What are B vitamins? Are you getting enough Vitamin B12?
Vitamins are substances that occur naturally in food, and are needed for many essential body functions. There are 13 vitamins required by our body- and 8 of these are types of Vitamin B. The B Vitamins have a wide variety of important roles in the body, particularly in relation to growth, repair and energy production. Whilst most healthy people who eat a broad and balanced diet will get enough B vitamins from their food, you can become deficient (low) in these vitamins for a variety of reasons.
You can develop low B12 if there is not enough of it in your diet, if you’re unable to absorb the vitamin properly, or if your body is using it up more quickly than usual (e.g. in pregnancy).
What does Vitamin B12 do?
Vitamin B12 (also known as Cobalamin) is important in the production of myelin- a protein which coats your nerves, and forms an “insulating layer”, allowing messages to travel efficiently from your brain and spinal cord to other parts of your body. Vitamin B12 also has vital roles in brain function, making blood cells, DNA production and energy production in your body
How much Vitamin B12 do you need?
The recommended dietary allowance (RDA) of Vitamin B12 is 2.4 mcg/day, though slightly more is needed by women who are pregnant (2.6mcg) or breastfeeding (2.8mcg). Dosages for babies and children are as follows:
- Infants up to 6 months: 0.4 mcg per day
- Babies from 7-12 months: 0.5 mcg per day
- Children from 1-3 years: 0.9 mcg per day
- Children from 4-8 years: 1.2 mcg per day
- Children from 9-13 years: 1.8 mcg per day
What are good sources of B12?
- You can get B12 in meat, milk, eggs, cheese, yeast extracts and fortified breakfast cereals
- B12 is the only vitamin not found in vegetables
- You can also get B12 supplements in tablet form in pharmacies, although people with low B12 who have problems absorbing the vitamin may need to see a doctor to discuss B12 injections instead.
What causes low Vitamin B12?
It’s not always clear why some people get low B12. It is seen more commonly in older people. If you have one of the following issues, it may be causing your low B12:
- Low B12 intake in your diet- e.g due to a vegetarian or vegan diet
- Pernicious Anaemia- an autoimmune condition which results in poor absorption of Vitamin B12 by the stomach
- A side effect of the contraceptive pill
- Other medications you take, such as certain diabetes medicine, and certain antacids.
- Chronic Alcoholism
- Pancreatic failure
- Pregnancy ( as the body is using up more Vitamin B12 than usual)
- Babies born to mums who have low B12 or who are vegan
- Coeliac disease
- A history of surgery on the stomach or small bowel
- Inflammatory bowel disease (such as Crohn’s disease)
- Blind loop syndrome or small bowel bacterial overgrowth
- Infection with fish tapeworm (more common in countries where raw fish is widely eaten)
What are the symptoms of low B12 ?
Mild B12 deficiency may cause you no obvious health issues, but as it gets worse, you may develop problems such as anaemia and nerve damage. Symptoms of low B12 can include:
- Tiredness- this is one of the most common symptoms
- Pale appearance, palpitations, and shortness of breath (if anaemia is present)
- A smooth tongue
- Constipation, diarrhoea and reduced appetite
- Low mood, reduced concentration and memory problems
- Nerve damage- this can lead to weaknesss, tingling and numbness
How is Vitamin B12 deficiency diagnosed?
Your doctor can check your Vitamin B12 levels by requesting a blood test. A full blood count (FBC) may be done, as anaemia is a complication of low B12. Folate levels tend to be assessed with B12, as folate and B12 have closely related roles in your body. If you have low B12, a blood test to check your autoimmune antibodies may be recommended, to check for Pernicious Anaemia. You may also be advised to have a blood test for coeliac disease.
Wondering about your B12? A Qoctor doctor can issue a pathology referral online, with results sent to your inbox. Arrange a blood test online.
How B12 is tested in Australia (and why results can be confusing)
The way B12 is tested in Australia changed on 1 July 2025, and it’s worth understanding, because it explains why some people get an “equivocal” or borderline result and a follow-up test they weren’t expecting.
Total B12 vs active B12. A standard blood test usually measures total B12, which includes both the portion your body can actually use and a portion that’s inactive. Active B12 (called holotranscobalamin) measures only the usable fraction, and is often a more accurate early marker of deficiency. Your doctor can request either as the first test; pregnant patients and children are generally tested with active B12.
