Vitamin B12 Deficiency

Vitamin B12 deficiency is a treatable condition that happens if you aren't consuming enough vitamin B12 in your diet or if your body isn't absorbing it properly. This essential nutrient, also known as cobalamin, is used as a cofactor for enzymes that are involved in the synthesis of deoxyribonucleic acid (DNA), fatty acids, and myelin. Without adequate B12, the body may struggle to produce healthy red blood cells and maintain proper nerve function.

According to an analysis of NHANES data from 2007–2018, approximately 3.6% of all adults age 19 and older have vitamin B12 deficiency. In the United States and the United Kingdom, the prevalence of vitamin B12 deficiency is approximately 6% in persons younger than 60 years, and nearly 20% in those older than 60 years. While deficiency may develop gradually over months or years due to the body's substantial stores of B12, depending on the cause of the deficiency, you may only need treatment until your vitamin B12 levels are back to normal, or you may need B12 therapy for the rest of your life.

Vitamin B12 deficiency happens if you aren't eating enough vitamin B12 or your body isn't absorbing the vitamin B12 you consume. People who don't eat enough foods that have vitamin B12 or don't eat foods fortified with B12 can develop a deficiency. Vitamin B12 (cobalamin) is a water-soluble vitamin that is derived from animal products such as red meat, dairy, and eggs.

The commonest cause nowadays is food-bound cobalamin malabsorption (FBCM). In FBCM, there is impaired release of vitamin B12 from ingested food. This can result from conditions like chronic gastritis, the use of acid-suppressing medications, or age-related changes in stomach acid production. Pernicious anemia is an autoimmune condition in which antibodies to intrinsic factors are produced, preventing the absorption of B12 from food. Other factors that may contribute to deficiency include certain medications like metformin, surgical procedures affecting the stomach or intestines, and conditions like celiac disease or Crohn's disease that affect nutrient absorption.

Testing for vitamin B12 deficiency should be considered when experiencing symptoms like persistent fatigue, numbness or tingling in the extremities, memory problems, or unexplained anemia. Screening may be warranted in patients with one or more risk factors, such as gastric or small intestine resections, inflammatory bowel disease, use of metformin for more than four months, use of proton pump inhibitors or histamine H2 blockers for more than 12 months, vegans or strict vegetarians, and adults older than 75 years.

Additionally, testing may be appropriate for individuals taking medications that can interfere with B12 absorption, those with digestive disorders, or people following restrictive diets that limit animal products. Early detection and treatment of vitamin B12 deficiency is important because some neurological effects can become permanent if left untreated for extended periods.

A serum B12 above 300 pg/mL is interpreted as normal. Patients with B12 levels between 200 and 300 pg/mL are considered borderline, and further enzymatic testing may be helpful in diagnosis. Patients with B12 levels below 200 pg/mL are considered deficient. However, it's important to understand that B12 test results should always be interpreted alongside symptoms and other laboratory findings.

If B12 levels are borderline, healthcare providers may order additional tests like methylmalonic acid (MMA) or homocysteine levels to confirm deficiency. B12 deficiency results in the accumulation of MMA and homocysteine. Thus, serum levels of MMA and homocysteine should both be elevated in cases of B12 deficiency. A complete blood count may show enlarged red blood cells (macrocytic anemia) or other blood abnormalities that can suggest B12 deficiency. Remember that some individuals may experience symptoms even with borderline B12 levels, and treatment decisions should consider both laboratory results and clinical presentation.

Maintaining adequate vitamin B12 levels often involves dietary considerations and lifestyle factors. Vitamin B-12 is mainly in meat, eggs and milk. So people who don't eat these foods may need to take B-12 supplements. Those following vegetarian or vegan diets should be particularly mindful of B12 intake through fortified foods or supplements, as plant-based foods naturally contain very little B12.

For individuals with absorption issues, dietary changes alone may not be sufficient, and medical treatment with supplements or injections may be necessary. Regular monitoring of B12 levels can be important for people with risk factors like gastrointestinal conditions, those taking certain medications, or individuals over 60 years of age. Limiting alcohol consumption and managing stress can also support overall nutrient absorption and general health.