Recent headlines have condemned plant-based imitation meats—such as veggie sausages and textured vegetable proteins—as unhealthy, claiming that their consumption is linked to increased risk of heart disease and death. But a closer look at the research backing up these claims suggests a more nuanced story.
The real culprits are actually “plant-based” ultra-processed foods as a whole, and not meat substitutes specifically, according to the headline-making article. But there’s an important caveat: “Plant-based” foods include foods you might not expect — like chocolate-covered cookies, frozen pizzas and sodas. The study, published earlier this month in the Lancet Regional Health–Europe, link between plant-based, ultra-processed foods and increased risk of cardiovascular disease and death.
However, plant-based meats represented a tiny fraction of the study participants’ overall food consumption, and the study wasn’t designed to pinpoint exactly which foods had the strongest links to poor health outcomes. Still, the confusing interpretations highlight how complex nutrition research can be, critics say, because food definitions used by scientists don’t always reflect what other people might interpret as a plant-based diet.
Foods are described as ultra-processed when they undergo an industrial transformation that significantly alters their original ingredients. These foods take a long journey before they end up on your plate. Pantry staples like instant noodles and store-bought cookies typically undergo multiple stages of processing that strip away the internal architecture of their raw ingredients. They’re then reconstituted in a form that prioritizes convenience and flavor — often with a mix of additives designed to improve appearance and shelf life. A rule of thumb is to “think of a food that you wouldn’t be able to make in your own kitchen,” either because of its chemical constituents or the industrial machinery required to prepare it, says Evangeline Mantzioris, a researcher and dietitian at the University of South Australia who was not involved in the study.
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In nutrition research, including this much-discussed article, a framework known as the NOVA classification system is used as a benchmark to group foods along a spectrum from unprocessed to ultra-processed based on the degree of alteration from their natural state. Most foods can be categorized intuitively. Broccoli or beans are not considered ultra-processed, while breakfast cereals and canned soups are. Others, however, may not be so obvious at first glance. For example, the new Lancet Regional Health-Europe study included beer and wine as examples of non-ultra-processed beverages, but spirits such as vodka were considered ultra-processed.
The idea behind using this framework in food research is that processing food can fundamentally change how it interacts with the body to affect health, says Fernanda Rauber, lead author of the new study and a nutritional epidemiologist at the University of São Paulo in Brazil. The health effects of food don’t “just come from the sum of its nutritional functions,” she says. “The way foods are combined, prepared and consumed as meals also plays a critical role in their health outcomes.”
In the study, Rauber and her colleagues linked what people ate in a day to their hospitalization and death rates related to cardiovascular disease. The researchers did this using data from more than 100,000 adults in the UK BioBank — a large database that tracks the health, lifestyle and genetic information of volunteers aged 40 to 69 in the United Kingdom
The plant-based category in the study was something of a catch-all, says Gunter Kuhnle, a nutritional epidemiologist at the University of Reading in England who was not involved in the study. When he first read the paper’s title, Kuhnle assumed it referred to plant-based meat substitutes, plant-based beverages, or plant-based milks — in other words, just substitutes for animal products. “When I read the paper, it became pretty clear that it wasn’t,” he says. The press release reinforced that interpretation, specifically stating in the first paragraph that products “intended to replace animal foods” — such as plant-based sausages, nuggets, and burgers — were linked to a higher risk of heart disease.
But there’s more to the story: Meat substitutes were evaluated alongside ultra-processed foods that were less intuitively “plant-based,” including bread, pastries, sugary sodas, chips and ketchup — foods that don’t immediately come to mind when people think of a plant-based diet, Kuhnle says. Such a broad categorization “wasn’t wrong,” he says. “It was just easy to get wrong.”
The study found that the more ultra-processed foods people ate, the more likely they were to develop or die from heart disease. These results were “not really surprising,” Kuhnle said, given the inclusion of “plant-based” foods that many dietary guidelines recommend eating in moderation, such as sugary foods or drinks.
As a percentage of total energy intake, the risk of cardiovascular disease increased by 5% for every 10% increase in consumption of ultra-processed plant foods — which include foods like cookies and chocolate bars, but also tofu and tempeh — and the risk of dying from the disease increased by 12%. The reverse was also true — for every 10% increase in consumption of foods that were not ultra-processed but still plant-based — such as pasta, beans and potatoes — the risk of heart disease decreased by 7% and death by 13%.
The problem is that this type of analysis can’t show whether one specific food is worse than another, because they’re assessed as a group. What’s more, the tofu, tempeh and textured vegetable protein products that were categorized as plant-based, ultra-processed foods only accounted for a fraction of the total calories people consumed — about 0.2 percent total — while other foods like packaged bread accounted for 10 percent. “We can’t draw any specific conclusions about this particular food type,” Rauber said, responding to the way the article has been portrayed in some media coverage.
Nevertheless, the findings add to a growing body of evidence linking ultra-processed foods to negative health outcomes. A recent review of multiple studies involving nearly 10 million people found that eating more ultra-processed foods was associated with a range of health risks, including cardiovascular disease. The health effects of imitation meat products are less clear. A recent study found that vegetarians and vegans consume more ultra-processed foods compared with meat eaters and that they prefer unhealthy plant foods over healthier alternatives, but it did not examine the long-term health effects of such diets. On the other hand, ultra-processed meats themselves, such as sausage and salami, have been linked to higher overall mortality and, in particular, colorectal cancer.
Exactly how ultra-processed foods can cause such health damage remains unclear. Some research points to the high levels of salt, sugar and fat in these foods as the culprits, but other studies suggest that the processing of a food – breaking down its natural structures and molding them into something new – can affect the body in ways we don’t yet understand. Chemical additives, such as the common flavor enhancer monosodium glutamate (MSG), and contaminants that can result from frying, baking or fermenting ultra-processed foods, such as acrolein, can also affect appetite and health; acrolein in particular has previously been linked to an increased risk of heart disease.
Rauber cautions that the study couldn’t tease out cause and effect. In reality, people’s eating habits are messy and they don’t usually stick to a strict regimen over long periods of time — making it challenging to design studies that can draw conclusions about whether certain diets cause disease. But given the number of observational studies available, “there’s a huge amount of evidence … to tell us that ultra-processed foods are probably not the best thing for our health,” Mantzioris says. Rauber’s study took into account other variables, such as the effect that family history, physical activity and ethnicity can have on an individual’s risk of developing heart disease.
Kuhnle says that ultra-processed foods aren’t necessarily a “good” or “bad” choice, but should be viewed in the broader context of a person’s diet, keeping in mind that the health effects of ultra-processed foods don’t develop overnight.
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