The reflex homocysteine test. Under the current Medicare rules, if your first B12 result comes back low or borderline (equivocal), the laboratory can automatically add a second test on the same blood sample, usually homocysteine, and sometimes methylmalonic acid (MMA). These are indirect markers: they tend to rise when B12 is genuinely lacking at a cellular level, so they help clarify an unclear result without needing a second blood draw. This is why you might see an extra test on your results that your doctor didn’t obviously order.
Why “equivocal” results happen. B12 status isn’t always clear-cut from a single number, and homocysteine in particular can be raised for reasons that have nothing to do with B12, including thyroid problems, kidney function, diet and genetic factors. So an equivocal result doesn’t necessarily mean you’re deficient; it means the picture needs interpreting alongside your symptoms and history. This is a conversation to have with your doctor rather than something to read from the number alone.
Active B12 and Medicare. Since the 2025 changes, Medicare reimburses either total or active B12, but only at the lower (total B12) rate, and generally only once every 11 months. Active B12 is still available, but if you request it specifically and don’t meet the rebate criteria, some labs charge an out-of-pocket fee (often around $45). Your GP can advise whether it’s worth it in your situation.
What is the treatment for low B12?
- Obviously, if you have any underlying causes such as medications, dietary issues or bowel problems, these should be identified and treated.
- Quite often a course of B12 injections will be prescribed by your doctor, as this will restore levels to normal quickly- this method will work even if you are unable to absorb B12 properly, as it bypasses your stomach and gut.
- If your Vitamin B12 deficiency is mild, oral treatment may be tried, with Vitamin B12 tablets (though this method may not work if your stomach and gut are not absorbing it properly).
- It may also help to obtain more B12 in your diet by sourcing foods high in B12- e.g. meat, milk, eggs, cheese, yeast extracts and fortified breakfast cereals.
- It’s important to discuss follow-up with your doctor- you may need to have your levels rechecked after treatment to ensure they do not drop again.
For more information on Vitamin B12 deficiency or the symptoms of low B12 speak to your doctor.
FAQs about Vitamin B12
Vitamin B12 supplements only helps tiredness if you’re genuinely B12 deficient AND if your tiredness is due to that deficiency, as opposed to other reasons. If your levels are already normal, taking extra B12, whether as tablets or injections, hasn’t been shown to boost energy, despite how it’s often marketed to consumers. Persistent tiredness has many possible causes, so if you’re feeling constantly fatigued and your B12 is normal, it’s worth speaking to a doctor about what else might be going on rather than assuming a supplement will fix it. They may run a wider set of blood tests, discuss your sleep quality, mental health, medications you take and other health issues that could be contributing.
Clinical review & governance
Medically reviewed by Dr AIFRIC BOYLAN
CEO
About Dr Aifric Boylan MB BCh BAO MICGP FRACGP DRCOG DCH Fellow of the Royal Australian College of General Practitioners, Dr Aifric Boylan is a general practitioner with more than 20 years' experience. She graduated in medicine from…
This health information has been clinically reviewed by an Australian doctor. Qoctor health pages are reviewed to support clear, evidence-informed guidance; they do not replace individual medical advice.
Telehealth is not suitable in all medical situations — patients will be advised if an in-person assessment is needed. In an emergency, call 000.
Mild deficiency may cause no obvious problems, but if it’s left untreated and worsens, it can lead to anaemia and, over time, nerve damage causing tingling, numbness or weakness. Some nerve-related effects can become long-lasting if deficiency is severe and prolonged, which is why it’s worth getting persistent symptoms like ongoing tiredness checked rather than assuming they’ll pass.
Clinical review & governance
Medically reviewed by Dr AIFRIC BOYLAN
CEO
About Dr Aifric Boylan MB BCh BAO MICGP FRACGP DRCOG DCH Fellow of the Royal Australian College of General Practitioners, Dr Aifric Boylan is a general practitioner with more than 20 years' experience. She graduated in medicine from…
This health information has been clinically reviewed by an Australian doctor. Qoctor health pages are reviewed to support clear, evidence-informed guidance; they do not replace individual medical advice.
Telehealth is not suitable in all medical situations — patients will be advised if an in-person assessment is needed. In an emergency, call 000.
