Quiz: What You Need to Know About Vitamin B12

Aging may reduce vitamin B12 absorption because stomach acid changes over time. Hydrochloric acid is needed to absorb vitamin B12 from food. Medications such as metformin and prolonged use of antacids can interfere with absorption.

People on vegan diets, individuals who have had gastric bypass surgery, those with celiac disease or pancreatic deficiencies, and older adults whose absorption may decrease with age may be at risk.

Vitamin B12 deficiency is one of the first conditions evaluated when someone develops unexplained cognitive impairment, because deficiency can cause memory problems and confusion. Correcting the deficiency often reverses those symptoms. But research has not shown that vitamin B12 supplements prevent or slow the progression of dementia or Alzheimer’s disease.