Mechanism of Action
Vitamin B6 acts in its active form, pyridoxal-5-phosphate, as a coenzyme in transamination reactions. These reactions allow the body to redistribute amino groups between amino acids, a central process for recycling and producing the molecules tissues require.
It is involved in the synthesis of four major neurotransmitters: serotonin, dopamine, GABA (a calming messenger of the nervous system) and noradrenaline. Each of these syntheses requires a B6-dependent enzyme. Insufficient intake can slow these production pathways.
In the methylation cycle, B6 drives the transsulfuration pathway. This pathway converts homocysteine into cysteine, an amino acid that serves as a precursor to glutathione (the body's primary intracellular antioxidant). The other arm of the cycle, remethylation, depends on vitamins B9 and B12. Covering both pathways simultaneously constitutes a coherent formulation approach.
B6 also participates in hemoglobin synthesis and glycogen metabolism, the energy reserve mobilized by muscles during physical effort.
Key Benefits
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Vitamin B6 contributes to normal functioning of the nervous system. As a coenzyme, it is required for the synthesis of serotonin, dopamine, GABA and noradrenaline, four neurotransmitters of mood, sleep and cognition.
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Vitamin B6 contributes to the reduction of tiredness and fatigue. The 30 nmol/L plasma pyridoxal-5-phosphate threshold is the value on which EFSA established adult reference intakes.
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Vitamin B6 contributes to normal psychological function. Pyridoxal-5-phosphate is the coenzyme of the decarboxylases that produce serotonin and dopamine from their amino acid precursors.
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Vitamin B6 contributes to normal homocysteine metabolism. It is the coenzyme of cystathionine beta-synthase, the enzyme that commits homocysteine to the transsulfuration pathway.
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Vitamin B6 contributes to the regulation of hormonal activity. It takes part in converting tryptophan into serotonin and then melatonin, the hormone that paces the sleep-wake cycle.
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Vitamin B6 contributes to normal protein and glycogen metabolism. Pyridoxal-5-phosphate is the coenzyme of the transaminases, which redistribute amino groups between amino acids, and of glycogen phosphorylase.
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Vitamin B6 contributes to the normal function of the immune system. Pyridoxal-5-phosphate takes part in the synthesis of the amino acids and nucleic acids that cell renewal draws on.
Dosage & Forms
Several forms of vitamin B6 are available for supplementation. Pyridoxine (pyridoxine hydrochloride) is the most common and least expensive form. Pyridoxamine, naturally present in animal-source foods, and pyridoxal-5-phosphate (P5P) complete the forms authorised for food supplements in the European Union.
P5P is the coenzyme form, the one enzymes bind to. Singular selects P5P monohydrate. Whichever form is ingested, phosphorylated vitamers are dephosphorylated before intestinal absorption, then rephosphorylated in the liver. The P5P route does not add the oxidation step that pyridoxine requires on top.
Adult reference intakes set by EFSA are 1.6 mg/day for women and 1.7 mg/day for men. The upper safety level, revised by the same authority in 2023, is 12 mg per day for vitamin B6, all forms included. It rests on the risk of peripheral neuropathy documented at high and prolonged intakes. No Singular tier exceeds it.
In the Singular Formula
Inclusion rationale
Vitamin B6 contributes to normal energy-yielding metabolism, to normal functioning of the nervous system, to normal psychological function, to the reduction of tiredness and fatigue, to normal protein and glycogen metabolism and to the regulation of hormonal activity. Cofactor of more than 100 enzymes, B6 is primarily involved in amino acid metabolism, neurotransmitter synthesis (serotonin, dopamine, GABA, noradrenaline) and hemoglobin synthesis. It also participates in the conversion of tryptophan to niacin (vitamin B3). In the methylation cycle, B6 is the cofactor of the transsulfuration pathway of homocysteine, complementary to the remethylation pathway dependent on vitamins B12 and B9. The P-5-P (pyridoxal-5-phosphate) form selected is the coenzyme vitamer, the one enzymes bind to. Its activation proceeds through phosphorylation by pyridoxal kinase, without the additional oxidation step that pyridoxine requires.
Selected form
Active form of vitamin B6: pyridoxal-5-phosphate (P5P) monohydrate, diluted on maltodextrin, its only declared carrier. P5P is the vitamer enzymes bind to: it serves as a coenzyme for more than 100 enzymes, particularly in amino acid metabolism and neurotransmitter synthesis. Its activation route proceeds through phosphorylation by pyridoxal kinase, without the additional oxidation step that pyridoxine requires. Vitamin B6 contributes to normal functioning of the nervous system and to the reduction of tiredness and fatigue.
Formula dosage
0 to 7 mg.
Dose expressed as active substance, excluding excipients and carriers of the raw material.
Synergies in the formula
Safety & Precautions
Vitamin B6 is well tolerated at nutritional doses. Documented adverse effects concern high and prolonged intakes, which can cause sensory peripheral neuropathy, most often reversible on discontinuation. This is the endpoint on which EFSA set its 12 mg per day level in 2023.
B6 supplementation is not recommended when taking levodopa alone (without a decarboxylase inhibitor), as B6 can accelerate the peripheral conversion of levodopa and reduce its efficacy. This interaction does not apply to the commonly prescribed levodopa-carbidopa combinations.
During pregnancy and breastfeeding, Singular caps vitamin B6 at the intermediate tier. The European level of 12 mg per day covers both situations. Professional advice remains recommended for any supplementation beyond reference intakes.
Scientific Studies
| Authors | Year | Type | Journal | |
|---|---|---|---|---|
| EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) | 2016 | Review | EFSA Journal | View on PubMed |
Dietary Reference Values for vitamin B6 European scientific opinion setting dietary reference values for vitamin B6. The panel takes plasma pyridoxal-5-phosphate as the status biomarker, and a population mean of 30 nmol/L as the adequacy cut-off. Adult reference intakes follow: 1.6 mg per day for women and 1.7 mg per day for men. | ||||
| EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) | 2023 | Review | EFSA Journal | View on PubMed |
Scientific opinion on the tolerable upper intake level for vitamin B6 European revision of the tolerable upper intake level for vitamin B6, published on 17 May 2023. The critical endpoint is peripheral neuropathy, whose relationship with excess intake is established. The level is set at 12 mg per day for adults, including pregnant and lactating women, and covers all forms of the vitamin. | ||||