How much B-12 should I take?

DanP · 05-11-2007, 02:23 PM

I'm a idiopathic PNer in my 21st year. My pain is controlled by the Fentanyl Transdermal System patches (generic Duragesic), 125mcg/hr, changed every 2 days. I've been taking 1000mcg of Methylcobalamin B-12 daily for the past 5 years and have noticed no change in my other PN symptoms, i.e., numbness, tingling, stinging, etc., and the feeling that my feet and legs from the knee down is wrapped too tight with ace bandages.

So, I ask: how much Methylcobalamin B-12 should I take and why and on what evidence?

rose · 05-11-2007, 03:46 PM

No guarantee that any dose will repair your damage, but very high doses have been shown very helpful in a significant percentage of people and animals with nerve damage. Even in cases where there is no evidence of B12 deficiency.

5000 mcg is not extremely high. I would certainly give at least that a try for a while. Whether you try several to a bunch of those daily must be up to you. Much evidence that it is safe. They have even given very large daily doses to people whose kidneys cannot eliminate it, so extremely high levels built up without a problem.

Lots of evidence for very high doses of methylcobalamin. Here are a few, chosen pretty much at random because I don't have much time.

Quote:

J Neurol Sci 1994 Apr;122(2):140-3

Ultra-high dose methylcobalamin promotes nerve regeneration in experimental acrylamide neuropathy.

Watanabe T, Kaji R, Oka N, Bara W, Kimura J

Department of Neurology, Kyoto University Hospital, Japan.

Despite intensive searches for therapeutic agents, few substances have been convincingly shown to enhance nerve regeneration in patients with peripheral neuropathies. Recent biochemical evidence suggests that an ultra-high dose of methylcobalamin (methyl-B12) may up-regulate gene transcription and thereby protein synthesis. We examined the effects of ultra-high dose of methyl-B12 on the rate of nerve regeneration in rats with acrylamide neuropathy, using the amplitudes of compound muscle action potentials (CMAPs) after tibial nerve stimulation as an index of the number of regenerating motor fibers. After intoxication with acrylamide, all the rats showed equally decreased CMAP amplitudes. The animals were then divided into 3 groups; rats treated with ultra-high (500 micrograms/kg body weight, intraperitoneally) and low (50 micrograms/kg) doses of methyl-B12, and saline-treated control rats. Those treated with ultra-high dose showed significantly faster CMAP recovery than saline-treated control rats, whereas the low-dose group showed no difference from the control. Morphometric analysis revealed a similar difference in fiber density between these groups. Ultra-high doses of methyl-B12 may be of clinical use for patients with peripheral neuropathies.

Quote:

Muscle Nerve 1998 Dec;21(12):1775-8

Effect of ultrahigh-dose methylcobalamin on compound muscle action potentials in amyotrophic lateral sclerosis: a double-blind controlled study.

Kaji R, Kodama M, Imamura A, Hashida T, Kohara N, Ishizu M, Inui K, Kimura J

To develop a symptomatic treatment for amyotrophic lateral sclerosis, we compared the effects of ultrahigh-dose and low-dose (25 and 0.5 mg/day, intramuscularly, for 14 days) methylcobalamin on averaged compound muscle action potential amplitudes (CMAPs) in a double-blind trial. No significant changes in CMAP amplitude were found in 12 patients who had the low-dose treatment at either 2 or 4 weeks after start of treatment. By contrast, 12 patients assigned to the ultrahigh-dose group demonstrated a significant increase at 4 weeks. This method may provide a clinically useful measure to improve or retard muscle wasting, if a larger extended trial fulfills its promise.

Quote:

Nippon Yakurigaku Zasshi 1976 Mar;72(2):259-68

[Pharmacological studies on degeneration and regeneration of peripheral nerves. (1) Effects of methylcobalamin and cobamide on EMG patterns and loss of muscle weight in rats with crushed sciatic nerve].

Yamatsu K, Kaneko T, Kitahara A, Ohkawa I

Experiments were performed to investigate the effects of Vitamin B12, i.e., methylcobalamin and cobamide, on the neural degeneration and regeneration. Male Wistar rats (140 to 150 g) under conditions of experimental unilateral sciatic nerve crushing were treated consecutively with methylcobalamin (50 and 500 mug/kg/day i.p.), cobamide (50 and 500 mug/kg/day i.p.) or saline. EMG recordings were periodically carried out and rats of each group were sacrificed to determine the weight-loss of denervated muscles 1, 2, 3 and 4 weeks after crush. Neither methylcobalamin nor cobamide exerted any significant effect on body-weight gain of the nerve-crushed rats with a daily injection of 50 and 500 mug/kg i.p.. The EMG pattern of the denervated biceps femoris muscle showed a total lack of fibrillation for 2 days after the nerve-crush. Thereafter, the fibrillation appeared and continued for 10 to 14 days until the nerve had regenerated, as evidenced by the appearance of a complex NMU voltage. The occurrence of fibrillation voltage was slightly delayed in methylcobalamin group (500 mug/kg/day) as compared with the saline control group. The re-appearance of normal NMU voltage was more rapid in the methylcobalamin 500 mug/kg group than in controls and other experimental groups. Neither methylcobalamin nor cobamide had any significant effect on the weight-loss of the gastrocnemius and tibialis anterior muscles following crush of the sciatic nerve. However, a daily injection of 500 mug/kg of methylcobalamin produced a significant increase in the weight of the soleus muscle which recovered to the extent of being the same weight of the contralateral 4 weeks after the nerve-crush. These results suggest that methylcobalamin may have an inhibitory effect on Wallerian degeneration and also a facilitatory effect on the neural regeneration of the crushed sciatic nerve of rats.

mrsD · 05-11-2007, 04:03 PM

You may need other vitamins for support. B12 is only one player.

Folic acid and B6 and EFAs are needed to restore nerve functions.

rose · 05-11-2007, 04:07 PM

Absolutely. Some may only need the methylcobalamin, but it is not worth the risk not to cover the possibility that another B is not getting through in sufficient quantities.

I second the motion: B complex, fish oil ....

rose

DanP · 05-12-2007, 12:29 AM

Thanks for the info. I only have one kidney and am extremely protective of it and I don't want to take anything that could possibly affect it negatively.

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