Final answer:
Vitamin B12 deficiency is commonly caused by inadequate absorption due to certain health conditions or insufficient dietary intake, especially in vegans and vegetarians. Long-term effects include neurological issues and an increased risk of birth defects during pregnancy. Adequate vitamin B12 intake is crucial to prevent these complications.
Step-by-step explanation:
The leading cause of vitamin B12 deficiency is poor absorption which can be due to conditions such as pernicious anemia, Crohn's disease, or following certain surgeries that affect the gastrointestinal tract. It can also result from dietary deficiencies, particularly in vegans and vegetarians who do not consume animal products, which are primary sources of vitamin B12.
Long-term risks of B12 deficiency include neurological complications, such as memory loss and motor control problems, and may also contribute to megaloblastic anemia, characterized by the production of abnormally large red blood cells. Deficiency during pregnancy is notably concerning as it is associated with birth defects like neural tube defects. Therefore, ensuring adequate intake of vitamin B12 and folate is crucial for overall health.
High levels of malnutrition can also lead to a B12 deficiency, as well as deficiencies in iron, folate, and other vital nutrients. This is particularly a problem for those with limited access to a diverse diet or with conditions that cause increased nutrient requirements.