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Are We Obtaining Enough B12?


B12 is a member of the B vitamin family. As an essential nutrient it is involved in DNA formation, metabolic processes and within the nervous system. The NHS suggests that around 1 in 10 people will be vitamin B12 deficient due to low intakes or poor absorption..


B12 is synthesised by bacteria and therefore only present in animal foods such as: fish, poultry meat, organ meat and seafood, with smaller amounts in dairy and eggs. An at risk group therefore includes those following a vegan or vegetarian dietary approach. Whilst many vegan diets obtain at least some B12 by eating some fermented or bacterial based foods such as: fermented beans, algae such as spirulina or nori, barley grass, mushrooms, miso, yeast extracts and vegan spreads, it is unlikely to provide enough for their needs.


Those people who do not absorb enough B12 are an risk category, in poor absorption rates 80-100% can be excreted and obtaining around just 20% of the recommended daily allowance. A common cause of low absorption is reduced stomach acid as B12 is absorbed best in an acidic environment. Gastric acid production reduces with age and therefore impairs B12 absorption; this places those of 50 years and over in the high risk category.


The American RDA for B12 is 2.4 micrograms, Germany is set at 3micrograms and 1.5 micrograms per day is recommended for adults in the UK; yet average dietary intake is around 4-5mcg, so shouldn’t this be enough to meet our needs? Most health experts believe the European RDA is much too low due to the complex processes involved in the absorption of B12 given those with adequate gut health are estimated to absorb just 30-60% of that consumed.


Vitamin B12 is bound to the animal proteins we eat. Gastrin, produced in the stomach, releases B12 from the protein. Parietal cells found in the stomach lining next produce Intrinsic Factor (IF) which next binds to the B12 so it can pass undigested to the intestines. The alkaline environment of the intestine now dissolves the IF, freeing B12 so it can bind to another protein called transcobalamin II; transporting B12 to the bloodstream and liver where it is involved in a process called methylation. Low levels of gastric acid can therefore reduce absorption rates. Medications that reduce acidity, such as proton-pump inhibitors also may put us at risk as do statins, Metaformin and some forms of birth control pills.


Digestive conditions such as coeliac disease and ulcerative gastritis or a high alcohol consumption can damage the parietal cells. IF facilitates the absorption of B12 helping it to pass through the stomach undigested; damage to the parietal cells causes reduced IF production and subsequent absorption rates.


Why are low levels dangerous?

Methionine is required in the process of creating and replicating out DNA; if breaks or incorrect sequences are created due to a lack of B12 damage at the cellular level can occur. B12 is required to turn homocysteine into methionine; complicated names but are simply units made from the proteins we eat. Folate is B12’s pairing and it is common to increase folate without considering B12, potentially increasing problems by keeping folate in an unusable form. Without enough B12 levels of levels of homocysteine rise and the level of methionine produced will drop. High levels of homocysteine are a risk factor associated with stroke, heart disease and breaks in our immune cells, a risk factor in the development of cancer.


B12 is also a vital nutrient for correct nerve and brain function, therefore symptoms can often include: tingling, pins and needles in the hands and feet, numbness, reduced sensitivity to pain or pressure, abnormal balance, weak muscles, blurred vision, poor memory, confusion, hallucinations, migraines, cognitive decline and affective disorders, such as depression, anxiety and panic attacks due to interference of serotonin. B12 is also involved red blood cell synthesis; these cells carry oxygen so deficiencies are often accompanied by fatigue, weakness, shortness of breath, dizziness, palpitations and yellow skin (due to the breakdown of red blood cells). A swollen tongue, stomach inflammation and a low appetite and digestive disorders are also common signs too.

Deficiencies in children are commonly a loss of energy and appetite and a ‘failure to thrive’ and there are even links with autism and anxiety. Deficiencies can occur much faster in children compared than adults so it is vital if your child is following a vegan diet and showing symptoms it is important to see your doctor; low levels in pregnancy have been associated with preeclampsia, neural tube defects in babies and reduced brain development.

In older adults, B12 deficiencies may accelerate neurodegenerative diseases such as Alzheimer’s, dementia and cause brain shrinkage and degeneration of the spinal cord. One study found that those participants of 65 years and older with low levels of B12 scored lower in cognitive tests and showed signs of brain damage.

A common cited example is of a 62 year old man, who, over the course of two months developed numbness, pins and needles, reduced walking ability, joint pain and became yellow and short of breath. Symptoms can gradually appear over a few years before a true deficency as the liver has storage for around 2500 mcg; symptoms begin once reserves are depleted, occurring over a period of months often leads to an incorrect diagnosis.

Most supplements come in a standard dosage of 500micrograms. Cyanocobalamin is a common form of supplemental B12 but it is cheap to produce and an unnatural product containing cyanide. The form Methylcobalamin is considered the more effective form and from a natural source; a sublingual form, placed under the tongue and by-pass digestive tract, therefore increasing absorption.

Blood tests for B12 can be unreliable, especially those taking algae supplements as algae or folate supplementation which can produce a false reading. Detection of a B12 deficency is often a missed consideration in the diagnosis of affective disorders, such as dementia in the elderly. Testing for blood homocysteine can be more accurate and you can ask your doctor. If you are over 50 and been following a vegan diet for many years it would be prudent to ask a doctor to check your levels if displaying some symptoms listed. Always speak with a nutritional therapist if you are worried your diet Is not complete and lacking nutrients. Always speak to the doctor if you feel you have any of the signs mentioned and if you are wishing to consider supplementation.

Homocysteine in health and disease, ed. Ralph Carmel and Donald W. Jacobsen, Cambridge University Press, 2001, ISBN 0-521-65319




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