- Food preservatives can be natural or synthetic and extend shelf life of food.
- Some common preservatives have been linked with an increased risk of cancer.
- Focusing on whole foods when possible may reduce cancer risk.
While the risk of dying from cancer has been steadily decreasing, the rates of cancer continue to rise, with over 2 million new cases expected to be diagnosed in 2026. Many factors can increase your risk of cancer, including genetics. And while genetics are out of your control, there are several lifestyle areas connected to cancer risk that you can play a role in changing, including smoking, drinking alcohol, physical activity and diet.
Regarding diet, there is no one anti-cancer miracle food. It’s important to take your whole diet into consideration. We do know that there’s a connection between a high consumption of ultra-processed foods and cancer (as well as cardiometabolic diseases, like heart disease and diabetes).
The reasons for this connection may be varied, but French researchers are honing in on preservatives and their relationship to cancer risk, since they tend to be common in ultra-processed foods. They published their findings in the BMJ. Let’s break down what they found.
How Was This Study Conducted?
Researchers drew data from the French NutriNet-Santé cohort for the years 2009 to 2023; this study was designed to investigate the associations between nutrition and health. There were over 105,000 participants, almost 80% of them female, with an average age at baseline of 42.
At registration and every six months, participants completed a series of three validated web-based 24-hour dietary records. At each period, the dietary records were randomly assigned to three nonconsecutive days over two weeks (two weekdays and one weekend day). Doing nonconsecutive days and including one weekend day helps provide a more accurate picture of one’s overall diet.
Researchers took the information from participants’ dietary records and broke down nutrient intakes, including vitamins C and E, which can be used as preservatives in some foods. In addition, using brand-specific data, researchers also broke down food additives, focusing especially on preservatives. They then quantified participants’ intakes of both naturally occurring preservatives (including acetic and citric acids, nitrites, nitrates and sulfites) and added preservatives. In all, 58 preservatives were investigated.
Participants reported any health-related incidents, including cancer diagnoses, throughout the study period, either in their biannual health questionnaires or at any time through their connected health portal. To ensure accuracy of participants’ reporting, a physician expert committee validated every reported cancer event against official medical records. In addition, the NutriNet-Santé cohort was linked to the national health insurance system database to collect additional information on medical treatments and consultations.
The cohort was also linked to the French national mortality registry to identify deaths and causes of death. For this study, incident cancer included all primary cancers diagnosed between enrollment into the study and December 31, 2023; the only cancer not included was basal cell carcinoma of the skin.
What Did This Study Find?
The average follow-up time for participants was almost eight years. This study found multiple associations between preservatives that are widely used in industrial foods and beverages in both U.S. and European markets and higher incidences of overall, breast and prostate cancers. In particular, these preservatives were connected to higher cancer risk:
- potassium sorbate
- potassium metabisulfite
- sodium nitrite
- potassium nitrate
- acetic acid
- sodium erythorbate
Most associations were observed for non-antioxidant preservatives. Among antioxidant preservatives, only total erythorbates and specific sodium erythorbate were found to be associated with a higher incidence of cancer. It’s important to remember that because this study is observational, it can only draw connections—or associations—which doesn’t mean causation. More research needs to be done to confirm these findings. Limitations of this study include the self-reporting of participants’ food intake, which may introduce bias. Researchers also note that it was difficult to estimate some of the naturally occurring preservatives in some foods.
How Does This Apply to Real Life?
The preservatives that were analyzed in this study are currently categorized by the U.S. Food & Drug Administration as Generally Recognized as Safe (GRAS). This means that to date, the FDA does not have enough evidence to ban them. This can change, however, as in the cases of the dye Red No. 3 and brominated vegetable oil. Unfortunately, it can take years of research and evidence to finally ban an additive, and in the meantime, they may affect your health.
Preservatives are often found in foods like alcoholic drinks, processed meats, refined grains, processed fruit and vegetables and breakfast cereals. Anything that is shelf-stable will likely contain preservatives.
If you’re trying to reduce your cancer risk, the American Cancer Society recommends being physically active, limiting sedentary time and getting to and maintaining a healthy weight to help lower cancer risk. They suggest eating more plants, including fruits, vegetables, legumes and whole grains, and fewer sugar-sweetened beverages, highly-processed foods and refined grains—which also means aiming for less added sugar overall. They also recommend reducing processed and red meat intake and avoiding alcohol.
There always seems to be a caveat with any recommendation, though. For example, with higher produce intake can come a higher consumption of herbicides and pesticides, which may also increase cancer risk. This isn’t a reason, however, to avoid fruits and veggies. Instead, you could buy organic produce, especially the fruits and vegetables on the Environmental Working Group’s Dirty Dozen List. If the expense of buying organic just isn’t feasible, that’s OK—try to thoroughly wash your produce before you cook or eat it, and if you’re still concerned, remove the peel after washing.
While there’s no one anti-cancer diet, a Mediterranean diet-style of eating covers all the bases the American Cancer Society recommends. If you’re new to this way of eating and want to give it a go, try our 5-Day Mediterranean Diet Meal Plan for Beginners. For those of you further along in your journey, try out our 30-Day No-Sugar Mediterranean Diet Meal Plan.
Our Expert Take
This study connected several commonly used preservatives to a higher risk of cancer. To reduce your risk, stick with mostly whole foods, including fruits, vegetables, whole grains, legumes, nuts, seeds and lean proteins. The Mediterranean diet has got you covered, and has also been linked with a lower risk of other diseases, including heart disease and diabetes. Still, this doesn’t mean you have to give up processed foods entirely. If you’re concerned, read the label closely and look to see if a product contains preservatives associated with cancer. Other lifestyle changes that may reduce your cancer risk include avoiding smoking and alcohol and engaging in regular physical activity.
