What is vitamin B12 and why do we need it? The understanding nutrients series

Welcome to the next edition of the understanding nutrients series! I started this series to give you a better understanding of the vitamins and minerals that your body needs. 

I’m doing vitamin B12 as following on from my last post about vegan diets here, I wrote about how a B12 deficiency can occur in plant based diets, so I thought I’d explain more about the vitamin.

Roles of B12:

Vitamin B12 has many roles in the body, so I’ll touch on a few of them.

Red blood cell formation: B12 is needed to form healthy red blood cells. Vitamin B12 allows for the red blood cells to rapidly increase in numbers during their creation process. When there isn’t enough B12, the red blood cells don’t develop properly.

Nervous system: The nervous system comprises of the brain, spinal cord, and all your nerve cells. B12 plays an essential role in the formation of the myelin sheath. This is a protective layer surrounding nerves cells. Without this myelin sheath, electrical signals can't be communicated across nerve cells. This means your brain can't communicate with the rest of the body efficiently. It also helps regenerate nerves after injury.

DNA synthesis: Another key role of vitamin B12 is in DNA synthesis. DNA is the genetic code that makes up every living thing. B12 acts as a helper for enzymes that are crucial in DNA synthesis. By acting as a helper, it allows other reactions to occur. It’s role as an enzyme helper also extends to protein and fat metabolism. This means it helps with chemical reactions involving fats and proteins.

How much vitamin B12 should you be having?

The amount of vitamin B12 adults should be having is 1.5µg, this is 1.5 micrograms, a day.

For reference, two boiled eggs contain 1.6µg of vitamin B12. But the absorption of B12 is complex and it’s estimated that about 50% of B12 consumed is actually absorbed.

Foods that are high in vitamin B12:

B12 is only found in animal products like meat and dairy. Other foods like cereal and plant-based milks have B12 added in the production process – this is called food fortification.

• 100g of beef liver has 18µg
• 100g of salmon has 3.2µg
• 250ml of skimmed milk has 1.3µg
• 100g of pork loin has 0.7µg
• 250ml of almond milk (fortified with B12) has 1µg
• 40g of fruit and fibre cereal (fortified with B12) has 0.6µg

What happens if you don’t get enough?

Possible causes of a B12 deficiency can be: not absorbing the B12 from food, following a poorly planned plant based diet, surgery in the gut, and certain medications.

 A deficiency of B12 can lead to megaloblastic anaemia. This means your red blood cells are abnormally large and not properly developed so they can't carry oxygen around the body well. 

This can leave you feeling tired, short of breath, and with a loss of appetite. A B12 deficiency can also affect your nerves and cause numbness or tingly feelings in hands and feet.

It’s estimated that 6% of people below the age of 60 have vitamin B12 deficiency, and it’s treated with injections of B12.

Key points:

• Vitamin B12 is needed for healthy red blood cells, nerve cell formation, and DNA synthesis.
• Every adult should be getting 1.5µg of vitamin B12 every day.
• Vitamin B12 is found in meat and dairy products, it’s also added to foods like cereal and non-dairy milk.
• A deficiency of B12 can lead to megaloblastic anaemia and neurological problems.

I hope you enjoyed this blog post; I’d love to hear your thoughts in the comments below!

Bye for now 👋

 

References:

How much should you be having? https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/743790/Dietary_Reference_Values_-_A_Guide__1991_.pdf

Absorption of B12 https://pubmed.ncbi.nlm.nih.gov/17959839/

Role of B12 https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

Healthy red blood cells: https://pubmed.ncbi.nlm.nih.gov/15189115/

Nervous system: https://journals.sagepub.com/doi/pdf/10.1177/0310057X1604400410 and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6930825/

B12 in foods https://www.healthlinkbc.ca/healthy-eating/vitamin-b12

B12 in almond milk https://www.tesco.com/groceries/en-GB/products/276761995  

B12 deficiency https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/ and https://cks.nice.org.uk/topics/anaemia-b12-folate-deficiency/background-information/prevalence/