risk of developing heart disease.
Kuhnle says ultra-processed foods are not necessarily a “good” or “bad” choice, but they should be viewed in the broader context of a person’s diet, bearing in mind that their health effects don’t appear overnight.