Vitamin B6 (Pyridoxine → PLP)

Overview
Vitamin B6 is a water-soluble vitamin that exists in several forms (pyridoxine, pyridoxal, pyridoxamine) which are converted to the active coenzyme form, pyridoxal 5′-phosphate (PLP), in the brain. PLP serves as a cofactor for the synthesis of all key neurotransmitters including dopamine, serotonin, GABA, and glutamate, supporting rate-limiting steps in catecholamine synthesis. B6 is also an essential cofactor in the remethylation of homocysteine to methionine, working with B2, folate, and B12 in methylation processes. The conversion to PLP requires PDXK (pyridoxal kinase) activity, which is supported by cofactors such as magnesium and ATP.
Dopamine regulation — a core neurotransmitter axis in ADHD — is closely tied to insulin function. Insulin shifts the balance of amino acids in the blood, allowing more tyrosine (dopamine's precursor) to cross into the brain, where it is converted into dopamine with the help of enzymes and cofactors including vitamin B6 Kennedy 2016.
Recipes
Foods
Biological Mechanisms and Implications
References
- Dopamine regulation is closely tied to insulin function; insulin shifts plasma amino acid balance, allowing more tyrosine to cross into the brain, where it is converted to dopamine with enzymatic cofactors including vitamin B6 Kennedy 2016
- B6 is a cofactor in the development of all key neurotransmitters; pyridoxine, pyridoxal, and pyridoxamine cross the blood–brain barrier in non-phosphorylated forms and are converted to PLP by PDXK Spector 1978
- PDXK activity is supported by cofactors such as magnesium and ATP; combined B6 and magnesium supplementation has been reported to reduce inattention and hyperactivity Mousain-Bosc et al. 2006
- B vitamins, particularly B6, B2, folate, and B12, are essential cofactors in remethylation of homocysteine to methionine, which is converted to SAMe
- Riboflavin coenzymes facilitate the metabolism of B12, vitamin B6, and niacin Aragão et al. 2024
- Both dopamine and serotonin synthesis pathways rely on cofactors including iron, B6, folate, omega-3s, and BH₄ to support rate-limiting steps in catecholamine synthesis Fanet et al. 2021
- Magnesium functions as an NMDA receptor antagonist and GABA receptor modulator Clerc et al. 2013
- Zinc acts as an allosteric modulator of the GABA receptor Peralta and Huidobro-Toro 2016
- Low levels of coenzyme B6 can cause dysfunctions prior to the formation of CoQ10 Pravst, Zmitek, and Zmitek 2010
- Since plant-based diets provide less bioavailable B6, deficiencies are more common in vegan and older populations Waldmann et al. 2006
- B6 deficiencies can result from celiac disease, alcoholism, and genetic mutations, leading to serious brain injury and epilepsy Wilson et al. 2019
Foods supply the named dietary input. They are not shown as containing the downstream metabolite. Conversion evidence does not establish a new downstream PM admission, effective dose or equivalent food intervention.
Vitamin B6 → Vitamer-specific endogenous activation; alternative ordered routes, not one chemical reaction → Pyridoxal 5′-phosphate (PLP)
BRS1-FM4-PM9: Maintain sufficient glutamate decarboxylase capacity, and sufficient PLP cofactor to support it, so GABA can be synthesised from glutamate.
Existing admission: Type A / derived; versioned-assessment. The complete derived relationship is admitted for this PM.
Dietary B6 provision of PLP precursors is supported, but increasing B6 intake has not been shown to increase human brain GABA synthesis; PLP supports many enzymes and is not GABA-specific.
