95-450: Vitamin B 12 is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. B12 or B-12 may also refer to: Vitamin B12 Vitamin B 12 , also known as cobalamin , is a water-soluble vitamin involved in metabolism . It is one of eight B vitamins . It is required by animals, which use it as
190-454: A cofactor in DNA synthesis , and in both fatty acid and amino acid metabolism . It is important in the normal functioning of the nervous system via its role in the synthesis of myelin , and in the circulatory system in the maturation of red blood cells in the bone marrow . Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it. Vitamin B 12
285-484: A dietary supplement or fortified foods for B 12 intake, or risk serious health consequences. Children in some regions of developing countries are at particular risk due to increased requirements during growth coupled with diets low in animal-sourced foods. The US National Academy of Medicine updated estimated average requirements (EARs) and recommended dietary allowances (RDAs) for vitamin B 12 in 1998. The EAR for vitamin B 12 for women and men ages 14 and up
380-676: A genetic predisposition , other cases have been associated with infectious triggers or exposure to environmental factors, implying a complex interplay between genes and environment in their etiology. Some of the most common diseases that are generally categorized as autoimmune include coeliac disease , type 1 diabetes , Graves' disease , inflammatory bowel diseases (such as Crohn's disease and ulcerative colitis ), multiple sclerosis , alopecia areata , Addison's disease , pernicious anemia , psoriasis , rheumatoid arthritis , and systemic lupus erythematosus . Diagnosing autoimmune diseases can be challenging due to their diverse presentations and
475-457: A crucial step in triggering autoimmune diseases. The exact mechanisms by which they contribute to disease onset remain to be fully understood. For instance, certain autoimmune conditions like Guillain-Barre syndrome and rheumatic fever are thought to be triggered by infections. Furthermore, analysis of large-scale data has revealed a significant link between SARS-CoV-2 infection (the causative agent of COVID-19 ) and an increased risk of developing
570-600: A dietary supplement is taken. A deficiency may be characterized by limb neuropathy or a blood disorder called pernicious anemia , a type of anemia in which red blood cells become abnormally large. This can result in fatigue , decreased ability to think, lightheadedness, shortness of breath, frequent infections , poor appetite , numbness in the hands and feet, depression, memory loss, confusion, difficulty walking , blurred vision , irreversible nerve damage, and many others. If left untreated in infants, deficiency may lead to neurological damage and anemia. Folate levels in
665-545: A few countries, primarily in Africa, have mandatory food fortification programs for either wheat flour or maize flour; India has a voluntary fortification program. What the nursing mother consumes is more important than her liver tissue content, as it is recently absorbed vitamin that more effectively reaches breast milk. Breast milk B 12 decreases over months of nursing in both well-nourished and vitamin-deficient mothers. Exclusive or near-exclusive breastfeeding beyond six months
760-403: A function that is compromised in autoimmune diseases. In healthy individuals, immune tolerance prevents the immune system from attacking the body's own cells. When this process fails, the immune system may produce antibodies against its own tissues, leading to an autoimmune response. The elimination of self-reactive T cells occurs primarily through a mechanism known as "negative selection" within
855-473: A genetic component. Some conditions, like lupus and multiple sclerosis, often occur in several members of the same family, indicating a potential hereditary link. Additionally, certain genes have been identified that increase the risk of developing specific autoimmune diseases. Evidence suggests a strong genetic component in the development of autoimmune diseases. For instance, conditions such as lupus and multiple sclerosis frequently appear in multiple members of
950-515: A higher concordance rate among identical twins compared with fraternal twins. For instance, the rate in multiple sclerosis is 35% in identical twins compared to 6% in fraternal twins. There is increasing evidence that certain genes selected during evolution offer a balance between susceptibility to infection and the capacity to avoid autoimmune diseases. For example, variants in the ERAP2 gene provide some resistance to infection even though they increase
1045-584: A large amount of hydroxocobalamin may be given intravenously and sometimes in combination with sodium thiosulfate . The mechanism of action is straightforward: the hydroxycobalamin hydroxide ligand is displaced by the toxic cyanide ion, and the resulting non-toxic cyanocobalamin is excreted in urine . Some research shows that most people in the United States and the United Kingdom consume sufficient vitamin B 12 . However, other research suggests that
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#17328513093691140-537: A microbiological assay with Lactobacillus delbrueckii subsp. lactis is used, as the bacteria can utilize the pseudovitamin despite it being unavailable to humans. To get a reliable reading of B 12 content, more advanced techniques are available. One such technique involves pre-separation by silica gel and then assessment with B 12 -dependent E. coli bacteria. A related concept is antivitamin B 12 , compounds (often synthetic B 12 analogues) that not only have no vitamin action, but also actively interfere with
