High intakes of certain preservatives found in processed foods increase the likelihood of developing Type 2 diabetes and cancer, French findings suggest.Christopher Katsarov/The Canadian Press
Unless you eat only fresh, unprocessed foods and prepare all your meals from scratch, it’s impossible to avoid consuming food preservatives used to maintain food safety and freshness.
These additives help prevent spoilage caused by moulds, bacteria and yeasts, including microbes that can cause serious, even life-threatening, food poisoning.
Another group of preservatives – known as antioxidants – delay the deterioration of a food’s colour, taste and texture due to oxygen exposure in packaging. Antioxidant preservatives also counteract nutrient loss.
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According to two new studies from France, food preservatives may do more than maintain the safety and quality of foods.
The findings suggest that high intakes of certain food preservatives increase the likelihood of developing Type 2 diabetes and cancer.
Here’s a breakdown of the research, along with its key takeaways.
About the NutriNet Santé studies
The new studies, both published on Jan. 7, analyzed health and diet data from NutriNet Santé, a large continuing French study, launched in 2009, that is investigating the links between diet, lifestyle and health.
The latest NutriNet Santé research is the first in the world to investigate the relationship between food preservative consumption and risk of Type 2 diabetes and cancer.
Both studies analyzed data from more than 100,000 adults aged 42, on average, at the study’s onset. Dietary information, collected every six months during the study period, was used to assess participants’ intake of food preservatives.
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In total, 58 preservative food additives were identified. Of these, 17 were consumed by at least 10 per cent of participants and, as such, were investigated individually in relation to Type 2 diabetes and cancer risk.
Preservatives were divided into two groups: non-antioxidants, which inhibit microbial growth to extend shelf life, and antioxidants, which prevent food spoilage caused by oxygen exposure.
Preservatives and Type 2 diabetes risk
The diabetes study, published in journal Nature Communications, followed participants for average of eight years during which time it tracked 1,131 new diagnoses of Type 2 diabetes.
A higher intake of 12 widely-used non-antioxidant and antioxidant food preservatives, all permitted for use in Canada and the U.S., was tied to a greater risk of diabetes.
These included potassium sorbate, potassium metabisulfite, sodium nitrite, acetic acid, calcium propionate, sodium acetate, sodium ascorbate, alpha-tocopherol, sodium erythorbate, citric acid, phosphoric acid and rosemary extracts.
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Participants with the highest overall intake of these preservatives were 47 per cent more likely to develop Type 2 diabetes during the study compared with those who consumed the least.
The link between preservative intake and diabetes risk remained significant even after accounting for the amount of ultra-processed foods consumed.
Preservatives and cancer risk
For the cancer study, 4,226 participants received a cancer diagnosis during an average follow up period of 7.5 years.
Six of the 17 studied food preservatives, mostly non-antioxidants, were associated with a modestly increased risk of overall cancer, breast cancer and prostate cancer. These included potassium sorbate, potassium metabisulfite, sodium nitrite, potassium nitrite, acetic acid and sodium erythorbate.
For example, compared to low or no consumption of sodium nitrite, a preservative used in many cured meats such as bacon, hot dogs and deli meats, a higher intake was tied to increased risk of prostate cancer.
A high intake of potassium sorbate, used to stop mould and yeast growth in foods such as yogurt, cheese, baked goods and beverages, was tied to a greater risk of overall cancer and breast cancer.
The findings were published in The BMJ.
Strengths, limitations, biological mechanisms
These were observational studies, so they can’t prove that food preservatives directly cause Type 2 diabetes or cancer. As well, diet information was self-reported, which can be prone to error.
The research is notable, however, for its large sample size, long follow-up and detailed measurement of preservative intake.
And there are plausible ways in which some preservatives could influence diabetes and cancer risk.
Previous laboratory and animal experiments have shown that some common preservatives can damage DNA, cause oxidative stress, alter the gut microbiome and interfere with metabolic processes such as glucose metabolism.
Certain preservatives may also disrupt immune and inflammatory pathways, potentially triggering cancer development.
Takeaways
The new findings, the first to associate preservative intake with health harm in people, are not definitive. They need to be replicated in other studies.
Even so, according to the study authors, these data call for a reassessment of regulations that govern the use of food preservatives.
Despite the clear benefits of food preservatives, an accompanying editorial in The BMJ concluded, “the widespread and often insufficiently monitored use of these additives, with uncertainties of their long-term health effects, call for a more balanced approach” from a food policy perspective.
In the meantime, the findings are another reason to focus on fresh, whole and minimally processed foods, such as vegetables, fruit, whole grains, beans, nuts and fresh meats.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan.
