Vitamin B12 After 60: Why Two Very Common Medicines Make It Harder to Absorb

“You’re just getting older”

Sometimes that is true.

But tiredness is a symptom with a long list of possible causes, and a few of them have answers. One of the most answerable — and one of the most commonly missed — is vitamin B12.

The reason it gets missed is almost too simple. Low B12 does not announce itself. It produces exactly the things everyone over 60 has already been told to expect: less energy, a bit more forgetful, legs that ache, hands that tingle. Every one of those gets filed under age and never investigated.

Tiredness that has an answer is much better news than tiredness that does not. This is one of the few worth ruling out properly.

What B12 actually does

Three jobs, and all three explain the symptoms.

It helps make red blood cells — the ones carrying oxygen around the body. Short of them, everything feels like more effort than it should.

It maintains the protective sheath around nerves. When that sheath degrades, the signals do not travel cleanly. That is where pins and needles, numbness in hands and feet, and unsteadiness come from.

And it is involved in the machinery the brain uses to make neurotransmitters, which is why low levels can show up as low mood or as thinking that feels slower than usual.

The nerve damage is the part that deserves emphasis. Caught early it usually improves. Left long enough, some of it does not. That is the honest reason not to wait and see.

Why absorbing it gets harder with age

B12 absorption is unusually complicated. Most nutrients simply cross the gut wall. B12 needs a chain of steps to work in order.

First, stomach acid has to release the B12 from the protein it arrived attached to. Then the stomach has to produce a carrier molecule called intrinsic factor. Then the pair travel the length of the small intestine to a specific stretch at the end, which is the only place B12 is absorbed.

Break any link and the chain fails.

The first link is the one that weakens with age. Many people produce less stomach acid as the decades pass — sometimes markedly less. The B12 is on the plate, it goes down, and it never gets released from its protein.

Which means something slightly unfair: you can eat a perfectly good diet and still run low.

The two medicines nobody mentions

This is the part of the story that rarely reaches the person taking the tablets.

Metformin, prescribed for type 2 diabetes and taken by an enormous number of people for decades at a time, is associated with reduced B12 absorption over the long term. Not overnight — over years. Which is precisely why it slips past: nobody connects a symptom appearing in year seven with a tablet started in year one.

Long-term stomach acid reducers — proton pump inhibitors such as omeprazole and lansoprazole, and to a lesser degree the older H2 blockers — work by suppressing stomach acid. That is the whole point of them, and for the condition they treat they do it well. But stomach acid is step one of the B12 chain. Suppress it for years and step one gets less reliable.

Now read that sentence carefully, because this is where people go wrong:

Neither of these is a reason to stop taking your medication.

Both treat conditions that are considerably more serious than a B12 level. Stopping a proton pump inhibitor on your own can bring back the problem it was controlling; stopping metformin without a plan is worse. This is not an argument against the tablets.

It is an argument for one blood test.

If you have been on either of these for years and have never had your B12 checked, that is a reasonable thing to raise at your next appointment — and a very reasonable thing for a doctor to agree to.

Where B12 comes from

Almost entirely from animal foods

Eggs

A convenient everyday source, and one most people already eat. Eggs also bring choline and, in the yolk, the pigments the eyes use — so they earn their place twice.

How to eat it: Two a day is unremarkable for most people. The long-standing worry about eggs and cholesterol has been substantially revised.

Milk, cheese and yoghurt

Dairy is a reliable everyday source, and one of the easier ones for a smaller appetite — a glass of milk asks nothing of you.

How to eat it: If appetite has dropped, liquid sources often land better than another plate of food. Milk on porridge counts.

Fish and meat

Oily fish, red meat and liver are the densest sources by some margin. Liver in particular is extraordinarily high in B12, which is why a small amount goes a long way.

How to eat it: Tinned salmon, sardines and mackerel are cheap, keep for years, and need no cooking at all.

If you eat little or no meat, this matters more, not less. Plants contribute almost no usable B12 — fortified foods and supplements become the practical route.

One word of caution about fortified foods. Some breakfast cereals and plant milks are fortified with B12 and some are not, and the packaging rarely makes it obvious from the front. If you are relying on them, the back of the box is the only place that tells the truth.

Why the test comes before the bottle

There is a whole aisle of B12 supplements, and some of them are genuinely useful. But buying one before you have been tested gets the order wrong, for three reasons.

You might not be low. In which case you have bought a solution to a problem you do not have, and the real cause of the tiredness is still sitting there unexamined.

Supplements can mask something. Low B12 sometimes shows up first as a particular kind of anaemia. Taking folic acid or a general multivitamin can correct the blood picture while the nerve problem quietly continues. The blood test looks better; the underlying issue does not.

If you are genuinely low, the cause matters. Low because of diet is a different problem from low because your stomach is no longer producing intrinsic factor. The second one is not solved by a tablet you swallow — it may need injections. Only a doctor can tell those apart.

One test. Then you know which conversation you are having.

Who should ask for the test

This is for you if

• You have been tired for months and it has simply been put down to age
• You take metformin, or have taken it for several years
• You take omeprazole, lansoprazole or a similar stomach acid tablet long term
• You have pins and needles, numbness or tingling in hands or feet
• You eat little or no meat, fish, eggs or dairy
• You have had stomach or bowel surgery, or a condition affecting absorption

Skip this if

• You have already been tested recently and told your level is fine — look elsewhere for the tiredness
• You are hoping a supplement will substitute for the conversation — this one really does need the test first

What to do this week

Write down two things and take them to your next appointment: how long you have felt like this, and the list of medicines you take every day.

Then ask one question — *”could we check my B12?”*

If the answer comes back normal, you have lost nothing and ruled out a real possibility. There are other causes of persistent tiredness worth working through, and we go through the main ones here.

If it comes back low, you have found something with an answer. And while you are eating more of the foods above, note that they are doing a second job too — the body needs more protein after 60, not less, and eggs, fish and dairy cover both at once.

Either way, finding a cause beats not finding one. Which, when the alternative was “that’s just your age”, is a considerably better outcome.

One email a week, in plain English. The things worth asking about, the things worth ignoring, and no supplement that promises to turn back the clock.