Why Do Some People Get Food Poisoning (and Others Don’t)?

• Foodborne illnesses are acquired from different types of food — Some of the more common culprits include deli meats, raw fruits and vegetables, raw or undercooked meat, eggs and seafood, and uncooked dough. Harmful germs like bacteria, viruses, and parasites get into these foods through different methods, such as during preparation or processing.

• You can’t always rely on smell, taste, or appearance — One of the most practical warnings was that contaminated food doesn’t always look, taste, or smell spoiled.³ Bacteria don’t necessarily change the texture, color, or scent of food, especially in the early stages. That makes it easy to eat something dangerous without even knowing it.

• The illness might not hit right away — While some bacteria cause symptoms within hours, others take days or even weeks to produce noticeable illness. This delay makes it harder to identify the source of the problem and easier to keep eating something that’s making you sick. If you’ve ever wondered why you got sick “out of nowhere,” there’s a good chance the contamination happened days earlier.

• High-risk groups are far more vulnerable to complications — Older adults, infants, pregnant women, and people with weakened immune systems are at far higher risk for serious illness and hospitalization. Even bacteria that cause only mild discomfort in healthy adults could lead to serious complications and even hospitalizations in these groups.⁴

• Your gut microbiome could be the deciding factor — Your body’s internal ecosystem, specifically your gut microbiome, determines how well you handle exposure to foodborne bacteria or viruses. Made up of trillions of bacteria living in your digestive tract, it’s responsible for more than digestion. It plays a central role in immune defense, inflammation, and even your ability to fight off pathogens in food.

If your microbiome is unhealthy, meaning it has low bacterial diversity and too many harmful bacteria, you’re more likely to get sick. As Mazur put it, “A person with an inadequate microbiome will experience food poisoning more often.”

• Certain lifestyle habits weaken your microbiome fast — For example, drinking alcohol has an immediate effect on your gut’s defense system. Mazur says that drinking heavily, even just for a day, disrupts your microbiome’s balance and makes your system more susceptible to pathogens in food.

“Alcohol intake damages the microbiome and is a lesser-known cause of dysbiosis — overgrowth of pathogenic bacteria — and is another risk factor for an inadequate microbiome,” he warns.

For more information on how alcohol harms your health, read “What Does the Science Say About Alcohol Consumption?”

• The kind of food you eat affects your risk — Consuming contaminated meat, undercooked seafood, and raw dairy products obviously puts you at risk, however, it’s actually your baseline diet that plays a major role in your outcomes. Mazur says that people who consume high levels of refined carbohydrates, processed junk foods, and refined sugar are more likely to damage their gut lining over time.

When your intestinal walls are inflamed, it’s easier for bacteria to get through and trigger an infection. If you’ve got low microbial diversity and an inflamed gut, you’re setting the stage for illness with every risky bite.

• The amount you eat matters — It’s not just what you eat, but how much you eat. According to Mazur, eating more of a contaminated food increases your chances of getting sick, and is one of the biggest factors. In other words, if you had three bites of the bad sushi and your friend only had one, you’re more likely to become ill. It’s about microbial load; the more pathogens you ingest, the harder your body has to work to fight them off.

• A compromised immune system opens the door — Dr. Elizabeth Sharp, a board-certified internal medicine physician, says that people with weakened immune systems — whether due to stress, poor diet, chronic illness, or medication — are far more likely to become infected after exposure. If your immune system is running low, you don’t have the reserves to mount an effective response against the bacteria or virus in your food.

Sharp also mentioned that if your gut is already inflamed from your lifestyle or environment, it’s easier for pathogens to breach the intestinal wall and start causing symptoms.

• A healthy microbiome acts like a shield — A strong, well-balanced microbiome will stop harmful invaders before they ever take hold. “Entrenched healthy bacteria support each other preferentially,” Mazur explained.

That means your good bacteria create an environment that’s hostile to pathogens. They outcompete the bad guys for space and resources, effectively locking them out. This microbial teamwork prevents invading bacteria from taking root and causing illness.

• Pathogens have to fight for survival inside your gut — Think of your gut as a battleground. When a foodborne pathogen enters, it has to survive stomach acid, compete with existing bacteria, and find a way to break through your intestinal barrier. If your system is already strong — with a balanced gut flora, strong mucus lining, and robust immune surveillance — most pathogens fail.

But if those defenses are weakened, even a small amount of contaminated food could trigger symptoms of food infection.

• Cross-contamination spreads bacteria invisibly — Cutting raw chicken on a board, then slicing your salad vegetables on the same board without washing it with soap in between? That’s one of the fastest ways to contaminate your meal.

Ideally, you should use different cutting boards for meat and produce to avoid cross-contamination. The same goes for kitchen knives — don’t use a knife that’s touched raw meat to chop fresh fruit. This mistake allows dangerous bacteria like Salmonella or E. coli to transfer to food that won’t be cooked, giving bacteria a free pass straight into your gut.