- Bananas — supplies Vitamin B6; verified; raw. Bananas, raw
Composition provenance
USDA SR Legacy April 2018
- Beef — supplies Vitamin B6; verified; raw. Beef, ground, 85% lean meat / 15% fat, raw (Includes foods for USDA's Food Distribution Program)
Composition provenance
USDA SR Legacy April 2018
- Black Beans — supplies Vitamin B6; verified; raw. Beans, black, mature seeds, raw
Composition provenance
USDA SR Legacy April 2018
- Broccoli Sprouts — supplies Vitamin B6; verified; raw. Broccoli sprouts, raw (sprout material, not mature broccoli)
Composition provenance
Norwegian Food Composition Table
- Broccoli — supplies Vitamin B6; verified; raw. Broccoli, raw
Composition provenance
USDA SR Legacy April 2018
- Chicken — supplies Vitamin B6; verified; raw. Chicken, broilers or fryers, meat and skin, raw
Composition provenance
USDA SR Legacy April 2018
- Chickpeas — supplies Vitamin B6; verified; raw. Chickpeas (garbanzo beans, bengal gram), mature seeds, raw
Composition provenance
USDA SR Legacy April 2018
- Chicory Root — supplies Vitamin B6; verified; raw. Chicory roots, raw (Cichorium intybus)
Composition provenance
USDA SR Legacy, FDC 169993
- Nori — supplies Vitamin B6; verified; dried. Purple laver (Porphyra spp.), dried, toasted
Composition provenance
MEXT Standard Tables of Food Composition in Japan (2023 supplement), food 09004
- Nutritional Yeast — supplies Vitamin B6; verified; dried. Marigold Engevita Nutritional Yeast Flakes with B12
Composition provenance
Marigold Health Foods label, Engevita with B12
Existing canonical composition record
- Potatoes — supplies Vitamin B6; verified; raw. Potatoes, flesh and skin, raw
Composition provenance
USDA SR Legacy April 2018
- Quinoa — supplies Vitamin B6; verified; uncooked. Quinoa, uncooked
Composition provenance
USDA SR Legacy April 2018
- Salmon Roe — supplies Vitamin B6; verified; form not known. Chum salmon (Oncorhynchus keta), salted roe (ikura)
Composition provenance
MEXT Standard Tables of Food Composition in Japan (2023 supplement), food 10140
- Soy — supplies Vitamin B6; verified; raw. Soybeans, mature seeds, raw
Composition provenance
USDA SR Legacy April 2018
- Spinach — supplies Vitamin B6; verified; raw. Spinach, raw
Composition provenance
USDA SR Legacy April 2018
- Turkey — supplies Vitamin B6; verified; raw. Turkey, whole, meat only, raw
Composition provenance
USDA SR Legacy April 2018
Alternative routes distinguish PL phosphorylation from PN/PM phosphorylation followed by oxidation. Total food vitamin B6 does not identify vitamer proportions, effective brain exposure or a predictable PLP yield.
Dependencies: B6 absorption and availability; Functional PDXK; PNPO and FMN for PNP/PMP routes
Pyridoxal conversion route
- Pyridoxal → pyridoxal-5-phosphate: ATP-dependent vitamer phosphorylation (PDXK; RHEA:10224). PN and PM phosphorylation produces PNP and PMP, not PLP directly. In-vitro metal efficacy does not establish a dietary zinc requirement.
Pyridoxine conversion route
- Pyridoxine → Pyridoxine 5-prime phosphate (PNP): ATP-dependent vitamer phosphorylation (PDXK; RHEA:25108). PN and PM phosphorylation produces PNP and PMP, not PLP directly. In-vitro metal efficacy does not establish a dietary zinc requirement.
- Pyridoxine 5-prime phosphate (PNP) → pyridoxal-5-phosphate: FMN-dependent oxidation to PLP (PNPO; RHEA:15149). Applies to phosphorylated PN/PM; PL does not require this oxidation step. Enzymology does not quantify neuronal PLP occupancy or food-level conversion yield.
Pyridoxamine conversion route
- Pyridoxamine → Pyridoxamine 5-prime phosphate (PMP): ATP-dependent vitamer phosphorylation (PDXK; RHEA:25104). PN and PM phosphorylation produces PNP and PMP, not PLP directly. In-vitro metal efficacy does not establish a dietary zinc requirement.
- Pyridoxamine 5-prime phosphate (PMP) → pyridoxal-5-phosphate: FMN-dependent oxidation to PLP (PNPO; RHEA:15817). Applies to phosphorylated PN/PM; PL does not require this oxidation step. Enzymology does not quantify neuronal PLP occupancy or food-level conversion yield.









