You can generally get all the vitamin B12 you need from food, but some may need to take supplements, One type of B12 supplement may cause this side effect.

People with sickle cell anemia are at a higher risk of health problems that impact the heart, lungs, kidneys, and other vital organs because they’re not receiving enough oxygen-filled blood.

Conditions affecting the stomach, such as pernicious anemia (an autoimmune condition affecting the stomach lining), gastric bypass surgery, or certain medications, can impair the absorption of vitamin ...