Why are strict vegetarians at risk of developing a vitamin B12 deficiency?

Question

BlackTom AI · Accepted Answer

To analyze why strict vegetarians are at risk for vitamin B12 deficiency, let's evaluate each statement in turn with accurate nutrition concepts.
Option 1: The majority of foods in a vegan diet inhibits the absorption of vitamin B12. In reality, vegan foods themselves do not universally inhibit B12 absorption; the issue is more about the presence or absence of B12 in the diet rather than inhibition of absorption. This statement misattributes the cause to absorption inhibition rather than to dietary content.
Option 2: A vegan diet causes increased excretion of vitamin B12. Vitamin B12 excretion is not characteristically increased by a vegan diet; the body conserves B12 as needed and excess excretion is not the defining problem of vegan-related B12 status. This claim does not align with established physiology of B12 handling.
Option 3: Only animal foods contain sufficient amounts of vitamin B12. This reflects the core dietary reality: natural, bioavailable B12 is abundant in animal-derived foods, whereas plant foods generally contain little or none unless fortified. Therefore, without fortified sources or supplementation, a vegan or strict vegetarian risk having insufficient B12 intake over time, potentially leading to deficiency.
Option 4: A vegan diet increases the rate of use of vitamin B12 by the body. The body’s use or turnover of B12 is not inherently higher on a vegan diet; the risk on a vegan diet arises from insufficient intake, not from an accelerated rate of utilization by the body. This misstates the underlying mechanism.
Option 5: Vitamin B12 is rare or unavailable in fortified foods. While it’s true that fortified foods can provide B12, saying B12 is rare or unavailable in fortified foods is incorrect. Many fortified foods (such as some cereals, plant milks, and nutritionalYeast products) are deliberate strategies to supply B12 to vegetarians and vegans. This makes the statement inaccurate as a general rule.
Overall, the options that incorrectly describe absorption dynamics, excretion, or fortification availability misrepresent the established dietary fact that natural B12 is primarily in animal foods, and fortified sources are the key for vegan diets to meet needs.

Why are strict vegetarians at risk of developing a vitamin B12 deficiency?单项选择题

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