Black tea is made from the leaves of a bush called Camellia sinensis. A process called oxidation turns the leaves from green to a dark brownish-black color. Oxidation means the leaves are exposed to moist, oxygen-rich air.
Tea manufacturers can control the amount of oxidation. Black tea is a fully oxidized tea. Green tea comes from the same plant, but is not oxidized.
Chlorella may make it harder for warfarin and other blood-thinning drugs to work.
Some chlorella supplements may contain iodine, so people with thyroid conditions may want to avoid taking chlorella.
Always tell your doctor about any supplements you are taking, including natural ones and those bought without a prescription. That way, your doctor can check on any potential side effects or interactions with any medications.