Even if there are adequate vitamins and minerals in one's diet, it's still possible that some people cannot absorb enough of them to form normal amounts of healthy red blood cells. This is called malabsorption or malabsorption syndrome.

Let me explain. Just like vitamin D is added to other foods to help the body absorb calcium, the body makes a substance called intrinsic factor, a protein made in the stomach, that helps absorb vitamin B12. If something prevents intrinsic factor from being made, the body is then not able to absorb vitamin B12 and this could lead to vitamin B12-deficiency anemia.

Malabsorption can also arise from gastric bypass surgery, which is a surgical procedure used to treat obesity. In gastric bypass surgery, the stomach is made smaller, and part of the small intestine is bypassed. Since the intrinsic factor is manufactured in the stomach, vitamin B-12 cannot be properly absorbed from food. People who have had gastric bypass may need to get vitamin B-12 injections at certain intervals throughout their lives because the body cannot absorb it.

Other factors that might prevent the absorption of nutrients include infections, diseases or medications.

We’ll talk a bit more about disease as being a cause of anemia on the next page.