Helicobacter pylori (H. pylori) is a spiral-shaped bacterium that colonizes the stomach lining, often leading to chronic inflammation known as gastritis, and is a major cause of peptic ulcers. H. pylori survives the stomach’s harsh, acidic environment by producing an enzyme called urease, which neutralizes the acid around it. Although many people carry the bacteria without symptoms, the infection is one of the most common worldwide, affecting over half the global population. Since H. pylori is transmitted through food and water, questions often arise about the safety of specific foods, particularly raw items like sushi.
How H. Pylori is Typically Transmitted
H. pylori is primarily an infection spread from person to person, often acquired during childhood. The most accepted routes of transmission are oral-oral and fecal-oral, indicating close contact with an infected individual is the main risk factor. Oral-oral spread can occur through contact with contaminated saliva, such as sharing utensils or close personal contact.
The fecal-oral route involves the bacteria spreading through contact with contaminated feces, often due to poor hygiene. This route links transmission to environmental factors, as H. pylori can spread by consuming contaminated water or food. In developing countries, untreated water and poor sanitation contribute significantly to higher infection rates. Food contamination can also occur when products are handled under poor hygienic conditions by an infected person.
The Specific Risk of H. Pylori from Sushi
The concern about contracting H. pylori from sushi stems from the possibility of foodborne transmission, yet the risk is generally considered negligible or non-existent in properly prepared sushi. H. pylori is a human pathogen, meaning it is specifically adapted to colonize the warm, acidic environment of the human stomach. Fish and other cold-blooded marine life are not considered natural hosts for this bacterium.
While some studies have occasionally detected H. pylori DNA in fish and other foods, this detection is usually attributed to cross-contamination from human handlers or contaminated water sources. The presence of the bacteria on the surface of raw fish does not mean the fish is a reservoir for the infection. The bacterium’s survival outside the human host, especially in the cold temperatures of refrigerated raw fish, is very limited.
Therefore, contracting H. pylori specifically from consuming raw fish or sushi is not a major concern based on current scientific understanding. The primary risk of infection remains through direct human contact or the consumption of water or food contaminated by an infected person.
Other Foodborne Pathogens Found in Raw Fish
While H. pylori risk from sushi is low, raw fish and seafood pose other, more recognized food safety concerns. The most common risks are parasitic infections, particularly from roundworms like Anisakis. These parasites live in marine fish and can cause a condition called anisakiasis if consumed live in raw or undercooked seafood.
To mitigate the risk of parasites, commercial sushi preparation adheres to strict safety measures, including freezing protocols. Freezing fish at a specified low temperature for a set duration is highly effective at killing parasites, though it does not eliminate all harmful organisms.
Common Bacterial Contaminants
Bacterial infections are also a concern, as raw seafood can be contaminated with environmental bacteria. Raw seafood may contain bacteria such as Vibrio, Salmonella, and Listeria. Vibrio species are naturally found in warm seawater and are a significant cause of foodborne illness from raw shellfish. Contamination can occur if the water is polluted or if poor hygiene is used during handling and processing.