Vitamin B-6 is a water-soluble compound and one of eight vitamins collectively called the B-complex. B-6 is arguably the most important vitamin for energy production, because it’s needed for amino acid metabolism and stomach acid production, and to govern the release of glucose into the bloodstream. However, B-6 is also required for healthy nerve function and the production of neurotransmitters, which are communication chemicals of the nervous system. Neurotransmitters also impact cognition and mood, so you could say that vitamin B-6 is essential for the physical nerves of the body and the “emotional” nerves of how you feel.
Vitamin B-6 Requirements
The recommended dietary allowance of vitamin B6 for adults is no more than 2 milligrams per day. That doesn’t sound like much, but a little goes a long way and too much might lead to nerve toxicity. Nerve toxicity, which often manifests as headaches, fatigue, and tingling, numbness or prickly pain in the arms and legs, is not thought to occur unless you take hundreds of milligrams daily. Consequently, most doctors recommend never taking more than 100 milligrams in a day, which is 50 times more than is probably needed. In contrast, not enough B-6 can manifest as neurological problems such as muscle weakness, spasms, reduced coordination and mood problems.
Vitamin B-6 is needed to make certain enzymes, which play important roles in the synthesis of neurotransmitters such as serotonin, dopamine, epinephrine, norepinephrine and gamma-aminobutyric acid or GABA. Neurotransmitters make it possible for the neurons in your brain and other nerve cells to communicate because they bridge the gaps, or synapses, between the cells. Some neurotransmitters are more involved with mood than others, and serotonin is an essential contributor to feelings of well-being and happiness. Other roles of serotonin include cognitive functions, such as memory and learning, and regulation of appetite, sleep and pain sensation. A lack of serotonin due to B-6 deficiency can lead to depression and a sense of having “frayed” nerves, or feeling anxious. Dopamine is also needed for good mood, but also normal muscle tone and the ability to focus. GABA is sometimes called “nature’s Valium” because it also promotes balanced mood.
Motor Nerve Function
Motor nerve function essentially refers to the ability for “motor” nerves to contract muscles. If not enough B-6 is in your system from dietary sources or supplementation, then a reduction in dopamine and other neurotransmitters can cause tight, twitchy and malfunctioning muscles that refuse to move the way you want them to. Dopamine is also depleted by taking some psychoactive medications, which produces an even more extreme muscle problem called tardive dyskinesia. Supplementing with B-6 might help prevent this debilitating condition, but more research is needed before specific recommendations can be made.
Vitamin B-6 toxicity cannot occur from consuming it via natural foods, but it can occur from supplementing with its synthetic form called pyridoxine. Good dietary sources of B-6 and many other B-vitamins include beef, organ meats, poultry, pork, fish, dairy products, eggs, nuts, wheat germ, beans and green leafy vegetables such as spinach.
- Contemporary Nutrition: Functional Approach; Gordon M. Wardlaw et al.
- Advanced Nutrition and Human Metabolism; James L. Groff et al.
- Textbook of Functional Medicine; David S. Jones
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.