There is some evidence suggesting an association between processed meat and stomach cancer. And a recent study found an increased risk of breast cancer among women who ate the most processed meats.

Processed meat refers to any meat, including pork, poultry, lamb, goat or others, that has been salted, smoked, cured, fermented or otherwise processed for preservation or to enhance the flavor. The category includes hot dogs, ham, bacon and turkey bacon, corned beef, pepperoni, salami, smoked turkey, bologna and other luncheon and deli meats, sausages, corned beef, biltong or beef jerky, canned meat and meat-based preparations and sauces, among others.

Many of these meats tend to be high in salt and saturated fat, though lean and low-sodium options are available.

Processed meats are often cured by adding sodium nitrite, which gives them a pink color and a distinct taste, or by adding sodium nitrite and lactic acid, which provides a tangy taste, according to The American Meat Institute. In the past, nitrates, in the form of saltpeter, were traditionally used. Nitrates or nitrites inhibit the growth of botulism and scientists suspect they may be involved in the formation of cancer-causing compounds in the body. (Vegetables also contain nitrates and nitrites, but eating them is not associated with an increased risk of cancer.)

Some products that claim to be “natural” or “organic” may say they are processed without nitrites or nitrates, and the label may say the item has “no artificial preservatives” or is “uncured.” But nutritionists warn that food manufacturers may still add vegetable powders or juices such as celery juice or beetroot juice that contain naturally occurring nitrates, which are converted to nitrites either in the food itself or when they interact with bacteria in our bodies.