Home › Vitamins Vitamin B12 (Cobalamin) What is Vitamin B12 (cobalamin) Health Benefits of Vitamin B12 Agonist / Synergist Antagonist Food Sources of Vitamin B12 Recommended Dietary Allowance Vitamin B12 Supplementation Deficiency Symptoms of Vitamin B12 Toxicity Symptoms of Vitamin B12 Precautions and Warnings What is Vitamin B12? Vitamin B-12 is also known as cobalamin and is the cobalt-containing vitamin. One of the main functions of all the B vitamins is converting carbohydrates into glucose which helps the body produce energy. B-complex vitamins are needed for healthy skin, hair, eyes, and liver. Many of the B-complex vitamins also play an important role in keeping the nervous system healthy and the brain functioning properly. Vitamin B12 is essential in the body and is required for many functions which includes the nervous system, formation of red blood cells, DNA synthesis and the metabolism of fatty acids and amino acids. The name cobalamin is a combination of the words ‘cobalt’ and ‘vitamin’. Health benefits of Vitamin B12 Improves homocysteine levels High homocysteine levels damage blood vessels and have been linked to cardiovascular disease, thrombin generation and neurodegeneration. Studies are showing vitamin B12 in addition to vitamin B6 and B9 can help lower homocysteine levels which helps to protect blood vessels and reduce the risk of cardiovascular disease and other health conditions linked to high homocysteine levels such as Alzheimer’s disease. [1] [2] [3] A deficiency of B12 can increase homocysteine levels which have been linked to the risk of neurological disorders Alzheimer’s disease and dementia. [4] Supports brain health and neurological functions Some studies have found a link between B12 deficiency and neurological conditions such as epilepsy, cognitive decline, Parkinson’s, Alzheimer’s and dementia. Some parts of the brain needed for cognitive functions such as memory and learning are affected by folate deficiency. Additionally high homocysteine levels have been associated with neurological disorders which can also be an indicator for low levels of B12 and other deficiencies such as B6 and B9. Deficiency of B12 can cause oxidative damage to brain cells leading to cognitive decline. In addition to B12 vitamin B9 is also needed to help the nerves function properly. [5] [6] Prevents stroke High levels of homocysteine can also lead to strokes and keeping homocysteine levels normal can prevent the condition. Some studies have shown that vitamin B12 supplementation in addition to other B vitamins can be effective in lowering homocysteine levels which are found to be high in those at risk of having a stroke. [7] [8] [9] [10] Prevents anemia In addition to B9 (folate), vitamin B12 is required for the formation of red blood cells (oxygen-carries) which when deficient can lead to megaloblastic anemia. In cases of anemia caused by a B12 deficiency supplementation can usually reduce feelings of tiredness and fatigue and other deficiency symptoms of B12. However it is also important to check for other deficiencies such as vitamin B9, iron, and copper which are all associated with anemia when levels are low. Prevents age-related macular degeneration Various factors influence the risk of developing age-related macular degeneration and includes a deficiency of folate. One study has shown that a deficiency of B12 and B9 increases risk of age-related macular degeneration with a number of participants supplementing with in these vitamins showing a reduced risk. [11] Supports thyroid health There are many studies suggesting a probable link between B12 deficiency and thyroid health, however more research and studies need to be carried out to determine its role for thyroid health. Vitamin B12 deficiency has been linked to hypothyroidism a condition where the thyroid gland does not produce sufficient amounts of hormones. Vitamin B12 is needed for iron metabolism with a deficiency causing anemia. Some people who have underactive thyroid glands have also shown to have low levels of B12. Copper deficiency is also associate with hypothyroidism and is required in the body for thyroid function and works synergistically with B12. [12] [13] Agonist / Synergist Vitamins: B1, B3, B5, B6, B9, B10, C, D, E Minerals: Ca, Co, Cu, Fe, Na, Se Other: Pepsin Vitamin B12 works synergistically with many of the B vitamins and is needed for their metabolism and utilization. However supplementing high amounts of other B vitamins without having an adequate supply of B12 can potentially reduce B12 levels as these vitamins may utilize vitamin B12 stores. This can lead to vitamin B12 deficiency and may be noticed through negative reactions from copper, iron, manganese or B vitamin intake. Vitamin B12 is required for folate