Mennyi orális b12 fogyás
Definition[ edit ] Vitamin B12, also known as cobalamin, is a water-soluble vitamin essential to the function of all cells. Cobalamins are characterized by a porphyrin -like corrin nucleus that contains a single cobalt atom bound to a benzimidazolyl nucleotide and a variable residue R group.
Because 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.
70 év feletti betegeknek 200x-os adag B12-vitamin szükséges
The vitamin activity is as a coenzymemeaning that its presence is required for some enzyme-catalyzed reactions. For hydroxocobalamin it is a hydroxyl group. Both of these can be converted to either of the two cobalamin coenzymes that are active in human metabolism: adenosylcobalamin AdoB12 and methylcobalamin MeB These enzymatically active enzyme cofactors function, respectively, in mitochondria and cell cytosol.
Bacterial fermentation creates AdoB12 and MeB12 which are converted to cyanocobalamin by addition of potassium cyanide in the presence of sodium nitrite and heat.
Once consumed, cyanocobalamin is converted to the biologically active AdoB12 and MeB Cyanocobalamin is the most common form used in dietary supplements and food fortification because cyanide stabilizes the molecule against degradation. Methylcobalamin is also offered as a dietary supplement. It can also be injected intravenously for the purpose of treating cyanide poisoning, as the hydroxyl group is displaced by cyanide, creating a non-toxic cyanocobalamin that is excreted in urine.
Mit ehetünk gyomorrák esetén?
This is due to the inhibition of DNA synthesis specifically purines and thymidine. Gastrointestinal symptoms: alteration in bowel motility, such as mild diarrhea or constipationand loss of bladder or bowel control. This may also be due to the autoimmune attack on the parietal cells of the stomach in pernicious anemia.
There is an association with gastric antral vascular ectasia which can be referred to as watermelon stomachand pernicious anemia. As with vegetarians, vegans can avoid this by consuming a dietary supplement or eating B12 fortified food such as cereal, plant-based milks, and nutritional yeast as a regular part of their diet. Determination of these values was based on the RDA of 2. 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 content that more effectively reaches breast milk. Children diagnosed with low serum B12 can be treated with intramuscular injections, then transitioned to an oral dietary supplement.
- Megnövekedett szükséglet terhesség, koraszülöttség, haemolysis, rákos megbetegedés.
- Hogyan lehet elveszíteni a hasi zsírtudományt
Roux-en-Y gastric bypass surgery RYGB but not sleeve gastric bypass surgery or gastric banding, increases the risk of vitamin B12 deficiency and requires preventive post-operative treatment with either injected or high-dose oral supplementation. In addition, on the peripheral blood smearmacrocytes and hypersegmented polymorphonuclear leukocytes may be seen. However, serum values can be maintained while tissue B12 stores are becoming depleted.
Therefore, serum B12 values above the cut-off point of deficiency do not necessarily confirm adequate B12 status. Preparations are usually bright red.
Vérzékenység: kinél és miért alakul ki, mit lehet tenni ellene?
Repletion of deficiency[ edit ] Severe vitamin B12 deficiency is corrected with frequent intramuscular injections of large doses of the vitamin, followed by maintenance doses of injections or oral dosing at longer intervals. One guideline specified intramuscular injections of micrograms μg of hydroxocobalamin three times a week for two weeks, followed by the same amount once every two or three months.
Oral supplementation with or μg of cyanocobalamin every few months was mentioned as an alternative for maintenance. RDA is higher than EAR so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy equals 2.
A folsav hatásai és a folsavhiány
RDA for lactation equals 2. For infants up to 12 months the adequate intake AI is 0. For children ages 1—13 years the RDA increases with age from 0. Because 10 to 30 percent of older mennyi orális b12 fogyás may be unable to effectively absorb vitamin B12 naturally occurring in foods, it is advisable mennyi orális b12 fogyás those older than 50 years to meet their RDA mainly by consuming foods fortified with vitamin B12 or a supplement containing vitamin B As for safety, tolerable upper intake levels known as ULs are set for vitamins and minerals when evidence is sufficient.
In the case of vitamin B12 there is no UL, as there is no human data for adverse effects from high doses. For women and men over age 18 the adequate intake AI is set at 4. AI for pregnancy is 4.
For children aged 1—17 years the AIs increase with age from 1. These AIs are higher than the U. Sources[ edit ] Most omnivorous people in developed countries obtain enough vitamin B12 from consuming animal mennyi orális b12 fogyás including meat, fish, eggs, and milk. Vegan sources in the common food supply are rare,  hence the recommendations to consume a dietary supplement or fortified foods. The first-passage of feces produced by this hindgut fermentationcalled " cecotropes ", are re-ingested, a practice referred to as cecotrophy or coprophagy.
Re-ingestion allows for absorption of nutrients made available by bacterial digestion, and also of vitamins and other nutrients synthesized by the gut bacteria, including vitamin B 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.
Most of these are in southeast Africa or Central America. In the US, non-prescription products can be purchased providing up to 5, µg each, and it is a common ingredient in energy drinks and energy shotsusually at many times the recommended dietary allowance of B The vitamin can also be a prescription product via injection or other means.
The metabolic fate and biological distribution of methylcobalamin are expected to be similar to that of other sources of vitamin B12 in the diet. To get a reliable reading of B12 content, more advanced techniques are available. One such technique involves pre-separation by silica gel and kdrama fogyás assessment with Bdependent E.
Reduced secretion of gastric acid and pepsin produced by H2 blocker or proton-pump inhibitor PPI drugs can reduce absorption of protein-bound dietary vitamin B12, although not of supplemental vitamin B H2-receptor antagonist examples include cimetidinefamotidinemennyi orális b12 fogyásand ranitidine. PPIs examples include omeprazolelansoprazolerabeprazolepantoprazoleand esomeprazole.
Clinically significant vitamin B12 deficiency and megaloblastic anemia are unlikely, unless these drug therapies are prolonged for two or more years, or if in addition the person's diet is below recommended intakes. Symptomatic vitamin deficiency is more likely if the person is rendered achlorhydric complete absence eco slim y étvágytalanság gastric acid secretionmennyi orális b12 fogyás occurs more frequently with proton pump inhibitors than H2 blockers.
If the deficiency is detected, metformin can be continued while the deficiency is corrected with B12 supplements. However, serum levels were higher in people prescribed valproate. Physically it resembles the other forms of vitamin B12, occurring as dark red crystals that freely form cherry-colored transparent solutions in water.