1235-534: A necessary amount. A person with cobalamin C disease (which results in combined methylmalonic aciduria and homocystinuria ) may require treatment with intravenous or intramuscular hydroxocobalamin or transdermal B 12 , because oral cyanocobalamin is inadequate in the treatment of cobalamin C disease . Conventional administration does not ensure specific distribution and controlled release of vitamin B 12 . Moreover, therapeutic protocols involving injection require health care people and commuting of patients to
1330-484: A pivotal role in the diagnosis of autoimmune diseases. These tests can identify the presence of certain autoantibodies or other immune markers that indicate a self-directed immune response. In some cases, imaging studies may be used to assess the extent of organ involvement and damage. For example, chest x-rays or CT scans can identify lung involvement in diseases like rheumatoid arthritis or systemic lupus erythematosus, while an MRI can reveal inflammation or damage in
1425-442: A potential causative factor in the development of autoimmune diseases, such as dermatomyositis. Furthermore, exposure to pesticides has been linked with an increased risk of developing rheumatoid arthritis. Vitamin D, on the other hand, appears to play a protective role, particularly in older populations, by preventing immune dysfunctions. Infectious agents are also being increasingly recognized for their role as T cell activators —
1520-480: A regular part of their diet. The elderly are at increased risk because they tend to produce less stomach acid as they age, a condition known as achlorhydria , thereby increasing their probability of B 12 deficiency due to reduced absorption. Nitrous oxide overdose or overuse converts the active monovalent form of vitamin B12 to the inactive bivalent form. The U.S. Recommended Dietary Allowance (RDA) for pregnancy
1615-440: A thorough evaluation of the patient's medical history and a comprehensive physical examination. Clinicians often pay close attention to the patient's symptoms, family history of autoimmune diseases, and any exposure to environmental factors that might trigger an autoimmune response. The physical examination can reveal signs of inflammation or organ damage, which are common features of autoimmune disorders. Laboratory testing plays
1710-427: A wide range of new-onset autoimmune diseases. Women typically make up some 80% of autoimmune disease patients. Whilst many proposals have been made for the cause of this high weighting, no clear explanation is available. A possible role for hormonal factors has been suggested. For example, some autoimmune diseases tend to flare during pregnancy (possibly as an evolutionary mechanism to increase health protection for
1805-626: Is 2.6 micrograms per day (μg/d) , for lactation 2.8 μg/d . Determination of these values was based on an RDA of 2.4 μg/d for non-pregnant women, plus what will be transferred to the fetus during pregnancy and what will be delivered in breast milk. However, looking at the same scientific evidence, the European Food Safety Authority (EFSA) sets adequate intake (AI) at 4.5 μg/d for pregnancy and 5.0 μg/d for lactation. Low maternal vitamin B 12 , defined as serum concentration less than 148 pmol/L, increases
1900-533: Is impaired absorption due to a loss of gastric intrinsic factor (IF) which must be bound to a food-source of B 12 in order for absorption to occur. A second major cause is an age-related decline in stomach acid production ( achlorhydria ), because acid exposure frees protein-bound vitamin. For the same reason, people on long-term antacid therapy, using proton-pump inhibitors , H 2 blockers or other antacids are at increased risk. The diets of vegetarians and vegans may not provide sufficient B 12 unless
1995-537: Is pernicious anemia , characterized by a triad of symptoms : Vitamin B 12 deficiency is most commonly caused by malabsorption, but can also result from low intake, immune gastritis, low presence of binding proteins, or use of certain medications. Vegans —people who choose to not consume any animal-sourced foods—are at risk because plant-sourced foods do not contain the vitamin in sufficient amounts to prevent vitamin deficiency. Vegetarians —people who consume animal byproducts such as dairy products and eggs, but not
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#17328513093692090-489: Is 2.0 μg/day; the RDA is 2.4 μg/d . RDA is higher than EAR so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy equals 2.6 μg/day. RDA for lactation equals 2.8 μg/d . For infants up to 12 months the adequate intake (AI) is 0.4–0.5 μg/day. (AIs are established when there is insufficient information to determine EARs and RDAs.) For children ages 1–13 years
2185-796: Is a strong indicator of low serum vitamin status in nursing infants. This is especially true when the vitamin status was poor during the pregnancy and if the early-introduced foods fed to the still breastfeeding infant are vegan. Risk of deficiency persists if the post-weaning diet is low in animal products. Signs of low vitamin levels in infants and young children can include anemia, poor physical growth and neurodevelopmental delays. Children diagnosed with low serum B 12 can be treated with intramuscular injections, then transitioned to an oral dietary supplement. Various methods of gastric bypass or gastric restriction surgery are used to treat morbid obesity. Roux-en-Y gastric bypass surgery (RYGB) but not sleeve gastric bypass surgery or gastric banding, increases
2280-421: Is a systemic autoimmune disease that affects multiple organs, including the skin, joints, kidneys, and the nervous system. It is characterized by a widespread loss of immune tolerance. The disease is characterized by periods of flares and remissions, and symptoms range from mild to severe. Women, especially those of childbearing age, are disproportionately affected. Type 1 diabetes is a condition resulting from
