September 2013 Issue

Safety of Preservatives Explored

“Natural” foods, free of preservatives, continue to trend. But is avoiding preservatives really necessary? EN explores their safety.

If you keep a loaf of homemade bread on the counter for a few days, the telltale signs of spoilage begin: mold, discoloration, and an off taste. The same thing will occur if you leave most perishable food products, such as cooked vegetables, meat, or eggs, at room temperature for too long; bacteria, microorganisms, and enzymes begin to do their job by essentially “feeding” on the food, resulting in food decay.

That’s why food companies add preservatives to foods: To help extend shelf life, maintain high quality, and prevent spoilage. Before the advent of modern chemical preservatives used by the food industry, such as sodium benzoate and sulfites, our ancestors used other means of preservation, like drying foods and adding salt. We know that too much salt in preserved foods isn’t good for us, but what about synthetic preservatives? While many preservatives appear to be safe and provide an important function in our food system, some of them may be of concern.

The benefits of preservatives. Many of our modern preservatives were introduced in the 1970s. “Before then, you couldn’t leave foods out at room temperature for long. The addition of preservatives has changed our behavior on how we store and use food,” says Roger Clemens, DPH, internationally recognized food science expert and professor of pharmacology at the University of Southern California. Now we have the ability to purchase larger amounts of foods less often, and fewer foods need to be refrigerated. Chemical preservatives function to preserve food in many ways, including preventing the growth of microorganisms, reducing moisture content, increasing acidity, preventing the natural ripening process, and acting as an antioxidant.   The biggest advantage of using preservatives is lowering food waste. “We are losing up to 50 percent of our food supply around the world due to food waste. We’re in a bit of a conundrum; we want healthy food that will last a long time, but if you don’t put preservatives in it you lose food due to spoilage,” says Clemens.

Preservatives also can help protect health by decreasing the risk of food-borne illness caused by microorganisms in food, and by lowering oxidation in the body, which may occur as a result of ingredients in foods that become oxidized (or rancid). Oxidized compounds in food products, in addition to environmental toxins, can promote the formation of free radicals in the body, which produces oxidative stress. It is well known that oxidative stress is linked with the development of diseases like cancer and heart disease. 

The risks of preservatives. The Food and Drug Administration (FDA) is responsible for ensuring the safety of foods, but they are not required to review preservatives currently in use that are considered “generally recognized as safe.” Although the Center for Science in the Public Interest (CSPI) has petitioned FDA to reevaluate the safety of some food additives, Clemens reports that FDA hasn’t made a move on this issue yet. Several food additives have been banned, because—after many years of use—they have been deemed unsafe.

Many food preservatives appear to be completely safe, including, alpha tocopheral (vitamin E), ascorbic acid (vitamin C), calcium propionate, nisin, tartaric acid, and TBHQ. However, others have been called into question because of potential carcinogen or allergen risks.

Questionable preservatives. The following additives have been questioned regarding their safety, according to CSPI. 

BHA (Butylated Hydroxyanisole). The US Department of Health and Human Services considers this chemical to be “reasonably anticipated to be a human carcinogen.”

Propyl Gallate. Animal studies suggest that this preservative might promote cancer, however additional research is needed.

Sodium Nitrite/Nitrate. These are used as preservatives in processed meats, linked to increased cancer and heart disease risk.  

Sodium Benzoate. While these chemicals appear to be safe for most people, some report severe allergic reactions. 

Sulfites. Though sulfites appear safe for non-sensitive people, they can cause severe allergies in some.

A high preservative diet. Of greater concern may be the sheer amount of preservatives that you’re getting. Many health experts fear that with our increasing intake of highly processed foods, we are inadvertently upping our intake of these additives. According to Clemens, when you consume too many foods with preservatives it may cause problems, which is true for most things in our diets.

A 2010 study by Swedish researchers found that when a small amount of a common preservative was added to different types of pork meat, it increased the amount of toxins produced by the bacteria in food. The toxins from food microorganisms are generally responsible for making you sick when you acquire a food-borne illness. The scientists reported that the preservatives may cause the bacteria to become stressed, which means they produce more toxins. However, when a large amount of preservative was added, the bacteria did not survive.

EN’s bottom line. The solution to eating a healthful diet seems clear. “Eating less packaged food is ultimately the solution,” says Gerri French, M.S., R.D., C.D.E, nutrition educator at Sansum Clinic in Santa Barbara, California. “Enjoy more fresh foods, including healthy fats, such as avocado, nuts, seeds, and quality oils, and eating less food products is the answer. Eat more dried fruit and nuts rather than nutrition bars; plain yogurt with fresh or frozen fruit rather than “fruit-flavored” yogurts, milk in coffee rather than artificial creamer.”  

When you do use packaged foods, avoid preservatives that are of the greatest concern. “Read the ingredients on food labels in addition to the Nutrition Facts. Look at the ingredients in the foods that you frequently use. The next time you shop for those foods, look for a substitute that does not contain the ingredient you’d like to avoid. There might be refrigerator options with fewer food additives for products like bottled salad dressings,” says French.  

—Sharon Palmer, R.D.