Vitamin B12 is a nutrient found naturally in animal products such as meat, fish and eggs.
The nutrient is perhaps best known for its relationship with a condition known as ‘pernicious anaemia’ – a form of anaemia caused by B12 deficiency which itself is caused by impaired absorption of B12 from the gut.
However, for some time now there has been specific interest in the role the B12 plays in brain function.
B12 deficiency linked to cognitive impairment
In particular, B12 deficiency is believed to play a potential role in the declining brain function (cognitive impairment) often seen in ageing.
One of the proposed mechanisms here concerns ‘homocysteine’ – an amino acid that is linked with adverse effects on health including cardiovascular issues such as heart disease and stroke.
Low levels of B12 can cause raised levels of homocysteine (as can low levels of other nutrients including folic acid and vitamin B6).
In fact, measuring homocysteine levels is sometimes used as a proxy for B12 status.
In a study published in the journal Neurology, vitamin B12 levels and brain structure and function was assessed in a group of individuals aged 65 or more.
Low B12 levels linked to brain shrink
B12 status was assessed with five tests including homocysteine levels and serum (blood) B12 levels. Four and a half years later, the individuals were assessed via tests for cognitive function as well as MRIs of the brain.
In general, tests which indicated low B12 status (e.g. raised homocysteine levels) were associated with lower cognitive function tests scores and smaller brain volume.
This was true for all of the 5 markers for B12 except serum B12 levels.
What this evidence suggests is that B12 may have an important role to play in the ageing brain, and that assessing levels via the standard blood test is not particularly useful.
This situation is reminiscent of tests for iron levels in the body. Serum iron is a generally useless test of actual iron levels in the body, while other tests (notably ‘ferritin’) are much more useful in practice.
The absorption of B12 is a quite complex process, and ageing may well lead to an impairment of B12 absorption and increase the risk of deficiency.
There is a risk, of course, that using the most common test for B12 levels (serum B12) runs the risk of missing genuine B12 deficiency. The end result might be someone languishing in a B12-deficient state, which may have profound implications for their health and wellbeing.
TO protect yourself against cognitive impairment and brain shrink check with a doctor skilled in nutritional medicine to access your own B12 status.
1. Tangney CC, et al. Vitamin B12, cognition, and brain MRI measures – A cross-sectional examination. Neurology 2011;77(13):1276-1282
Dr. John Briffa is a graduate of the University College London School of Medicine. Since qualifying as a doctor, Dr Briffa has developed a special interest in nutritional and naturally-oriented medicine.
He is in private practice in London, and his aim is to assist individuals identify and remedy the underlying cause of chronic symptoms and conditions.
Dr Briffa is a former columnist for the Daily Mail and the Observer, and is a regular contributor to newspapers and magazines. He is a former recipient of the Health Journalist of the Year award in the UK. He has written 6 books on the subject of nutrition and natural health and has been a major contributor to 3 others.
Dr. Briffa lectures internationally to corporations, members of the public and health professionals, and is a regular guest on radio and TV.
You can read more at www.drbriffa.com.
Latest posts by Dr. John Briffa (see all)
- Mental Illness Is Not “All in the Mind” - October 1, 2015
- Drop Self-Criticism and Drop Pounds Too - September 28, 2015
- B12 Deficiency Linked with Brain Shrinkage in Later Life - October 2, 2011