In 1954, similar blended fruit and vegetable drink recipes were published in "Nutrition For Health"  by Dr. Alice Chase.

In 1955, similar blended recipes called Sunshine Cocktails were included in "New Guide to Intelligent Reducing" by G. Hauser.

Green Smoothie History

Big Band Leader Fred Waring

These are some examples of very early green smoothie recipes from 1940, just two years after the introduction of the Waring Blendor which was the first modern electric blender on the market.  In 1954, the millionth Waring Blendor was sold. 

In 1952, the recipes above were also published in a book titled "Electric Blender Recipes" by Mabel Stegner.