Vitamin B12 is found almost entirely in animal products: meat, fish, eggs, milk and cheese, along with some fortified foods like certain breakfast cereals and yeast extracts. It’s the only vitamin not found naturally in plant foods, which is why people following a vegan or strict vegetarian diet are more likely to need a supplement or fortified foods to get enough.
Clinical review & governance
Medically reviewed by Dr AIFRIC BOYLAN
CEO
About Dr Aifric Boylan MB BCh BAO MICGP FRACGP DRCOG DCH Fellow of the Royal Australian College of General Practitioners, Dr Aifric Boylan is a general practitioner with more than 20 years' experience. She graduated in medicine from…
This health information has been clinically reviewed by an Australian doctor. Qoctor health pages are reviewed to support clear, evidence-informed guidance; they do not replace individual medical advice.
Telehealth is not suitable in all medical situations — patients will be advised if an in-person assessment is needed. In an emergency, call 000.
It depends. Oral vitamin B12, in the form of tablets and sublingual drops, is freely available at pharmacies and supermarkets, and is enough for many people whose deficiency is dietary. Injectable B12 (hydroxocobalamin) is a different matter: in Australia it’s technically a prescription-strength medicine, but in practice some pharmacies will sell the ampoules over the counter at the pharmacist’s discretion, sometimes in limited quantities, while others (including some larger chains) will ask for a prescription. Even where you can buy it, the injection needs to be given by a doctor or practice nurse. It’s important to have your levels checked and the cause looked into. A doctor can confirm whether you’re deficient, look for the underlying cause, and prescribe or arrange injections if you need them.
Clinical review & governance
Medically reviewed by Dr AIFRIC BOYLAN
CEO
About Dr Aifric Boylan MB BCh BAO MICGP FRACGP DRCOG DCH Fellow of the Royal Australian College of General Practitioners, Dr Aifric Boylan is a general practitioner with more than 20 years' experience. She graduated in medicine from…
This health information has been clinically reviewed by an Australian doctor. Qoctor health pages are reviewed to support clear, evidence-informed guidance; they do not replace individual medical advice.
Telehealth is not suitable in all medical situations — patients will be advised if an in-person assessment is needed. In an emergency, call 000.
Some people are told they should have an MTHFR gene test, often after seeing a naturopath or reading about “methylation.” The idea is that it explains fatigue, high homocysteine, or how your body processes B12 and folate.
It’s worth knowing the mainstream medical position. Australia’s pathology and GP colleges (the RCPA and RACGP) don’t recommend MTHFR testing for routine use, for a few reasons. The gene variants involved are very common, with around two-thirds of people carrying at least one. The link between them and actual symptoms is weak. And, most importantly, the result doesn’t change what you’d do about it: if your homocysteine is high and your B12 is low or borderline, the treatment is the same either way, which is to supplement your B12 and, sometimes, monitor it over time.
Because it isn’t considered clinically useful in most cases, MTHFR testing generally isn’t covered by Medicare, and is only available privately at your own cost. If you’ve been advised to get one, it’s worth talking to a GP first, who can explain whether it would actually tell you anything useful.
Clinical review & governance
Medically reviewed by Dr AIFRIC BOYLAN
CEO
About Dr Aifric Boylan MB BCh BAO MICGP FRACGP DRCOG DCH Fellow of the Royal Australian College of General Practitioners, Dr Aifric Boylan is a general practitioner with more than 20 years' experience. She graduated in medicine from…
This health information has been clinically reviewed by an Australian doctor. Qoctor health pages are reviewed to support clear, evidence-informed guidance; they do not replace individual medical advice.
Telehealth is not suitable in all medical situations — patients will be advised if an in-person assessment is needed. In an emergency, call 000.
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Clinical review & governance
Medically reviewed by Dr AIFRIC BOYLAN
CEO
About Dr Aifric Boylan MB BCh BAO MICGP FRACGP DRCOG DCH Fellow of the Royal Australian College of General Practitioners, Dr Aifric Boylan is a general practitioner with more than 20 years' experience. She graduated in medicine from…
This health information has been clinically reviewed by an Australian doctor. Qoctor health pages are reviewed to support clear, evidence-informed guidance; they do not replace individual medical advice.
Telehealth is not suitable in all medical situations — patients will be advised if an in-person assessment is needed. In an emergency, call 000.