2375-443: Is adequate or prophylactic B 12 supplementation is given. If the deficiency is detected, metformin can be continued while the deficiency is corrected with B 12 supplements. Autoimmune disorder An autoimmune disease is a condition that results from an anomalous response of the adaptive immune system , wherein it mistakenly targets and attacks healthy, functioning parts of the body as if they were foreign organisms. It
2470-427: Is associated with an increased risk of central nervous system cancer, primarily in the brain. Rheumatoid arthritis (RA) primarily targets the joints, causing persistent inflammation that results in joint damage and pain. It is often symmetrical, meaning that if one hand or knee has it, the other one does too. RA can also affect the heart, lungs, and eyes. Additionally, the chronic inflammation and over-activation of
2565-467: Is available in 5 mg tablets. The metabolic fate and biological distribution of methylcobalamin are expected to be similar to that of other sources of vitamin B 12 in the diet. The amount of cyanide in cyanocobalamin is generally not a concern, even in the 1,000 μg dose, since the amount of cyanide there (20 μg in a 1,000 μg cyanocobalamin tablet) is less than the daily consumption of cyanide from food, and therefore cyanocobalamin
2660-448: Is conjectured to be a circulating storage function. Several serious, even life-threatening diseases cause elevated serum haptocorrin, measured as abnormally high serum vitamin B 12 , while at the same time potentially manifesting as a symptomatic vitamin deficiency because of insufficient vitamin bound to transcobalamin II which transfers the vitamin to cells. Severe vitamin B 12 deficiency
2755-492: Is correlated with lymphoproliferative disorders . Graves' disease is a condition characterized by development of autoantibodies to thyroid-stimulating hormone receptors. The binding of the autoantibodies to the receptors results in unregulated production and release of thyroid hormone , which can lead to stimulatory effects such as rapid heart rate, weight loss, nervousness, and irritability. Other symptoms more specific to Graves' disease include bulging eyes and swelling of
2850-533: Is cyanocobalamin. Microbial fermentation yields adenosylcobalamin, which is then converted to cyanocobalamin by addition of potassium cyanide or thiocyanate in the presence of sodium nitrite and heat. As of 2019, nineteen countries require food fortification of wheat flour, maize flour or rice with vitamin B 12 . Most of these are in southeast Africa or Central America. Vegan advocacy organizations, among others, recommend that every vegan consume B 12 from either fortified foods or supplements. Vitamin B 12
2945-529: Is equipped with several mechanisms to maintain a delicate balance between defending against foreign invaders and protecting its own cells. To achieve this, it generates both T cells and B cells , which are capable of reacting with self-proteins. However, in a healthy immune response, self-reactive cells are generally either eliminated before they become active, rendered inert via a process called anergy, or their activities are suppressed by regulatory cells. A familial tendency to develop autoimmune diseases suggests
B12 (disambiguation) - Misplaced Pages Continue
3040-442: Is estimated that over 80 recognized types of autoimmune diseases exist, this section provides an overview of some of the most common and well-studied forms. Coeliac disease is an immune reaction to eating gluten , a protein found in wheat , barley , and rye . For those with the disease, eating gluten triggers an immune response in the small intestine , leading to damage on the villi , small fingerlike projections that line
3135-429: Is estimated that there are more than 80 recognized autoimmune diseases, with recent scientific evidence suggesting the existence of potentially more than 100 distinct conditions. Nearly any body part can be involved. Autoimmune diseases are a separate class from autoinflammatory diseases . Both are characterized by an immune system malfunction which may cause similar symptoms, such as rash, swelling, or fatigue, but
3230-553: Is included in multivitamin pills; in some countries grain-based foods such as bread and pasta are fortified with B 12 . In the US, non-prescription products can be purchased providing up to 5,000 μg each, and it is a common ingredient in energy drinks and energy shots , usually at many times the recommended dietary allowance of B 12 . The vitamin can also be supplied on prescription and delivered via injection or other means. Sublingual methylcobalamin , which contains no cyanide ,
3325-617: Is initially corrected with daily intramuscular injections of 1000 μg of the vitamin, followed by maintenance via monthly injections of the same amount or daily oral dosing of 1000 μg . The oral daily dose is far in excess of the vitamin requirement because the normal transporter protein mediated absorption is absent, leaving only very inefficient intestinal passive absorption. Injection side effects include skin rash, itching, chills, fever, hot flushes, nausea and dizziness. Oral maintenance treatment avoids this problem and significantly reduces cost of treatment. For cyanide poisoning,
3420-493: Is not conclusive, as it is also seen in people with folate deficiency. In addition, elevated methylmalonic acid levels may also be related to metabolic disorders such as methylmalonic acidemia . If nervous system damage is present and blood testing is inconclusive, a lumbar puncture may be carried out to measure cerebrospinal fluid B 12 levels. Serum haptocorrin binds 80-90% of circulating B 12 , rendering it unavailable for cellular delivery by transcobalamin II . This
