Vitamin B6 – An overview
Vitamin B6 is a collective term for pyridoxines, water-soluble vitamins responsible for more than 100 enzyme reactions, mostly concerned with nucleic acid and protein metabolism. (1,2) Vitamin B6 status can have a significant impact on immune function due to its role in promoting lymphocyte and IL-2 production, and hemoglobin formation. (1,2)
Foods with naturally occurring vitamin B6 include fish, beef, organ meats, starchy vegetables, fruit (but not citrus), and fortified cereals, and it is also possible to get vitamin B6 in supplement form. (1)
Vitamin B6 deficiency
Isolated vitamin B6 deficiency is relatively uncommon, as it usually occurs alongside vitamin B12 and folate deficiency. (1) Deficiency is most common in people with malabsorption syndromes, including celiac disease, Crohn’s disease, and ulcerative colitis. It is also reasonably common in women of childbearing age, the elderly, the obese, and pregnant women, especially those with pre-eclampsia or eclampsia. (1, 3) Borderline deficiency can go unnoticed for months, or even years, but even a mild deficiency has been associated with a weakened immune system. (1)
Vitamin B6 – Role in Immune Function
Many studies have shown that a deficiency in vitamin B6 can impair immune responses, resulting in higher likelihood of developing infections and disease. (3, 4) Vitamin B6, along with vitamin B9, B12, A and D, enhance the cell-mediated immune response by producing more cytokines, antibodies, and T-lymphocytes, as well as assisting with the communication between the cytokines and chemokines. (4) A deficiency in vitamin B6 may weaken immunity by decreasing the serum antibody and IL-2 production and increasing the level of IL-4. (3)
Vitamin B6 deficiency also reduces lymphocyte growth and proliferation, as well as T cell activity. (3,4) This reduction in the number of T lymphocytes may be due to an impaired immune function in response to the stimulation of ConA by a diet deficient in vitamin B6. (3) These responses in the body all directly impact immune response.
Vitamin B6 also acts as a cofactor for certain enzymes, assisting them with their particular functions. (4) The blood levels of homocysteine, a common amino acid, is also regulated by vitamin B6 status, and high amounts of homocysteine in the blood are associated with increased heart disease and cardiovascular death. (4)
Our bodies need vitamin B6 for optimal absorption of vitamin B12 in the body, as well as to produce red blood cells and other immune cells. (4) Vitamin B6 is also important in the production of several neurotransmitters, which are chemicals that carry signals from one nerve cell to another. (4) One such neurotransmitter is serotonin, which can only be synthesized by tryptophan, a conversion which relies on the presence of pyridoxal phosphate, a derivative of vitamin B6. (4)
Vitamin B6 – Supplementation
Supplementation of vitamin B6 can also affect the differentiation of immature T cells to mature T cells, potentially increasing their immune responsiveness. (3) Studies have shown that vitamin B6 supplementation can assist in improving the immune system impairments caused by short-term vitamin B6 deficiency. (3) Most vitamin B6 supplements are available in the form of pyridoxine. (1)
1. National Institutes of Health. Vitamin B6 Fact Sheet for Health Professionals [Internet]. 2020 [cited July 16 2020]. Available from: https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/
2. Rall LC, Meydani SN. Vitamin B6 and immune competence. Nutrition reviews. 1993;51(8):217-25.
3. Qian B, Shen S, Zhang J, Jing P. Effects of Vitamin B6 Deficiency on the Composition and Functional Potential of T Cell Populations. Journal of Immunology Research. 2017;2017.
4. Aslam MF, Majeed S, Aslam S, Irfan JA. Vitamins: Key Role Players in Boosting Up Immune Response - A Mini Review. Vitamins & Minerals. 2017;6(1).