Fruit

"Fruits are alkalizing and cooling, except for certain tropical fruits such as mango and lichee, which are warming.

Fruits are very easy to digest and metabolize, but only when eaten on an empty stomach.

In fact, most fruits go straight through the stomach into the duodenum for digestion, which means if you put fresh fruit on top of a big meal, it has to sit and wait in the top of the stomach until the other food is digested, during which delay bacteria attack the fruit and ferment it, gobbling up all the nutrients and leaving you with gas and metabolic wastes.

The best rule to follow with fruits is; 'Eat them alone, or leave them alone.' This is particularly true for melons and citrus fruits.

Fresh fruits are even more cleansing to the digestive tract than vegetables.

A good way to detoxify and balance the pH of the entire alimentary canal is to eat nothing but fresh fruit for a period of one to seven days.

It is best to select just one variety of fruit for cleansing purposes, top choices being grapefruit, lemon (as juice, diluted with water), watermelon, apple, or black grapes. 

You may eat the fruit whole or as a juice, the latter being somewhat more effective for cleansing purposes."

Source: Daniel Reid.