Dear Dr. Si,
Could you please tell me what my vitamin B-12 level should be? JR, Camus, WA
Vitamin B-12 (B-12) plays many important roles in our bodies. It is necessary for the formation of red blood cells as well as a large number of other roles probably the most important of which is maintenance of proper nerve function.
B-12 is found in a variety of foods including red meat with especially high amounts in liver and kidney. It is also found in eggs, shellfish and dairy products. Normally most people get enough B-12 in their diet to maintain adequate levels in their body. It is normally absorbed in the stomach and the body can store a 3-year supply or more, mostly in the liver. But, some people have B-12 levels that are too low which can cause problems. People who become B-12 deficient are typically either vegetarians or vegans who don’t have enough B-12 in their diets, or they may have a problem that prevents or decreases the ability of their stomachs from properly absorbing dietary B-12 such as people with Crohn’s disease, other bowel conditions, and in those who lack an important natural compound found in the stomach that promotes B-12 absorption. Advancing age can result in B-12 deficiency and it is common for people over age 60 to be deficient, especially if they regularly take proton pump inhibitors (PPIs) or other medicines that decrease stomach acid or if they take the diabetes medicine metformin.
Symptoms of B-12 deficiency include “paresthesias” where a person feels a tingling sensation in their nerves which may be fleeting and recurring. Symptoms indicating more serious nerve damage include numbness, weakness, loss of mobility and balance, confusion, behavioral problems and memory loss. In fact, when a person develops confusion or memory problems and is being evaluated to see if they may have Alzheimer’s disease it is routine for their health care provider to check the level of B-12 in their blood to see if low levels may be contributing to their mental problems. If B-12 deficiency is allowed to continue, nerve damage can become permanent. B-12 deficiency is potentially a very serious problem and it has been called an “epidemic” and a “tragedy,” which is unfortunate because it is so easy to diagnose and treat.
People with low B-12 levels need supplementation which may reduce and eliminate their symptoms of deficiency. B-12 supplements can easily get a person to the proper level, but, what should that level be? Surprisingly, there is no consensus on what the B-12 level should be for good health. To be complete I’ll note that B-12 levels measured in the blood are reported in units of picograms per milliliter (pg/ml). A picogram is one trillionth of a gram but for the purpose of my discussion I will just refer to the number, and will not include the picogram unit. In the United States B-12 levels between 200 and 300 are generally considered to be normal but some U.S. B-12 experts prescribe B-12 supplements when the level is less than 450. In Japan and Europe health care providers commonly consider the low limits of normal to be 500 to 550. It is known that nerve problems can occur with levels around 500 so my opinion is that a level of 1000 or slightly higher, such as 1200, is needed to be certain that the body has sufficient B-12 for proper cellular function. B-12 is extremely safe and the body safely and easily eliminates excess B-12.
The Daily Recommended Intake of B-12 is 2 to 3 micrograms (mcg.) (a microgram is one-millionth of a gram) but more B-12 will be needed to boost low levels. There are many forms of B-12 supplements that are widely and inexpensively available in pharmacies and grocery outlets. The most common are tablets that are swallowed. There are also tablets designed to dissolve under the tongue which may increase the amount of B-12 absorbed into the body but usually the swallowed tablets provide enough B-12. Content may vary from 50 mcg to 5,000 mcg. per tablet. There is also a B-12 solution that can be injected into a muscle. Everyone responds differently but typically a 1000 or 2000 mcg daily tablet intake will get a person up to their desired level. If a person is having symptoms of B-12 deficiency it would be likely that their health care provider may recommend higher doses, perhaps by injection, especially in cases where a person can’t absorb B-12 taken by mouth. In any case, it is easy enough to have your health care provider order a serum B-12 level to check the results.
An important mantra regarding the use of medicines in all people, but especially baby boomers and elderly individuals, is that a medicine’s benefit should exceed its potential risks and B-12 is the poster child for that mantra. The risks of B-12 supplementation are miniscule and the potential benefits of achieving and maintaining appropriate B-12 blood levels are off the charts in favor of benefits.