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It’s no secret that most highly processed foods aren’t the healthiest. But new research points to one specific class of additives that might be more dangerous than you thought. And if you’re worried about your heart health, they’re worth avoiding.

For the study, published in the British Journal of Medicine, a research team based in France examined data from more than 95,000 individuals collected between 2009 and 2021 to determine the effect of emulsifiers on heart health.

Emulsifiers are food additives that help two ingredients that wouldn’t otherwise combine well — like oil and water — mix in a food product. They also help extend the shelf life of processed foods. To make mayonnaise, for example, egg is added because it contains the natural emulsifier lecithin, which allows the fat and water to blend.

But not all emulsifiers are created equal. The researchers discovered that several types used in large-scale food production negatively impact heart health.

For one, particular types of mono- and diglycerides — which have generally been considered safe and are found in plant oils such as palm, sunflower, coconut, and canola oils — were linked to higher risk of cardiovascular disease (CVD), coronary heart disease, and cerebrovascular disease (which affects blood flow to the brain). Monoglycerides and diglycerides are used as emulsifiers in foods such as baked goods, ice cream, and frozen meals.

A higher intake of cellulose, which was previously considered to be harmless and is used as an emulsifier and thickener in food products like ice cream and whipped toppings, was associated with an increased risk for CVD and coronary heart disease.

The emulsifier and preservative trisodium phosphate, considered safe by the FDA and commonly found in processed meats and other food products like cereal and baked goods, was linked to an increased risk of coronary heart disease.

But not all studied emulsifiers were linked to heart health harms. For example, lecithins (found in eggs, for example) and carrageenans (made from red seaweed) were not associated with increased risk for these diseases.

“Owing to the observational nature of our study, we were unable to confirm that emulsifiers are causally related to CVD risk,” only that there’s an association between them, the study authors wrote. “However, we have as much as possible isolated the role of emulsifiers by adjusting for the proportion of ultra-processed foods in the diet, as well as for several dietary features that might causally impact CVD risk, including intakes of sugar, sodium, saturated fatty acids, energy, fibre, and artificial sweeteners.”

Although the participant pool was large, it was comprised predominately of women and people with high levels of education, and most of the participants were French, which means more research is needed to determine if the results are repeatable across populations. Also, participants self-reported food intake in food journals, which can introduce errors.

Despite these shortcomings, “these findings may have important public health implications given that these food additives are used ubiquitously in thousands of widely consumed ultra-processed food products,” the research team wrote. “Meanwhile, several public health authorities recommend limiting the consumption of ultra-processed foods as a way of limiting exposure to non-essential controversial food additives.”

The emulsifiers the researchers found to be connected with various diseases of the heart are found in a wide variety of processed foods. If you want to avoid them and their potential heart health risk, eat fresh, unprocessed foods as much as possible. And when you do want a baked good, ice cream, or another processed treat, be sure to check the ingredients label.