Nitrates, the hidden ingredient in processed foods that can increase risk of cancer

As France cuts the additive on health grounds, doctors say consumers should limit their intake but not cut it altogether

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  An average hot dog sausage contains about 50 micrograms of nitrates per 100g of meat. Photo: AFP

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  Bacon is incredibly high in both nitrites and nitrates, with up to 380 mcg of nitrates per five rashers. Photo: AFP

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  Deli meats such as salami, pastrami and prosciutto are a major source of harmful nitrates. Photo: Reuters

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  Although nitrates have been removed by the smoking process of many brands, some smoked salmon still contains high levels of sodium nitrates. Photo: Boa

New regulatory standards in France will limit the amount of nitrates used in processed foods after the nation’s health agency warned they increased the risk of cancer.

But what exactly are they?

Food producers often add nitrates and nitrites to cured and processed meats, like ham, bacon and hot dogs, to give them the distinct colour and flavour we love.

There is strong research that shows a diet high in processed meats increases the risk of colon cancer

Zehour Ibrahim Mohamed,
NMC Royal Hospital Abu Dhabi

Nitrite salts are commonly used as a curing agent to extend cured meat's expiry date and decrease the risk of salmonella in smoked sausages.

Phasing out

But their use to prolong the shelf life of foods has been gradually reduced in France, and elsewhere in farming in the Netherlands and Germany, owing to their impact on human health.

However some natural foods, such as leafy greens and root vegetables, contain healthy nitrates that can help blood and oxygen flow.

Doctors said mounting scientific evidence linked highly processed meats with some cancers. That should encourage consumers to limit their intake, but nitrates should not be cut out altogether.

“The salt of nitrite and nitrates are mostly used for curing meat or added to food to preserve it,” said Zehour Ibrahim Mohamed, a clinical dietitian at NMC Royal Hospital, Khalifa City, Abu Dhabi.

“Nitrite and nitrate together are added to meat to keep it red and give flavour, while nitrates can be added to prevent certain cheeses from bloating during fermentation.

“It can lead to less oxygen transported through the body and possible formation of compounds known to be carcinogenic.

“There is strong research that shows a diet high in processed meats increases the risk of colon cancer.”

Carcinogenic risks

Research by the World Health Organisation’s International Agency for Research on Cancer in 2014 concluded the eating of large amounts of processed meats caused colorectal cancer.

Limited studies have also linked nitrates and nitrites ingested from processed meat to other cancers, such as ovarian, kidney, pancreatic and breast cancer.

Although not considered as dangerous as smoking or exposure to asbestos, processed meat with nitrates were classed in the same category of risk for carcinogenics.

The most recent Global Burden of Disease study in 2019, published in The Lancet medical journal, estimated around 304,000 cancer deaths were attributable to diets high in processed meat.

However, not all nitrates are bad and they are often found in natural foods with antioxidant properties.

Some found in leafy green vegetables can be converted into healthy nitric oxide that improves blood flow, transporting nutrients and oxygen effectively around the body.

According to the European Food Safety authority, accepted daily intakes for nitrite are 0.06 and 0.07mg per kilogram of bodyweight a day. For nitrate it is 3.7mg/kg of bodyweight per day.

In the US, one of largest consumers of processed meats, the average person eats about 75-100mg of nitrates a day.

Worst five processed foods for nitrates

Ham - a single 100g serving of cured ham can contain as much as 0.89mg of nitrates and gives the meat its pink colouring

Bacon - a meat incredibly high in both nitrites and nitrates, with up to 0.38mg of nitrates in every 100g, and more than 0.1mcg of nitrites per 100g serving, or about five rashers

Deli Meat - salami, pastrami, prosciutto and other cured meats are a major source of harmful nitrates. On average, these kind of processed foods have up to 0.5mg of nitrates per 100g serving, uncured meats have about 0.2mg fewer nitrates for the same amount

Hot dogs - an average hot dog sausage contains around 0.05mg of nitrates per 100g of meat

Smoked salmon - although nitrates have been removed from the smoking process of many brands, some still contain high levels of sodium with a 100g serving containing up to 0.6mg of nitrates

Top five natural foods with healthy nitrates

Bok choy - the leafy green contains a whopping 300mg of nitrates per 100g serving, and can help lower blood pressure

Spinach - a staple of a healthy diet, packed with vitamins and nutrients, it is also a good source of natural nitrates. A 100g serving of fresh spinach can contain up to 380mg

Lettuce - served in salads, this green vegetable contains a significant amount of natural nitrates, up to 267mg in a 100g serving

Carrots - this root vegetable is another great source of natural nitrates, producing anything from 90-190mg of nitrates for every 100g portion

Parsley - like other fresh herbs such as basil, thyme and dill, parsley can top up naturally produced nitrate levels by as much as 213mg per 100g