CBD tinctures are available as oil based or water soluble products. 

CBD and other cannabinoids are diluted in tinctures to achieve the CBD content shown on the tinctures label.  CBD is generally diluted in another oil, called a “carrier oil”, or processed to be water soluble.  CBD products diluted in carrier oils are generally less expensive than water soluble CBD products because they are less expensive to make. 

Although many oils are used as carrier oils, including hemp seed oil, the most popular is MCT oil.  MCT (Medium-Chain-Triglycerides) is a natural oil usually derived from coconuts or palm oil.  Using MCT as a carrier has many purported benefits.  One is faster CBD absorption.  It has been shown to limit bacterial growth giving products longer shelf life.   It is tasteless and odorless.  And research indicates It may contribute to weight loss.

However, Water Soluble CBD is said to have higher bioavailability which means CBD taken orally (swallowed, not held under the tongue) is better absorbed by the body.  The literature suggests this is the way to go if you intend to put your CBD into a liquid like your coffee or juice drink.  Otherwise, until future research indicates otherwise, CBD products using MCT as the carrier oil is usually the most cost effective and beneficial way to get relief from your CBD tinctures.