It’s impossible to underestimate the importance of the hard-working vitamin, B12, which plays a major role in metabolism, the formation of red blood cells, maintenance of the central nervous system, and creation of DNA. In fact, vitamin B12 deficiency is serious business, which can result in megaloblastic anemia (a blood disorder with larger than normal red blood cells) and symptoms that may include numbness and tingling in the arms, difficulty walking, memory loss, and disorientation.
Getting enough B12. While most Americans probably get enough, an estimated 10-15 percent of adults over age 60 may experience vitamin B12 deficiency. This may occur because of impaired absorption, previous gastrointestinal surgery or digestive disorders, or dietary habits. (Vitamin B12 is found only in animal products, so people who limit their animal intake due to dietary preferences may fall short.) In fact, the National Institutes of Health recommends that all adults over age 50 receive most of their vitamin B12 through supplements and fortified foods to counter the potential for malabsorption. Some, but not all, nutritional yeasts contain vitamin B12 as do foods fortified with vitamin B12, such as some soy milk and breakfast cereals, and dietary supplements.
B12 and disease fighting. The amino acid homocysteine has been a subject of interest among health researchers for some time; a number of studies have found that elevated levels of homocysteine in the blood increase the risk for cardiovascular disease. Some evidence suggests that vitamin B12 deficiency can cause elevated homocysteine levels, while supplementation of vitamin B12 shows a seven percent reduction in homocysteine concentrations, according to a meta-analysis of a number of randomized trials. However, not all studies have found that vitamin B12 supplementation reduces cardiovascular disease risk.
Vitamin B12 also may have protective effects on cognition and depression, though more science is needed to confirm these results. In a study published in Neurology, low blood levels of B12 were associated with doubling the risk of Alzheimer’s. And, the Rotterdam Study which investigated 3,884 elderly men and women with depressive disorders, found that participants with vitamin B12 deficiency were nearly 70 percent more likely to experience depression than those with normal levels. More research is needed to understand the role that vitamin B12 plays in health, but it seems clear that you should aim to fill your B12 nutrition needs through foods and supplements.