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General Nutrition and Diet Facts

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Vitamin B12

 

<!--<h1>Vitamin B12 </h1>--> Vitamin B12 helps maintain healthy nerve cells and red blood cells. It is also needed to help make DNA, the genetic material in all cells. Vitamin B12 is also called cobalamin because it contains the metal cobalt.<br> Vitamin B12 is bound to the protein in food. Hydrochloric acid in the stomach releases vitamin B12 from proteins in foods during digestion. Once released, vitamin B12 combines with a substance called intrinsic factor (IF). This complex can then be absorbed by the intestinal tract.<br><br> <strong>Foods that provide vitamin B12</strong><br><br> Vitamin B12 is naturally found in foods that come from animals, including fish, meat, poultry, eggs, milk, and milk products. Fortified breakfast cereals are a particularly valuable source of vitamin B12 for vegetarians. <br><br> <strong> Selected food sources of vitamin B12</strong><br><br> <table border= 1 width=90% align=center> <tr> <td align=center><strong>Food</strong></td> <td align=center><strong>Micrograms (g)per serving </strong></td> <td align=center><strong>Percent DV*</strong></td> </tr> <tr> <td cellspacing="2" cellpadding="4"> &nbsp;&nbsp;Mollusks, clam, mixed species, cooked, 3 ounces </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;84.1</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1400</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Liver, beef, braised, 1 slice</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;47.9</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;780</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Fortified breakfast cereals, (100%) fortified), cup</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;6.0 </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;100</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Trout, rainbow, wild, cooked, 3 ounces</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;5.4</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;90</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Salmon, sockeye, cooked, 3 ounces</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;4.9</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;80</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Trout, rainbow, farmed, cooked, 3 ounces</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;4.2</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;50</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Beef, top sirloin, lean, choice, broiled, 3 ounces</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;2.4 </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;40</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Fast Food, Cheeseburger, regular, double patty & bun, 1 sandwich</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.9</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;30</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Fast Food, Taco, 1 large</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.6</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;25</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Fortified breakfast cereals (25% fortified), cup</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.5</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;25</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Yogurt, plain, skim, with 13 grams protein per cup, 1 cup</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.4</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;25</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Haddock, cooked, 3 ounces</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.2</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;20</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Clams, breaded & fried, cup</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.1</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;20</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Tuna, white, canned in water, drained solids, 3 ounces</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.0</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;15</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Milk, 1 cup </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;0.9 </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;15</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Pork, cured, ham, lean only, canned, roasted, 3 ounces</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;0.6</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;10</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Egg, whole, hard boiled, 1</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;0.6</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;10</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;Chicken, breast, meat only, roasted, breast</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;0.3</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;6</td> </tr> </table><br> *DV = Daily Value. <br><br> <strong>Recommended dietary intake for vitamin B12</strong><br><br> <strong> Recommended Dietary Allowances (RDA) for vitamin B12 for children and adults</strong><br><br> <table border= 1 width=90% align=center> <tr> <td align=center><strong>Age (years)</strong></td> <td align=center><strong>Males and Females (g/day) </strong></td> <td align=center><strong>Pregnancy (g/day)</strong></td> <td align=center><strong>Lactation (g/day)</strong></td> </tr> <tr> <td cellspacing="2" cellpadding="4"> &nbsp;&nbsp;1-3</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;0.9 </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;N/A </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;N/A</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;4-8 </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.2 </td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;N/A</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;N/A</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;9-13</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;1.8</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;N/A</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;N/A</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;14-18</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;2.4</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;2.6</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;2.8</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;19 and