Vitamin B12

Definition

Vitamin B12, also known as cobalamin, is a water-soluble vitamin that plays a crucial role in the formation of red blood cells, DNA synthesis, and the proper functioning of the nervous system. Deficiencies in vitamin B12 can lead to various health issues, particularly affecting the peripheral nervous system, where it can cause nerve damage and symptoms like weakness, numbness, and balance problems.

5 Must Know Facts For Your Next Test

1. Vitamin B12 is primarily found in animal products such as meat, fish, eggs, and dairy; strict vegetarians and vegans are at higher risk for deficiency.
2. The body stores significant amounts of vitamin B12 in the liver, which can take years to deplete even when dietary intake is insufficient.
3. Deficiency symptoms can include fatigue, weakness, numbness or tingling in the hands and feet, difficulty walking, and cognitive disturbances.
4. Vitamin B12 is necessary for myelin sheath formation around nerves; without it, nerve transmission can be impaired, leading to neurological issues.
5. Diagnosis of vitamin B12 deficiency often involves blood tests measuring levels of the vitamin as well as methylmalonic acid (MMA) and homocysteine levels.

Review Questions

• How does vitamin B12 deficiency specifically impact the peripheral nervous system?
  • Vitamin B12 deficiency impacts the peripheral nervous system by disrupting the formation of myelin, the protective sheath around nerves. This leads to nerve damage that manifests as symptoms like numbness, tingling, and balance issues. Without sufficient vitamin B12, the proper functioning of nerves is compromised, resulting in potential long-term neurological consequences if not addressed.
• Discuss the relationship between vitamin B12 and megaloblastic anemia.
  • Megaloblastic anemia is directly related to vitamin B12 deficiency because this vitamin is essential for DNA synthesis during red blood cell formation. When there isn't enough vitamin B12 available, red blood cells cannot mature properly and remain large and immature. This leads to a decrease in the overall number of healthy red blood cells, causing anemia symptoms like fatigue and weakness.
• Evaluate how intrinsic factor affects vitamin B12 absorption and the implications for individuals with gastrointestinal disorders.
  • Intrinsic factor is crucial for the absorption of vitamin B12 in the intestines; without it, even sufficient dietary intake can result in a deficiency. Individuals with gastrointestinal disorders such as pernicious anemia or certain surgeries may produce inadequate intrinsic factor, leading to impaired absorption of vitamin B12. This situation necessitates monitoring and possibly supplementation to prevent neurological and hematological complications associated with deficiency.

Related terms

Neuropathy: A condition resulting from damage to the peripheral nerves, which can lead to weakness, numbness, and pain, often associated with vitamin B12 deficiency.

Megaloblastic Anemia: A type of anemia caused by a deficiency of vitamin B12 or folate, characterized by the presence of large, immature red blood cells in the bloodstream.

Intrinsic Factor: A glycoprotein produced in the stomach that is essential for the absorption of vitamin B12 in the intestines.