En español | Catching an intestinal illness from something you eat is unpleasant at any age, but the stakes grow higher the older you get, the U.S. Centers for Disease Control and Prevention (CDC) warns.
"Older adults in general are more likely to have severe illness [from food poisoning] that could land them in the hospital,” says Patricia Griffin, M.D., chief of the CDC's Enteric Diseases Epidemiology branch, which tracks foodborne illnesses. Nearly half of people 65 and older with a confirmed foodborne illness caused by salmonella, campylobacter, listeria or E. coli end up hospitalized, according to the CDC.
As you age, your immune system slows down, curbing its ability to fight off germs. You're also more likely to develop a chronic health condition, such as diabetes or heart disease, when you're older. Both factors increase the risk of getting food poisoning and developing a serious illness from it. Even otherwise healthy older adults who take stomach-acid reducers may be creating a dangerous situation for themselves, Griffin adds, because stomach acid helps kill harmful germs found in foods.
"Many older adults are quite healthy and don't think of themselves as having increased risk,” she says. “But they should recognize that as we all age, our immune system becomes a little more sluggish, and we need to take more precautions to prevent ourselves from getting sick."
A top precaution from the CDC is to cook food until it reaches its safe internal temperature, to kill any harmful bacteria, viruses or parasites that may be present. Other safety measures include washing your hands with soap and water for 20 seconds before preparing food, rinsing fresh produce under running water before eating it and avoiding cross-contamination in the kitchen — in particular, raw meat, poultry, seafood and eggs — when preparing meals.
Here are seven types of foods that the CDC warns can cause intestinal illness, along with the most common disease-causing germs associated with each and safety tips to avoid them.
1. Chicken, beef, pork and turkey
Undercooking and cross-contamination are the two biggest risks posed by meats. Wash your hands; keep raw meat away from other ingredients; and cook chicken, beef, pork and turkey to safe temperatures. The CDC recommends using a cooking thermometer, though Griffin acknowledges that not everyone has one or uses it regularly.
Safe minimum cooking temperatures
• Ground beef, pork, veal, lamb: 160 degrees
• Ground chicken, turkey: 165 degrees
• Steaks, roasts, chops: 145 degrees
• Poultry: 165 degrees
• Fresh pork, ham: 145 degrees
• Precooked ham: 165 degrees
• Egg dishes: 160 degrees
• Leftovers, casseroles: 165 degrees
• Fish with fins: 145 degrees
"You have to rely often on getting something steaming hot that looks to you well cooked,” she says. “A thermometer is best. But cooking your meat products really well is very important."
Safety tips: Ignore recipes that advise rinsing raw meats with water. The practice doesn't make your food any safer, and splashed water can spread germs from the raw meat to other food, utensils and surfaces.
Always make sure your meat is sufficiently cooked. Older adults who prefer the taste of rare beef or pork are taking a risk, Griffin says.
Leftovers should be refrigerated at 40 degrees or colder within two hours of preparation. Large cuts of meat should be portioned into small quantities to cool fast enough and prevent bacteria from growing.
2. Fruits and vegetables
Produce can pick up germs anywhere along the way, from the farm where it was grown to the store where it was sold — even from your kitchen counter once you get it home. Proper washing is the key to safety.
"On a per-serving basis, raw vegetables are not horribly risky except for certain ones, like sprouts,” Griffin says. “Vegetables and fruit are a really important part of a healthy diet, and there are so many wonderful ways to cook vegetables, and they are delicious."
Common foodborne germs: Salmonella, E. coli, listeria
Safety tips: Before and after preparing any produce, wash your hands for at least 20 seconds with warm soap and water. Cut away any damaged or bruised areas before preparing or eating.
When washing produce, always use running water. Soaking may remove the germs initially, but the now-tainted water can recontaminate the fruits and vegetables as well as contaminate nearby surfaces. The U.S. Food and Drug Administration doesn't recommend using soap, detergent or commercial produce wash.
3. Raw milk and cheese products
The routing availability of pasteurized milk became widespread in the U.S. by the 1950s and significantly reduced the number of people who became ill from raw milk and raw-milk products such as soft cheeses. The pasteurization process involves heating raw milk to a high enough temperature for a long enough time to kill dangerous particles, according to the CDC.
