Download Neurotropic B Vitamins and Their Role in Nerve Care

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Nourishing our
Nerves: Neurotropic
B Vitamins and Their
Role in Nerve Care
Overview of neurotropic B vitamins
Neurotropic B vitamins are a combination of vitamins that
play an important role in the health of the nervous system;
they nourish and help regenerate nerves. These vitamins,
thiamine (B1), pyridoxine (B6), and cobalamin (B12), are
naturally obtained by eating meat, eggs, and grains.1,2
Because of the unique roles each of the neurotropic vitamins
play in the health of the nervous system, all of them are
essential, and a combination of all three may be needed to
treat deficiencies. In an animal model, a combination of
neurotropic B vitamins was found to be more effective at
alleviating symptoms of neuropathy than B1, B6, or B12 given
alone. 10
Deficiencies in neurotropic B vitamins
Neurotropic B vitamin deficiencies occur for various reasons,
such as malabsorption (e.g. post-bariatric surgery), low
intake due to malnutrition or specific nutritional habits e.g.
vegetarians, increased demand (e.g. pregnancy), or increased
loss or malfunction associated with certain disease states
(e.g. renal disease).
Many conditions that cause B vitamin deficiency are chronic
and/or irreversible, such as diabetes, renal impairment,
gastrointestinal diseases, and advanced age. 5,11 These
patients should be monitored and potentially treated as
long as the condition causing B vitamin deficiency is present
(e.g. long term treatment may be required). In most of these
conditions, patients are deficient in all three neurotropic
B vitamins – B1, B6 and B12.
Symptoms of B vitamin deficiency vary. Neurological symptoms can include sensory disorders, peripheral neuropathy,
polyneuritis, and weak muscle reflexes and/or coordination disorders (including gait impairment). Other possible
symptoms are tiredness, hyperhomocysteinaemia, anaemia,
cardiovascular dysfunction, or (in chronic deficiency) emotional disturbance. 3,5,7,12-14
In cases where B vitamin deficiency is suspected, neurotropic
B vitamin supplementation is a well-tolerated approach
to provide treatment. Some deficiency-related disease/
symptoms can be reversed with neurotropic B vitamin
supplementation. 15 However, early diagnosis is crucial for
avoiding irreversible neurological damage. 14
At therapeutic levels, neurotropic B vitamins have been
shown to have a restorative effect on peripheral nerve
Structure of a healthy peripheral nerve:
The neurotropic B vitamins contribute to nerve health via different mechanisms.
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SA Pharmacist’s Assistant [Winter 2016]
SUPPLEMENTS
Dietary sources of the neurotropic B vitamins
Vitamin B1
Vitamin B6
Vitamin B12
Meat (especially pork and beef), liver,
eggs, yeast, some species of fish,
whole grain cereals and bread, nuts,
pulses, potatoes
Chicken, liver, pork and veal, fish, nuts,
bread, corn and whole grain cereals
Animal protein, liver, kidney,
fish, eggs, dairy
Vitamin Role in nerve health
B1
Other contributions to health and metabolism
Involved in providing energy to nerve cells, maintenance of
Energy metabolism, muscle function
myelin sheath which covers the axon of nerves, nerve stimulation
and synthesis of neurotransmitters (acetylcholine, amino acids)
3-5
B6
Synthesis of key signalling molecules in the nervous system:
neurotransmitters (epinephrine, norepinephrine, dopamine,
serotonin, glycine, and gamma-aminobutyric acid [GABA]) 6-8
Carbohydrate and fat synthesis and breakdown, protein and
amino acid metabolism, haemoglobin synthesis, homocysteine
metabolism
B12
Nerve cell maturation and regeneration, nerve cell metabolism
(transmethylation processes), and formation of nerve myelin
sheaths/remyelination (lipid and carbohydrate metabolism
therein) 2,9
Fatty acid synthesis, nucleic acid/DNA synthesis, energy
production, formation of red blood cells and maturation of other
cells
Vitamin
Therapeutic dose
Recommended daily allowance (RDA)
B1
100 – 300mg (oral application) 5
1.1 – 1.2 mg 5,16
B6
50 – 600 mg (oral application)
1.3 – 1.7 mg 13,16
B12
0.2 – 2 mg (oral application)
2.0 – 2.4 μg* 9,14-16
function. 7 The levels of B vitamins present in a healthy diet
do not provide these pharmacological effects and would not
serve the needs of patients at risk.
6. Frye RE, Jabbour SA. Pyridoxine Deficiency. Secondary Pyridoxine Deficiency 2014.
http://emedicine.medscape.com/article/124947-overview#showall.
For vitamin B deficiencies associated with chronic disease
or which are irreversible, long-term treatment with a
pharmacological dose of neurotropic B vitamins may be
required. 14
8. Dakshinamurti K, Paulose CS, Viswanathan M, et al. Neurobiology of pyridoxine.
Annals of the New York Academy of Sciences 1990;585:128-44.
References
11.Head KA. Peripheral neuropathy: pathogenic mechanisms and alternative
therapies. Altern Med Rev 2006;11(4):294-329.
1. Watanabe T, Kaji R, Oka N, et al. Ultra-high dose methylcobalamin promotes nerve
regeneration in experimental acrylamide neuropathy. Journal of the neurological
sciences 1994;122(2):140-3.
12. Bernstein AL. Vitamin B6 in clinical neurology. Ann N Y Acad Sci 1990;585:250-60.
2. Zhang M, Han W, Hu S, et al. Methylcobalamin: a potential vitamin of pain killer.
Neural Plast 2013;2013:424651.
3. Singleton CK, Martin PR. Molecular mechanisms of thiamine utilization. Curr Mol
Med 2001;1(2):197-207.
4. Smithline HA, Donnino M, Greenblatt DJ. Pharmacokinetics of high-dose oral
thiamine hydrochloride in healthy subjects. BMC Clin Pharmacol 2012;12:4.
5. Sriram K, Manzanares W, Joseph K. Thiamine in nutrition therapy. Nutr Clin Pract
2012;27(1):41-50.
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SA Pharmacist’s Assistant [Winter 2016]
7. Reyes-Garcia G, Medina-Santillan R, Flores-Murrieta FJ, et al. Analgesic effects of B
vitamins: A review. Curr Topics in Pharmacology 2006;10(1).
9. Stabler SP. Vitamin B12 deficiency. The New England journal of medicine
2013;368(21):2041-2.
10. Jolivalt CG, Mizisin LM, Nelson A, et al. B vitamins alleviate indices of neuropathic
pain in diabetic rats. Eur J Pharmacol 2009;612(1-3):41-7.
13. Kjeldby IK, Fosnes GS, Ligaarden SC, et al. Vitamin B6 deficiency and diseases in
elderly people--a study in nursing homes. BMC Geriatr 2013;13:13.
14. Briani C, Dalla Torre C, Citton V, et al. Cobalamin deficiency: clinical picture and
radiological findings. Nutrients 2013;5(11):4521-39.
15. Woo KS, Kwok TC, Celermajer DS. Vegan diet, subnormal vitamin B-12 status and
cardiovascular health. Nutrients 2014;6(8):3259-73.
16. World Health Organization, Food and Agriculture Organization of the United
Nations. Vitamin and mineral requirements in human nutrition: Second edition.
China, 2004.