A plant-based diet can offer numerous health benefits, but a new study suggests that the quality of these foods matters significantly.
Consuming sugar and chips, although technically plant-based, may increase the risk of heart attacks and premature death.
The study, published Monday in The Lancet Regional Health — Europe, found that plant-based ultra-processed foods — such as donuts, pop and chips — increased the risk of cardiovascular disease by five per cent and early death by 12 per cent.
Conversely, the study found that replacing plant-based ultra-processed foods with fresh, frozen, or minimally processed plants, such as veggies and fruits, reduced the risk of developing cardiovascular disease by seven per cent and lowered the risk of dying from heart disease by 15 per cent.
“Modern plant-sourced diets may incorporate a range of ultra-processed foods, such as sugar-sweetened beverages, snacks, confectionery, but also the ‘plant-sourced’ sausages, nuggets, and burgers that are produced with ingredients originating from plants and marketed as meat and dairy substitutes,” the authors stated in the study.
“We observed that higher dietary contribution of plant-sourced non-ultra-processed foods were associated with a lower risk of fatal and nonfatal cardiovascular events, while contribution of plant-sourced ultra-processed food was associated with a higher risk of cardiovascular events,” the authors added.
Canadians get nearly 50 per cent of their daily calories from ultra-processed foods, according to the Heart and Stroke Foundation. These foods, such as candy, soft drinks, pizza and chips, have been significantly altered from their original state with added salt, sugar, fat, additives, preservatives and artificial colors.
And consumption of these highly processed foods can lead to poorer overall health quality, such as cancer, major heart and lung conditions, mental health disorders and early death.
“Ultra processed food contains little or no whole foods, so you’re not eating a whole food during the processing of food,” said Carol Dombrow, registered dietician and nutrition consultant with the Canadian Heart and Stroke Foundation.
“A lot of the important nutrients, like vitamins and minerals, and fibre are removed. And then there’s salt and sugar is added as well as other additives. So what you think you’re buying is not, plant-based food. It’s not a food per se,” she told Global News.
She added that plant-based foods, like legumes and whole grains, can be incredibly healthy, but it’s important to understand their nutritional content when they are packaged or processed.
An ultra-processed plant-based diet
The Lancet study acknowledged that, although many studies link ultra-processed foods to health risks, there is limited evidence on how these foods affect the relationship between plant-based diets and cardiovascular disease outcomes.
The authors characterized a plant-sourced dietary pattern as involving low consumption or complete omission of eggs, dairy products, fish and meat. They noted that this diet has been associated with a reduced risk of several chronic diseases and has substantial environmental benefits.
“However, plant-sourced dietary patterns are heterogeneous and may differ widely in their dietary composition, type, and quality, and evidence has shown the potential protective effect of plant-sourced diets on CVD may vary accordingly,” the study stated.
The researchers argued that despite their plant-based nature, diets rich in ultra-processed foods may still pose health risks due to the negative effects caused by their composition and processing methods. These foods often contain high levels of unhealthy fats, sodium, and added sugars, which can contribute to hypertension, insulin resistance, obesity, and metabolic disorders — all of which are risk factors for cardiovascular disease.
To further investigate the link, the researchers looked at data from the U.K. Biobank, a longitudinal study involving participants from England, Scotland and Wales, with over 118,000 people aged 40 to 69 answering questions about their diet between 2007 and 2010. Food groups were categorized as plant-sourced or non-plant and animal-sourced, further classified as non-ultra-processed or ultra-processed.
The researchers found that plant-sourced ultra-processed foods were associated with an increased risk of both cardiovascular disease and coronary heart disease.
“These findings advance current knowledge by highlighting that a higher intake of plant-sourced foods may only bring about better cardiovascular health outcomes when largely based on minimally processed foods while a higher intake of plant-sourced ultra-processed foods may have detrimental effects on health,” the study stated.
Reservations about the findings
In an editorial published by the Science Media Centre, a team of health experts shared their insights on the Lancet paper, emphasizing certain concerns with the report.
Some of the authors of the editorial were Sarah Nájera Espinosa, a researcher in nutrition and climate change at the Department of Population Health; Pauline Scheelbeek, an associate professor in nutritional epidemiology and planetary health; and Rosie Green, a professor of environment, food, and health, all affiliated with the London School of Hygiene and Tropical Medicine.
“Some people could get the impression from the first paragraph of the press release that the study only looked into meat alternatives, when in fact, it considered many other ultra-processed foods products such as industrial breads, biscuits, confectionery, etc,” they stated.
For example, in the Lancet study, while meat alternatives (such as veggie burgers) were classified as ultra-processed foods, they constituted only 0.2 per cent of the energy from such foods consumed by participants. The main plant-based ultra-processed foods identified included processed baked goods like packaged breads, pastries, cakes, and cookies, as well as chips and soft drinks.
The editorial raised another concern about the findings, arguing that the distinction between animal and plant-based ultra-processed foods is misleading. They pointed out that in most studies examining highly processed foods, a significant proportion of plant-based foods would be included in their analyses if the ultra-processed food category encompassed all products such as cakes, industrial bread, and confectionery.
This is because these products are typically made from plant-sourced ingredients like flour, plant-based oils, and sugar.
Although many plant-based foods can fall into the ultra-processed category, Dombrow said that if done right, the diet can be excellent for your health.
“If you’re vegetarian or vegan, you have to be smarter than the average Canadian because it’s more complicated. It’s not as easy as picking up a chicken breast or making scrambled eggs,” she said.
“If you’re a strict vegetarian or vegan, then you need to choose whole foods like beans and lentils and tofu and fruits and vegetables.”