Vitamin B12 - Cobalamin

Question 1

Vitamin B12 - Cobalamin

Answer 1

• 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.

Question 2

Vitamin B12 - Storage

Answer 2

B12 storage in the liver lasts between 3-5 years.

Question 3

Vitamin B12 - Food Sources

Answer 3

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).

Question 4

Vitamin B12 - Roles

Answer 4

Nervous System
Erythropoesis
Methylation
Energy Production

Question 5

Vitamin B12: Nervous System - Functions

Answer 5

• Myelin production
• Neurotransmitter production (dopamine, seratonin)
• Choline key for brain function

Question 6

Vitamin B12: Nervous System - Therapeutic uses

Answer 6

• MS
• Tingling / Pins and Needles
• Sciatica

Question 7

Vitamin B12: Erythropoesis - Functions

Answer 7

B12 is required for erythropoiesis.

Question 8

Vitamin B12: Erythropoesis - Therapeutic uses

Answer 8

Megaloblastic Anaemia

Question 9

Vitamin B12: Methylation - Functions

Answer 9

• Homocysteine cycle (conversion of the amino acid homocysteine to methionine)

Question 10

Vitamin B12: Methylation - Therapeutic Uses

Answer 10

• Cardiovascular disease

* Alzheimer’s

Question 11

Vitamin B12: Energy Production - Functions

Answer 11

• Energy production from fats and proteins

Question 12

Vitamin B12: Energy Production - Therapeutic uses

Answer 12

Fatigue

Question 13

Vitamin B12 - Deficiency causes

Answer 13

• 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.

Question 14

Vitamin B12 - Deficiency States

Answer 14

• 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.

Question 15

Vitamin B12: Deficiency Signs and Symptoms

Answer 15

• 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.

Question 16

Vitamin B12 - Testing

Answer 16

• Serum B12 Testing reference ranges are typically anything between from 110ng/L up to 900ng/L. This is the most common means of assessing B12 conventionally.
• However, many people experience signs of B12 deficiency with normal B12 serum.
• A more accurate reflection of B12 levels would involve testing MethylMalonic Acid (available in serum or urine testing) gives an indication of how B12 is used in cell metabolism and is the gold standard test.

Question 17

Vitamin B12 - Toxicity

Answer 17

• Vitamin B12 is one of the safest vitamins. No adverse effects have been associated with large intakes (2mg) of vitamin B12 from food or supplements in healthy people.

Question 18

Vitamin B12 - Drug Interactions

Answer 18

• The OCP, metformin, excessive alcohol, proton pump inhibitors and H2 receptor antagonists lower B12 levels.
• Calcium may enhance B12 absorption, including with metformin use.
• People with autoimmune disease are considered more at risk of pernicious anaemia.