Fasted vs fed states - CBD absorption is 3-5 times greater when taken with food compared to an empty stomach. Due to the fat-soluble nature of CBD, including a healthy fat in your meal like avocado, salmon, nuts or seeds etc, will help even more. By doing so, the CBD dissolves in the dietary fats and disperse into smaller particle sizes that are easier to absorb. Food also slows down the clearance rate (rate at which CBD is removed from the blood). 

Health conditions - liver function is responsible for removing CBD from circulation and preparing it to be exported from the body. One study on participants with moderate/severe liver impairment had higher blood CBD concentrations and longer clearance rate after the same dose to those with healthy liver functions.  

Piperine supplements - commonly found in black pepper, this compound can boost absorption effects greatly. Piperine stimulates transporter molecules in the intestinal lining that are responsible for bringing CBD across the membrane and into the bloodstream. 

In a CBD oral supplement that was formulated with piperine, there was a 6-fold increase in maximum concentration in the blood compared to the same extract without piperine.