Vitamin B6, also known as pyridoxine, is a water-soluble vitamin that caries out several functions in your body. It’s significant to protein, fat and carbohydrate metabolism and the creation of red blood cells and neurotransmitters. (1) Vitamin B6 plays a key role in keeping the brain and nervous system functioning. 

Vitamin B6 is important for mood regulation and needed for healthy brain development in kids. It helps the body to produce the hormones serotonin and norepinephrine which are vital for your body to cope with stress. Vitamin B6 also plays a role in decreasing high blood levels of the amino acid homocysteine, which has been linked to depression and other psychiatric issues. (2) It also helps the body make melatonin, which is important in helping regulate internal clock and sleep. According to the University of Maryland Medical Center, Vitamin B6 is used to produce several neurotransmitters in the brain. Neurotransmitters are chemicals that carry signals from one nerve cell to another and important for processing thought and healthy brain development. 

Because our body cannot absorb other forms of vitamin B without vitamin B6, inadequate vitamin B6 status is usually associated with low concentrations of other B-complex vitamins, such as vitamin B12 and folic acid. In young children, vitamin B12 deficiency may cause various symptoms including failure to thrive, poor development, and difficulties with movement. (3) Without early treatment, some of the changes may be permanent. Also, Symptoms of vitamin B6 deficiency include a weak immune system, anemia, itchy rashes, cracks at the corners of the mouth and a swollen tongue. Other symptoms of a very low vitamin B6 level include depression and confusion. Some research has associated low plasma vitamin B6 concentrations with an increased risk of certain kinds of cancer. For example, a meta-analysis of prospective studies found that people with a vitamin B6 intake in the highest quintile had a 20% lower risk of colorectal cancer than those with an intake in the lowest quintile. (4)

Vitamin B6 may also be helpful in preventing and treating anemia caused by a deficiency of aiding hemoglobin production. (5) Less hemoglobin can develop anemia and a feeling of weakness and tiredness because the cells are not getting enough oxygen. In addition, Vitamin B6 may prevent clogged arteries and minimize heart disease risk. Research shows that people with low blood levels of vitamin B6 have almost double the risk of getting heart disease compared to those with higher B6 levels. (6) This is likely due to the role of B6 in decreasing elevated homocysteine levels associated with several disease processes, including heart disease. (7) One study shows the beneficial effect of B6 in preventing heart disease. (8) A randomized controlled trial in 158 healthy adults who had siblings with heart disease showed the group that took B6 and folic acid had lower homocysteine levels and less abnormal heart tests during exercise than the placebo group, putting them at an overall lower risk of heart disease. 

References: 

1. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline The National Academies of SCIENCES ENGINEERING MEDICINE. 1998; 

2. Folstein M, Liu T, Peter I, Buell J, Arsenault L, Scott T, Qiu WW. The homocysteine hypothesis of depression. Am J Psychiatry. 2007 Jun;164 (6): 861-7. 

3. Bjørke Monsen AL, Ueland PM. Homocysteine and methylmalonic acid in diagnosis and risk assessment from infancy to adolescence. Am J Clin Nutr. 2003 Jul; 78 (1): 7-21. 

4. Vitamin B6, Medline Plus; Retrieved from: https://medlineplus.gov/ency/article/002402.htm

5. Spinneker A, Sola R, Lemmen V, Castillo MJ, Pietrzik K, González-Gross M. Vitamin B6 status, deficiency and its consequences--an overview. Nutr Hosp. 2007 Jan-Feb; 22 (1): 7-24. 

6. Lin PT, Cheng CH, Liaw YP, Lee BJ, Lee TW, Huang YC. Low pyridoxal 5'-phosphate is associated with increased risk of coronary artery disease. Nutrition. 2006 Nov-Dec; 22 (11-12): 1146-51. 

7. Vermeulen EG, Stehouwer CD, Valk J, van der Knaap M, van den Berg M, Twisk JW, Prevoo W, Rauwerda JA. Effect of homocysteine-lowering treatment with folic acid plus vitamin B on cerebrovascular atherosclerosis and white matter abnormalities as determined by MRA and MRI: a placebo-controlled, randomized trial. Eur J Clin Invest. 2004 Apr; 34 (4): 256-61. 

8. Vermeulen EG, Stehouwer CD, Twisk JW, van den Berg M, de Jong SC, Mackaay AJ, van Campen CM, Visser FC, Jakobs CA, Bulterjis EJ, Rauwerda JA. Effect of homocysteine-lowering treatment with folic acid plus vitamin B6 on progression of subclinical atherosclerosis: a randomised, placebo-controlled trial. Lancet. 2000 Feb 12; 355 (9203): 517-22.