Vitamin B12 - Cobalamin Flashcards
Vitamin B12 - Cobalamin
• Vitamin B12 refers to a family of cobalamin compounds containing the essential mineral cobalt in the centre.
• The most active B12 analogs include: methylcobalamin , hydroxycobalamin, adenosyl cobalamin and cyanocobalamin These are the only analogs recognised by the body. There are others found in nature but they are not bioavailable to humans.
• Vitamin B12 is synthesised by bacteria. Vitamin B12 found in animal based foods originates from their ingestion of bacterial contaminated feed, or from B12 that has been given to the animal.
The human microbiota produces B12, but it is not absorbed.
Vitamin B12 - Storage
B12 storage in the liver lasts between 3-5 years.
Vitamin B12 - Food Sources
Vegan B12 Food Sources:
• Chlorella pyrenoidosa (e.g. 9g per day)
• A substantial amount (133.8 μg /100 g) of vitamin B12 has also been found in dried Korean purple laver Porphyra sp.).
• Nutritional yeast, nori and kombu sea vegetables (nori, kombu, kelp and dulse), shiitake & Lions mane mushrooms.
Animal B12 Food Sources:
• Meat, liver, milk, cottage and feta cheese, organic eggs, fish (esp. sardines, mackerel and wild salmon).
Vitamin B12 - Roles
Nervous System
Erythropoesis
Methylation
Energy Production
Vitamin B12: Nervous System - Functions
- Myelin production
- Neurotransmitter production (dopamine, seratonin)
- Choline key for brain function
Vitamin B12: Nervous System - Therapeutic uses
- MS
- Tingling / Pins and Needles
- Sciatica
Vitamin B12: Erythropoesis - Functions
B12 is required for erythropoiesis.
Vitamin B12: Erythropoesis - Therapeutic uses
Megaloblastic Anaemia
Vitamin B12: Methylation - Functions
• Homocysteine cycle (conversion of the amino acid homocysteine to methionine)
Vitamin B12: Methylation - Therapeutic Uses
- Cardiovascular disease
* Alzheimer’s
Vitamin B12: Energy Production - Functions
• Energy production from fats and proteins
Vitamin B12: Energy Production - Therapeutic uses
Fatigue
Vitamin B12 - Deficiency causes
• Poor nutrition (malnutrition):
- Lack of dietary B12 intake, and a diet rich in highly processed, nutrient depleted foods. VEGAN
• GIT causes (malabsorption):
- Stomach problems (e.g. lack of intrinsic factor, low hydrochloric acid production)
- Low pancreatic enzymes, small intestine issues (e.g. Crohn’s disease, coeliac), high alcohol.
•Note: if a client has a good dietary intake of B12, yet is deficient, it highlights a possible absorption issue or problem with methylation.
Vitamin B12 - Deficiency States
- The most common cause of deficiency is malabsorption due to inadequate intrinsic factor (IF) production . It is called pernicious anaemia. Helicobacter pylori infection is also implicated.
- Pernicious anaemia is associated with an autoimmune attack on parietal cells in the stomach (the cells that synthesise intrinsic factor).
- Increased vitamin B12 requirements are associated with: pregnancy, thyrotoxicosis, malignancy, liver & kidney disease.
Vitamin B12: Deficiency Signs and Symptoms
- Megaloblastic anaemia: presenting as fatigue, breathlessness, pallor, etc. Supplementation with B9 will alleviate the anaemia, however other symptoms of vitamin B12 deficiency progress.
- Neurological abnormalities: tingling, numbness, loss of balance, burning sensations, weakness, confusion and decreased reflexes.
- Anaemia typically develops first, but not always if the person is consuming lots of folate.
- Changes occur slowly, and once the patient experiences neurological symptoms, they may be irreversible.
