"Tap water isn't safe. Buy good bottled water. Showering and bathing with tap water is OK, and brushing teeth, but no swallowing," Dr. Richard Lee said in a statement.

"The Chinese cook food well, including street food, so if it's cooked in front of you and it's hot, it's OK. Fruit on the street? You don't know where it's been. Be cautious about salads. They probably are OK at a 5-star hotel, but I'd rather eat stir-fried vegetables."

Dog meat is off the menu during the Olympics but there are cat specialty restaurants.

"The air quality can be awful and the smog can be pretty bad. Indoor air is just as bad, or worse. Tobacco still has a grip on China and there are few limitations on where people can smoke," Lee said. "If you have respiratory problems requiring oxygen, don't go."

If visitors do get sick, healthcare in Beijing can be superb, Lee said. Many of the specialty hospitals have British, U.S. and EU-trained doctors and, Beijing has state-of-the-art imaging and technology.