metabolism. Vitamin B12 increases needs for B9 (Folate) for the methylation cycle. [14] Vitamin B12 works synergistically with vitamin B9 (Folate) and vitamin C to help the body synthesise and process protein. Vitamin B1 (thiamine) metabolism is required by adequate intake of B6 and B12 and deficiency of these two vitamins have shown to reduce thiamine. [15] Calcium is needed for Vitamin B12 absorption. [16] Calcium intake reverses vitamin B12 malabsorption in those taking metformin. [17] Vitamin B12 helps with iron absorption. Vitamin E can help protect against reduced coenzyme form of Vitamin B12. [18] High supplemental intake of other vitamins and minerals may deplete B12 levels such as iron and many of the other B vitamins as they help use up the vitamin which is needed to work synergistically. Antagonists Vitamins: B1, C Minerals: K, Mg, Zn Other: Pectin, Nitrous oxide, Alcohol, Colchicine, Proton Pump Inhibitors (PPI), Metformin, Chloramphenicol, Histamine 2 Receptor Antagonists (H2RA), Omeprazole, Nicotine, Aspirin, Antibiotics Nitrous oxide is found in laughing gas which can also be used in dentistry, nitrous oxide anesthesia and also found nitrous oxide emissions from catalytic converters in automobiles. [19] [20] Pectin may reduce B12 levels. [21] Histamine 2 Receptor Antagonists (H2RA) High gastric pH (alkaline) can impair pepsin from activating which is needed for the absorption of protein bound vitamin B12 which is then needed to bind to an R-binder. Pepsin is needed for this absorption, however high pH impairs pepsinogen conversion to pepsin ineffective. [22] [23] Vitamin C has an indirect antagonistic effect on B12 by increasing absorption of iron. Iron has antagonistic effect on cobalt, an essential part of vitamin B12 which may be rare and likely in people who have iron overload disorders according to research by Hoffer, Pauling and others. Long term metformin intake can increase B12 deficiency. [24] Food sources of Vitamin B12 Vitamin B12 can be found mostly in animal foods which includes meat, poultry, liver, fish, eggs and dairy. B12 can be found in high amounts in lamb liver, beef liver, clams, oysters, wild salmon, herrings, trout and canned sardines. There are no B12 in nuts, seeds and fruits. Vegetables are also a poor source of B12 which a very minimal amount contained in mushrooms. Some foods such as cereals may be fortified with vitamin B12, however this may be an inactive form which some people may be unable to utilize. Recommended Dietary Allowance The amounts recommended for vitamins and minerals are different for each country which can be found on the government website of host country. The nutritional data for each country are based on scientific research which are presented by the scientific academies in each country to help advise governmental departments for food and human nutrition. Below is a list of some of the countries and the EU for which nutritional guidelines are available found on corresponding official government website (including the national academy of science website for the USA). USA The 2015–2020 Dietary Guidelines for Americans - Dietary Reference Intakes Recommended Dietary Allowances and Adequate Intakes from Food and Nutrition Board, Institute of Medicine, National Academies Dietary Reference Intakes (DRIs) Food and Nutrition Board, Institute of Medicine, National Academies Dietary Reference Intakes (DRIs): Tolerable Upper Intake Levels (UL) Canada Dietary Reference Intakes includes Tolerable Upper Intake Levels UK Nutrition Requirements Safe Upper Levels (SULs) for Vitamins and Minerals Australia and New Zealand Nutrient Reference Values (NRVs) and Upper Level Intake EU Dietary Reference Values for nutrients Tolerable Upper Intake Levels For Vitamins and Minerals It is advisable for those older than 50 years to meet their RDA of vitamin B12 by consuming food fortified with vitamin B12 or a vitamin B12 supplement since people above this age are likely to have malabsorption of food bound B12. No Tolerable Upper Intake Level (UL) has been set for B12 and insufficient evidence to suggest toxicity from excess B12 intake. [25] Vitamin B12 Supplementation Vitamin B12 are available in a variety of forms including tablets, sublingual tablets, sprays, capsules, liquids, powders, patches and injections. B12 is sometimes diluted in DMSO to increase uptake, caution is advised when using DMSO as it is highly potent and may have associated risks when using this method however anecdotal reports have shown positive results when the two are combined. DMSO and vitamin B12 solution is generally used for transdermal delivery and may be useful for those who have impaired digestion or absorption issues. Oral supplements taken internally include enteric coated vitamin