older</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;2.4</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;2.6</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;2.8</td> </tr> </table><br><br> <strong> Adequate Intake (AI) for vitamin B12 for infants</strong><br><br> <table border= 1 width=90% align=center> <tr> <td align=center><strong>Age (months)</strong></td> <td align=center><strong>Males and Females (g/day) </strong></td> </tr> <tr> <td cellspacing="2" cellpadding="4"> &nbsp;&nbsp;0-6 months</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;0.4</td> </tr> <tr> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;7-12 months</td> <td cellspacing="2" cellpadding="4">&nbsp;&nbsp;0.5</td> </tr> </table><br><br> <strong>Deficiency of vitamin B12 </strong><br><br> The deficiency may occur as a result of an inability to absorb vitamin B12 from food and in strict vegetarians who do not consume any foods that come from animals. As a general rule, most individuals who develop a vitamin B12 deficiency have an underlying stomach or intestinal disorder that limits the absorption of vitamin B12. Sometimes the only symptom of these intestinal disorders is subtly reduced cognitive function resulting from early vitamin B12 deficiency. Anemia and dementia follow later.<br><br> Signs, symptoms, and health problems associated with vitamin B12 deficiency: <br><br> Characteristic signs, symptoms, and health problems associated with vitamin B12 deficiency include anemia, fatigue, weakness, constipation, loss of appetite, and weight loss.<br> Deficiency also can lead to neurological changes such as numbness and tingling in the hands and feet.<br> Additional symptoms of vitamin B12 deficiency are difficulty in maintaining balance, depression, confusion, dementia, poor memory, and soreness of the mouth or tongue.<br> Signs of vitamin B12 deficiency in infancy include failure to thrive, movement disorders, delayed development, and megaloblastic anemia.<br> Many of these symptoms are very general and can result from a variety of medical conditions other than vitamin B12 deficiency. It is important to have a physician evaluate these symptoms so that appropriate medical care can be given. <br><br> <strong>Do pregnant and/or lactating women need extra Vitamin B12?</strong><br><br> During pregnancy, nutrients travel from mother to fetus through the placenta. Vitamin B12, like other nutrients, is transferred across the placenta during pregnancy. Breast-fed infants receive their nutrition, including vitamin B12, through breast milk. Vitamin B12 deficiency in infants is rare but can occur as a result of maternal insufficiency. Breast-fed infants of women who follow strict vegetarian diets have very limited reserves of vitamin B12 and can develop a vitamin B12 deficiency within months of birth. This is of particular concern because undetected and untreated vitamin B12 deficiency in infants can result in permanent neurologic damage. Consequences of such neurologic damage are severe and can be irreversible. Mothers who follow a strict vegetarian diet should consult with a pediatrician regarding appropriate use of vitamin B12 supplements for their infants and children. <br><br> Others who need a vitamin B12 supplement to prevent a deficiency: <ul> <li> Individuals with pernicious anemia or with gastrointestinal disorders may benefit from or require a vitamin B12 supplement. </li> <li> Older adults and vegetarians may benefit from a vitamin B12 supplement or an increased intake of foods fortified with vitamin B12.</li> <li> Some medications may decrease absorption of vitamin B12. Chronic use of those medications may result in a need for additional vitamin B12. </li> </ul> <strong>Individuals with pernicious anemia</strong><br><br> Anemia is a condition that occurs when there is insufficient hemoglobin in red blood cells to carry oxygen to cells and tissues. Common signs and symptoms of anemia include fatigue and weakness. Anemia can result from a variety of medical problems, including deficiencies of vitamin B12, vitamin B6, folate and iron. Pernicious anemia is the name given more than a century ago to describe the then-fatal vitamin B12 deficiency anemia that results from severe gastric atrophy, a condition that prevents gastric cells from secreting intrinsic factor. Intrinsic factor is a substance normally present in the stomach. Vitamin B12 must bind with intrinsic factor before it can be absorbed and used by your body. An absence of intrinsic factor prevents normal absorption of vitamin B12 and results in pernicious anemia. <br> Most individuals with pernicious anemia need parenteral (deep subcutaneous) injections (shots) of vitamin B12 as initial therapy to replenish depleted body stores of vitamin B12. Vitamin B12 body stores can then be managed by a daily oral supplement of vitamin B12. A physician will manage the treatment required to maintain the vitamin B12 status of individuals with pernicious anemia.<br><br> <strong>Individuals with gastrointestinal disorders</strong><br><br> Individuals with stomach and small intestine disorders may be unable to absorb enough vitamin B12 from food to maintain healthy body stores. Intestinal disorders that may result in malabsorption of vitamin B12 include:<br><br> Sprue, often referred to as celiac disease (CD), is a genetic disorder. People with CD are intolerant to a protein called gluten. In CD, gluten can trigger damage to the small intestines, where most nutrient absorption occurs. People with CD often experience nutrient malabsorption. They must follow a gluten-free diet to avoid malabsorption and other symptoms of CD. <br> Crohn's disease is an inflammatory bowel disease that affects the small intestines. People with Crohn's disease often experience diarrhea and nutrient malabsorption. <br> Surgical procedures in the gastrointestinal tract, such as surgery to remove all or part of the stomach, often result in a loss of cells that secrete hydrochloric acid and intrinsic factor. Surgical removal of the distal ileum, a section of the intestines, also can result in the inability to absorb vitamin B12. Anyone who has had either of these surgeries usually requires lifelong vitamin B12 supplements to prevent a deficiency. These individuals would be under the routine care of a physician, who would periodically evaluate vitamin B12 status and recommend appropriate treatment. <br><br> <strong>Older adults</strong><br><br> Hydrochloric acid helps release vitamin B12 from the protein in food. This must occur before vitamin B12 binds with intrinsic factor and is absorbed in your intestines. Atrophic gastritis, which is an inflammation of the stomach, decreases the secretion of gastric juices, including hydrochloric acid. Less hydrochloric acid decreases the amount of vitamin B12 separated from proteins in foods and can result in poor absorption of vitamin B12. . Decreased hydrochloric acid secretion also results in growth of normal bacteria in the small intestines. The bacteria may take up vitamin B12 for their own use, further contributing to a vitamin B12 deficiency.