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Your nose always tips you off when a carton of milk turns sour, and when you spot some mold growing on your leftovers, you know better than to dig in. But don't assume that everything that looks or smells good is perfectly safe.

"Many of the organisms that cause foodborne illness can't be easily seen, smelled, or tasted," said Mindy Costello, a consumer information specialist at the National Science Foundation (NSF), a national public health and safety organization.

Perhaps that's why 1 in 6 people get sick each year thanks to something they ate, according to the Centers for Disease Control and Prevention (CDC).

Food poisoning symptoms can range from a slightly upset tummy to severe diarrhea, vomiting, dehydration, and even death (here’s how to tell if you have food poisoning). While people who are immune compromised, very young, elderly, or pregnant are most likely to suffer serious complications, anyone can be impacted by the dangerous bugs that may contaminate food during the growing, harvesting, or processing stages. Here's a look at 12 items that are often flagged by the FDA, and info on how to protect yourself. (Just can’t shake the weight? See if your thyroid is the problem—and learn how to take control—with Rodale’s The Thyroid Cure.)

Leafy greens

Lettuce, spinach, kale, and other leafy greens are packed with nutrients, but they might also be loaded with hazardous bacteria. These veggies account for about 24 percent of all food outbreaks, according to a report released by the Center for Science in the Public Interest (CSPI). While the numbers vary from year to year, in early 2016 the CDC and the FDA investigated a multistate outbreak of listeria that infected 19 people, resulting in 19 hospitalizations and one death.

"It stems back to where they're grown: If cattle are being raised nearby, feces or other cattle residue can drift over into the field, depositing pathogens," said David Plunkett, senior staff attorney for food safety at CSPI.

Protect yourself: Wash greens thoroughly before you eat them, and avoid bagged salads—especially the "prewashed" kind.  (The commercial washing systems used can harbor bacteria, says Plunkett.) You should also know that sautéing your spinach is far safer than eating it raw in a salad, as heat kills listeria. (You know you’re curious…check out these 7 things your poop says about you.)

Eggs

The oh-so-perfect breakfast food is also a potent breeding ground for salmonella. "The most common type of salmonella we see is Salmonella enteritidis, which infects the ovaries of otherwise healthy hens and contaminates the eggs before the shells are even formed," explains Plunkett. (Are you making any of these 7 mistakes with your scrambled eggs?)

Protect yourself: Opt for boiled or scrambled over poached or sunny-side-up, since cooking eggs thoroughly is the best way to kill salmonella, said Jennifer Fitzgibbon, RD, CDN, a registered oncology dietitian at Stony Brook Cancer Center. (She works with many immune-compromised patients, who need to be extra careful about what they eat.) Meanwhile, don't eat any products that contain raw eggs, like uncooked cookie dough (sorry). You may also want to consider ordering pancakes when you're out for brunch; about half of all egg-related outbreaks happen in restaurants and other food establishments, according to the CSPI.

Tuna

This type of fish may contain scombrotoxin, which causes flushing, headaches, and cramps, says Fitzgibbon. Scombrotoxin develops when natural chemicals in tuna and other fish, including mackerel, build up as the fish starts to spoil. This toxin can't be destroyed by cooking; the best way to avoid it is to keep the fish as cool as possible from the moment it's caught.

Protect yourself: Unless you're catching your own dinner, you have to trust the store or restaurant you're purchasing the tuna from. Keeping the fish appropriately cold from the moment it comes out of the water until it's ready to be cooked and served is the only surefire safeguard. Do your part by getting it home from the store promptly, and stash it in the fridge until you're ready to cook. (Read these 5 things to know before you buy tuna again.)

Oysters

They're considered a delicacy, but oysters can ruin your elegant dinner party in a flash.

"They can be harvested from waters contaminated with norovirus, so if they're served raw, they can cause gastroenteritis, an inflammation of your GI tract," Plunkett said.

But this pales beside another life-threatening bacteria they can harbor: vibrio, which is a cousin of cholera. It can infect your bloodstream, causing fever, chills, lowered blood pressure (septic shock), and blistering skin lesions that can ultimately kill you. There was a big outbreak in 2013, with 104 cases across 13 states that led to six hospitalizations.

Protect yourself: Shun raw oysters in favor of steamed or baked ones.

"Every time you eat a raw oyster, you're playing Russian roulette with your life," Plunkett said.

Potatoes

It's entirely possible to be sickened by spuds, which may contain a variety of bacteria, including C. botulinum (which causes botulism) and E. coli. Salmonella is the biggest threat, as it's been associated with almost 30 percent of potato outbreaks, according to the CSPI.

