Vitamin B-12 deficiency can be difficult to diagnose clinically, as its symptoms are often nonspecific including:
- Cognitive impairment that could be attributed to old age
Moreover, symptoms vary and often don’t include the classic signals such as:
- macrocytic anemia
- peripheral neuropathy
- subacute combined degeneration of the spinal cord
Standard tests to assess vitamin B-12 concentrations are limited because the clinical severity of vitamin B-12 deficiency is unrelated to vitamin B-12 concentrations.
Accurate identification of vitamin B-12 deficiency is important for a number of reasons. For example, macrocytic anemia, which can be a signal of vitamin B-12 deficiency, may also be caused by folate deficiency. The anemia may have different neurologic features depending on the cause. Therefore, inappropriately treating the condition with folic acid will correct the hematologic signs of vitamin B-12 deficiency but will not address the neurologic symptoms.
Vitamin B-12 deficiency results in elevated serum concentrations of methylmalonic acid (MMA); therefore elevated concentrations of MMA have been suggested to indicate vitamin B-12 deficiency.
However, there is no consensus on cut-off levels of MMA to use to define vitamin B-12 deficiency among elderly people. Among this group, impaired renal function can be an important confounding factor.
Both vitamin B-12 deficiency and folate deficiency are common among older people.
In one study, MMA of less than 200 pmol/L was used to define individuals as being at high risk of vitamin B-12 deficiency.
However, 15 percent to 30 percent of people with high vitamin B-12 concentrations also had elevated MMA concentrations, which indicates that elevated MMA is not always a reliable indicator.
Instead, the ultimate indicator for vitamin B-12 deficiency may be the reduction in MMA concentrations and improvement in clinical symptoms after being treated with vitamin B-12.
Researchers gave the following recommendation for a more reliable screening of vitamin B-12 deficiency: If vitamin B-12 concentration is less than 150 pmol/L, more detailed investigation is required to find an underlying cause and treatment. If vitamin B-12 concentration is between 150 and 200 pmol/L, then use of MMA may help to identify those who require more detailed investigation and treatment.
American Journal of Clinical Nutrition May, 2003;77(5):1241-7 (Free Full Text Article)
This is an excellent study that provides one of the most current assessments on how to scientifically document vitamin B-12 deficiency.
This is the approach you could use if you were compelled to know for certain that there was a B-12 defiency. However, if you look at the big picture it would seem more than reasonable to give a therapeutic trial of B-12 and see if the symptoms improve.
This is more than reasonable considering that B-12 is virtually non-toxic and very inexpensive. This approach would likely cost less than 90 percent of the cost of the test, and even if one did the test, it is common to challenge the results with this type of therapeutic trial as discussed in the article.
So what type of B-12 can you use?
As I said in the past:
It is important to know that most oral vitamin B-12 supplements do not work well at all. Vitamin B-12 is the largest known vitamin; it is a very large molecule, and it is not easily absorbed. Your body has developed a very sophisticated system to absorb B-12, which involves the production of intrinsic factor in the stomach that attaches to the B-12 and allows it to be absorbed in the end of the small intestine.
If your stomach lining is damaged from an ulcer or a Helicobacter infection, you will not produce intrinsic factor very well, and you will not be able to absorb B-12 very well, if at all. An imbalance of bacteria in the small intestine can also produce impaired absorption, as would removal of a portion of the small intestine (commonly done in Crohn's disease).
Vitamin B-12 deficiency is quite common in vegetarians and vegans who do not supplement with B-12 or use fortified foods, since B-12 is not readily available, if available at all, in plants. If you are a vegetarian who eats eggs or fish, the risk for B-12 deficiency is considerably reduced, though you should still consider B-12 supplementation. If you are a vegan avoiding all animal products, and you do not already supplement with B-12 (it seems many already do), you should seriously consider it.
So, if you suspect you are deficient in vitamin B-12, I would encourage you to obtain your B-12 in a more absorbable form. The common recommendation is to use injections. My recommendation for that would be to use 1 ml once a day for two weeks and then three times a week until the 30-ml bottle is finished.
An alternative to the injections would be to use DMSO and vitamin B12. The DMSO causes the B12 to be absorbed very similarly to an injection without the cost or pain of a needle. Intranasal B12 is also available, but unless you have a prescription card I would not recommend it, as it is VERY expensive.
One strong inhibitor of vitamin B-12 absorption is the very popular drug Prilosec (omeprazole), which has been clearly shown to decrease B-12 absorption.