Vitamin B12 - what does it do?

Author: Emily Seddon   Date Posted:7 November 2016 

While Vitamin B12 is essential for normal blood and neurological function, deficiency is common in the elderly, with studies estimating that up to 40% of over 60’s may be affected.

What is Vitamin B12?

Vitamin B12, also known as cobalamin, is a water soluble vitamin and the largest of the B vitamin family. It is unique among vitamins in that it contains a metal ion, cobalt.

Because Vitamin B12 is synthesized only by certain bacteria, it is mostly found in animal protein products (those high in the food chain). Foods such as meat, milk, cheese, eggs, fish, and shellfish (aka foods derived from animals) are the major dietary sources of Vitamin B12.

There is debate about whether some plant based foods – such as nori – contain biologically active B12, however it is undeniably harder for vegetarians and vegans to maintain a steady intake of B12.

What is intrinsic factor?

Intrinsic factor is crucial for the absorption of Vitamin B12. Vitamin B12 in food is bound to proteins until it is released from the proteins by hydrochloric acid. The parietal cells of the gastric mucosa secrete intrinsic factor, which attaches to free cobalamin. This complex is then absorbed in the small intestine and transported throughout the body. A lack of intrinsic factor causes a B12 deficiency.

Pernicious anaemia is an autoimmune condition targeting parietal cells, however generally all causes of a B12 deficiency anaemia are referred to as pernicious anaemia.

What does Vitamin B12 do in the body?

  • Vitamin B12 is essential for the normal function of all cells as it affects DNA synthesis cell growth and replication.
  • Like all B vitamins, it’s also involved in the metabolism of carbohydrates, lipids and protein.
  • Vitamin B12 is involved in the production of red blood cells in bone marrow. When there isn’t enough B12, red blood cells are still formed but are enlarged, oval shaped, immature cells.
  • Vitamin B12 has a close relationship with folate (Vitamin B9). Both play essential roles in a cycle called methylation. During methylation cobalamin is activated into methylcobalamin, which aids in the conversion of homocysteine to methionine.
    • Without this conversion, the subsequent accumulation of homocysteine levels in blood has been associated with an increased risk to your cardiovascular health.
    • Methionine is used as part of S-adenosyl-L-methionine (SAMe), which is essential for maintenance of myelin nerve sheath integrity and nerve function.

Vitamin B12 1000mcg

What happens without Vitamin B12?

The most common signs of deficiency are:

  • Weakness & fatigue.
  • Light-headedness.
  • Rapid heartbeat & breathing.
  • Pale skin colour.
  • Easy bruising or bleeding, including bleeding gums.
  • Sore, smooth, thick, red or “beefy” looking tongue.
  • Weight loss, diarrhoea or constipation.

A severe deficiency may result in anaemia and damage to the nerves, with tingling or numbness to the fingers and toes, difficulty walking, mood changes, depression and loss of cognitive function.

Deficiency most often occurs in elderly populations, people following a vegan or vegetarian diet, parasitic infections, health conditions that affect gastrointestinal absorption (for example dysbiosis, Coeliac’s disease, atrophic gastritis) and with medications that reduce stomach acid.

How can you maintain your Vitamin B12 levels?

Most people are able to prevent a Vitamin B12 deficiency by eating regular meat, poultry, seafood, dairy products and eggs.

If you have low levels of B12 due to a plant-based diet or other factors, supplementation may be a suitable option. B12 tablets and intramuscular injections can be used, depending on the person, existing conditions and the severity of their deficiency.

A B vitamin complex is also a good option to consider, as B vitamins assist in the absorption and utilisation of each other.

Before beginning any supplementation, or if you suspect you may have low levels of Vitamin B12, it is recommended to have a check-up with your health practitioner.

Written by Emily Seddon
Emily Seddon

Emily (BHSc Naturopathy) is a qualified naturopath with a love of science. Growing up with a hippy mum and dad, Emily grew used to thinking outside the box for her own health. She has since completed a degree in Health Science, majoring in Naturopathy, combining that passion for healthy living with scientific and traditional evidence to help others to live happy and healthy lives.

She loves using herbal and nutritional medicine to treat ailments and lives by the philosophy of “there is no such thing as too much tea."

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