• One of the most overlooked risks is poor refrigeration — If you leave perishable foods — like fresh meat, milk, or fish — out at room temperature for more than two hours uncooked, bacteria begin multiplying rapidly. At 90 degrees F (32 degrees C) or higher, that timeframe shrinks to just one hour.

• Reheating contaminated leftovers doesn’t always make them safe again — Many people assume they’re in the clear once they microwave their leftovers, but reheating food doesn’t always kill all bacteria, especially if the food wasn’t cooled or stored properly in the first place. In fact, some bacteria produce toxins that aren’t destroyed by heat. That means if you left your rice or meat out overnight and then reheated it the next day, you’re still at risk.

• Thawing food on the counter is a setup for sickness — Letting frozen meat or poultry thaw on the counter seems harmless, but it actually allows the surface of the food to reach unsafe temperatures while the inside is still frozen. That outer layer becomes a playground for bacteria. The safest method is to thaw it in the refrigerator, in cold water (changed every 30 minutes).

• Your hands are the No. 1 tool for either safety or risk — Dirty hands are one of the most common causes of foodborne illness. Wash your hands with warm, soapy water for 20 seconds before and after handling food, especially raw meat, eggs, and seafood. Make sure to scrub under your fingernails and between skin creases to remove bacteria.

• Cooking temperatures are your final line of defense — When cooking, you must know what’s the correct internal cooking temperature to kill bacteria effectively. For example, ground beef should be cooked to at least 160 degrees F (71 degrees C) and poultry to 165 degrees F (73 degrees C). Leftovers must be reheated to 165 degrees F as well. Use a food thermometer, especially since color alone isn’t reliable, especially with ground meats or stuffed dishes.

• Leftovers must be stored safely — Refrigerate leftovers as soon as they have cooled, and make sure to eat them within three to four days. Don’t rely on the “sniff test.” Many bacteria don’t alter the smell, taste, or look of food, meaning it could still make you sick even if it seems fine. When in doubt, throw it out.

• Eliminate vegetable oils from your diet — Consuming excessive amounts of linoleic acid (LA) from vegetable oils disrupts your mitochondrial function and, in turn, how your cells make energy, which ultimately wrecks your gut environment. Switch to butter, ghee, or tallow instead. This will significantly improve your cellular energy production, which allows your gut to maintain a hospitable environment for beneficial bacteria.

• Optimize your carbohydrate intake — Your body needs around 200 to 250 grams of carbohydrates daily to maintain optimal cellular energy production. It’s best to start with easily digestible carbohydrates, particularly if your gut health is compromised.

• If you have severe gut issues, start with dextrose water — Sip it slowly throughout the day as a temporary rescue strategy to help heal your gut (take note that this is not a long-term solution). One or two weeks is typically sufficient. As your gut heals, gradually add in whole fruit, white rice or juice with pulp before heavier starches or fibrous vegetables.

• Once your gut feels better, eat more fiber — This is the primary fuel for your beneficial gut microbes, allowing them to produce short-chain fatty acids (SCFAs) like butyrate that strengthen your gut barrier. Also, eat more resistant starches like cooked-then-cooled potatoes or green bananas, as they fuel butyrate production.

• Introduce Akkermansia supplements wisely — Akkermansia muciniphila is a key bacterium that strengthens your gut barrier, but most people have very low levels. After you eliminate vegetable oils for at least half a year, consider taking a timed-release Akkermansia supplement. A time-released delivery system ensures more of the bacteria survive and reach your colon.

• The small things matter — Never let leftovers sit out for more than two hours, use separate cutting boards for meat and vegetables, and wash your hands with soap for 20 full seconds before touching food. Always check your fridge temperature — it needs to stay below 40 degrees F. These strategies will cut off bacteria from the environment before it ever reaches your plate.

For more information on keeping your kitchen clean, read “What’s the Most Germ-Ridden Object in Your Kitchen? It’s Not the Sponge.”

• Don’t trust your nose — trust the temperature — If you’ve ever sniffed a piece of chicken and thought, “Seems fine,” that’s not enough. Bacteria don’t always smell. They don’t change the color or taste of your food. That’s why when cooking, it’s best to use a meat thermometer. Once you make this a habit, it’s fast, easy, and it gives you peace of mind every single meal.

• Eat smart when your defenses are down — If you just finished antibiotics, are recovering from illness, or have been under major stress, your gut and immune system are weaker. During these times, avoid higher-risk foods like deli meat, sushi, raw dairy, and other foods that easily spoil left at room temperature.

I also advise avoiding buying products from confined animal feeding operations (CAFOs) in general, even if you’re in optimal health, because pathogenic bacteria are rampant in these settings, further increasing your chances of bacterial contamination.

• Prepare for group meals with safety in mind — Bulk-cooked food at weddings, potlucks, or parties is a major source of foodborne illness. If you’re cooking for a group, divide large dishes into shallow containers and refrigerate them right away; don’t leave them to cool on the counter.

If you’re eating food someone else made, choose items that were cooked fresh and kept hot. Skip anything that’s been sitting at room temperature for hours, especially rice, casseroles, or meat trays.