Vitamin B6 and its role in neurotransmitter production
Vitamin B6 has many important roles.
· Protein metabolism
· Haemoglobin synthesis
· Contributing to normal energy metabolism and production
· Neurotransmitters production, including serotonin, adrenaline, and noradrenaline
· Normal functioning of the nervous system (1, 2, 3, 4)
Foods Containing Vitamin B6
Dietary sources of vitamin B6 include animal products, especially meat, poultry, fish and game products. Other excellent sources include chickpeas, tofu, dairy products and fortified cereals, as well as many vegetable products. (2)
Vitamin B6 Deficiency
The main symptoms of vitamin B6 deficiency are neurological, and include depression, dementia, reduced cognition and neuropsychiatric behaviours. (5) Teenagers are at high risk for vitamin B6 deficiency, as are women, smokers, and underweight people. (2) Many studies have shown that vitamin B6 levels are low in children with ADHD. (5)
Vitamin B6, Gut Microbes, and ADHD
Norepinephrine, tryptophan, serotonin, dopamine and GABA are all either metabolized or formed by enzymes that depend on the active form of vitamin B6 (coenzyme pyridoxal phosphate, or PLP). (6) PLP is also essential for the synthesis of sphingolipids for myelin sheath formation. (3) Myelin sheaths are important to allow for speedy, efficient transmission of electrical impulses along nerve cells, and without them, nerve fibers can die.
In ADHD, an altered composition affecting the immunologic and metabolic function of the gut microbiota early in life has been observed. More research needs to be done on the causal relationship, but there are existing hypotheses that early life disturbance of the microbial metabolism, with subsequent disturbances of tryptophan, serotonin, dopamine, norepinephrine, and GABA metabolism or formation. (6)
A substantial quantity of vitamin B6 is produced in the large intestine by the gut microbes. (6) It has been suggested that disruption of vitamin B6 metabolism is the core biochemical background of ADHD symptoms. (6)
Vitamin B6 Supplementation
Most multi-vitamin supplements contain vitamin B6 in the form of pyridoxine. Although it is almost impossible to get ‘too much’ vitamin B6 from food, you can overdose from supplements, and should stick to the recommended limits to avoid unwanted side effects such as nerve damage, nausea, and heartburn. (2)
1. Federal Register of Legislation. Australia New Zealand Food Standards Code – Schedule 4 – Nutrition, health and related claims. FSANZ [Internet]. 2017 [cited June 21 2020]. Available from: https://www.legislation.gov.au/Details/F2017C00711
2. National Institutes of Health. Vitamin B6 Fact Sheet for Health Professionals [Internet]. 2020 [cited June 22 2020]. Available from: https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/.
3. Braun La, Cohen M. Herbs & natural supplements : an evidence-based guide. Volume 2. Fourth edition. ed: Churchill Livingstone/Elsevier; 2015.
4. Department of Health and Ageing, National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Including Recommended Dietary Intakes. Canberra: Commonwealth of Australia; 2006.
5. Sandgren AM, Brummer RJM. ADHD-originating in the gut? The emergence of a new explanatory model. Medical Hypotheses. 2018;120:135-45.
6. Altun H, Şahin N, Belge Kurutaş E, Güngör O. Homocysteine, Pyridoxine, Folate and Vitamin B12 Levels in Children with Attention Deficit Hyperactivity Disorder. Psychiatria Danubina. 2018;30(3):310-6.