3515-436: Is not considered a health risk. Injection of hydroxycobalamin is often used if digestive absorption is impaired, but this course of action may not be necessary with high-dose oral supplements (such as 0.5–1.0 mg or more), because with large quantities of the vitamin taken orally, even the 1% to 5% of free crystalline B 12 that is absorbed along the entire intestine by passive diffusion may be sufficient to provide
3610-490: Is not one of the supplements recommended by the World Health Organization for healthy women who are pregnant, however vitamin B 12 is often suggested during pregnancy in a multivitamin along with folic acid especially for pregnant mothers who follow a vegetarian or vegan diet. Low vitamin concentrations in human milk occur in families with low socioeconomic status or low consumption of animal products. Only
3705-448: Is produced in nature by certain bacteria , and archaea . It is synthesized by some bacteria in the gut microbiota in humans and other animals, but it has long been thought that humans cannot absorb this as it is made in the colon , downstream from the small intestine , where the absorption of most nutrients occurs. Ruminants , such as cows and sheep, are foregut fermenters, meaning that plant food undergoes microbial fermentation in
3800-485: Is sometimes referred to as "cobalamins". These chemical compounds have a similar molecular structure, each of which shows vitamin activity in a vitamin-deficient biological system, they are referred to as vitamers . The vitamin activity is as a coenzyme , meaning that its presence is required for some enzyme-catalyzed reactions. Cyanocobalamin is a manufactured form of B 12 . Bacterial fermentation creates AdoB 12 and MeB 12 , which are converted to cyanocobalamin by
3895-514: Is sufficient. In the case of vitamin B 12 there is no UL, as there is no human data for adverse effects from high doses. Collectively the EARs, RDAs, AIs and ULs are referred to as dietary reference intakes (DRIs). The European Food Safety Authority (EFSA) refers to the collective set of information as "dietary reference values", with population reference intake (PRI) instead of RDA, and average requirement instead of EAR. AI and UL are defined by EFSA
B12 (disambiguation) - Misplaced Pages Continue
3990-664: Is the most chemically complex of all vitamins, and for humans the only vitamin that must be sourced from animal-derived foods or supplements. Only some archaea and bacteria can synthesize vitamin B 12 . Vitamin B 12 deficiency is a widespread condition that is particularly prevalent in populations with low consumption of animal foods. Such diets can be due to a variety of reasons, such as low socioeconomic status, ethical considerations, or lifestyle choices such as veganism . Foods containing vitamin B 12 include meat, shellfish , liver , fish, poultry , eggs , and dairy products . Many breakfast cereals are fortified with
4085-542: The Academy of Nutrition and Dietetics considers plant and algae sources "unreliable", stating that vegans should turn to fortified foods and supplements instead. Natural plant and algae sources of vitamin B 12 include fermented plant foods such as tempeh and seaweed-derived foods such as nori and laverbread . Methylcobalamin has been identified in Chlorella vulgaris . Since only bacteria and some archea possess
4180-536: The bioavailability from eggs is less than 9%, compared to 40% to 60% from fish, fowl and meat. Insects are a source of B 12 for animals (including other insects and humans). Animal-derived food sources with a high concentration of vitamin B 12 include liver and other organ meats from lamb , veal , beef , and turkey ; also shellfish and crab meat . There is some evidence that bacterial fermentation of plant foods and symbiotic relationships between algae and bacteria can provide vitamin B 12 . However,
4275-403: The rumen before entering the true stomach ( abomasum ), and thus they are absorbing vitamin B 12 produced by bacteria. Other mammalian species (examples: rabbits , pikas , beaver , guinea pigs ) consume high-fibre plants which pass through the gastrointestinal tract and undergo bacterial fermentation in the cecum and large intestine . In this hindgut fermentation , the material from
4370-455: The RDA increases with age from 0.9 to 1.8 μg/day. Because 10 to 30 percent of older people may be unable to effectively absorb vitamin B 12 naturally occurring in foods, it is advisable for those older than 50 years to meet their RDA mainly by consuming foods fortified with vitamin B 12 or a supplement containing vitamin B 12 . As for safety, tolerable upper intake levels (known as ULs) are set for vitamins and minerals when evidence
4465-484: The activity of true vitamin B 12 . The design of these compounds mainly involve replacement of the metal ion with rhodium , nickel , or zinc ; or the attachment of an inactive ligand such as 4-ethylphenyl. These compounds have the potential to be used for analyzing B 12 utilization pathways or even attacking B 12 -dependent pathogens. Gastric acid is needed to release vitamin B 12 from protein for absorption. Reduced secretion of gastric acid and pepsin , from
4560-423: The addition of potassium cyanide in the presence of sodium nitrite and heat. Once consumed, cyanocobalamin is converted to the biologically active AdoB 12 and MeB 12 . The two bioactive forms of vitamin B 12 are methylcobalamin in cytosol and adenosylcobalamin in mitochondria . Cyanocobalamin is the most common form used in dietary supplements and food fortification because cyanide stabilizes
