While some research has shown that preservatives could be linked to cancer, the science is limited and contradictory.
A century ago, people could die from eating a sausage. Before the advent of modern preservatives, sausages were prone to harboring Clostridium botulinum, the bacteria that causes potentially deadly botulism. In the first half of the 20th century, scientists conducted a significant amount of research on the antibacterial effects of nitrite—a preservative that is especially good at killing C. botulinum and is still widely used in processed meats today. There’s only one problem: some research suggests that nitrates, which become nitrites when our bodies digest them, could be linked to cancer.
Other artificial food preservatives have come under scrutiny as well. The Center for Science in the Public Interest, an independent consumer advocacy group, recommends avoiding several food preservatives, including nitrites, due to their potential cancer link. But, some experts caution, the science is still limited and sometimes contradictory.
One of the major roles of preservatives is to increase the shelf life of foods. This has allowed stores to pack shelves with unhealthful items, such as sugary treats and processed foods, but it has also improved access to healthful foods, such as whole-wheat products and oils with unsaturated fats, says Karen Collins, a nutrition adviser for the American Institute for Cancer Research.
Preservatives also kill potentially dangerous microorganisms, such as the food poisoning culprit Listeria monocytogenes. “If you eliminated preservatives from the meat industry, there would probably be an outbreak of food-borne illness and death from C. botulinum and other toxins,” says Nathan Bryan, a biochemist at the University of Texas Health Science Center at Houston.
The vast majority of research looks at specific preservatives. Among the most studied and the most controversial preservatives are nitrates/nitrites and BHA (butylated hyrdoxyanisole).
Nitrates and nitrites are found in processed and cured meats, such as hot dogs, bacon and lunch meats. A study published in 2012 found that American women with the highest dietary nitrate intake had a 31 percent greater risk of ovarian cancer than women with the lowest nitrate intake.
Another study found that people with the highest consumption of nitrites from animal sources were more likely to develop renal cell carcinoma. Nitrites can form nitrosamines, which are known carcinogens, but experts disagree on the extent to which these preservatives may contribute to cancer.
BHA is found in cereals, vegetable oils and snack chips. Some animal studies have linked the antioxidant BHA to certain forms of cancer, leading the government’s National Toxicology Program to conclude that BHA is “reasonably anticipated to be a human carcinogen.” Yet, the only recent human study on BHA and cancer, published in 2000, found no association between BHA and stomach cancer.
So, should people avoid preservatives? Lisa Lefferts, a senior scientist for the Center for Science in the Public Interest, says that many artificial preservatives can be replaced by using other chemicals, such as vitamin E, or alternative packaging processes.
“Of course, it’s important to understand that there are much bigger risks in the food supply, such as too much salt, sugar or trans fat,” Lefferts adds.
The bottom line: “Overall, when we look at preservatives, they are really unlikely to be a large portion of cancer risk,” Collins says. “It’s important for people to know that with a healthy lifestyle—physical activity, a basic healthy diet with a focus on plant foods and avoiding tobacco—we can prevent more than half of cancers.”