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Nutrient - Vitamin B12


By Cathy Robinson BSc DipNutMed

Vitamin B12 has many roles in the body. It is important for red blood cell formation, energy production, nerve function, cell division and detoxification, and is involved in the synthesis of DNA, the genetic blueprint of our body. In common with some other B vitamins, B12 also provides a chemical grouping called a methyl group, which plays a vital part in energy metabolism. 

A shortage of methyl-donating nutrients is connected with an elevated homocysteine level, which is thought to be an indicator for coronary heart disease.

With so many varied roles within the body, there is no doubting the importance of vitamin B12. Severe deficiency is characterised by symptoms such as tiredness and palpitations, shortness of breath, dizziness, chest pain and headache. Other signs of B12 deficiency include depression, memory loss, sleep disturbances and numbing, burning or tingling of the hands and feet. However, even mild deficiency can lead to symptoms like low energy, impaired nerve function and muscle weakness.

Vitamin B12 deficiency is very common in the elderly. Pernicious anaemia can develop in severe deficiency. It is estimated that around one in a thousand people over the age of 60 will develop pernicious anaemia, a serious condition that can be fatal if not identified but is treatable if caught early. Women are slightly more at risk than men and there are genetic factors involved.

Deficiency of B12 is an important factor in dementia. Nerve and brain function are affected critically in B12 deficiency and are the major precursor of depression and mental confusion in the elderly.

B12 is found mainly in natural foods of animal origin, so those who are vegetarian or vegan may be missing out. The vegetarian B12 found in tempeh and other fermented foods is not in a form we can use efficiently. The richest sources are liver and kidney, followed by eggs, fish, cheese and meat and Brewer’s yeast. B12 can be destroyed when foods are overcooked.

The process of vitamin B12 absorption begins in the stomach, where digestive enzymes, in the presence of enough stomach acid, separate the B12 from protein in food. B12 then binds with intrinsic factor, excreted by parietal cells in the stomach wall, before passing to the small intestine where it is absorbed. This process requires adequate levels of stomach acid and the effective production of the substance intrinsic factor.

The parietal cells can be damaged in those with inflammation of the stomach or gastritis, or even destroyed by the body’s own immune cells. This leads to impaired intrinsic factor production as well as decreased stomach acid, resulting in B12 deficiency, even if the sufferer is eating plenty of B12-rich foods, because they are unable to absorb it adequately. Because good levels of B12 are stored in the body, it can take a number of years to reach a state of B12 deficiency. Elderly people often have low stomach acid and low intrinsic factor, which leads to poor absorption of B12 and eventual deficiency.

To make things worse, an imbalance in the beneficial bacteria of the digestive system can separate vitamin B12 from the intrinsic factor, preventing it from being absorbed. Imbalances in bacterial flora are common in those with digestive complaints such as IBS and especially after antibiotic use. A supplement containing friendly bacteria can be useful in maintaining the correct balance of healthy bacteria.

One way to get around the potential problem with absorption is to take a form of B12 that is delivered straight into the bloodstream neatly bypassing any failings of the digestive system. Sublingual B12, taken under the tongue in a fruit-based powder form, is both pleasant and easy to take, and delivers B12 straight to the blood vessels there. Folic acid deficiency will often mask vitamin B12 deficiency in the elderly and it is important, therefore, to supplement with both vitamins. 

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