Question

why are older adults at increased risk for vitamin b - 12 deficiency compared to younger people?
multiple choice
as you age, your metabolism slows and a rapid metabolism is required for optimal vitamin b - 12 absorption.
as you age, your macula begins to turn yellow—a sign of excessive folate absorption, which masks vitamin b - 12 deficiency.
as you age, your bones become more porous; porous bones do not absorb vitamin b - 12 as well as dense bones do.
as you age, your stomach produces less acid, which limits cleavage of vitamin b - 12 from food. in addition, decreased production of intrinsic factor by the stomach limits vitamin b - 12 absorption.

Explanation:

Vitamin B - 12 absorption in the body is a complex process. Stomach acid is required to release vitamin B - 12 from food proteins. As people age, the stomach may produce less acid, which limits the cleavage of vitamin B - 12 from food. Additionally, intrinsic factor (produced by the stomach) is necessary for the absorption of vitamin B - 12 in the small intestine. A decrease in intrinsic factor production (which can occur with aging) also limits vitamin B - 12 absorption.

• The first option about metabolism is incorrect. Vitamin B - 12 absorption is more related to digestive processes (acid and intrinsic factor) rather than overall metabolism speed.
• The second option about the macula and folate is incorrect. Macula changes (like yellowing) are not related to the direct absorption mechanism of vitamin B - 12. Also, while folate can mask some symptoms of vitamin B - 12 deficiency (like megaloblastic anemia), it does not explain the absorption difference between older and younger adults.
• The third option about bone porosity is incorrect. Vitamin B - 12 absorption occurs in the digestive tract (primarily the small intestine after processing in the stomach), not in the bones. Bone porosity is more related to conditions like osteoporosis (which is affected by factors like calcium, vitamin D, etc., but not directly by vitamin B - 12 absorption in the way described in this option).

Answer:

As you age, your stomach produces less acid, which limits cleavage of Vitamin B - 12 from food. In addition, decreased production of intrinsic factor by the stomach limits vitamin B - 12 absorption.