The phrase "to filter the blood" means to remove harmful substances and waste products from the bloodstream in order to keep the body healthy and functioning properly. Full definition
It's job is to filter the blood of foreign substances and the 500 billion worn out red blood cells that naturally die every hour. (drvitaminsolutions.com)
Our liver filters our blood to remove toxins and breaks down toxins within the body via a two phase process. (conscious-foodie.com)
They are important to filter your blood as well as playing a role in keeping your urinary system healthy as a whole. (healthywildandfree.com)