Protect yourself: Rinse potatoes thoroughly before washing them, and skip the aluminum foil wrap if you're going to bake them (the foil prevents the heat from killing C. botulinum spores). It also pays to be cautious with potato-based salads. While many people think the mayo is the problem, that's not entirely right: Mayonnaise doesn't go bad faster than the potatoes, but it does provide moisture that helps bacteria in the potatoes to grow. Keeping potato salad cool is essential; it can be unrefrigerated for 2 hours, max (1 hour if the temp is above 90°F). Potato salad that you make and eat at home is safer than picking up something at the deli counter; 40 percent of outbreaks are linked to restaurants, grocery stores, and delis, most likely due to inadequate refrigeration.

Soft cheeses

Most cheeses are now made with pasteurized milk, which greatly reduces the risk of bad bacteria. But some soft cheeses—such as feta, brie, camembert, blue-veined, and Mexican-style cheese like queso blanco—might not be, which means they could carry listeria. The good news is that symptoms are often minor, but last year there was an outbreak of listeria in soft cheese among 30 people that caused 28 hospitalizations and 3 deaths.

Protect yourself: If you're pregnant (listeriosis can cause miscarriage), immune-compromised, or elderly, make sure any cheese you eat has been pasteurized.

Ice cream

Whether you top yours with nuts or hot fudge, there's a chance your sweet treat might be accompanied by a sprinkling of dangerous bacteria.

"The biggest outbreak was in 1994, when an ice cream manufacturer used the same truck to haul raw, unpasteurized eggs and pasteurized ice cream premix," Plunkett said.

Thousands of people were sickened in 41 states. And just last year, there was an outbreak of listeria in Blue Bell ice cream: It sickened 10 people, all of whom had to be hospitalized, and 3 died.

Protect yourself: The safest bet is to stick to large, reputable brands, advises Plunkett. If you're pregnant, avoid soft ice cream, which can harbor listeria, and don't make your own ice cream, however fun it may seem: Almost half of all ice-cream outbreaks occur in private homes, says the CSPI, probably due to undercooked eggs.

Tomatoes

They're tasty and loaded with lycopene, but they can sometimes harbor salmonella. This bacteria can enter tomato plants through the roots, or get into the fruit through small cracks in the skin.

Protect yourself: Washing tomatoes under running water for about 20 seconds just before eating, cutting, or cooking (even if you plan to peel them) will help remove salmonella that may be lurking on the skin, advises Fitzgibbon. You should also keep raw tomatoes separate from other foods in your fridge or on your counter, since salmonella can grow and spread to other foods in its vicinity.

Sprouts

They may have an uber-healthy reputation, but they're also highly vulnerable to bacterial contamination. "The seeds sprout in warm, moist conditions, which bacteria thrive on," explains Fitzgibbon.

Protect yourself: Both the FDA and the CDC recommend that the elderly, young children, and those with weakened immune systems avoid eating raw sprouts. Healthy people may want to be cautious as well, Fitzgibbon said, who recommends sautéing sprouts before eating them.

Berries

Colorful berries are loaded with antioxidants, but they're also sometimes contaminated with cyclospora, a parasite that causes severe diarrhea, dehydration, and stomach cramps and requires treatment with antibiotics.

Protect yourself: Wash all berries for 20 seconds in water before eating them, advises Plunkett. Doing so won't bring your risk down to zero, but it can help dramatically.

Peanut butter

This protein-packed spread can become infected with salmonella during processing, says Fitzgibbon. In 2014, six people in five states became ill after consuming contaminated nut butter.

Protect yourself: Watch closely for recall notices, and/or consider shopping at retailers who will notify you if you buy a product that is later subject to a recall, Fitzgibbon recommended.

Cantaloupe

Cantaloupe has been the cause of several big outbreaks of foodborne illness over the past few years, including one in 2012 that infected 261 people with salmonella, triggering 94 hospitalizations and 3 deaths. While most of the outbreaks have centered on salmonella, there was also an outbreak of listeria in 2011 that killed 33 people. "The company slicing the cantaloupe used the wrong equipment, which infected the sliced fruit with listeria," says Plunkett.

Protect yourself: Don't buy cantaloupe (or any fruit, for that matter) that's been precut, advises Plunkett. It might save time, but there's a greater chance that bacteria has been introduced. Instead, choose whole melons that are free of any cuts, sunken areas, or mold growth, since pathogens can use those as a way to invade. Store the melons in your fridge, ideally in the crisper, and eat them within about 5 days. Before you slice them, wash the rind under running water and use a vegetable brush to thoroughly remove bacteria from the surface.

This article originally appeared on Prevention.com.