Preservatives in cured meats could raise the risk of type 2 diabetes by more than half, a study suggests.
Researchers say they have found a link between nitrites – used to add colour and flavouring to meats such as sausages and bacon – and an increased risk of type 2 diabetes.
The team accessed data collected from more than 100,000 people in France who have been tracked since 2009.
Researchers say they have found a link between nitrites – used to add colour and flavouring to meats such as sausages and bacon – and an increased risk of type 2 diabetes
Participants enrolled voluntarily and self-reported their medical history, diet, lifestyle and major health updates, and were followed for around seven years.
What are nitrites? And how do they differ from nitrates?
Nitrites and nitrates are commonly used for curing meat and other perishable produce.
They are also added to meat to keep it red and give flavour.
Nitrates are also found naturally in vegetables, with the highest concentrations occurring in leafy vegetables like spinach and lettuce.
It can also enter the food chain as an environmental contaminant in water, due to its use in intensive farming methods, livestock production and sewage discharge.
Nitrites in food (and nitrate converted to nitrite in the body) may contribute to the formation of a group of compounds known as nitrosamines, some of which are carcinogenic – ie, have the potential to cause cancer.
In 2015 the World Health Organization warned there were significant increases in the risk of bowel cancer from eating processed meats such as bacon that traditionally have nitrites added as they are cured.
The current acceptable daily intake for nitrates, according to the European Food Safety Authority (EFSA), is 3.7 milligrams per kilogram of body weight per day.
The EFSA’s acceptable daily intake for nitrites is 0.07mg per kilogram of weight each day.
Analysis suggests those who had the highest total dietary nitrite intake had a 27 per cent increased risk of developing the reversible condition.
The scientists also discovered people with the highest intake of sodium nitrite – the most important additive responsible for the characteristic colour and flavour associated with cured meats – had a 53 per cent higher risk of developing type 2 diabetes.
Lead author Dr Bernard Srour, from Sorbonne Paris Nord University, said: ‘These results provide a new piece of evidence in the context of current discussions regarding the need for a reduction of nitrite additives’ use in processed meats by the food industry.
‘In the meantime, several public health authorities worldwide already recommend citizens to limit their consumption of foods containing controversial additives, including sodium nitrite.’
The amount of nitrites that people consumed from food additives in the study was, on average, 0.51mg per day.
The group who consumed the most nitrites had, on average, 0.62mg per day.
One rasher of bacon contains around 0.25mg of nitrites, according to previous research.
Roughly one in 12 adults in the UK and US has type 2 diabetes and of these, 90 per cent are overweight or obese.
Previous studies have shown eating a lot of red and especially processed meat is linked with a greater risk of the obesity-driven condition.
However, other experts have raised concerns about the most recent findings and how food additive intake was assessed.
They also warned that nitrites from food additives only contribute to around 4 to 6 per cent of total nitrite intake, with the rest coming from other sources such as drinking water.
Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London, said: ‘Estimates were based on recalls of dietary intake on two separate occasions at the beginning of the study with no further estimates in the follow up period of over seven years.
‘The researchers had to guess which foods contain the various nitrite additives, the levels used in the products and the amounts of the food consumed.’
Dr Duane Mellor, a registered dietitian and senior lecturer at Aston University, said: ‘When considering the meaning of this data, it is perhaps worth noting that the use of nitrites as an additive is often as sodium nitrite which is used to cure meats like bacon, which if someone is seeking to reduce their risk of type 2 diabetes would be something people would be encouraged to eat less of.
‘The best way to reduce your risk of developing type 2 diabetes is to be physically active, maintain a healthy weight for you and eat a varied diet based on vegetables, pulses, nuts, seeds and fruit along with wholegrain and moderate intakes of dairy foods and meat – especially processed meats.’
The findings were published in the journal Plos Medicine.