Research suggests ‘direct association’ between nitrites from food additives and diabetes risk

Nitrites are highly contentious food additives, having been associated with gastrointestinal tumours, stomach cancer, and the so-called baby blue syndrome.

It has also been suggested that the formation of nitrosamines might have adverse effects on insulin and insulin-like growth factor (IGF), and therefore could play a role in insulin resistance development and its related metabolic disorders such as diabetes.

In fresh research out of France, a study has sought to investigate whether dietary exposure to nitrates and nitrates, through their use as food additives, is associated with type 2 diabetes risk.

Findings put suggest another black mark should be placed against nitrites and nitrates being used as food additives by industry.

Focus on additives-originated nitrites and nitrates​

Nitrites and nitrates are naturally present in water and soil, which means that humans consume the substances through some fresh foods, such as green leafy vegetables and beetroots.

Yet dietary exposure to nitrites and nitrates also occurs through food additives. The compounds are used by the food industry as preservatives to improve shelf life and provide a characteristic pinkish colour and fresh meat flavour to some processed meats.

As a food additive, nitrites and nitrates are contentious. In 2015, the International Agency for Research on Cancer (IARC) classified processed meat, including deli meat, as carcinogenic due to its links with higher risk of colon cancer, amongst other things.

There has also been much debate about banning the use of nitrites and nitrates as preservatives, including in France where it is estimated that more than 15,000 packaged items on the market currently contain added nitrites or nitrates. Nitrite bans have also been debated in Germany and the UK.

In a context where several public health authorities around the world are questioning a possible suspension of the use of nitrites and nitrates as food additives, a team of nutritional epidemiology researchers in France have sought to investigate whether dietary exposure to nitrites/nitrates can be associated with another type of illness: type 2 diabetes.

‘A new piece of evidence’​

The study, conducted by researchers from Inserm, Inrae, Université Sorbonne Paris Nord, Université Paris Cité and Cnam, turned to the large prospective cohort NutriNet-Santé for data.

The French NutriNet-Santé cohort study ran from 2009 to 2021 and included 104,168 adults. The researchers were able to make associations between self-reported exposure to nitrites and nitrates (and differentiate dietary exposure from food and water, from food additives), and assess type 2 diabetes risk. In follow-ups, 969 cases of type 2 diabetes were noted.

The researchers observed that total nitrites and foods and water-originated nitrites were both positively associated with a higher risk of type 2 diabetes. But participants that had the higher exposure to sodium nitrite (e250) were found to have a higher type 2 diabetes risk compared to those not exposed to additives-originated nitrites.

These findings are potentially a first, according to the researchers. “We found for the first time to our knowledge, an association between additives-originated nitrites and specifically sodium nitrite (e250) with type 2 diabetes risk,” ​noted the study authors.

“Our findings suggest a direct association between additives-originated nitrites and type 2 diabetes risk, and corroborate previously suggested associations between total dietary nitrites and type 2 diabetes risk.”​

At the same time, no health benefit for dietary nitrites and nitrates were identified.

Potential to feed into nitrites laws​

The researchers are describing their findings as a ‘new piece of evidence’ in the context of current debates about updating regulation to limit the use of nitrites as food additives.

Campaigns to reduce, or ban, the use of nitrites and nitrates as food additives have been rife across western Europe. In France, a high-profile campaign against nitrates was instigated by Foodwatch, Yuka and the League Against Cancer. They put together a petition that attracted more than 363,000 signatures.

Around the same time, France’s National Assembly backed the principle to lower the trajectory of maximum levels of nitrates that can be added to charcuterie meats.

Although the researchers acknowledge confirmation is required by other prospective studies and experimental research, they believe their findings provide a new piece of evidence for this contentious debate. It could also support the need for better regulation of soil contamination, they observed.

Source: Plos Medicine​
‘Dietary exposure to nitrites and nitrates in association with type 2 diabetes risk: Results from the NutriNet-Santé population-based cohort study’
Published 17 January 2023
DOI: https://doi.org/10.1371/journal.pmed.1004149
Authors: Bernard Srour, Eloi Chzelas, Nathalie Druesne-Pecollo et al.