New research suggests a concerning link between ultra-processed plant-based diets and a significantly higher risk of heart disease, challenging the widespread perception that all vegan diets are inherently heart-healthy. While plant-based eating is often lauded for its fiber and nutrient content, scientists have found that these benefits are negated when such diets heavily feature ultra-processed foods, which can be as detrimental as other forms of junk food.

The study, published in The Lancet, meticulously tracked over 63,800 middle-aged adults in France for an average of just over nine years. Its findings underscore that plant-based diets only confer cardiovascular protection when they are founded on whole, minimally processed foods. Clémentine Prioux, lead author and a nutrition researcher at Sorbonne University, emphasized, 'Our findings reinforce the necessity of advocating not only for a reduction in animal products but also encouraging the consumption of minimally processed plant-based foods to improve cardiovascular health.'

Participants adhering to a nutritionally complete, largely unprocessed plant-based diet showed a remarkable 44 percent lower likelihood of developing coronary heart disease—a condition leading to issues like chest pain, heart attacks, and heart failure. Conversely, those whose plant-based diets were predominantly composed of ultra-processed foods faced a 46 percent higher risk of coronary heart disease and a 38 percent increased risk of overall cardiovascular disease, an umbrella term for conditions affecting the heart and blood vessels.

These at-risk participants typically consumed more items such as supermarket bread, ready-made pasta dishes, packaged soups, and prepared salads laden with heavy dressings. These foods frequently contain industrial ingredients like stabilisers, emulsifiers, and added fats. Previous studies have indicated that individuals following plant-based diets might inadvertently consume more ultra-processed foods than meat-eaters, largely due to the widespread availability of processed meat substitutes.

Interestingly, the research also revealed that individuals who consumed some animal products but strictly avoided ultra-processed foods were no more likely to develop heart disease than those following healthy, whole-food plant-based diets. This crucial insight suggests that the quality of food and the degree of its processing are more significant determinants of heart health than whether a diet is strictly plant-based or includes animal products.

The data for this comprehensive analysis originated from the French NutriNet–Santé study. This study assessed how both the nutritional quality and the level of processing of plant-based foods influence heart health. Participants provided detailed annual health questionnaires, and their diets were evaluated using repeated 24-hour dietary records at the study's outset and every six months thereafter. Researchers meticulously adjusted for confounding factors such as smoking status, physical activity levels, and other lifestyle elements. All foods and drinks, including snacks, were recorded, with portion sizes estimated using photographs or standardized containers. Nutrient intake was precisely calculated using a validated food composition database and cross-referenced with blood and urine biomarkers.

Foods were systematically categorized using the NOVA classification system, established in 2009, which groups foods by their degree and purpose of processing. Under this system, unprocessed or minimally processed foods encompass items like fresh fruit, vegetables, whole grains, pasta, and fresh or frozen meat and fish—foods altered only by basic methods such as freezing, drying, or pasteurisation. Processed foods are those made by adding ingredients like salt, sugar, or oil to whole foods, examples being cheese, freshly baked bread, or canned vegetables. Ultra-processed foods, however, are distinct: they are industrial formulations produced through multiple processing steps and contain ingredients not typically found in home cooking, such as emulsifiers, flavorings, colorings, and preservatives. These products are often characterized by being high in energy, added sugar, saturated fat, and salt, while simultaneously being low in fiber and essential micronutrients.

The researchers ultimately concluded that nutritionally healthy plant-based diets, built around unprocessed foods, offered the most substantial protection against coronary heart disease. Conversely, no such protective benefit was observed when plant-based diets relied heavily on processed or ultra-processed foods. The most severe health outcomes, including a nearly 40 percent increase in heart disease risk, were recorded in individuals consuming ultra-processed plant-based diets. Moreover, the study highlighted that ultra-processed animal-based foods were associated with an even higher risk of heart disease.

These findings align with broader concerns about cardiovascular health, especially given recent NHS data showing a worrying rise in heart attacks among younger adults over the past decade. The most significant increase, a 95 percent surge, was observed in the 25 to 29-year-old demographic, although experts caution that small absolute numbers can exaggerate percentage changes. This trend is believed to be partly attributable to rising rates of obesity and poor dietary habits, particularly the increased consumption of ultra-processed foods, which have been repeatedly linked to life-threatening heart issues. Experts have called for a drastic reduction of ultra-processed foods from diets as a preventative measure.

Cardiovascular disease, commonly caused by the accumulation of fatty deposits in the arteries, restricts blood flow and elevates the risk of blood clots. It can also lead to arterial damage in vital organs such like the brain, heart, kidneys, and eyes. Despite being one of the leading causes of death and disability in the UK, many cases are preventable through healthier diets and lifestyles. The study's authors emphasized the critical importance of considering three dimensions for cardiovascular prevention: the balance between plant- and animal-based foods, overall nutritional quality, and the degree of food processing. They also noted the particular relevance of these findings to the UK, where a wider array of ultra-processed plant-based products is available, leading to significantly higher consumption compared to some other European countries.