Vitamin B12, or cobalamin, is a water-soluble vitamin essential for healthy nerve cells, red blood cell formation, and DNA synthesis. The body cannot produce B12, so it must be obtained through diet, primarily from animal products or fortified foods. This article explores the connection between low vitamin B12 levels and cancer.
Low B12 and Cancer: The Direct Connection
Low vitamin B12 levels are generally not a direct sign of cancer. While severe illnesses, including some cancers, can impact nutrient absorption, a B12 deficiency is not a diagnostic marker. Most low B12 cases stem from reasons unrelated to cancer. In cancer patients, low B12 is often a consequence of the disease or its treatments.
Common Causes of Low B12
Many factors contribute to low vitamin B12 levels. Dietary insufficiency is a common cause, particularly for individuals following vegetarian or vegan diets, as B12 is primarily found in animal products. Malabsorption issues frequently lead to deficiency, such as in pernicious anemia, an autoimmune condition where the body cannot produce intrinsic factor, a protein necessary for B12 absorption. Digestive disorders like Crohn’s disease and celiac disease can also impair B12 absorption due to inflammation or damage to the intestinal lining.
Certain medications can interfere with B12 absorption. Proton pump inhibitors (PPIs) and metformin can reduce stomach acid needed to release B12 from food or otherwise hinder its uptake. Gastric bypass surgery or other stomach surgeries can lead to B12 deficiency by altering the digestive tract and reducing the production of intrinsic factor. Advancing age can also contribute to lower B12 absorption.
How B12 Levels Relate to Cancer
While low B12 is not a direct sign of cancer, there are nuanced ways B12 levels can relate to cancer, both indirectly with low levels and more significantly with elevated levels. Some cancers or their treatments can indirectly lead to B12 deficiency. For example, chemotherapy or surgeries affecting the digestive tract can impair the body’s ability to absorb B12 or increase its demand.
Elevated B12 levels, however, can sometimes be observed in the presence of certain cancers and other conditions. This elevation is often linked to an increased production of B12-binding proteins by tumor cells, or it can be a result of liver dysfunction, as the liver stores a large amount of B12.
Cancers like liver cancer, certain blood cancers such as leukemia (especially chronic myelocytic leukemia), and some solid tumors have been associated with high B12 levels. For instance, in chronic myelocytic leukemia, the rapid production of white blood cells can lead to an increased release of B12 into the bloodstream. While high B12 can be a marker, it is not specific to cancer and warrants further investigation for underlying causes.
Addressing a Low B12 Diagnosis
Consulting a healthcare professional is important to identify the underlying cause of low B12. Common symptoms of B12 deficiency include fatigue, weakness, numbness or tingling in hands and feet, vision problems, and issues with memory or confusion. Diagnosis involves blood tests, including a complete blood count and a vitamin B12 blood level test. A level below 150 pg/mL often indicates a deficiency.
Treatment approaches depend on the identified cause. Dietary changes, such as increasing intake of animal products or fortified foods, may be recommended for nutritional deficiencies. For absorption issues, vitamin B12 supplements, either oral or through injections, are common. Injections are often used initially for severe deficiencies or when absorption is significantly impaired, with ongoing treatment tailored to the individual’s needs, potentially lifelong for conditions like pernicious anemia.