What does vitamin B12 do for men?
Healthy blood, nerves and energy from food. If you eat meat, fish or dairy, you should get enough. Yet the commonest UK cause of low B12 isn’t about what you eat.
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What are the benefits of vitamin B12 for men?
B12 does the same jobs in men as in anyone else. The NHS says it helps your body make red blood cells, keep the nervous system healthy and release energy from food. It also helps your body use folate, another B vitamin.
| B12 helps you | Why it matters |
|---|---|
| Make red blood cells | Too little can lead to anaemia (too few healthy red blood cells). |
| Keep your nerves healthy | Low B12 can cause pins and needles, muscle weakness, and memory or vision problems. |
| Release energy from food | Extreme tiredness and a lack of energy are on the NHS list. |
| Use folate | Folic acid tablets can hide low B12, so your GP checks B12 first. |
Sources: NHS: B vitamins; NHS: B12 deficiency; NHS: treatment
So the benefit comes from having enough. A diet with meat, fish and dairy usually provides enough.
Feel tired, tingly or foggy? Check the full list of low B12 symptoms.
Does B12 give men more energy?
If you’re low, treatment can help. Extreme tiredness is on the NHS list of low B12 problems, and many symptoms improve with treatment.
If your level is normal, none of the NHS pages we checked say extra B12 gives men more energy. The same goes for testosterone and muscle.
| Claim | What the evidence says |
|---|---|
| More energy | Low B12 can cause extreme tiredness. No NHS page we checked says it boosts energy when levels are normal. |
| Sharper memory and thinking | In healthy adults, mostly in their 60s and 70s, B vitamin tablets probably made little or no difference. |
| Fertility | Low B12 can sometimes cause temporary infertility (trouble having a baby). This usually improves with treatment. |
| Testosterone and muscle | None of the NHS pages or trials we checked support it. |
Sources: NHS; NHS: complications; Cochrane 2018
The memory finding comes from a Cochrane review of 14 trials and 27,882 people. People took folic acid, B12, B6 or a mix, with results followed for up to 5 years.
Tired all the time with normal B12? Look at other causes. See why you might be always tired and low testosterone and tiredness.
How much B12 do men need?
Adults aged 19 to 64 need about 1.5 micrograms a day. Good sources are meat, fish, milk, cheese, eggs and some fortified breakfast cereals.
| If you | NHS advice |
|---|---|
| Eat meat, fish or dairy | You should be able to get enough B12 from your diet. |
| Are vegan | Have cereals and unsweetened soya drinks fortified with B12, yeast extract or fortified yeast flakes. You may need a supplement. |
| Take a supplement | 2mg or less a day is unlikely to cause any harm. |
Sources: NHS: B vitamins; NHS: vegan diet
That 2mg is 2,000 micrograms, over 1,000 times what you need each day. The NHS says there’s not enough evidence on what high daily doses do.
For meals that cover your 1.5 micrograms, see foods high in B12.
Why can a man who eats meat be low on B12?
The commonest UK cause is pernicious anaemia.
Your immune system attacks cells in your stomach. Those cells make a protein you need to take in B12. Without it, your body is unable to absorb vitamin B12.
It’s more common in women around 60 and people with a family history. It’s also more common in people with another condition where the immune system attacks the body, such as Addison’s disease or vitiligo.
Other causes the NHS lists:
- Stomach surgery, or a gut condition such as Crohn’s disease.
- Medicines such as metformin (for diabetes), PPIs (for heartburn) and nitrous oxide (laughing gas).
- A vegan diet without B12 supplements or fortified foods.
- Getting older. Low B12 or folate affects around 1 in 20 people aged 65 to 74, and 1 in 10 aged 75 or over.
Never stop or change a prescribed medicine without your prescriber.
Your body’s store can last around 2 to 5 years. So a cause that started years ago may only show now.
If any of these apply to you, ask your GP whether you need a B12 test.
How do men get a B12 test?
What usually happens if your GP thinks you’re low
- 1
Blood test
Checks your red blood cells, B12 and folate.
- 2
Your symptoms
Count too. Normal levels don’t always rule it out.
- 3
Find the cause
Your GP may test for pernicious anaemia.
- 4
Treatment
Injections at first, then tablets or injections.
Sources: NHS: diagnosis; NHS: treatment
Some people have symptoms with normal-looking levels, and some are low with no symptoms. So tell your GP everything you’ve noticed.
If diet isn’t the cause, you’ll usually need an injection every 2 to 3 months for life. Read your numbers with our B12 blood test guide, or see what B12 injections involve.
What to do about B12 this week
- Get B12 from meat, fish, milk, cheese, eggs or fortified breakfast cereals.
- If you’re vegan, have B12-fortified foods or take a B12 supplement.
- If you take a supplement, keep it to 2mg or less a day.
- If you take metformin or a PPI, ask your GP whether you need a B12 check.
- Write down any tiredness, pins and needles or memory changes, and when they started.
- Think you may be low? Book a GP appointment.
Sources: NHS; NHS: causes; MHRA
When to speak to a GP
The NHS says to see a GP if you think you may be low. Some problems can’t be undone, so go sooner rather than later. Book an appointment if:
- You have extreme tiredness, a lack of energy, a sore red tongue, mouth ulcers, muscle weakness, shortness of breath, headaches or a pounding heartbeat.
- You have pins and needles, numbness, low mood, anxiety or confusion, or problems with balance, coordination, vision, memory or judgement. The longer low B12 goes untreated, the higher the chance of lasting damage.
- You take metformin and have any of these symptoms. Low B12 may affect up to 1 in 10 people who take it, and the MHRA advises a B12 blood test.
- You’re vegan, don’t take B12 or eat fortified foods, and have any of these symptoms.
Over 50 and choosing supplements? See vitamins for men over 50.