Traveler’s diarrhea pulls down even the stoutest of Peru travelers eventually and can be very unpleasant. It can be caused by parasites or viruses, but most often it is caused by bacteria carried in food or water. Plenty of other diseases in Peru are spread this way, including cholera, hepatitis A, and typhoid. Nothing is more important for you healthwise than thinking carefully about everything you eat and drink.
Only drink bottled water or water that has been previously boiled. Instead of buying an endless succession of plastic bottles, which will end up in a landfill, travel with a few reusable, hard plastic bottles and ask your hotel to fill them with boiling water every morning. Refilling bottles is especially easy at hotels that have water tanks, or bidones, of purified water. Order drinks without ice unless you acan be assured it is bagged ice or previously boiled water in order to make ice. Wipe the edges of cans and bottles before drinking or carry straws.
Avoid street vendors and buffets served under the hot sun. Instead, choose restaurants that come well recommended for taking precautions for foreigners. If the kitchen looks clean and the restaurant is full, it is probably all right. Before and after you eat, wash your hands with soap where available. Carry an antibacterial hand sanitizer as a backup.
The safest foods in restaurants are those that are served piping hot. Soups, well-cooked vegetables, rice, and pastas are usually fine. Eat salads and raw vegetables with extreme caution and confirm beforehand that they have been previously soaked in a chlorine solution. Better yet, prepare your own salads with food disinfectants for sale in most Peruvian supermarkets if you have the facilities to cook your own meals.
An exception to the no-raw-foods rule is cebiche, which is raw fish marinated in bacteria-killing lime juice. As long as you are in a reputable restaurant, cebiche is a safe bet.
Market foods that are safe include all fruits and vegetables that can be peeled, like bananas, oranges, avocados, and apples. Many local fruits are okay as well, including chirimoya, tuna (the prickly cactus fruit), and granadilla. Dangerous items include everything that hangs close to the ground and could have become infected with feces in irrigation water. These include strawberries, mushrooms, lettuce, and tomatoes. There are plenty of safe things to buy in the market and, when combined with other safe items like bread and packaged cheese, make for a great lunch.
© Ross Wehner and Renée del Gaudio from Moon Peru, 3rd Edition