4655-457: The animal must consume sufficient amounts of cobalt . Soil that is deficient in cobalt may result in B 12 deficiency, and B 12 injections or cobalt supplementation may be required for livestock. Animals store vitamin B 12 from their diets in their livers and muscles and some pass the vitamin into their eggs and milk . Meat, liver, eggs and milk are therefore sources of the vitamin for other animals, including humans. For humans,
4750-470: The bacterium that causes strep throat , Streptococcus pyogenes , might trigger rheumatic fever , an autoimmune response affecting the heart. Similarly, some studies propose a link between the Epstein–Barr virus , responsible for mononucleosis, and the subsequent development of multiple sclerosis or lupus. Another area of interest is the immune system's ability to distinguish between self and non-self,
4845-497: The blood has a lower than normal number of red blood cells, due to a deficiency of vitamin B 12 . The ability to absorb the vitamin declines with age, especially in people over 60. Vitamin B 12 is a coordination complex of cobalt , which occupies the center of a corrin ligand and is further bound to a benzimidazole ligand and adenosyl group. A number of related species are known and these behave similarly, in particular all function as vitamins. This collection of compounds
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#17328513093694940-492: The body's immune system mistakenly attacking its own cells and tissues, causing inflammation and damage. However, due to the broad range of autoimmune diseases, the specific presentation of symptoms can significantly vary based on the type of disease, the organ systems affected, and individual factors such as age, sex, hormonal status, and environmental influences. An individual may simultaneously have more than one autoimmune disease (known as polyautoimmunity), further complicating
5035-497: The body's self-molecules. This phenomenon, known as molecular mimicry , can lead to cross-reactivity, where the immune response to such infections inadvertently results in the production of antibodies that also react with self-antigens. An example of this is Guillain–Barré syndrome , in which antibodies generated in response to a C. jejuni infection also react with the gangliosides in the myelin sheath of peripheral nerve axons. Diagnosing autoimmune disorders can be complex due to
5130-728: The brain and nervous system. Deficiency at levels only slightly lower than normal can cause a range of symptoms such as fatigue , feeling weak, lightheadedness , dizziness , breathlessness, headaches, mouth ulcers , upset stomach, decreased appetite, difficulty walking (staggering balance problems), muscle weakness, depression , poor memory , poor reflexes, confusion, and pale skin, feeling abnormal sensations , among others, especially in people over age 60. Vitamin B 12 deficiency can also cause symptoms of mania and psychosis . Among other problems, weakened immunity, reduced fertility and interruption of blood circulation in women may occur. The main type of vitamin B12 deficiency anemia
5225-923: The cardinal cause or mechanism of the diseases are different. A key difference is a malfunction of the innate immune system in autoinflammatory diseases, whereas in autoimmune diseases there is a malfunction of the adaptive immune system . Symptoms of autoimmune diseases can significantly vary, primarily based on the specific type of the disease and the body part that it affects. Symptoms are often diverse and can be fleeting, fluctuating from mild to severe, and typically comprise low-grade fever , fatigue , and general malaise . However, some autoimmune diseases may present with more specific symptoms such as joint pain , skin rashes (e.g., urticaria ), or neurological symptoms. The exact causes of autoimmune diseases remain unclear and are likely multifactorial, involving both genetic and environmental influences. While some diseases like lupus exhibit familial aggregation, suggesting
5320-524: The cecum is expelled as " cecotropes " and are re-ingested, a practice referred to as cecotrophy . Re-ingestion allows for absorption of nutrients made available by bacterial fermentation, and also of vitamins and other nutrients synthesized by the gut bacteria, including vitamin B 12 . Non-ruminant, non-hindgut herbivores may have an enlarged forestomach and/or small intestine to provide a place for bacterial fermentation and B-vitamin production, including B 12 . For gut bacteria to produce vitamin B 12 ,
5415-422: The child), when hormone levels are high, and improve after menopause, when hormone levels decrease. Women may also naturally have autoimmune disease trigger events in puberty and pregnancy. Under-reporting by men may also be a factor, as men may interact less with the health system than women. Certain viral and bacterial infections have been linked to autoimmune diseases. For instance, research suggests that
5510-580: The clinical state of the patient and the results of investigations." The vitamin deficiency is typically suspected when a routine complete blood count shows anemia with an elevated mean corpuscular volume (MCV). In addition, on the peripheral blood smear , macrocytes and hypersegmented polymorphonuclear leukocytes may be seen. Diagnosis is supported based on vitamin B 12 blood levels below 150–180 pmol/L (200–250 pg/mL ) in adults. However, serum values can be maintained while tissue B 12 stores are becoming depleted. Therefore, serum B 12 values above
5605-442: The complexity and multifaceted nature of these conditions. Various environmental triggers are identified, some of which include: Chemicals, which are either a part of the immediate environment or found in drugs, are key players in this context. Examples of such chemicals include hydrazines , hair dyes , trichloroethylene , tartrazines , hazardous wastes, and industrial emissions. Ultraviolet radiation has been implicated as
