Misconceptions about a B12 deficiency


1. Serum B12 is a conclusive test

The serum B12 test is still widely used as thé test to confirm or rule out a vitamin B12 deficiency. However, a normal blood value cannot rule out a B12 deficiency, as has often been shown in scientific medical literature. Serum B12 can be false normal or even false high, while a deficiency is present.

A value above the reference value does not automaticcaly rule out a deficiency and a (slightly) lower value does not automatically mean a B12 deficiency, although a B12 value beneath 150 pmol/L has a specificity of 95% or more. There is a large grey area wherein a deficiency is possible, despite a normal serum B12 value.

By using serum B12 alone, many patients are being missed. Because a B12 deficiency can lead to permanent neurological damage, one should never rely on serum-B12 alone (unless obviously low) and always test at least MMA when a deficiency is suspected. Especially when neurological and/or neuropsychiatric symptoms are present, as they can become permanent without timely treatment.

We advice to combine serum B12 or Active B12 with MMA when a deficiency is suspected for increased accuracy. The problem however is that many physicians do not know these tests (MMA, homocysteine, Ative B12) or do not know how to interpret them. And if they know them, the are considered too expensive to do. Of course the cost of years of visiting doctors, sometimes with very expensive other tests, and years of medication, are much higher.

As there is no ‘golden’ test, patients with clear neurological symptoms, and no other obvious cause for those problems, should be treated with B12 injections. When clinical improvement occurs the treatment should be continued. There are numerous stories of patients who have benefited from B12 treatment, despite normal blood results.

2. A B12 deficiency always causes anaemia

Often patients are being told they cannot have a B12 deficiency, or their deficiency is nothing serious, because they do not have anaemia. They are told it must be because they did not eat well or the test must be wrong and there is no problem.

Our survey showed that only 28% of the respondents who knew their blood levels had anaemia and only 15% had enlarged red blood cells. A B12 deficiency can lead to serious neurological and neuropsychiatric problems, long before anaemia develops. This has been known for a long time, but the misconception still persists today.

  • 1905: Langdon (JAMA): a group of patients developed neurological and mental symptoms before anaemia developed
  • 1929: McAlpine (Lancet): neurologic and psychiatric symptoms can predate changes in blood with many months in pernicious anaemia
  • 1960: Smith (BMJ) in his article Megaloblastic Madness wrote that physicians should be aware that combined degeneration of the spinal cord can occur before anaemia develops, and that an early diagnosis (and treatment) is essential.
  • 1990: Lindenbaum et al (NEJM): 44% of patients with B12 deficiency had no anaemia
  • 2003: Dutch Health Council: hematological indicators (like Hb and MCV) are not specific and sensitive enough; indications that neurologic and hematological symptoms are inversly related

3. A B12 deficiency is rare and only occurs in older people

A B12 deficiency is not rare at all; it is quite common. Several studies through the years showed that between 3 and 5% of the population has a B12 deficiency. One article in the Dutch Medical Journal even said 5 to 10% based on a serum B12 of 148 pmol/L).
A deficiency does occur more in older people than in the young, but the prevalence is high in all ages.
A deficiency in children is even more unknown, not looked for and not taken seriously.
1 in 200 children under 19 (1 in 112 teenagers) have a clear deficiency.
Furthermore test results for children are interpreted as if they were adults, when research has shown that B12 is supposed to be higher and MMA and homocysteine lower. Homocysteine at least, has age-related reference values in some hospitals.

4. There is only one cause for a B12 deficiency, auto-immune pernicious anaemia.

After a B12 deficiency is diagnosed, several tests can be done to try to find the cause of the deficiency. Often nothing is tested at all, because it is believed that a cause often can’t be found. Only in 34% of cases people are tested for causes according to our survey. But whén the tests are done a cause is found in 50% of the cases.

