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Vitamin B12

Age related illnesses, Vitamins | April 30, 2019 | Author: Naturopath

dementia, autoimmune

Vitamin B12

Are you a bit confused about vitamin B12? Do you need it? Tablets, sprays, injections – what are the differences? Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in the metabolism of every cell in the body. It is needed for the production of red blood cells and the functioning of the nervous system as well as the synthesis of DNA and the metabolism of fatty acid and amino acids. B12 is responsible for the protective sheath which surrounds the nerve fibres. Bone cell activity and metabolism are also dependants of B12. 

The absorption of B12 is complex.

From your diet, the food containing Vitamin B12 meets hydrochloric acid (HCl) (stomach acid) and the digestive enzyme, pepsin, which release vitamin B12 from the protein it is attached to. It then binds with an intrinsic factor made in the stomach. This complex then travels through the small intestine where the vitamin is gradually absorbed into the bloodstream. Transport through the blood then depends on specific binding proteins. B12 and folate both follow the enterohepatic circulation route (through the liver) where they are continuously secreted into bile, delivered into the intestine and reabsorbed. Because it is reabsorbed it is rare for healthy people to develop a deficiency even if the diet of B12 is low.

What could go wrong

The missing link

B12 missing from the diet – even though we recycle B12 we cannot make it ourselves so it must be obtained from our diet (or supplemented – discussed later).

B12 is available through animal-based foods – meat, fish, poultry, dairy, eggs; and nori seaweed.

Eliminating these foods from your diet might not reduce your B12 status immediately, in fact it may take years before the body has exhausted its supply, due to the continuous recycling process.

Low or no levels of Intrinsic factor. This can be a problem as we get older, or it could be from a rare autoimmune disorder or atrophic gastritis. This is called pernicious anaemia.

Low acid stomach. Some medications used for reflux which lower the acid in the stomach could prevent the breakdown of protein containing B12.

Most B12 deficiencies reflect inadequate absorption rather than dietary intake, with the main culprits being insufficient stomach acid or intrinsic factor. Remember - hydrochloric acid releases B12 from protein, and intrinsic factor binds B12 for absorption. 

Folate deficiency - activation depends on B12 (and vice versa) – B12 removes a methyl group from the folate enzyme to activate it and that methyl group then activates the B12 enzyme. The regeneration of methionine and DNA and RNA synthesis rely on both B12 and folate. Thus, if you are low in folate your B12 may not be working for you. You can also have lots of folate showing in your blood test, only without B12 it cannot be activated. This is called methylfolate. DNA synthesis will slow down and rapidly growing blood cells are affected. It is important to determine which element is deficient.
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Only B12 maintains and protects nerve fibres. A deficiency will cause progressive nerve damage.

Atrophic gastritis – A common condition for people generally over the age of 60 which damages the cells of the stomach. Causes could include iron deficiency or infection with helicobacter pylori – the bacteria implicated in the development of stomach ulcers.

Without healthy stomach cells, the production of intrinsic factor and hydrochloric acid is reduced.

Malabsorption - this may happen because of diseases involving the bowel or if part of the bowel has been removed. Crohns diseaseulcerative colitis and coeliac disease are examples. 

People most at risk of B12 deficiency

  • The elderly - aging digestive system, medications
  • Vegans - lack of B12 containing foods
  • Those who have had bowel removed or suffer bowel disease - malabsorption or deficiencies

 

Common signs and symptoms you may be B12 deficient

  • Pale or jaundice skin (from anaemia)
  • Weak and fatigued (lowered red blood cells to carry oxygen)
  • Swollen tongue (glossitis - due to anaemia)
  • Mood changes/depression
  • Neuropathy - pins and needles sensation (serious long-term deficiency)
  • Dementia, attention deficits, memory impairment – corrected with supplementation
  • Optic neuropathy characterised by progressive vision loss
  • Balance and movement – (long term deficiency)

What to do

People who choose not to eat Vitamin B12 rich foods and those with malabsorption disorders will need to supplement B12.

Food sources of Vitamin B12Increasing your B12 levels naturally involves eating foods containing this vitamin.

Food sources of Vitamin B12

  • Meat
  • Fish
  • Poultry
  • Eggs
  • Dairy
  • Fortified foods (foods where vitamin b12 is added in processing)
  • Nori

A survey of naturally occurring and high Vitamin B12-containing plant-derived food sources showed that nori, which is formed into a sheet and dried, is the most suitable Vitamin B12 source for vegetarians presently available.

Consumption of approximately 4 g of dried purple laver (Vitamin B12 content: 77.6 μg /100 g dry weight) supplies the RDA of 2.4 μg/day (1)

Can you test for B12 deficiency?

Diagnosing deficiencies of B12 can be hard as there is no single parameter which can be used – serum test may not tell the true story. Methylmalonic acid (MMA) and homocysteine (tHcy) are recognized indicators of vitamin B12 status as their measurement can indicate a sub-clinical deficiency. Medical history, age and diet can help determine a possible deficiency.

Correcting the deficiency

Vitamin B12 deficiency causes a wide range of haematological, gastrointestinal, psychiatric and neurological disorders. Prevention and replacement are the most important. Correcting the deficiency

The recommended daily intake for adults is 2.4m micrograms. 

Vitamin B12 parenteral through intramuscular injections to bypass malabsorption issues are the most common and most effective means of correcting a deficiency. The replacement regime will depend on deficiency and be determined by the physician.

B12 taken orally is poorly absorbed so amounts of 1000ug/day are suggested. These can be taken as sublingual tablets dissolved in the mouth or oral sprays. Sublingual enables B12 to bypass the digestive system. 

In summary

Vitamin B12 deficiency is common. You could be deficient in B12 if you are vegan, elderly, on long-term medication or have a digestive disorder.

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References

Whitney, Eleanor Noss; Cataldo, Corinne Balog; Rolfes, Sharon Rady; 2002, Understanding Normal and Clinical Nutrition 6th Edition, Wadsworth/Thompsons Learning, Australia

Cobalamin deficiency. https://www.ncbi.nlm.nih.gov/pubmed/22116706

[Clinical manifestations of the mouth revealing Vitamin B12 deficiency before the onset of anemia]. https://www.ncbi.nlm.nih.gov/pubmed/12671582

Vitamin B12 Deficiency and Depression in the Elderly: Review and Case Report https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781043/

Vitamin B12-Containing Plant Food Sources for Vegetarians https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4042564/

Cobalamin deficiency: clinical picture and radiological findings. https://www.ncbi.nlm.nih.gov/pubmed/24248213

Vitamin B12 in Health and Disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3257642/

https://www.healthed.com.au/clinical-articles/vitamin-b12-deficiency/

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