This may be due to surgery to your stomach or small intestine (such as gastric bypass surgery), abnormal bacterial growth in your small intestine, or an intestinal disease, such as Crohn's disease or celiac disease, that interferes with absorption of the vitamin.

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Because gluten exposure damages the small intestine in those with celiac disease, causing nutritional deficiencies, research has revealed that multiple parts of the body can be affected, including the brain.

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Aside from immediate symptoms, like abdominal pain and diarrhea, celiac disease can cause serious damage to the small intestine over time, leading to poor absorption of nutrients and vitamins.

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It can lead to serious long-term complications, such as the brittle bone disease osteoporosis, infertility and cancer of the small intestine.

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