Vitamin B12 exists as an active and an inactive form in the blood. Active B12 is the biologically active component of B12. A low active B12 level is proposed to be the earliest marker of Vitamin B12 deficiency. Between 15%-40% of patients with low inactive B12 results do not have B12 deficiency. Therefore active B12 testing allows confident diagnosis of B12 deficiency.

Vitamin B12 sufficiency requires adequate dietary B12 intake, intact gastric parietal cells for Intrinsic Factor (IF) and gastric acid production, and normal terminal ileum function. Pernicious anaemia accounts for about 75% of B12 deficiency.

Although there is only 10-30% of active Vitamin B12 circulating in the blood it is the only form of Vitamin B12 that is taken up and used by cells of the body. Vitamin B12 works together with folate in the synthesis of DNA and red blood cells so folate deficiency may present identically.

It’s also involved in the production of the myelin sheath around the nerves, and the conduction of nerve impulses. Neural damage is due to methionine deficiency as B12 is required to convert homocysteine to methionine. Methionine is required for myelin synthesis and hence demyelination may ensue. Deficiency of vitamin B12 leads to storage of homocysteine.

Vitamin B12 and therefore increased homocysteine levels are associated with methylation issues, cardiovascular disease, dementia and mental health disorders.

The process of methylation is involved with activities such as, detoxification, repairing and building DNA and RNA, processing hormones,  building immune cells, producing energy, repairing cell membranes, turning the stress response on and off, supporting neurotransmitters – the brain’s communication chemicals and supporting fat metabolism.

Possible methylation issues could show high red cell folate, high homocysteine, high inflammatory markers, low Active B12 levels, low methylated folate (5MTHF) and high LDL.

Vitamin B12 deficiency presents with limb weakness, sore tongue and ascending paraesthesia (sensations of cold, numbness, tightness in the tips of toes and fingers and loss of pinprick and vibration). Less common findings include depression, memory loss, erectile dysfunction, incontinence, light-headedness and impaired taste and smell. Vague constitutional symptoms e.g. fatigue, malaise and GIT symptoms occur in about 50% of patients.

Vitamin B12 deficiency is common, so many patients are candidates for Vitamin B12 testing.

The following groups are at greatest risk for B12 deficiency:

– Vegetarians and vegans – studies show that up to 50% of long-term vegetarians and 80% of vegans are deficient in B12
– People aged 60 or over
– People who regularly use PPIs or acid suppressing drugs
– People on diabetes drugs like metformin
– People with Crohn’s disease, ulcerative colitis, coeliac or IBS
– Women with a history of infertility and miscarriage

Serum (Blood Draw)

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