“Acceptable” B12 Levels: Too Low?

We’ve talked before about vitamin B12 as a possible migraine-fighter. You may have had your vitamin B12 levels tested, and found in the normal range. But is the “normal range” wrong?

Of course this will very much depend on the lab that does the test, or the country you’re in. A recent study published in the Annals of Neurology (February 2025) turned up problems in people with “acceptable” B12 levels – acceptable, but in the lower range.

B12 levels are especially a concern for those on a vegetarian or vegan diet, or for older people. In this study, the patients were older – median age 71.2. In short, the study did find brain issues in patients with low but “normal” vitamin B12. (See the study here: Vitamin B12 Levels Association with Functional and Structural Biomarkers of Central Nervous System Injury in Older Adults)

Dr. Alexander Mauskop of the New York Headache Center commented on the study:

The current normal levels for vitamin B12 were determined decades ago, and it is not clear how reliable the research that led to these values was. Quest and Labcorp, two major chains of laboratories, define normal levels as 200 – 1,000 pg/ml and 232 -1,245 pg/ml, respectively. The WHO considers 480 pg/ml to be the bottom of the normal range, while it is 500 pg/ml in Japan. Some experts suggest these higher standards may contribute to lower rates of Alzheimer’s and dementia in Japan.

Vitamin B12: “Normal” blood Levels are often not normal

Dementia is only one possible result of low B12 – weakness, anxiety, and even numbness may be symptoms. And of course we’re concerned about headache and migraine, which is related to overall brain health.

It may be wise to have your levels checked, and to ask for the actual number. If you’re “normal” but in the low range, try at the very least to increase the vitamin B12 in your diet, or talk to your doctor about supplements.

Vitamin B12 deficiency is fairly uncommon, but it wouldn’t be surprising if at least 1 in 25 people had a deficiency, and the number may be even higher if the “acceptable” levels are wrong.

Low levels may be caused by diet, or be more common with age. But there are other possible causes, such as certain medications (e.g. metformin and antacid medications) and especially gut/stomach conditions and diseases. Alcohol abuse can also cause problems with B12 absorption.

Read more here: Vitamin B12 Deficiency (Cleveland Clinic)