Are processed meats safe?
Hot dogs and deli meats are delicious every now and then. But are processed meats really safe? Here’s what the research has to say
Have you ever bitten into a hot dog or a ham sandwich and wondered if it was bad for you—or whether any deli meats are safe to eat? We checked it out.
There isn’t an exact definition of 'processed meat,' but most often (including in this article), it refers to meats preserved by smoking, curing, salting or adding chemicals such as sodium nitrite. They include ham, bacon, corned beef, salami, bologna, pastrami, hot dogs and bratwurst.
Studies have examined whether they increase your risk of cancer or other diseases. The news isn’t good.
• A Swedish study looked at data collected on more than 4,700 patients from 15 studies published from 1966 through 2006. It found that eating 30 grams of processed meat a day (the equivalent of about one hot dog) was linked to a 15 to 38 percent increase in stomach cancer risk.
• In 2007, the American Institute for Cancer Research reviewed more than 7,000 studies on all aspects of diet and cancer risk. Its mammoth report stated there was convincing evidence that cured and processed meats cause colorectal cancer. Every 50 grams of processed meat (about two slices of Black Forest ham), eaten daily, increases your risk of colorectal cancer by an average of 21 percent.
• In 2009, the National Cancer Institute in the U.S. released results of a study that followed 550,000 people over 10 years. Those who ate the most processed meat (22 grams a day) had a higher risk of death from all causes than those who ate the least (under two grams a day).
• In May 2010, a study published in the journal Circulation found that eating processed meat was associated with a 42 percent higher risk of heart disease and a 19 percent higher risk of type 2 diabetes. The study did not find this increased risk among those who ate unprocessed meat—e.g., pork, beef and lamb. (In 2009, the Canadian Cancer Society updated its red meat guidelines: no more than three servings of 85 grams, or three ounces, per week.)
It’s not the nitrites
In the 1970s, scientists thought the culprit was the additive, sodium nitrite. This gives processed meats their taste and characteristic pink hue, and also acts as a preservative to give them a longer fridge life. It also prevents botulism, which is lethal. But Levente Diosady, director of the food engineering program
in the department of chemical engineering and applied chemistry at the University of Toronto, says sodium nitrite doesn’t pose a health risk directly, though it can react with amines that occur naturally in foods like cheese and meat to form tiny amounts of nitrosamines, which are carcinogens.
In the late 1970s, because of this cancer risk, Health Canada limited the maximum amount of sodium nitrite that can be added to meat to no more than 200 parts per million (and in most cases, a lower amount is used—120 parts per million). In addition, scientists learned it’s possible to prevent the formation of nitrosamines by adding erythorbic acid (a close relative of vitamin C). Most processed meats now contain this.
But it looks like sodium nitrite itself is not a bad thing—and surprisingly, we get it naturally from vegetables. Joe Schwarcz, a McGill University chemistry professor who has written science and nutrition books including An Apple a Day and Brain Fuel, says, "Believe it or not, vegetables are a bigger source of nitrites than processed meats." And, of course, we shouldn’t be avoiding vegetables.
Vegetables, particularly celery, lettuce, beets, radishes and spinach, absorb sodium nitrate from the soil. This is converted to sodium nitrite in our stomachs. Schwarcz says a person eating 250 grams (about 2 .5 cups) of vegetables a day would acquire about as much sodium nitrite as she’d get from eating 10 hot dogs a day! "Yet no study has shown a cancer link to vegetables," states Schwarcz. "This may be because veggies also contain a host of compounds, including vitamin C, that prevent nitrosamine formation."
More research is needed
So what is the problem with processed meats? Scientists are not sure. Says Diosady, "If there were a single cause, science would be on top of it by now. It’s complex."
Experts say it could be the smoking process in smoked meats, the salt, the fat (though products lower in salt and fat are available at grocery stores), the fact that many of these are red meats, or a combination of these factors. Regardless, more research is needed.
According to Heather Chappell, director of cancer control policy at the Canadian Cancer Society, we don’t even know if processed white meats and processed red meats pose the same risk. And we don’t know if people at higher risk—for example, those with a family history of cancer—need to be more careful.
This much is known: We should be cautious about how much processed meat we eat. If a deli ham sandwich is regularly part of your lunch and a pepperoni pizza a weekly staple, rethink this. Chappell advises, "Save processed meat for special occasions, such as a ham for a holiday dinner or a hot dog at the game."
This article was originally titled "Processed Meats: Are They Safe?," in the September 2010 issue of Best Health. Subscribe today to get the full Best Health experience—and never miss an issue!—and make sure to check out what's new in the latest issue of Best Health.