B12 – How Did I Go So Low?

We’ve been a bit lethargic in our blogging lately, lost the pep from our step, fuggy headed and generally laid low.

Nutritionists don’t generally believe that a vitamin deficiency is something that can ever happen to them – but it did to me!  With hindsight, it isn’t so surprising that I’m deficient in B12, it isn’t particularly uncommon, I just didn’t see it coming.

How do people get to be deficient in B12? 

It happens gradually.

You can be vegan and get none from your diet – it’s only present in foods of animal origin.

You can have coeliac disease or inflammatory bowel disease and not absorb nutrients from part of the intestine

You can be on medication like Metformin for diabetes or antacids which reduce stomach acidity and these can limit your absorption of B12

Or, like me, your stomach acid is lacking.

B12 naturally occurring in food, exists bound to protein, which the acid in the stomach should release allowing the free cobalamin or vitamin B12, to be absorbed in the small intestine.

Poor Absorption can be exacerbated by a diet low in B12

I never thought that this was me – but I was probably wrong.

How much B12 do we need?

Recommendations vary but around 2.4micrograms/day

Where do we find it?

Shell fish is massive –  a portion of clams or oysters comes top with a huge 84mcg, salmon per portion is 4.8mcg, canned tuna 2.5mcg.

Meat is pretty good at 1.4mcg for a portion of beef, paler meats do less well with chicken at 0.3mcg.

Dairy is great, a cup of milk has 1.2mcg and an egg  0.6mcg

Food supplemented with B12

Many foods are supplemented with B12 and this is an interesting proposition.  The synthetic B12 isn’t bound to a protein and is more easily absorbed.

It’s not naturally present in Vegemite but is added to the low salt version and also added to Marmite.  Packaged breakfast cereals have it added.

I thought that the soya milk I use for porridge was fortified, but found that I’d switched brands and the new one isn’t – I’ve gone back to the old brand and get 1mcg B12 per cup.



Guts and Bugs

B12 is intricately involved with our microbiome. Our gut bacteria can be helping themselves to our slim intake of B12 and leave little for us, or make plenty themselves, or in susceptible individuals taking supplements, allowing acne producing bacteria to flourish.

If you are concerned about your B12 status, your GP can check it with a simple blood test. Like most deficient people, I’ve had the intramuscular B12 injection and take a supplement sprayed under the tongue to avoid digestion and happily have the pep back in my step!