B 12
By 4muskateers
04-18-08
Individuals with gastrointestinal disorders
Individuals with stomach and small intestine disorders may be unable to absorb enough vitamin B12 from food to maintain healthy body stores [19]. Intestinal disorders that may result in malabsorption of vitamin B12 include:
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.
Crohn's disease is an inflammatory bowel disease that affects the small intestines. People with Crohn's disease often experience diarrhea and nutrient malabsorption.
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 [7,20-21]. 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.
Older adults
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 [10,22-26]. 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 [27].
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 [7].
Researchers have long been interested in the potential connection between vitamin B12 deficiency and dementia [28]. A recent review examined correlations between cognitive skills, homocysteine levels, and blood levels of folate, vitamin B12 and vitamin B6. The authors suggested that vitamin B12 deficiency may decrease levels of substances needed for the metabolism of neurotransmitters [29]. Neurotransmitters are chemicals that transmit nerve signals. Reduced levels of neurotransmitters may result in cognitive impairment. In 142 individuals considered at risk for dementia, researchers found that a daily supplement providing 2 milligrams (mg) folic acid and 1 mg vitamin B12, taken for 12 weeks, lowered homocysteine levels by 30%. They also demonstrated that cognitive impairment was significantly associated with elevated plasma total homocysteine. However, the decrease in homocysteine levels seen with the use of vitamin supplements did not improve cognition [30]. It is too soon to make any recommendations, but is an intriguing area of research.
Individuals with stomach and small intestine disorders may be unable to absorb enough vitamin B12 from food to maintain healthy body stores [19]. Intestinal disorders that may result in malabsorption of vitamin B12 include:
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.
Crohn's disease is an inflammatory bowel disease that affects the small intestines. People with Crohn's disease often experience diarrhea and nutrient malabsorption.
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 [7,20-21]. 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.
Older adults
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 [10,22-26]. 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 [27].
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 [7].
Researchers have long been interested in the potential connection between vitamin B12 deficiency and dementia [28]. A recent review examined correlations between cognitive skills, homocysteine levels, and blood levels of folate, vitamin B12 and vitamin B6. The authors suggested that vitamin B12 deficiency may decrease levels of substances needed for the metabolism of neurotransmitters [29]. Neurotransmitters are chemicals that transmit nerve signals. Reduced levels of neurotransmitters may result in cognitive impairment. In 142 individuals considered at risk for dementia, researchers found that a daily supplement providing 2 milligrams (mg) folic acid and 1 mg vitamin B12, taken for 12 weeks, lowered homocysteine levels by 30%. They also demonstrated that cognitive impairment was significantly associated with elevated plasma total homocysteine. However, the decrease in homocysteine levels seen with the use of vitamin supplements did not improve cognition [30]. It is too soon to make any recommendations, but is an intriguing area of research.
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