4. B. Metformin — and any combination pill that contains it (such as Metaglip, Actoplus Met, or Avandamet) — can cause vitamin B12 deficiency. How metformin reduces absorption of B12 is not yet clear, but it’s likely related to changes in intestinal mobility, small bowel bacterial overgrowth, and/or changes in B12 absorption by intestinal cells (a process that requires calcium to take place). In some cases, taking calcium supplements improves vitamin B12 absorption.
The longer a person is on metformin or combination drugs that include it, and the higher the dose, the greater the likelihood of developing a vitamin B12 deficiency. Use of prescription or over-the-counter antacid medicines called histamine-2 receptor antagonists (such as Pepcid, Zantac, or Tagamet) or proton pump inhibitors (including Prilosec, Prilosec OTC, and Prevacid) while taking metformin further increases the risk of B12 deficiency. Additionally, certain other health conditions increase the probability of B12 deficiency for various reasons, including diseases of the gastrointestinal tract (such as Crohn disease or ulcerative colitis), gastric bypass surgery, HIV, multiple sclerosis, and some autoimmune diseases. Thiazolidinediones, sulfonylureas, and DPP-4 inhibitors do not cause vitamin B12 deficiency.
5. A, B, C, and D. Everyone should consume a wide variety of either naturally occurring or fortified food sources of vitamin B12, but if supplementation is needed, a person’s symptoms, drug history, and overall health determine the best way to boost his intake. People with clear clinical deficiency and its associated symptoms (especially neurological symptoms), as well as people at high risk of deficiency and those with conditions that make it impossible to absorb enough B12 from the digestive process should receive injections of vitamin B12. Individuals who are asymptomatic but at low or moderate risk for B12 deficiency typically can supplement their intake orally with pills or nasally with a spray or gel. A skin patch is also available.
6. TRUE. The saying “An ounce of prevention is worth a pound of cure” rings true when it comes to vitamin B12 deficiency. Restoration of vitamin B12 levels in the blood resolves the anemia, fatigue, weakness, and gastrointestinal maladies associated with vitamin B12 deficiency, but the neurological and mental symptoms (poor memory, depression, irritability) may be permanent. If the deficiency is identified and treated early enough, these abnormalities typically improve. However, the longer the symptoms have been present and the more intense the symptoms are, the lower the likelihood of reversal.