A higher intake of some food preservatives is associated with a modestly increased risk of cancer, according to a new study published in The BMJ.

Researchers analysed 105,260 participants’ dietary records, health questionnaires, and official medical and death records. Results showed that for several individually studied preservatives, a higher intake was associated with a higher risk of cancers. 11 of the preservatives examined in the study were not associated with cancer incidence, and no link was found between total preservatives intake and cancer incidence.

The All Ireland Science Media Centre asked experts to comment.

Professor William Gallagher, School of Biomolecular and Biomedical Science, University College Dublin, comments: 

“This is a large-scale observational study, which means there were no specific interventions, where dietary patterns were tracked over 24 hour periods, and then subsequent cancer incidence tracked in a long-term view (up to 14 years). Importantly, one cannot make causal links directly from this study, but it does make some interesting observations particularly in respect to an association between higher intake of non-antioxidant preservatives and higher rates of overall cancer, breast and prostate cancer. These higher rates of cancer are modest (e.g. 10-30% increased risk) but are significant when taken at a population-based level in terms of potential impact.

“From my perspective, the work stands out as it did not particularly focus on ultra-processed foods, but took a broader view of dietary intake of food additives, using brand-specific information rather than a generalised assessment. Indeed, only about a third of the additive preservatives examined in this study were from ultra-processed foods.

“Of interest, while a substantial number of study participants took part (>100,000), nearly 80% of them were women, tended to be older and ate less processed meat. This suggests a slight bias to the study, but it looks like they tried their best to control for this.

“This work is unique in its scale of assessment of food additives in a large number of study participants, and also puts added focus on the recognition by the International Agency for Research on Cancer  (IARC) that food additive nitrites and nitrates are probably carcinogenic.

“The challenge for a lot of these studies is the lack of direct causal link, although there are some other, separate studies which have examined the direct impact of these sort of additives on tumour behaviour in model systems (cell cultures from humans and animal models).

“I believe the study to be an important piece of work, which is challenging to do, especially at this scale and over the time duration studied. It has potentially important public health implications.”

Declarations of interest: I don’t have any relevant conflict of interests. For full disclosure, I am part time Chief Scientific Officer of OncoAssure, a molecular diagnostics company. I don’t have any links with the food industry.

Professor Mark Lawlor, Professor of Digital Health, Queen’s University Belfast and Academic Lead of the Peace Plus Digital ONEHEALTH Hub, comments: 

“Increasingly, we are recognising that a OneHealth approach, embracing not just the health of the individual but also the health of the food that we eat, the water that we drink and the air that we breathe, is critical to ensuring our collective health and wellbeing. This current study, a detailed analysis on a cohort of over 105,000 individuals, shows the importance of balancing the use of food preservatives to extend shelf life with the risk of a number of these food additives contributing to the development of cancer.

“Some of the increased risks observed by the researchers give cause for concern, for example potassium sorbate was associated with a 26% increased risk of developing breast cancer, while sodium nitrite was associated with a 32% increased risk of prostate cancer development. These data highlight the importance  of pursuing a holistic OneHealth approach and ensuring that regulatory agencies consider both the negative and the positive effects of food additives when making decisions on the food that we eat.”

Declarations of interest: “no relevant declarations of interest”