Food preservatives are used in hundreds of thousands of industrially produced foods.
Antioxidant food preservatives help keep foods from spoiling by slowing changes in colour and flavour caused by exposure to oxygen. Non-antioxidant food preservatives, on the other hand, prevent spoilage caused by moulds, bacteria and yeasts – including microbes that can cause serious food-borne illness.
Safety evaluations of food preservatives are largely based on toxicology studies, not long-term human health outcomes. So while experimental studies have suggested some food preservatives may affect cardiovascular health, data from human studies have been limited.
New research, however, suggests that certain widely used preservative food additives are tied to a higher risk of high blood pressure and cardiovascular disease.
Here’s what to know about the latest study – and what it means for you.
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About the new research
The new findings, published May 20 in the European Heart Journal, are the latest from NutriNet-Santé, a large French study that launched in 2009.
The current study included 112,395 NutriNet-Santé participants who were, on average, in their early 40s and had no history of high blood pressure or cardiovascular disease at enrolment.
Participants were followed for eight years, during which time they provided detailed diet information to researchers, including brand names of commercial food products they consumed.
Health conditions and medical treatments were tracked every six months, or more often if needed, and were validated by an expert physician committee.
Eight preservatives tied to hypertension, heart disease
Food preservatives were widely consumed, with 99.5 per cent of participants consuming at least one within the first two years of enrolment. In total, 58 preservative additives were identified. Researchers examined possible links between 17 of them (consumed by at least 10 per cent of participants) and the risk of hypertension and cardiovascular disease.
Overall, they found that people who consumed the most non-antioxidant preservatives had a 29 per cent increased risk of developing high blood pressure compared with those whose diets contained the least.
They were also 16 per cent more likely to develop conditions of cardiovascular disease, including heart attack, stroke and angina, during the eight-year follow-up. Participants with the highest (versus lowest) intake of antioxidant preservatives had a 22 per cent greater risk of hypertension.
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Of the 17 commonly consumed preservatives looked at, researchers identified eight that were significantly associated with high blood pressure. They were potassium sorbate, potassium metabisulphite, sodium nitrite and five antioxidant additives: ascorbic acid (a.k.a. vitamin C), sodium ascorbate, sodium erythorbate, citric acid and rosemary extract.
Ascorbic acid was also specifically tied to cardiovascular disease. While ascorbic acid in fruits and vegetables has been consistently linked to better heart health, as an isolated preservative it may behave differently in the body.
Many of these additives are commonly used in foods such as processed meats, baked goods, packaged snacks, beverages and condiments.
To arrive at their findings, the researchers controlled for many factors that influence health including age, sex, smoking, body mass index, family medical history, physical activity, calorie intake, diet quality and alcohol intake.
Not surprisingly, participants’ preservative intake tracked with higher consumption of ultraprocessed foods. But the link between preservatives and cardiometabolic outcomes persisted even after accounting for ultraprocessed food intake, which suggests that the association isn’t fully explained by greater consumption.
Strengths, caveats
Major strengths of the study include its large sample size and long follow-up period. As well, the researchers assessed participants’ diets repeatedly throughout, allowing them to capture long-term food intake.
What’s more, they looked at the specific brands of packaged products people ate – not just the type of food – to identify which additives were actually present.
A key limitation is the study’s observational design, which can’t prove long-term consumption of food preservatives directly causes hypertension or cardiovascular disease.
Findings align with previous research
There is emerging evidence to suggest that some preservatives may be tied to multiple cardiometabolic conditions, however, not just one.
The new results are supported by another recent NutriNet-Santé study published in January, in which higher consumption of certain preservatives was linked to an elevated risk of type 2 diabetes.
A large U.S. study published in 2017 also found an association between a higher intake of nitrites in processed meat and an increased risk of dying from coronary heart disease.
Even before human studies, experimental research had raised concerns about some food preservatives. Nitrites, for example, have been shown to promote oxidative stress and may contribute to insulin resistance.
Cell and animal studies also suggest that some preservatives can damage cells, affect blood vessel function, alter the gut microbiome and disrupt metabolic pathways linked to insulin resistance.
Take-away
The new findings do not mean that all food preservatives are harmful. Rather, they suggest that even additives considered safe in small amounts may not be risk-free when consumed regularly over time.
According to the study authors, the results offer new insights that could help inform how the risks and benefits of food preservatives are evaluated, particularly in relation to cardiovascular health.
In the meantime, they certainly support existing recommendations to emphasize whole and minimally processed foods.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan.