tablets or capsules. Enteric coating acts as a preservative to avoid destroying the tablet or capsule so that it can be appropriately absorbed in the intestines. There are two forms of vitamin B12 and are either active or inactive. The active form includes methylcobalamin and adenosylcobalamin and found in humans. Methylcobalamin is needed to convert homocysteine into methionine. Adenosylcobalamin has an important role in producing energy from fats and proteins. Animal food sources of vitamin B12 which include eggs, milk, meat and fish is easily converted into these active forms. The inactive form of vitamin B12 inlcudes cyanocobalamin, which is the synthetic form and converts into the active forms of B12. This is the common form in supplements as it is inexpensive and easy to produce. A very small amount of cynaocobalamin is converted into the active forms. Hydroxocobalamin is another inactive form of vitamin B12 and is easily converted to the active forms of vitamin B12. Hydroxocobalamin is a food source vitamin B12 found in animal sources and also dietary supplements. It has a long shelf life and has also been used as an antidote for cynade poisoning. Hydroxocobalamin is also the form found in vitamin B12 injections. Anecdotal reports of DMSO in combination with vitamin B12 suggest a positive transdermal absorption of vitamin B12 with some individuals suggesting immediate relief of a vitamin B12 deficiency and a boost of energy although this is only recommended after discussing with your doctor or health care specialist. Deficiency symptoms of Vitamin B12 Weakness, tiredness (Fatigue) Lightheadedness Heart palpitations Shortness of breath Pale skin Burning sensation in the mouth Smooth or sore tongue (glossitis) Mouth Ulcers Constipation Diarrhea Gas Nausea, vomiting Loss of appetite Weight loss Numbness Pins and needles Muscle weakness Muscle Ache Problems walking Vision loss Psychiatric symptoms Anxiety Paranoia [26] Hallucinations Behavioral changes Depression Memory loss Headache Irritability Difficulty thinking Anemia (megaloblastic) Feeling faint Pale skin Yellow tinge to skin Having vitamin B9 and B12 deficiency means the body is unable to produce adequate amounts of red blood cells which can lead to anemia. This can also cause blood pressure to drop leading to symptoms of low blood pressure (hypotension). Causes of vitamin B12 deficiency includes: Malabsorption Gastrointestinal conditions (Crohn's disease, celiac disease, bacterial overgrowth, parasite infection) Older people (difficult absorbing through diet in people of 50+ years) Weight loss surgery or other operation of the stomach (Gastric Bypass) Thinned stomach lining (Atrophic gastritis) Pernicious anaemia Hereditary conditions Immune system disorders (Graves' disease or lupus) Insufficient nutritional vitamin b12 intake Vegan or strict vegetarian diets Low protein diets Excessive consumption of alcohol Prolonged use of antacid medications Pernicious anemia Some medications Nitrous oxide (through inhalation) Excess intake of antagonistic nutrients which reduces B12 [27] [28] [29] [30] [31] [32] Deficiency of B12 is defined by a level below 200 ng/mL in blood serum. The standard blood testing determines total amount of cobalamin of both active and inactive forms of the vitamin. This means a significant amount of cobalamin in the blood can be the inactive form suggesting levels are normal, however this can still cause symptoms of deficiency but not be detected properly in a blood test and unable to reveal a true deficiency. Some tests can check for levels of only the active form which will be able to detect if amounts are adequate or deficient and are available in some health centres or online testing. [33] [34] [35] Toxicity symptoms of Vitamin B12 Vitamin B12 toxicity is rare as it is a water soluble vitamin which is excreted through urine. Taking extremely high doses have been found to cause the following side effects: Restenosis after stent placement (recurrence of abnormal narrowing of an artery or valve) High blood pressure (after injecting vitamin B-12) Dizziness Headache Cold symptoms, coughing, runny nose (nasopharyngitis) Anxiety Nausea Vomiting Diarrhea Rash Itchy or burning skin Pink or red skin discoloration Joint and muscle pain Swelling of limbs or whole body (edema) Facial flushing Urine discoloration Numbness Increase in blood volume and red blood cells Decreased potassium levels Gout flare-up Precautions and warnings When taking any medications it is important to discuss with your doctor or other health professional before supplementing with any form of vitamin B12 as it may interact or inhibit the effects of various drugs. Some medications may also lower vitamin B12 levels. Vitamin B12 can also cause a flare up of gout.