5700-501: The cut-off point of deficiency do not necessarily confirm adequate B 12 status. For this reason, elevated serum homocysteine over 15 micromol/L and methylmalonic acid (MMA) over 0.271 micromol/L are considered better indicators of B 12 deficiency, rather than relying only on the concentration of B 12 in blood. However, elevated MMA is not conclusive, as it is seen in people with B 12 deficiency, but also in elderly people who have renal insufficiency, and elevated homocysteine
5795-429: The daily value was 6.0 μg, but on May 27, 2016, it was revised downward to 2.4 μg. Compliance with the updated labeling regulations was required by 1 January 2020 for manufacturers with US$ 10 million or more in annual food sales, and by 1 January 2021 for manufacturers with lower volume food sales. A table of the old and new adult daily values is provided at Reference Daily Intake . Vitamin B 12
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#17328513093695890-447: The development and progression of various autoimmune diseases, either directly or as catalysts. Current research suggests that up to seventy percent of autoimmune diseases could be attributed to environmental influences, which encompass an array of elements such as chemicals, infectious agents, dietary habits, and gut dysbiosis. However, a unifying theory that definitively explains the onset of autoimmune diseases remains elusive, emphasizing
5985-424: The diagnosis of an autoimmune condition, often in conjunction with tests for specific biological markers, but also help monitor disease progression and response to treatment. Ultimately, due to the diverse nature of autoimmune diseases, a multidimensional approach is often needed for the management of these conditions, taking into consideration the variety of symptoms and their impacts on individuals' lives. While it
6080-430: The diagnostic criteria established for any one connective tissue disease. Some 30–40% transition to a specific connective tissue disease over time. The exact causes of autoimmune diseases remain largely unknown; however, research has suggested that a combination of genetic, environmental, and hormonal factors, as well as certain infections, may contribute to the development of these disorders. The human immune system
6175-402: The early 1900s, and since then, advancements in understanding and management of these conditions have been substantial, though much more is needed to fully unravel their complex etiology and pathophysiology . Autoimmune diseases represent a vast and diverse category of disorders that, despite their differences, share some common symptomatic threads. These shared symptoms occur as a result of
6270-502: The flesh of any animal—are also at risk. Vitamin B 12 deficiency has been observed in between 40% and 80% of the vegetarian population who do not also take a vitamin B 12 supplement or consume vitamin-fortified food. In Hong Kong and India, vitamin B 12 deficiency has been found in roughly 80% of the vegan population. As with vegetarians, vegans can avoid this by consuming a dietary supplement or eating B 12 fortified food such as cereal, plant-based milks, and nutritional yeast as
6365-450: The gastrointestinal tract and some lymphoproliferative cancers. Multiple sclerosis (MS) is a neurodegenerative disease in which the immune system attacks myelin , a protective covering of nerve fibers in the central nervous system, causing communication problems between the brain and the rest of the body. Symptoms can include fatigue, difficulty walking, numbness or tingling, muscle weakness, and problems with coordination and balance. MS
6460-476: The genes and enzymes necessary to synthesize vitamin B 12 , plant and algae sources all obtain the vitamin secondarily from symbiosis with various species of bacteria, or in the case of fermented plant foods, from bacterial fermentation. Foods for which vitamin B 12 -fortified versions are available include breakfast cereals , plant-derived milk substitutes such as soy milk and oat milk , energy bars , and nutritional yeast . The fortification ingredient
6555-470: The hospital thus increasing the cost of the treatment and impairing the lifestyle of patients. Targeted delivery of vitamin B 12 is a major focus of modern prescriptions. For example, conveying the vitamin to the bone marrow and nerve cells would help myelin recovery. Currently, several nanocarriers strategies are being developed for improving vitamin B 12 delivery with the aim to simplify administration, reduce costs, improve pharmacokinetics, and ameliorate
6650-491: The hydroxyl group is displaced by cyanide, creating a non-toxic cyanocobalamin that is excreted in urine. "Pseudovitamin B 12 " refers to compounds that are corrinoids with a structure similar to the vitamin but without vitamin activity. Pseudovitamin B 12 is the majority corrinoid in spirulina , an algal health food sometimes erroneously claimed as having this vitamin activity. Vitamin B 12 deficiency can potentially cause severe and irreversible damage, especially to
6745-452: The immune system attacking insulin-producing beta cells in the pancreas , leading to high blood sugar levels. Symptoms include increased thirst , frequent urination , and unexplained weight loss . It is most commonly diagnosed in children and young adults. Undifferentiated connective tissue disease occurs when people have features of connective tissue disease, such as blood test results and external characteristics, but do not fulfill
6840-406: The immune system creates an environment that favors further malignant transformation of other cells, perhaps explaining the associations with cancer of the lungs and skin as well as the increased risk of other hematologic cancers, none of which are directly affected by the inflammation of joints. Psoriasis is a skin condition characterized by the rapid buildup of skin cells, leading to scaling on
