Tofu & Food Poisoning

Tofu is a nutritious source of protein made from coagulated soy milk. It is popular in East Asian cuisine, and is a commonly consumed plant-based protein. While tofu is a perishable food that may harbor pathogens, or disease-causing microorganisms, it is not a common cause of foodborne illness. To safely enjoy your tofu, however, certain precautions are needed to reduce the risk of food poisoning.

According to the CDC, food can be a source of illness when pathogens from the fecal matter of animals or humans contaminate the food, or when food is exposed to the ideal temperature range long enough to allow any disease-causing microorganisms to flourish. Some of these potential pathogens are harmless if the food is cooked properly and stored at the correct temperatures. Cross-contamination is another means of transmission, where knives or cutting boards used with raw meat or chicken can in turn taint other foods. Food handlers infected with Staphylococcus aureus, or staph, may transmit this bacteria by exposing food to infected cuts or by coughing into food. While many pathogens can be destroyed by heat, microorganisms can form toxins in foods exposed to unsafe temperatures, and these may not be destroyed by cooking.

The Centers for Disease Control and Prevention (CDC) estimates that each year, approximately 1 in 6 people in the U.S. get sick from foodborne illness. The most common pathogens that lead to foodborne illness are disease-causing bacteria and viruses, although parasites, fungi, natural food toxins and even heavy metals can also be to blame. Since soy milk is thoroughly heated prior to making tofu, killing most bacteria and viruses in the soy, properly processed and handled tofu is not likely to be contaminated.

Although uncommon, there are a few ways in which tofu may cause foodborne illness. One of these is contamination of the tofu itself -- for example, by unclean equipment at the food processing facility. Tofu can also be contaminated by the food preparer -- unwashed hands, sneezing or coughing on foods, or contact with pathogens from another food -- such as raw chicken. Tofu may also be exposed to pathogens if stored in contaminated water. There are more safety concerns if purchasing tofu sold in bulk -- stored in a large bin of water -- as unwashed hands or unclean water, for example, can infect the entire batch of tofu.

To minimize the risk of food poisoning, store tofu according to package directions. Some forms of tofu can be kept at room temperature until opened, then need to be refrigerated. Many forms of tofu are individually water-packed and refrigerated. If you purchase tofu in bulk, choose reputable sources only and ask questions about how often a new batch is made and how often the water is changed. When preparing tofu, use clean utensils and containers to avoid cross contamination. Also store any leftovers in the refrigerator promptly, as bacteria grow best when exposed to the danger zone of 40 to 140 degrees Fahrenheit.

Symptoms of food poisoning may differ based on the source of infection, but can include gas, bloating, cramps, nausea, vomiting, fever, headache or diarrhea. Talk to your doctor if you think you have food poisoning. See your doctor right away if you have bloody diarrhea, fever, diarrhea for more than a few days or if you are very dehydrated. Urgent medical attention is particularly important for anyone at risk for severe infection and related complications, such as pregnant women, infants, adults over the age of 65 and anyone with a weakened immune system.

Reviewed by: Kay Peck, MPH, RD