What is the Relationship Between Vitamin B12 and Folate?

The relationship between vitamin B12 and folate can be beneficial or detrimental depending on the levels of each in the blood. Studies have shown that an imbalance in vitamin B12 and folate intake or absorption can affect several body systems and promote or mask disease, particularly when blood levels of vitamin B12 are low and folate levels are high. Cognitive difficulties, cardiovascular disease risk, and a type of anemia have been associated with an imbalance in vitamin B12 and folate.

When difficulties arise from a blood imbalance in vitamin B12 and folate, they typically manifest in the elderly as problems with memory, visual-spatial skills, and maintaining attention. These problems develop when those over the age of 60 have low vitamin B12 levels and high folate levels. Conversely, when seniors have normal B12 levels and high or normal folate levels, they tend to score better on cognitive testing.

Anemia has been found more often in seniors with low vitamin B12 and high folate in the blood. There is also a folate deficiency anemia, however, for which doctors often prescribe large amounts of folic acid, the synthetic form of folate. Before offering folic acid supplementation for anemia, doctors should determine which type is being treated, as high doses of folic acid can mask a vitamin B12 deficiency and allow that untreated deficiency to cause neurological damage in the patient.

On the positive side, there is some evidence that taking vitamin B12 and folic acid together can decrease homocysteine levels in the blood. As an amino acid used by the body to make certain proteins, homocysteine in elevated concentrations is associated with an increased risk of stroke, heart disease, and Alzheimer’s disease. In some studies, researchers have found that adding vitamin B6 to vitamin B12 and folic acid supplementation can help lower homocysteine levels.

Deficiencies in vitamin B12 and folate can be caused by some medications. Oral contraceptives, some antibiotics, and estrogen supplements can decrease blood levels of vitamin B12. Other medications, including large doses of aspirin and ibuprofen, blood pressure drugs, anticonvulsants, and anti-ulcer preparations, can inhibit the absorption of folate. Methotrexate, a drug used to treat autoimmune diseases such as rheumatoid arthritis, lupus, psoriasis, and scleroderma, is also known to inhibit folate absorption.

There are additional reasons why vitamin B12 and folate levels can vary from normal. Some diseases can cause malabsorption of both nutrients, including alcoholism, celiac disease, and Crohn’s disease. Vitamin B12 and folate malabsorption also can be caused by aging, gastric inflammation, and tapeworm infections.