Here's what I've learned about chlorella and spirulina. They are antioxidants. If your liver and colon is dirty, your whole body is dirty and that includes the blood because the liver can't properly filter it. Since you will be detoxing on a cellular level with this stuff, it's going to make you sick for a few days. The toxins, like MH said in so many words, will go out of the tissues and into the blood, and if they can't get out of the system because of the aforementioned reason--the blood can't handle it, they will make you sick for a while, then go right back into the organs from the blood. The answer? clean the body out before you start taking any high amount of antioxidants. BECAUSE they clean out the body on a cellular level.
In order for organs to heal, you've got to rid the body of parasites, chemical poisons and radiation by cleaning it out. That includes getting rid of diabetes and every other disease. The cells are the last to clean out and that means organs. The cells can't clean out individually until the rest of your body is clean enough for it to happen.