6935-442: The individual may affect the course of pathological changes and symptomatology of vitamin B 12 deficiency. Vitamin B 12 deficiency in pregnant women is strongly associated with an increased risk of spontaneous abortion, congenital malformations such as neural tube defects, problems with brain development growth in the unborn child. Vitamin B 12 was discovered as a result of pernicious anemia, an autoimmune disorder in which
7030-624: The location and type of autoimmune response. For instance, in rheumatoid arthritis, an autoimmune disease primarily affecting the joints, symptoms typically include joint pain, swelling, and stiffness. On the other hand, type 1 diabetes, which results from an autoimmune attack on the insulin-producing cells of the pancreas, primarily presents with symptoms related to high blood sugar, such as increased thirst, frequent urination, and unexplained weight loss. Commonly affected areas in autoimmune diseases include blood vessels, connective tissues, joints, muscles, red blood cells, skin, and endocrine glands such as
7125-420: The lower legs . Inflammatory bowel disease encompasses conditions characterized by chronic inflammation of the digestive tract, including Crohn's disease and ulcerative colitis . In both cases, individuals lose immune tolerance for normal bacteria present in the gut microbiome . Symptoms include severe diarrhea, abdominal pain, fatigue, and weight loss. Inflammatory bowel disease is associated with cancers of
7220-400: The molecule against degradation. Methylcobalamin is also offered as a dietary supplement. There is no advantage to the use of adenosylcobalamin or methylcobalamin forms for the treatment of vitamin B 12 deficiency. Hydroxocobalamin can be injected intramuscularly to treat vitamin B 12 deficiency. It can also be injected intravenously for the purpose of treating cyanide poisoning, as
7315-579: The overactive immune response. In certain cases, intravenous immunoglobulin may be administered to regulate the immune system. Despite these treatments often leading to symptom improvement, they usually do not offer a cure and long-term management is often required. In terms of prevalence, a UK study found that 10% of the population were affected by an autoimmune disease. Women are more commonly affected than men. Autoimmune diseases predominantly begin in adulthood, although they can start at any age. The initial recognition of autoimmune diseases dates back to
7410-454: The person's dietary intake is below recommended levels. Symptomatic vitamin deficiency is more likely if the person is rendered achlorhydric (a complete absence of gastric acid secretion), which occurs more frequently with proton pump inhibitors than H 2 blockers. Reduced serum levels of vitamin B 12 occur in up to 30% of people taking long-term anti-diabetic metformin . Deficiency does not develop if dietary intake of vitamin B 12
7505-492: The proportion of people with low or marginal levels of vitamin B 12 is up to 40% in the Western world . Grain -based foods can be fortified by having the vitamin added to them. Vitamin B 12 supplements are available as single or multivitamin tablets. Pharmaceutical preparations of vitamin B 12 may be given by intramuscular injection . Since there are few non-animal sources of the vitamin, vegans are advised to consume
7600-714: The quality of patients' lives. Pseudovitamin-B 12 refers to B 12 -like analogues that are biologically inactive in humans. Most cyanobacteria, including Spirulina , and some algae, such as Porphyra tenera (used to make a dried seaweed food called nori in Japan), have been found to contain mostly pseudovitamin-B 12 instead of biologically active B 12 . These pseudo-vitamin compounds can be found in some types of shellfish, in edible insects, and at times as metabolic breakdown products of cyanocobalamin added to dietary supplements and fortified foods. Pseudovitamin-B 12 can show up as biologically active vitamin B 12 when
7695-671: The risk of autoimmunity (positive selection). In contrast, variants in the TYK2 gene protect against autoimmune diseases but increase the risk of infection (negative selection). This suggests the benefits of infection resistance may outweigh the risks of autoimmune diseases, particularly given the historically high risk of infection. Several experimental methods such as the genome-wide association studies have been used to identify genetic risk variants that may be responsible for diseases such as type 1 diabetes and rheumatoid arthritis. A significant number of environmental factors have been implicated in
7790-716: The risk of miscarriage, preterm birth and newborn low birth weight. During pregnancy the placenta concentrates B 12 , so that newborn infants have a higher serum concentration than their mothers. As it is recently absorbed vitamin content that more effectively reaches the placenta, the vitamin consumed by the mother-to-be is more important than that contained in her liver tissue. Women who consume little animal-sourced food, or who are vegetarian or vegan, are at higher risk of becoming vitamin depleted during pregnancy than those who consume more animal products. This depletion can lead to anemia, and also an increased risk that their breastfed infants become vitamin deficient. Vitamin B 12
7885-435: The risk of vitamin B 12 deficiency and requires preventive post-operative treatment with either injected or high-dose oral supplementation. For post-operative oral supplementation, 1000 μg/d may be needed to prevent vitamin deficiency. According to one review: "At present, no 'gold standard' test exists for the diagnosis of vitamin B 12 deficiency and as a consequence the diagnosis requires consideration of both
