Nitrates & Nitrites in Food: Bad or Not?

Nitrates and nitrites are compounds that occur naturally in the human body and some foods, such as vegetables. Manufacturers also add them to processed foods, such as bacon, sausages, and deli meats, to preserve them and make them last longer on shelves and in transport.

Nitrates themselves are relatively inert, which means they’re stable and unlikely to change and cause harm. However, bacteria in the mouth or enzymes in the body can convert them into nitrites when you consume the food, which have the potential to be very harmful.

When the compounds are added to foods, they’re responsible for preventing the growth of harmful bacteria, adding a little saltiness to the flavour, and giving the food that characteristic red-pink colour we associate with meat. Normally, this isn’t a problem.

Nitrates and nitrites are essential compounds, but they can become hazardous if they form nitrosamines. Nitrosamines can form if you cook nitrates or nitrites at high heat. There are different types of nitrosamines, and many can increase the risk for cancer. 

Bacon, hot dogs, and processed meat can contain high levels of both sodium nitrite. They’re also high in protein, which is made up of amino acids. On exposure to high heat, this combination creates the perfect conditions for nitrosamines to form.

When the nitrites manufactured in our mouth are swallowed, one of the things that can happen is that they react in the strongly acidic environment of the stomach to form nitrosamines – some of which are carcinogenic and have been linked with bowel cancer.

But are they really that bad? In the UK, for example, six out of 100 people will get bowel cancer in their lives. Of those who eat 50 grams processed meat (about three rashers of bacon) daily, the chance goes up to only seven out of 100 people. Not a huge difference.

Importantly, nitrates and nitrites also occur naturally in vegetables, which may reduce the risk for some types of cancer and other diseases, dependent on many other factors such as how they’re cooked, any GM that has happened or fertiliser used.

Nitrates and nitrites in fact may be useful in keeping your body healthy, as they seem to function as antimicrobials in the digestive system. They can also help to kill harmful bacteria such as salmonella, and can help reduce blood pressure as nitric oxide.

So, what’s the verdict? Are they good or bad for you? Like all additives to food nowadays, there’s no simple answer. They may have positives and negatives, and it varies widely depending on if and how you cook the food containing them, and how much you consume altogether.