Many older adults have a vitamin B12 deficiency. Reasons for this include which of the following? (Select all that apply.)

A. Proton pump inhibitors, a frequently prescribed medication in older adults, impair absorption of vitamin B12 from food. PPIs reduce gastric acid, which is needed to release B12 from food. Chronic use is a known risk factor for deficiency. B. The major source of vitamin B12 is sunlight, and older adults are less likely to be outdoors and absorb vitamin B12 in this manner. Vitamin D, not B12, is synthesized via sunlight. B12 is obtained from dietary sources. C. Vegetarian diets increase the risk of vitamin B12 deficiency. B12 is primarily found in animal products. Strict vegetarians or vegans may not get enough from diet alone. D. Most older adults do not consume five servings of fruits and vegetables daily, which is the main dietary source of vitamin B12. B12 is not found in significant amounts in fruits and vegetables. This is false. E. Normal age-related changes in the stomach include a lower production of gastric acid making vitamin B12 absorption less efficient. Hypochlorhydria (low stomach acid) is common with aging and impairs the release of B12 from food, leading to deficiency.