7980-527: The same as in the United States. For women and men over age 18 the adequate intake (AI) is set at 4.0 μg/day. AI for pregnancy is 4.5 μg/day, for lactation 5.0 μg/day. For children aged 1–14 years the AIs increase with age from 1.5 to 3.5 μg/day. These AIs are higher than the U.S. RDAs. The EFSA also reviewed the safety question and reached the same conclusion as in the United States—that there
8075-538: The same family, signifying a potential hereditary link. Furthermore, certain genes have been identified that augment the risk of developing specific autoimmune diseases. Experimental methods like genome-wide association studies have proven instrumental in pinpointing genetic risk variants potentially responsible for autoimmune diseases. For example, these studies have been used to identify risk variants for diseases such as type 1 diabetes and rheumatoid arthritis. In twin studies, autoimmune diseases consistently demonstrate
8170-484: The skin's surface. Inflammation and redness around the scales is common. Some individuals with psoriasis also develop psoriatic arthritis , which causes joint pain, stiffness, and swelling. Sjögren syndrome is a long-term autoimmune disease that affects the body's moisture-producing glands (lacrimal and salivary), and often seriously affects other organ systems, such as the lungs, kidneys, and nervous system. Systemic lupus erythematosus , referred to simply as lupus,
8265-457: The small intestine and promote nutrient absorption. This explains the increased risk of gastrointestinal cancers , as the gastrointestinal tract includes the esophagus, stomach, small intestine, large intestine, rectum, and anus, all areas that the ingested gluten would traverse in digestion. The incidence of gastrointestinal cancer can be partially reduced or eliminated if a patient removes gluten from their diet. Additionally, coeliac disease
8360-631: The symptomatology. Symptoms that are commonly associated with autoimmune diseases include: Specific autoimmune diseases have a wide range of other symptoms, with examples including dry mouth, dry eyes, tingling and numbness in parts of the body, unexpected weight loss or gain, and diarrhoea. These symptoms often reflect the body's systemic inflammatory response. However, their occurrence and intensity can fluctuate over time, leading to periods of heightened disease activity, referred to as flare-ups, and periods of relative inactivity, known as remissions. The specific presentation of symptoms largely depends on
8455-414: The thymus, an organ responsible for the maturation of T cells. This process serves as a key line of defense against autoimmunity. If these protective mechanisms fail, a pool of self-reactive cells can become functional within the immune system, contributing to the development of autoimmune diseases. Some infectious agents, like Campylobacter jejuni , bear antigens that resemble, but are not identical to,
8550-400: The thyroid gland (in diseases like Hashimoto's thyroiditis and Graves' disease) and the pancreas (in type 1 diabetes). The impacts of these diseases can range from localized damage to certain tissues, alteration in organ growth and function, to more systemic effects when multiple tissues throughout the body are affected. The appearance of these signs and symptoms can not only provide clues for
8645-405: The transient nature of many symptoms. Treatment modalities for autoimmune diseases vary based on the type of disease and its severity. Therapeutic approaches primarily aim to manage symptoms, reduce immune system activity, and maintain the body's ability to fight diseases. Nonsteroidal anti-inflammatory drugs (NSAIDs) and immunosuppressants are commonly used to reduce inflammation and control
8740-558: The use of H 2 blocker or proton-pump inhibitor (PPI) drugs, can reduce absorption of protein-bound (dietary) vitamin B 12 , although not of supplemental vitamin B 12 . H 2 -receptor antagonist examples include cimetidine , famotidine , nizatidine , and ranitidine . PPIs examples include omeprazole , lansoprazole , rabeprazole , pantoprazole , and esomeprazole . Clinically significant vitamin B 12 deficiency and megaloblastic anemia are unlikely, unless these drug therapies are prolonged for two or more years, or if in addition
8835-487: The vitamin. Supplements and medications are available to treat and prevent vitamin B 12 deficiency. They are usually taken by mouth, but for the treatment of deficiency may also be given as an intramuscular injection . Vitamin B 12 deficiencies have a greater effect on young children, pregnant and elderly people, and are more common in middle and lower developed countries due to malnutrition. The most common cause of vitamin B 12 deficiency in developed countries
8930-414: The wide range of diseases within this category and their often overlapping symptoms. Accurate diagnosis is crucial for determining appropriate treatment strategies. Generally, the diagnostic process involves a combination of medical history evaluation, physical examination , laboratory tests , and, in some cases, imaging or biopsies . The first step in diagnosing autoimmune disorders typically involves
9025-479: Was not sufficient evidence to set a UL for vitamin B 12 . The Japan National Institute of Health and Nutrition set the RDA for people ages 12 and older at 2.4 μg/day. The World Health Organization also uses 2.4 μg/day as the adult recommended nutrient intake for this vitamin. For U.S. food and dietary supplement labeling purposes, the amount in a serving is expressed as a "percent of daily value" (%DV). For vitamin B 12 labeling purposes, 100% of
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