When fruits and vegetables are squeezed or used raw, bacteria from the products can end up in the juice or cider. Unless the product or juice has been pasteurized or otherwise treated to destroy any harmful bacteria, the juice could be contaminated. A high intake of fruits and vegetables shows promise in many areas of health. For example, juices can reduce the risk of heart disease.
Apple and pomegranate juices have been linked to lower blood pressure and cholesterol levels (11, 1). In the United States, most commercially sold juices are processed or pasteurized to kill harmful bacteria that cause foodborne illnesses. However, if fruits and vegetables are “freshly squeezed” to be converted into juice, there is a risk that the final product will contain harmful foodborne bacteria. Drinking juice for breakfast or doing a juice cleanse may seem like a good idea, but this habit can actually be harmful to some people.
If the consumer is going to prepare “freshly squeezed juice” at home, the Michigan State University Extension recommends that they wash their hands for at least 20 seconds before preparing the juice. Juice alone is fine, but just drinking juice during a cleanse is when things get problematic, as there's no fiber that crosses your gastrointestinal tract to keep you regular. So a small amount of fruit juice seems OK, but too much sugar from all sources, including juice, is linked to poor health outcomes. If the juice is for someone who is at risk of contracting a foodborne illness, it should be boiled and cooled before serving.
Some farmers' markets, roadside stalls, juice bars, and even some restaurants can sell freshly squeezed juice by the glass. The idea behind a juice cleanse is that drinking juice as the only source of food allows the body to rid itself of “toxins”.