Often only one test is done: antibodies against the intrinsic factor. When they are not found it is often, falsly, concluded there is no pernicious anemia, or even, there is no deficiency at all. But this test is negative in 30 to 50% of the patients wíth pernicious anaemia. Besides that, there are many more causes for a deficiency, many of them not well known. Some causes, like parasites, can be treated so vitamin absorption can be restored.


Problems patients face with getting the right treatment are pretty much the same everywhere:
You finally have the diagniosis, and then the next battle starts: getting treated at all, getting a loading dose and getting enough B12 according to your needs.

Firstly there are many different guidelines for the treatment.
Treatment guidelines differ from country to country and from physician to physician. Guidelines are often not followed, or only half. Loading doses differ from daily to none at all, and maintenance from twice weekly to none. Often, after a loading dose maintenance treatment is insufficient.
Treatment is seldomly based on symptoms and too often on the B12 blood value. We also see, too often, that treatment is stopped completely because the blood value is considered too high or the deficiency is considered temporary.
Which brings me to the next misconception:

5. Serum B12 can be used to monitor treatment:

One of the most common problems in the treatment of a vitamin B12 deficiency is that people receive insufficient injections to feel well. Often the serum B12 value is used to ascertain the frequency, or base treatment upon, but there is no correlation between the serum B12 value and the symptoms experienced by patients.
During vitamin B12 injections, transcobalamin and haptocorrin (transportproteins) are fully saturated with vitamin B12. So, serum and Active B12 values cannot be used to ascertain the effect of treatment; levels rise regardless of therapeutic effectiveness.

Some patients can have a bi-monthly maintenance dose straight after the loading dose. However, a large number of patients experience recurring symptoms on bi-monthly injections. Large groups of people need much more vitamin B12 than the recommended maintenance dose to feel well, and prevent recurring symptoms. Symptoms should be used as a guideline, not blood values.
Also many physicians are, erroneously, afraid of an overdose.

6. B12 can be toxic in high doses

In the past 60 years harmful effects have never been shown from overdose. No single case has been found in medical literature. After an injection the serum B12 value rises quickly to far above the upper reference value (on average 150-700 pmol/L), followed by a slow decrease. Apparently the underlying thought is that is it is necessary to keep the value between the (upper and lower) reference values. However the blood level of serum B12 rises regardless of therapeutic effectiveness, as I mentioned before.

Treatment guidelines in Holland give no reference to serum values or a danger of overdosing. This is further underlined by the advice to inject twice a week with obvious neurological problems, for up to 2 years if necessary.
A high serum B12 value does not mean that symptoms are treated sufficiently. This presumption can have damaging effects for patients with neurological symptoms, which can become irreversible with insufficient treatment.

Maybe the concern for a possible overdose is caused by the knowledge that some life threatening diseases can be accompanied by a strong increase in the B12 blood value, in some cases to even 30 times the upper reference value. Elevated B12 values are always cause for further testing, but of course, reversibly, it cannot be concluded that elevated levels áfter B12 injections lead to serious disease.
The treatment with high dose B12 injections is not only completely safe but fortunately also very effective. With the right treatment patients can recover completely. Starting straight away with treatment is essential, as is the continuing treatment in order to give the body enough B12 to fully recover. Therefore it is essential that patients are no longer exposed to the real danger of irreversible symptoms because of the imaginary fear of overdosing.


A B12 deficiency is often misdiagnosed as depression, ME/CFS, fibromyalgia, iron-deficiency-anemia, MS or hypochondria. Patients have often been to the doctor many times, visited multiple doctors and have had numerous tests done, before the B12 deficiency was found. This is costing society millions of euro’s every year, and patients years of unnecessary suffering, misdiagnoses with the accompanying stress, and most of all, the risk of permanent neurological damage.

Considering 7 in 10 patients report neurological symptoms, which can become permanent, it is clear the problem is huge.
If we could at least correct these misconceptions, we would be a lot closer to an earlier and better diagnosis, and better treatement, and so save many people from unnecessary suffering ánd save millions of euro’s.


PowerPoint presentation Misconceptions about a B12 defiency:

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