Everyone knows someone who seems to have an “iron stomach.” They eat leftovers that sat on the counter all night or sushi from a questionable vendor and walk away unscathed. Meanwhile, another person in the same household gets violently ill from a slightly undercooked burger. Why does food poisoning strike some more often than others? The answer lies in biology, not luck.
Age is one of the biggest factors. Children under five and adults over sixty-five are significantly more vulnerable to foodborne illness because their immune systems are either still developing or beginning to weaken. Pregnant women are also at heightened of acquiring food poisoning due to immune changes that make them more susceptible to infections like Listeria, which can cause miscarriage or premature birth.
Medications also change the equation. People taking antacids, for example, reduce the acidity in their stomachs—acidity that normally acts as the first line of defense against bacteria. Antibiotics disrupt gut flora, clearing out beneficial bacteria that help keep pathogens in check. Chemotherapy, immunosuppressants, and chronic conditions like diabetes further weaken the body’s ability to fight back once harmful microbes are ingested.
Genetics even play a surprising role. Research on norovirus, the notorious “cruise ship virus,” shows that some people lack the specific gut receptors the virus needs to attach. For them, exposure may not lead to infection at all. Others are genetically more vulnerable, explaining why outbreaks can hit households or classrooms unevenly.
Behavior matters, too. High-risk eaters—those who enjoy raw oysters, unpasteurized cheeses, rare meat, or home-fermented foods—simply roll the dice more often. Combine that with individual vulnerabilities, and one person may experience repeated bouts of illness while their friends remain unaffected.
The lesson is that food poisoning isn’t random or purely bad luck. Understanding your personal risk factors can help guide safer choices. For vulnerable groups, avoiding raw seafood, reheating leftovers thoroughly, and steering clear of unpasteurized products can make a significant difference. For those on immune-altering medications, extra caution is critical. And for everyone, proper handwashing, safe cooking temperatures, and refrigerator vigilance remain non-negotiables.
The next time someone boasts about never getting food poisoning, remember: it’s probably less about their courage and more about their biology.
