Vitamin B12
Vitamin B12
Vitamin B12 is a water-soluble vitamin that is important in enzymatic reactions, normal blood formation, neural function, and metabolism of proteins, fats, and carbohydrates. It plays a vital role in the functioning of our nervous system. Vitamin B12 is vital in the creation of cells within our body. Red blood cells help carry oxygen throughout the body and require vitamin B12 to function. If vitamin B12 is low this causes a change in the size of the red blood cells.
Normally, vitamin B12 is readily absorbed in the last part of the small intestine (ileum), which leads to the large intestine. However, to be absorbed, the vitamin must combine with intrinsic factor, a protein produced in the stomach. Without intrinsic factor, vitamin B12 moves through the intestine and is excreted in stool without absorption leading to deficiency.
B12 is necessary for the formation of mature blood cells, deficiency of this vitamin can result in anemia.
Factors that may cause vitamin B12 deficiency:
• Avoiding animal products. People who do not eat meat, fish, poultry, or dairy are at risk of becoming deficient in vitamin B12, since it is only found naturally in animal products. Studies have shown that vegetarians have low vitamin B blood levels.
For this reason, those who follow a vegetarian or vegan diet should include B12-fortified foods or a B12 supplement in their diets. This is particularly important for pregnant women, as the fetus requires adequate vitamin B12 for neurologic development and deficiency can lead to permanent neurological damage.
• Lack of intrinsic factor. Pernicious anemia is an autoimmune disease that attacks and potentially destroys gut cells so that intrinsic factor is not present, which is crucial for vitamin B12 to be absorbed. If vitamin B12 deficiency ensues, other types of anemia and neurological damage may result. Even the use of a high-dose B12 supplement will not solve the problem, as intrinsic factor is not available to absorb it.
• Inadequate stomach acid or medications that cause decreased stomach acid. A much more common cause of B12 deficiency, especially in older people, is a lack of stomach acid, because stomach acid is needed to liberate vitamin B12 from food. An estimated 10-30% of adults over the age of 50 have difficulty absorbing vitamin B12 from food. People who regularly take medications that suppress stomach acid for conditions like gastroesophageal reflux disease (GERD) or peptic ulcer disease—such as proton-pump inhibitors, H2 blockers, or other antacids—may have difficulty absorbing vitamin B12 from food. Certain diabetes medicines such as metformin (Glucophage).These drugs can slow the release or decrease production of stomach acid. In theory this can prevent the vitamin from being released into its free usable form in the stomach; however, research has not shown an increased prevalence of a deficiency in people using these medications. Anyone using these medications for an extended time and who are at risk for a vitamin B12 deficiency for other reasons should be monitored closely by their physician. They may also choose to use fortified foods or supplements with vitamin B12, as these forms are typically absorbed well, and do not require stomach acid.
• Atrophic gastritis, in which your stomach lining has thinned
• Intestinal surgeries or digestive disorders that cause malabsorption. Surgeries that affect the stomach where intrinsic factor is made, or the ileum (the last portion of the small intestine) where vitamin B12 is absorbed, can increase the risk of a deficiency.
Certain diseases including Crohn’s (an inflammatory disease that can cause ulcerations throughout the GI tract, specifically affecting the small bowel and colon. If there is uncontrolled inflammation in the terminal ileum, this will lead to vitamin B12 deficiency) and celiac disease that negatively impact the digestive tract also increase the risk of deficiency.
• Alcohol misuse or heavy drinking can make it harder for your body to absorb nutrients or prevent you from eating enough calories. One sign that you lack enough B12 may be glossitis, or a swollen, inflamed tongue.
• Immune system disorders, such as Graves’ disease or lupus
What are the signs and symptoms of B12 deficiency?
Vitamin B12 deficiency can cause a wide range of symptoms. These usually develop gradually, but can worsen if the condition goes untreated.
A B12 deficiency can lead to many changes in the body. Usually, symptoms are subtle and can include feeling more irritable than normal, forgetting things easier and even difficulty with balance. Deficiency can cause optic nerve damage as the nervous signal that travels from the eye to the brain is disturbed due to this damage, leading to impaired vision.
Other symptoms may include:
• extreme tiredness (fatigue)
• lack of energy (lethargy)
• breathlessness
• feeling faint
• headaches
• pale skin
• noticeable heartbeats (palpitations)
• hearing sounds coming from inside the body, rather than from an outside source (tinnitus)
• loss of appetite and weight loss
• megaloblastic anemia—a condition of larger than normal sized red blood cells and a smaller than normal amount; this occurs because there is not enough vitamin B12 in the diet or poor absorption
• pernicious anemia
• depression
• seizures
• a pale yellow tinge to your skin
• a sore and red tongue (glossitis)
• mouth ulcers
• pins and needles (paraesthesia)
• changes in the way that you walk and move around
• disturbed vision
• irritability
• changes in the way you think, feel and behave
• a decline in your mental abilities, such as memory, understanding and judgement (dementia)
• weakness, tiredness, or lightheadedness
• heart palpitations and shortness of breath
• pale skin
• a smooth tongue
• constipation, diarrhea, loss of appetite, or gas
As a B12 deficiency worsens, it can dramatically impact our nervous system causing numbness with loss of feeling in our arms and legs. These effects are typically reversible once proper B12 levels have been restored.
When diet is not an issue, B12 deficiency generally has to do with an inability to absorb the vitamin properly. B12 requires special proteins and stomach acid to be adequately absorbed in the small bowel or terminal ileum, which is the last part of the small bowel before connecting to the colon.
Conditions can Impair Dietary Vitamin B12 Absorption including:
• Vegan diet (long-term); poor intake of vitamin B12-rich food
• Gastrectomy, pernicious anemia
• Gastric bypass surgery, small bowel surgery (especially in the ileum),
• Disease in the ileum (Crohn’s disease, cancer), short bowel syndrome, fistulas
• Reduced gastric acid (>65 years of age, gastric cancer, H. pylori infection)
• Bacterial overgrowth, long-term TPN, tapeworm
Diagnosis of Vitamin B12 Deficiency
• Blood tests
• Sometimes endoscopy
Treatment of Vitamin B12 Deficiency
• Vitamin B12 supplements
• For people with nerve damage, vitamin B12 given by injection
Vitamin B12 Dietary Sources
• meats organ meats like liver or kidneys
• eggs
• fish
• dairy products
• nutritional yeast
• almond
• fortified cerial
• carrots
• sweet potatoe
• squash
• broccoli
• peppers
• avocado
• apricots
• peaches
• melon
• mangoes