Vitamin B12 (Cobalamin)
Humans need 13 different vitamins to sustain life and health. If we do not take in enough of a particular vitamin our bodily supplies decrease and a deficiency ensues. Of the 13 vitamins our bodies need, one is B12. It is unique because it is the only vitamin that cannot be obtained from plants or sunlight (as plants don't need B12, so do not produce or store it), it is produced by bacteria in the gut of animals and absorbed in the small intestine. Therefore to obtain B12 from the diet you need to eat animal products- meat, fish or dairy products. However even a diet high in these foods may not supply enough B12. In fact it is remarkably easy to become deficient in B12 as many people can neither absorb nor use B12. Vegans and vegetarians are particularly prone to deficiency. The route that B12 takes from the mouth to the blood is complex and there can be problems at any point. The steps of the B12 pathway are:
- Food containing B12 is bound to animal proteins and needs to be freed. So when the food reaches the stomach it is split by an enzyme Pepsin (produced in the stomach only if sufficient amounts of Hydrochloric acid )
- The stomach also produces intrinsic factor (IF) , a protein that is needed later in the pathway.
- Other proteins known as R-Binders carry the B12 into the small intestine
- In the intestine, intrinsic factor (from the stomach ) attaches itself to the B12 and transports it to the last section of small intestine, the ileum. The cells lining the ileum contain receptors that grab onto the B12-Intrinsic factor complex and drag it into the blood stream
- In the bloodstream, another protein, transcobalamin2 carries the Vitamin B12 to all the cells in the body, transporting any extra to the liver for storage
Methylcobalamin is the most natural form of B12 and needs noconverting. It is already in its “ready to use” form. Methylcobalamin is the active coenzyme form necessary for any biological activity. It also is the least stable with the shortest shelf life, converting back to hydroxycobalamin if not stored correctly. Methylcobalamin is sometimes referred to as “active B12” as it is in a form ready to be used by the cells.
What does Vitamin B12 do?
- It contributes to the reduction of tiredness and fatigue
- It contributes to normal energy yielding metabolism
- It contributes to normal functioning of the nervous system
- It contributes to normal red blood cell formation
- It has a role in the process of cell division
- It contributes to normal homocysteine metabolism
- It contributes to normal psychological function
- It contributes to normal functioning of the immune system
Mental changes include irritability, apathy, sleepiness, paranoia, personality changes, depression, memory loss, dementia, hallucinations, violent behaviour and in children developmental delay and/or autistic behaviour.
Neurological signs and symptoms include pain, tingling or numbness, decreased sense of touch, pain or temperature, weakness, loss of awareness of body position, clumsiness, tremor, symptoms mimicking Parkinsons disease or multiple sclerosis, spastic muscles, incontinence, paralysis, visual changes and damage to the optic nerve
Vascular changes include, transient ischaemic attacks (TIAs or mini strokes), CVA or stroke, coronary artery disease, heart attack, congestive heart failure, palpitations, low blood pressure when standing causing fainting, deep vein thrombosis (blood clot in the arm or leg) and pulmonary embolism.
Other signs and symptoms may include shortness of breath, generalized weakness, chronic fatigue or tiredness, loss of appetite and weight loss, epigastric pain (poor digestion, full or bloated feeling after eating normal or small meals), diarrhoea or constipation, increased susceptibility to infection, poor wound healing, failure of new born to thrive, tinnitus, vitiligo (white patches of skin), or hyperpigmentation, premature grey hair and impotence. Anybody at any age can become deficient but people may be at an increased risk if they are:
- Vegans and vegetarians
- Over 60
- Have eating disorders such as anorexia or bulimia
- Take antacids or diabetes related drugs that may interfere with B12 absorption
- Have a history of alcoholism
- Have a family history of pernicious anaemia
- Are diagnosed with anaemia
- Have Crohns disease, irritable bowel or any disease causing malaborption of nutrients
- Have an autoimmune disease, type 1 diabetes, SLE, Addisons disease
- Women with a history of infertility or multiple miscarriages
- Infants born to women or breast fed by women who are already deficient or at risk of B12 deficiency