Metformin B12 malabsorbtion - It has been suggested that an increased intake of calcium reverses the vitamin b12 Malabsorption induced by metformin.

Serum vitamin B12 WITH neurological symptoms  

Serum vitamin B12 WITHOUT neurological symptoms 

Folate

• levels should always be checked in vitamin B12 deficient patients
• If low levels are found prescribe folic acid 5 mg tablets daily
• Usually, treatment will be required for 4 months, however, folic acid may need to be taken for longer (sometimes for life) if the underlying cause of deficiency is persistent

Neurological symptoms 

• Partial or complete paralysis
• Muscle weakness
• Unexplained pain
• Pins and needles (parathesia)
• Partial or complete loss of sensation
• damage to parts of the nervous system (peripheral neuropathy); particularly in the legs
• Seizures
• Vision problems
• Memory loss
• loss of physical co-ordination (ataxia), which can affect whole body and cause difficulty speaking or walking
• Difficulty reading and writing
• Poor cognitive abilities
• Decreased alertness

Dietary sources

Vitamin B12

• Eggs
• Foods which have been fortified with vitamin B12 (for example some soy products, and some breakfast cereals and breads) are good alternative sources to meat, eggs, and dairy products
• Meat
• Milk and other dairy products
• Salmon and cod

Folic acid  

• Asparagus
• Broccoli
• Brown rice
• Brussels sprouts
• Chickpeas
• Peas

Monitoring

• Perform a full blood count and reticulocyte count:
  • Within 7–10 days of starting treatment
    • A rise in the haemoglobin level and an increase in the reticulocyte count to above the normal range indicates that treatment is having a positive effect
    • If there is no improvement, check serum folate level (if this has not been done already)
  • After 8 weeks of treatment, and also measure iron and folate levels
    • The mean cell volume (MCV) should have normalised
  • On completion of folic acid treatment to confirm a response
• Measuring cobalamin levels is unhelpful as levels increase with treatment regardless of how effective it is, and retesting is not usually required
  • However, cobalamin can be measured 1–2 months after starting treatment if there is no response
• Neurological recovery may take some time — improvement begins within one week and complete resolution usually occurs between six weeks and three months
• Ongoing monitoring is unnecessary unless a lack of compliance with treatment is suspected, anaemia recurs, or neurological symptoms do not improve or progress