<br> Up to 30 percent of adults aged 50 years and older may have atrophic gastritis, an increased growth of intestinal bacteria, and be unable to normally absorb vitamin B12 in food. They are, however, able to absorb the synthetic vitamin B12 added to fortified foods and dietary supplements. Vitamin supplements and fortified foods may be the best sources of vitamin B12 for adults older than age 50 years. <br><br> <strong>Vegetarians</strong><br><br> The popularity of vegetarian diets has risen along with an interest in avoiding meat and meat products for environmental, philosophical, and health reasons. However, the term vegetarianism is subject to a wide range of interpretations. Some people consider themselves to be vegetarian when they avoid red meat. Others believe that vegetarianism requires avoidance of all products that come from animals, including meat, poultry, fish, eggs, and dairy foods. The most commonly described forms of vegetarianism include: <ul> <li> "lacto-ovo vegetarians", who avoid products that come from meat, poultry, and fish but consume eggs and dairy foods; </li> <li> "strict vegetarians", who avoid meat, poultry, fish, eggs, and dairy foods; and </li> <li> "vegans", who avoid meat, poultry, fish, eggs, and dairy foods and also do not use products that come from animals such as honey, leather, fur, silk, and wool. </li> </ul> Strict vegetarians and vegans are at greater risk of developing vitamin B12 deficiency than lacto-ovo vegetarians and nonvegetarians because natural food sources of vitamin B12 are limited to foods that come from animals. Fortified cereals are one of the few sources of vitamin B12 from plants, and are an important dietary source of vitamin B12 for strict vegetarians and vegans. Strict vegetarians and vegans who do not consume foods that come from plants that are fortified with vitamin B12 need to consider taking a dietary supplement that contains vitamin B12 and should discuss the need for vitamin B12 supplements with their physician. <br><br> When adults adopt a strict vegetarian diet, deficiency symptoms can be slow to appear. It may take years to deplete normal body stores of vitamin B12. However, breast-fed infants of women who follow strict vegetarian diets have very limited reserves of vitamin B12 and can develop a vitamin B12 deficiency within months. This is of particular concern because undetected and untreated vitamin B12 deficiency in infants can result in permanent neurologic damage. Consequences of such neurologic damage are severe and can be irreversible. There are many case reports in the literature of infants and children who suffered consequences of vitamin B12 deficiency. It is very important for mothers who follow a strict vegetarian diet to consult with a pediatrician regarding appropriate use of vitamin B12 supplements for their infants and children.<br><br> <strong>Folic Acid and vitamin B12 deficiency</strong><br><br> Folic acid can correct the anemia that is caused by vitamin B12 deficiency. Unfortunately, folic acid will not correct the nerve damage also caused by vitamin B12 deficiency. Permanent nerve damage can occur if vitamin B12 deficiency is not treated. Folic acid intake from food and supplements should not exceed 1,000 g daily in healthy individuals because large amounts of folic acid can trigger the damaging effects of vitamin B12 deficiency. <br><br> <strong>Relationship between vitamin B12 homocysteine, and cardiovascular disease</strong><br><br> Cardiovascular disease involves any disorder of the heart and blood vessels that make up the cardiovascular system. Coronary heart disease occurs when blood vessels which supply the heart become clogged or blocked, increasing the risk of a heart attack. Vascular damage can also occur to blood vessels supplying the brain, and can result in a stroke. <br> In recent years, researchers have identified another risk factor for cardiovascular disease: an elevated homocysteine level. Homocysteine is an amino acid normally found in blood, but elevated levels have been linked with coronary heart disease and stroke. Elevated homocysteine levels may impair endothelial vasomotor function, which determines how easily blood flows through blood vessels. High levels of homocysteine also may damage coronary arteries and make it easier for blood clotting cells called platelets to clump together and form a clot, which may lead to a heart attack.<br> Vitamin B12, folate, and vitamin B6 are involved in homocysteine metabolism. In fact, a deficiency of vitamin B12, folate, or vitamin B6 may increase blood levels of homocysteine. Recent studies found that vitamin B12 and folic acid supplements decreased homocysteine levels in subjects with vascular disease and in young adult women. The most significant drop in homocysteine level was seen when folic acid was taken alone.<br> Evidence supports a role for folic acid and vitamin B12 supplements for lowering homocysteine levels, however this does not mean that these supplements will decrease the risk of cardiovascular disease. Clinical intervention trials are underway to determine whether folic acid, vitamin B12, and vitamin B6 supplements can lower risk of coronary heart disease. It is premature to recommend vitamin B12 supplements for the prevention of heart disease until results of ongoing randomized clinical trials positively link increased vitamin B12 intake from supplements with decreased homocysteine levels AND decreased risk of cardiovascular disease. <br><br> <strong>Health risk of too much vitamin B12</strong><br><br> It has been found that there are no adverse effects have been associated with excess vitamin B12 intake from food and supplements in healthy individuals. In fact, it is recommended that adults older than 50 years get most of their vitamin B12 from vitamin supplements or fortified food because of the high incidence of impaired absorption in this age group of vitamin B12 from foods that come from animals. <br> Different foods contain different nutrients and other healthful substances. No single food can supply all the nutrients in the amounts you need.

 


 
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