Vitamin B12 Deficiency and Peripheral Neuropathy
Not everybody suffering from peripheral neuropathy needs Vitamin B12, but for patients at our clinic, we always recommend supplementing with it. This article hopefully will explain our thinking.
Deficiency – Who and How
B12 (also known as “cobalamin”), like all vitamins, is a compound that our bodies can’t make that’s needed to function properly. Much of the function of vitamin B12 in our bodies is shared by another B vitamin, folic acid, so if you have adequate stores of folic acid many of the signs of B12 deficiency are covered up. The classic symptom of B12 deficiency (shared with folic acid) is the development of anemia and subsequent tiredness and low energy. Getting B12 shots to relieve this has been a common medical practice for many years.
The area that vitamin B12 seems to have all to its own is in the manufacture of “myelin” which acts as an insulator for nerves, the same way that rubber coating protects electrical wiring. This means that vitamin B12 deficiency leads to nerve damage, even if folic acid is present in good supply and anemia is not present.
Vitamin B12 requirements go up if we have low levels of vitamins C and B1, as well as the amino acid carnitine. Perhaps this is why these substances have also been reportedly helpful for neuropathy.
It’s estimated that Vitamin B12 deficiency affects 10%-15% of people over the age of 60, but you can be deficient if younger. Vitamin B12 is found in animal products so strict vegetarians and vegans have to be aware that they are also at risk. We have about a 5 year storage supply of B12 so symptoms don’t typically appear for some time after we stop taking it in.
B12 in food is bound to other compounds and needs to be freed to be absorbed. Doing this requires normal production of stomach acid and pancreatic digestive enzymes. Cells in the small intestines can then pick up the B12.
Vitamin B12 can also be absorbed by passive diffusion, but this process is very inefficient—only about 1% absorption of the vitamin B12 dose is absorbed passively.
The most common causes of vitamin B12 deficiency are: 1) an autoimmune condition known as pernicious anemia and 2) food-bound vitamin B12 malabsorption. even though they are separate conditions the resulting B12 deficiency is the same and replacement through supplementation is needed to treat the resulting deficiency.
High-dose oral supplementation is a good and inexpensive treatment option, because consuming 1,000 mcg (1 mg)/day of vitamin B12 orally should result in the absorption of about 10 mcg/day (1% of dose) by passive diffusion. In fact, high-dose oral therapy is considered to be as effective as intramuscular injection .
As overall medication use has increased, so have the numbers of medications that can result in B12 deficiency. A short list of drugs that can reduce B12 are:
Unfortunately, there’s not a great way to test for B12 deficiency. The commonly used serum B12 test was shown unreliable many years ago, with many people clinically confirmed to be B12 deficient testing within the “normal” range. The danger is in having too little B12: some of the better “normal” ranges do not have an upper number.
Confirmatory tests for homocysteine(HC) and methylmalonic acid (MMA), products involved in B12 metabolism, have been used more and more recently to better identify problems.
These tests should be given anyone who has symptoms OR a B12 serum less than 350 pg/mL. Unfortunately, they become less useful in those people already taking B12 — the levels may show up as normal since HC and MMA normalize very quickly and stay normal for a long time in spite of deficiency. Additionally, a small percentage of people who are B12 deficient and have had no treatment will simply not show any problems with HC and MMA..
The methylmalonic acid and homocysteine tests cannot rule out B12 deficiency 100%, but taken together they will help a great deal in diagnosing most people with B12 deficiency who have not already begun treatment.
Oral supplementation can work well for most people. It should be taken on an empty stomach, because passive absorption is how the B12 is going to be absorbed in the intestine. Remember, only about 1% is absorbed, so taking seemingly large doses is needed.
Since Vitamin B12 has no known toxic levels taking large doses is very safe.
Although the RDA is only 2 micrograms (mcg) a day, generally, I recommend 5000 mcg (micrograms) a day for those neuopathy sufferers whose blood work shows B12 levels less than 1000. (Note that this blood level would be considered high for many labs, but again toxicity is not an issue here, so don’t be too concerned.)
You can take 5000 mcg (which is the same as 5 mg, by the way) in a single tablet very cheaply in any drug store, and often more cheaply online. Click Here for online stores I’ve found that sell major brands for great prices.
Take one of these daily on an empty stomach for 2 to 3 months then get retested. If you show levels above 1000. You can continue at 5000 mcg/day if you feel you need it or you can reduce to 1000 to 2000 mcg a day, thereafter.
If B12 deficiency is treated early enough, damage may be repaired quickly and completely. However, the longer treatment is delayed, the more likely recovery will take many months to years with the increasing likelihood of being incomplete.
IMPORTANT It sometimes happens that a symptom becomes worse at some point after treatment begins, sometimes dramatically so. This is temporary, but may last a while. This is more likely to happen when damage has been serious.
Another phenomenon is what has been called the “honeymoon”. This is when there a great improvement in the first few days or weeks that really offers hope to people. Then as the body really starts to heal, they experience great fatigue and increased symptoms, leading to a fear that the supplementation isn’t working. Don’t fall for it.
Recovering from nerve damage is hardly ever fast or straightforward. It’s not like recovering form a cold or flu. Unfortunately, many friends, family, and even doctors understand this. Many health care providers assume that as soon as the B12 deficiency is corrected, the body will miraculously be back as good as new. It just isn’t true.
Remember that you are actually growing nerve tissue and sometimes that growth yields odd results. Repair of nerve damage is, as one woman reported “a wild ride”.
I can only urge you to stick with it.