A new French study shows that common preservatives used to kill bacteria and mold in many store-bought foods can increase blood pressure by 29% and increase the risk of heart disease and stroke by 16%.
Studies have found that even with so-called “natural” antioxidant preservatives such as citric acid and ascorbic acid (commonly known as vitamin C) used to stop discoloration, people who ate more foods containing these ingredients had a 22 percent increased risk of high blood pressure.
While antioxidants such as citric acid and ascorbic acid occur naturally in foods such as fruits, they are “not completely natural” when used as preservatives, senior author Mathilde Tourvel said in an email. Touvier is the principal investigator of the NutriNet-Santé study used to conduct the study.
“Naturally occurring ascorbic acid and added ascorbic acid (which may be chemically manufactured) may have different effects on health,” said Tourvier, who is also director of research at the French National Institute of Health and Medical Research in Paris.
“Therefore, the results observed here for these food additives do not apply to naturally occurring substances found in fruits and vegetables,” she added.
More than just ultra-processed foods
Tracy Parker, head of nutrition at the British Heart Foundation in London, said in a statement that the study reveals how different additives in ultra-processed foods (UPF) play a role in cardiovascular risk and “echoes the recent consensus from the European Society of Cardiology, which highlighted UPF as a global public health issue.” Parker was not involved in the study.
Ultra-processed foods are associated with an approximately 50% increased risk of death from cardiovascular disease and may increase the risk of obesity by 55%, sleep disorders by 41%, and type 2 diabetes by 40%. Obesity, diabetes and poor sleep are closely linked to poor heart health.
“This is one of the first large studies to look at individual preservatives rather than treating ultra-processed foods as a single category,” Parker said. “UPFs have long attracted concern for their high levels of sugar, salt and fat, but those factors alone have never fully explained why they appear to be more harmful than their nutritional content suggests. These findings help fill some of the gaps.”
However, previous research by Touvier and her team found that ultra-processed foods accounted for only 35% of the foods people eat that contain preservatives. This means “preservatives are everywhere,” said the study’s lead author Anaïs Hasenböhler, a doctoral student in the Nutritional Epidemiology Research Group at the University of Paris-Nord-Sorbonne.
“There is no food group/item that can be removed from the diet to solve the problem,” Hasenbrough said in an email. “These results also support the suggestion that consumers favor non-processed foods.”
Choose fresh, uncooked, unprocessed foods, or if looking for the fastest preparation and consumption, choose frozen foods that are “preserved by cryogenics, not necessarily by adding food additive preservatives,” she adds.
More ‘natural’ preservatives linked to risks
The study, published Wednesday in the European Heart Journal, examined the effects of 58 preservatives on the cardiovascular health of more than 112,000 people aged 15 and over. All are involved in NutriNet-Santé, an organization that has been analyzing the diets of volunteers across France since 2009.
To participate in the study, each participant tracked every bite of food and drink they ate with the brand name for three days every six months. The researchers then used a database of product ingredients to identify common preservatives and compared consumption levels over the years with medical data stored in France’s national health care system.
Researchers took an in-depth look at 17 preservatives consumed by at least 10 percent of the participants and found that eight of them were linked to high blood pressure over the next decade. Three of them – potassium sorbate, potassium metabisulfite and sodium nitrite – are “non-antioxidant” preservatives, meaning they kill bacteria, mold and yeast that cause food to spoil.
Potassium sorbate is commonly used in wine, baked goods, cheeses and sauces. Potassium metabisulfite releases sulfur dioxide when dissolved and is found in wine, juice, cider, beer and other fermented beverages. Sodium nitrite is a chemical salt commonly used in processed meats such as bacon, ham and deli meats.
Foods such as red and processed meat contain nitrates and sulfur-based compounds, which are known to increase the risk of heart disease. Therefore, some experts say the findings are not surprising.
In addition, Gunter Kuhnler, professor of food and nutritional sciences at the University of Reading in the UK, said that if consumers want to continue to buy food that can be stored and eaten, preservatives need to be added. He was not involved in any research.
“Preservatives play an important role in the food system, not only by preventing foodborne illness but also by preventing spoilage, reducing food waste and extending shelf life,” Kuhnle said in a statement.
The remaining preservatives linked to high blood pressure in the study — ascorbic acid, sodium ascorbate, sodium erythorbate, citric acid and rosemary extract — are so-called natural “antioxidant” preservatives, used to reduce the oxidation that causes foods to brown and go rancid.
Studies have found that ascorbic acid (vitamin C) is also closely related to cardiovascular disease.
Similar preservatives linked to cancer, type 2 diabetes
These results support those of two other studies by Touvier and her team, which found similar links between preservatives and a higher risk of cancer and type 2 diabetes.
Six preservatives – sodium nitrite, potassium nitrate, sorbate, potassium metabisulfite, acetate and acetic acid – were linked to a 32% increased risk of prostate, breast and various cancers. All but one of the preservatives increased the risk of type 2 diabetes by 49%.
While the new study’s results are observational and cannot prove cause and effect, the study did a good job of controlling for other factors that may affect health, such as age, body mass index or body mass index, smoking, physical activity and general diet, said Rachel Richardson, method support unit manager at the Cochrane Collaboration, an international nonprofit respected for its scientific approach to research. She was not involved in the study.
“Other strengths of this study include the way they assessed people’s diet and their comprehensive approach to identifying hypertension and cardiovascular disease,” Richardson said in a statement. “While they cannot prove cause and effect, there are signals in the results that warrant further investigation.”
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