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Related Concept Videos

Vitamins01:30

Vitamins

Vitamins, derived from the Latin word for life, are essential organic substances required in small quantities for optimal growth and overall well-being. Unlike other organic nutrients, vitamins don't act as sources of energy or building materials but rather facilitate these nutrients' utilization by the body. Vitamins are predominantly coenzymes, assisting enzymes in specific chemical actions, like the oxidation of glucose for energy involving B vitamins. Most vitamins are not produced in our...
Role of Vitamins in Maintaining Bone Health01:25

Role of Vitamins in Maintaining Bone Health

The growth and maintenance of bone are regulated by a combination of nutritional factors, including vitamins, such as vitamin A, B12, C, D, and K.
Vitamin A
Vitamin A is involved in the process of bone remodeling. Retinoic acid, the active metabolite of Vitamin A, has nuclear receptors in osteoblasts and osteoclasts, which are involved in bone remodeling.
Vitamin B12
Vitamin B12 acts as a cofactor during the formation of osteoblast-related proteins, such as osteocalcin. Vitamin B12 plays a role...
Minerals01:26

Minerals

Minerals are essential nutrients that the human body needs in small amounts to work properly. They play a vital role in many bodily functions, such as building strong bones and transmitting nerve impulses. Some minerals are needed for hormone production or to maintain a normal heartbeat. Major minerals include calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium, while trace minerals include iron, manganese, copper, iodine, zinc, cobalt, fluoride, and selenium.
Multiple Sclerosis l: Introduction01:19

Multiple Sclerosis l: Introduction

Multiple sclerosis is a chronic autoimmune disease of the central nervous system (CNS) that affects the brain, spinal cord, and optic nerves. It is an inflammatory demyelinating disorder and a leading cause of neurological disability in young adults.EpidemiologyMS commonly begins between 20 and 40 years of age and is twice as common in women. Its exact cause remains unclear, but genetic susceptibility contributes, with higher risk in first-degree relatives and identical twins. A greater...
Inborn Errors of Metabolism01:20

Inborn Errors of Metabolism

Phenylketonuria (PKU) is a protein metabolism disorder characterized by high blood levels of the amino acid phenylalanine. This results from a mutation in the gene responsible for phenylalanine hydroxylase, an enzyme that converts phenylalanine into tyrosine. When this enzyme is deficient, phenylalanine builds up in the blood, leading to symptoms such as vomiting, rashes, seizures, growth deficiency, and severe mental retardation. An early diagnosis and a diet restricting phenylalanine intake...
Sulfur Assimilation01:20

Sulfur Assimilation

Sulfur is an essential element in biological systems, contributing to synthesizing key biomolecules, including amino acids such as cysteine and methionine, and cofactors such as coenzyme A and biotin. Microorganisms primarily assimilate sulfur as sulfate (SO₄²⁻) from the environment, which must undergo a series of biochemical transformations before it can be incorporated into cellular components. As sulfate is highly oxidized, it must undergo assimilatory sulfate reduction to become...

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Updated: Jun 26, 2026

Modifying Levels of Maternal Dietary Folic Acid or Choline to Study the Impact of Deficiencies on Offspring Health Outcomes
03:19

Modifying Levels of Maternal Dietary Folic Acid or Choline to Study the Impact of Deficiencies on Offspring Health Outcomes

Published on: June 28, 2024

Functional vitamin B12 deficiency.

Martin R Turner1, Kevin Talbot

  • 1Department of Neurology, John Radcliffe Hospital, University of Oxford, Oxford, UK.

Practical Neurology
|January 20, 2009
PubMed
Summary
This summary is machine-generated.

Functional vitamin B12 deficiency, caused by impaired transport, can present with normal serum B12 levels. Early diagnosis is crucial to prevent permanent neurological damage from conditions like subacute combined degeneration.

Related Experiment Videos

Last Updated: Jun 26, 2026

Modifying Levels of Maternal Dietary Folic Acid or Choline to Study the Impact of Deficiencies on Offspring Health Outcomes
03:19

Modifying Levels of Maternal Dietary Folic Acid or Choline to Study the Impact of Deficiencies on Offspring Health Outcomes

Published on: June 28, 2024

Area of Science:

  • Neurology
  • Biochemistry
  • Hematology

Background:

  • Vitamin B12 is essential for neurological function and DNA synthesis.
  • Serum vitamin B12 levels are commonly used to diagnose deficiency.
  • Subacute combined degeneration of the spinal cord is a serious neurological complication of B12 deficiency.

Observation:

  • A patient presented with neurological symptoms suggestive of subacute combined degeneration.
  • Repeated serum vitamin B12 measurements were within the normal range.
  • This led to a diagnostic delay and potential for permanent neurological damage.

Findings:

  • Functional vitamin B12 deficiency can occur despite normal serum B12 levels.
  • Impaired intracellular transport of vitamin B12 by transcobalamin-2 is a potential cause.
  • Elevated methylmalonic acid or homocysteine with low transcobalamin-2 suggests functional deficiency.

Implications:

  • Relying solely on serum B12 levels can lead to misdiagnosis and delayed treatment.
  • Functional vitamin B12 deficiency should be considered in patients with neurological symptoms and normal B12 levels.
  • High-dose vitamin B12 therapy may benefit patients with functional deficiency, even with normal serum levels.