Vitamin B-12 deficiency is a common problem in older adults. Historically, it was a common diagnosis by primary care physicians without the benefit of laboratory testing. Tiredness was frequently manifested by no pep or energy and a run-down feeling. Many of the patients who presented with these complaints were treated with B-12 injections, usually 1,000 micrograms intramuscularly weekly and later monthly, although there wasn’t any satisfactory blood testing available to validate significant improvement.
We now know blood levels below 160 micrograms are definitely low, but there is a gray zone between 160 to 400 micrograms which may be abnormal in some patients. Fortunately, we now have other biochemical tests which can validate if B-12 levels below 400 micrograms are truly abnormal.
Physicians have also learned low B-12 levels can contribute to anemia (low red blood cell count). To make matters more confusing, one usually will not observe anemia unless the B-12 levels are less than 160 micrograms. Other symptoms include memory loss, depression and other psychiatric symptoms, a sore tongue, numbness and/or sharp shooting pains (peripheral neuropathy), loss of appetite, weight loss and poor balance.
Vitamin B-12 is not produced by the human body. Rather, B-12 is found in dietary sources, primarily meat and dairy products. Vegetarians are at an increased risk of experiencing B-12 deficiency since B-12 isn’t found in plant foods. The minimum daily requirement of B-12 is 2.5 micrograms. B-12 can be stored in the body for many months. If an individual suddenly experiences a decreased intake of vitamin B-12 for several months, he or she will have plenty of it in his or her body to sustain daily needs for a number of months.
When vitamin B-12 is ingested, it eventually passes to the end of the small bowel (ilium) where it is absorbed. This means if someone has a chronic illness with inflammation at the terminal ilium or has had part of their small bowel removed, they may have trouble absorbing B-12. In these situations, B-12 must be given by injections. In the past, it was thought the only way B-12 deficiency can be treated is by injection, but medical research has taught physicians that taking large amounts of B-12 by mouth will be effective in replenishing the body’s depletion of the vitamin. It is only in rare situations that patients with vitamin B-12 deficiency will require B-12 by injections.
Most vitamins have B-12 included in the composition of the vitamin, although some multiple vitamin pills have more B-12 than others. For example, the Centrum® Silver multiple vitamin, or its generic equivalent, has 25 micrograms of B-12. Even though 25 micrograms is more than adequate for a person’s daily needs, some people may require a higher level of vitamin B-12 due to absorption problems. There isn’t total agreement among physicians as to what is the appropriate amount of B-12 supplement needed for patients who are deficient. Some people respond to 100 micrograms a day while others may require up to 1,000 micrograms a day.
Obtaining blood levels will enable a physician to determine the amount of B-12 required in a patient who is B-12 deficient. There is no scientific evidence to date which would indicate taking too much vitamin B-12 is associated with any toxicity to the human body.