A French study, which investigated the relationship between intake of nitrites and nitrates (all sources combined) and the risk of cancer, found that food additive nitrates and nitrites were positively associated with breast and prostate cancer risks, respectively.
Data from more than 100,000 individuals were analysed, with the results showing an increase of close to 25% in the risk of breast cancer among those who frequently consumed nitrate-containing products in their diet and an increase of close to 60% in the risk of prostate cancer among those who frequently ate nitrite-containing food products.
No association was demonstrated with regard to exposure to natural sources of nitrites and nitrates.
Why is this important?
Nitrites and nitrates occur naturally in water and soils, but they are also used as preservatives in processed meats. Although the results need to be confirmed by other large-scale prospective studies, they certainly add new food for thought in the lively debate on a potential precautionary ban on the use of these additives. Various international public health authorities already recommend limiting consumption of foods containing controversial additives.
Methodology
The study included adults from the ongoing NutriNet-Santé cohort, which began in 2009 (median follow-up, 6.7 years).
Exposure to nitrites and nitrates was analysed on the basis of participants’ consumption over 24 hours, which was determined using a food composition database and the trade names and brands of the industrial products in question.
Main findings
Of the 101,056 adults enrolled, 78.5% were women, and the mean age at enrolment was 42.3 years. The mean number of 24-hour consumption records was 5.5 per individual.
In the full cohort, 3,311 incident cases of cancer were diagnosed during follow-up. Compared with those who did not consume foods containing nitrates in the form of food additives, the largest consumers of these products had a 24% higher risk of developing breast cancer, particularly before menopause (hazard ratio [HR], 1.24; 95% CI, 1.03 – 1.48; P = .02), especially in the case of exposure to potassium nitrate.
The risk of prostate cancer was increased by 58% (HR, 1.58; 95% CI, 1.14 – 2.18; P = .008), particularly for sodium nitrite exposure.
The risk of developing colorectal cancer was not significantly increased by these two families of additives. The authors hypothesised that the study lacked statistical power for these latter analyses.
No association was demonstrated between consumption of nitrites or nitrates from natural sources and the development of cancer.
The authors suggest that these preservatives may lead to the formation of N-nitroso compounds, which are potentially carcinogenic substances for humans.
Study details
Nitrites and nitrates from food additives and natural sources and cancer risk: results from the NutriNet-Santé cohort
Eloi Chazelas, Fabrice Pierre, Nathalie Druesne-Pecollo, Younes Esseddik, Fabien Szabo de Edelenyi, Cédric Agaesse, Alexandre De Sa, Rebecca Lutchia, Stéphane Gigandet, Bernard Srour, Charlotte Debras, Inge Huybrechts, Chantal Julia, Emmanuelle Kesse-Guyot, Benjamin Allès, Pilar Galan, Serge Hercberg, Mélanie Deschasaux-Tanguy, Mathilde Touvier.
Published in International Journal of Epidemiology on 18 March 2022
Abstract
Background
Nitrates and nitrites occur naturally in water and soil. They are also used as food additives (preservatives) in processed meats. They could play a role in the carcinogenicity of processed meat. The objective was to investigate the relationship between nitrate and nitrite intakes (natural food, water and food additive sources) and cancer risk in a large prospective cohort with detailed dietary assessment.
Methods
Overall, 101,056 adults from the French NutriNet-Santé cohort (2009-ongoing, median follow-up 6.7 years) were included. Nitrites/nitrates exposure was evaluated using repeated 24-h dietary records, linked to a comprehensive composition database and accounting for commercial names/brands of industrial products. Associations with cancer risk were assessed using multi-adjusted Cox hazard models.
Results
In total, 3,311 incident cancer cases were diagnosed. Compared with non-consumers, high consumers of food additive nitrates had higher breast cancer risk [hazard ratio (HR) = 1.24 (95% CI 1.03-1.48), P = 0.02], more specifically for potassium nitrate. High consumers of food additive nitrites had higher prostate cancer risk [HR = 1.58 (1.14-2.18), P = 0.008], specifically for sodium nitrite. Although similar HRs were observed for colorectal cancer for additive nitrites [HR = 1.22 (0.85-1.75)] and nitrates [HR = 1.26 (0.90-1.76)], no association was detected, maybe due to limited statistical power for this cancer location. No association was observed for natural sources.
Conclusion
Food additive nitrates and nitrites were positively associated with breast and prostate cancer risks, respectively. Although these results need confirmation in other large-scale prospective studies, they provide new insights in a context of lively debate around the ban of these additives from the food industry.
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