"Unpasteurized milk is risky because if you make a mistake with one or a few cows, you may not just get that udder perfectly clean, and then you've contaminated that entire batch,” Griffin says.
Although the pasteurization process inactivates some of the milk's enzymes, scientists do not believe those enzymes are critical to dairy health benefits.
Common foodborne germs: Brucella, campylobacter, Cryptosporidium, E. coli, listeria, salmonella
Safety tips: If you have raw milk, you can pasteurize it at home by heating it to 165 degrees for 15 seconds using an oven or double boiler. You can also eat raw cheese safely if you cook it thoroughly.
Eggs usually get contaminated when a hen has an infection around the tissues of its ovaries, which can introduce salmonella into its egg. Eggs are less likely to be contaminated today, though, than they were in the 1980s and early 1990s because producers have worked to decrease infections that cause the bacteria.
"Most batches of eggs are going to be completely safe,” Griffin says. “But some batches are going to be from a chicken that was stressed enough that salmonella was coming out as they laid their egg, and your risk of getting sick is going to be increased."
Common foodborne germ: Salmonella
Safety tips: Avoid foods that contain raw or undercooked eggs, like handmade (not commercially bottled) Caesar salad dressing, eggnog and raw dough. Cook eggs until the yolks and whites are firm, and keep them refrigerated at a minimum of 40 degrees.
5. Seafood and raw shellfish
Vibrio are bacteria that live in healthy seawater, so shellfish containing vibrio aren't technically contaminated. Still, the bacteria can lead to an infection called vibriosis, which poses significant health risks to those 65 and older. Contaminated shellfish can also contain norovirus, which can cause symptoms in older adults that may lead to dehydration.
Common causes of foodborne intestinal illness
• Brucella: bacteria found in raw milk, milk products
• Campylobacter: bacteria found on raw poultry
• Clostridium perfringens: bacteria found on raw meat, poultry
• Cryptosporidium: parasite commonly spread by water
• E. coli: bacteria found outdoors, on food and in intestines of animals
• Listeria: bacteria often found in dairy products, produce
• Norovirus: virus often found in shellfish, produce
• Salmonella: bacteria found in a variety of foods, including eggs
• Vibrio: bacteria found in raw, undercooked oysters
• Yersinia: bacteria found in raw, undercooked pork
Source: Centers for Disease Control and Prevention
Although undercooked fish has not been a major cause of bacterial illnesses, when eaten raw, it can contain parasites that can make you sick, Griffin warns.
"Major illnesses that we see are really from oysters, because people like to eat them raw,” she says. Some restaurants may offer oysters that have been treated to reduce the levels of vibrio in them, but this precaution doesn't necessarily remove all of the harmful germs.
Undercooked seafood typically causes people to have a diarrheal illness, which can be especially serious for those with conditions such as liver disease. In these instances, bacteria can get into the bloodstream and require hospitalization.
Common foodborne germs: Norovirus, vibrio
Safety tips: Cook seafood to 145 degrees, and heat leftovers to 165 degrees. Before cooking, throw out any shellfish with open shells, and after cooking, throw out any shells that do not fully open. Always make sure to cover any wounds that may come in contact with raw seafood, and wash your hands before and after handling it.
Eating raw or lightly cooked sprouts of any kind — such as alfalfa, mung bean or clover — can lead to food poisoning from harmful germs. The reason is that the seed itself is contaminated; yet there's so little contamination on the seed that, even if you culture it, it can't be detected. But as the seed (cultivated in warm, humid conditions) provides nutrition to grow the sprout it is also encouraging bacteria to grow.
"So as the sprout is sprouting, not only is the sprout happily growing, bacteria are happily growing,” Griffin explains.
Common foodborne germs: E. coli, listeria, salmonella
Safety tips: If you eat sprouts, cook them thoroughly; otherwise, avoid them.
7. Raw flour
Raw flour is not treated to kill germs that may have contaminated the grains while in the field or during the production process. Germs are killed when food made with the flour is cooked properly.
Common foodborne germs: E. coli, salmonella
Safety tips: Never eat raw dough or batter, and make sure to clean off all surfaces that the raw flour may have come in contact with.
Editor's note: This article has been updated with additional information.