B6 – former, produktmängder och gränser för vad forskningen visar

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URL: https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/
Source date: 2023-06-16
Acquisition: Official NIH page rendered by web reader. Whole selected paragraphs; link markers replaced with their displayed labels only. No HTML/full article file fetched. Not an original clinical trial. Source line capture SHA-256: 700530f0c2a250e814732c3b1bd03bb3afdbd7e2df4c12bcc1132512d87a0bd9

Vitamin B6 is a water-soluble vitamin that is naturally present in many foods, added to others, and available as a dietary supplement. It is the generic name for six compounds (vitamers) with vitamin B6 activity: pyridoxine, an alcohol; pyridoxal, an aldehyde; and pyridoxamine, which contains an amino group; and their respective 5'-phosphate esters. Pyridoxal 5' phosphate (PLP) and pyridoxamine 5' phosphate (PMP) are the active coenzyme forms of vitamin B6 [1 ,2 ].

Substantial proportions of the naturally occurring pyridoxine in fruits, vegetables, and grains exist in glycosylated forms that exhibit reduced bioavailability [3 ].

Vitamin B6 is available in multivitamins, in supplements containing other B complex vitamins, and as a stand-alone supplement [7 ]. The most common vitamin B6 vitamer in supplements is pyridoxine (in the form of pyridoxine hydrochloride [HCl]), although some supplements contain PLP. Vitamin B6 supplements are available in oral capsules or tablets (including sublingual and chewable tablets) and liquids.

Absorption of vitamin B6 from supplements is similar to that from food sources and does not differ substantially among the various forms of supplements [1 ]. Although the body absorbs large pharmacological doses of vitamin B6 well, it quickly eliminates most of the vitamin in the urine [8 ].

Scientists have hypothesized that certain B vitamins (folic acid, vitamin B12, and vitamin B6) might reduce cardiovascular disease risk by lowering homocysteine levels [1 ,13 ]. Therefore, several clinical trials have assessed the safety and efficacy of supplemental doses of B vitamins to reduce heart disease risk. Evaluating the impact of vitamin B6 from many of these trials is challenging because these studies also included folic acid and vitamin B12 supplementation.

For example, the Heart Outcomes Prevention Evaluation 2 (HOPE 2) trial, which included more than 5,500 adults with known cardiovascular disease, found that supplementation for 5 years with vitamin B6 (50 mg/day), vitamin B12 (1 mg/day), and folic acid (2.5 mg/day) reduced homocysteine levels and decreased stroke risk by about 25%, but the study did not include a separate vitamin B6 group [14 ].

Moreover, most other large clinical trials have failed to demonstrate that supplemental B vitamins actually reduce the risk of cardiovascular events, even though they lower homocysteine levels. For example, a randomized clinical trial in 5,442 women age 42 or older found no effect of vitamin B6 supplementation (50 mg/day) in combination with 2.5 mg folic acid and 1 mg vitamin B12 on cardiovascular disease risk [15 ].

Two large randomized controlled trials, the Norwegian Vitamin Trial and the Western Norway B Vitamin Intervention Trial, did include a group that received only vitamin B6 supplements (40 mg/day). The combined analysis of data from these two trials showed no benefit of vitamin B6 supplementation, with or without folic acid (0.8 mg/day) plus vitamin B12 (0.4 mg/day), on major cardiovascular events in 6,837 patients with ischemic heart disease [13 ].

In a trial of adults who had suffered a nondisabling stroke, supplementation with high or low doses of a combination of vitamins B6 and B12 and folic acid for 2 years had no effect on subsequent stroke incidence, cardiovascular events, or risk of death [16 ].

The research to date provides little evidence that supplemental amounts of vitamin B6, alone or with folic acid and vitamin B12, can help reduce the risk or severity of cardiovascular disease and stroke.

High intakes of vitamin B6 from food sources have not been reported to cause adverse effects [1 ]. However, chronic administration of 1–6 g oral pyridoxine per day for 12–40 months can cause severe and progressive sensory neuropathy characterized by ataxia (loss of control of bodily movements) [10 ,30-33 ]. Symptom severity appears to be dose dependent, and the symptoms usually stop if the patient discontinues the pyridoxine supplements as soon as the neurologic symptoms appear.

Other effects of excessive vitamin B6 intakes include painful, disfiguring dermatological lesions; photosensitivity; and gastrointestinal symptoms, such as nausea and heartburn [1 ,2 ,30 ].

The scientific literature includes isolated case reports of congenital defects in the infants of women who took pyridoxine supplements during the first half of pregnancy [7 ]. However, a more recent observational study found no association between pyridoxine supplementation (mean dose 132.3 ± 74 mg/day) in pregnant women starting at 7 weeks gestation and continuing for 9 ± 4.2 weeks and teratogenic effects in their infants [34 ].

The FNB has established ULs for vitamin B6 that apply to both food and supplement intakes (Table 3) [1 ]. The FNB noted that although several reports show sensory neuropathy occurring at doses lower than 500 mg/day, studies in patients treated with vitamin B6 (average dose of 200 mg/day) for up to 5 years found no evidence of this effect. Based on limitations in the data on potential harms from long-term use, the FNB halved the dose used in these studies to establish a UL of 100 mg/day for adults.

ULs are lower for children and adolescents based on body size. The ULs do not apply to individuals receiving vitamin B6 for medical treatment, but such individuals should be under the care of a physician.

In 2023, the Panel on Nutrition, Novel Foods and Food Allergens of the European Food Safety Authority (EFSA) released a scientific opinion on the tolerable upper intake levels for vitamin B6 [35 ].

Based on systematic reviews that examined associations between vitamin B6 and peripheral neuropathy, the panel set an upper limit for vitamin B6 of 12 mg/day for all adults, including women who are pregnant or lactating, with lower amounts ranging from 2.2 to 10.7 mg/day for infants and children, depending on age.

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Full current exact imported definitions of distinct identities; not an identity merge

{"id":"chebi-16709","version_id":"01baf522-b060-4121-8576-d95e56bf43ec","name":"pyridoxine","definition":"A hydroxymethylpyridine with hydroxymethyl groups at positions 4 and 5, a hydroxy group at position 3 and a methyl group at position 2. The 4-methanol form of vitamin B<small><sub>6</sub></small>, it is converted intoto pyridoxal phosphate which is a coenzyme for synthesis of amino acids, neurotransmitters, sphingolipids and aminolevulinic acid."}

{"id":"chebi-27306","version_id":"4b26fee1-ea19-44d7-9ead-2e0617ac22c6","name":"vitamin B6","definition":"Any member of the group of pyridines that exhibit biological activity against vitamin B<small><sub>6</sub></small> deficiency. Vitamin B<small><sub>6</sub></small> deficiency is associated with microcytic anemia, electroencephalographic abnormalities, dermatitis with cheilosis (scaling on the lips and cracks at the corners of the mouth) and glossitis (swollen tongue), depression and confusion, and weakened immune function. Vitamin B<small><sub>6</sub></small> consists of the vitamers pyridoxine, pyridoxal, and pyridoxamine and their respective 5'-phosphate esters (and includes their corresponding ionized and salt forms)."}

{"id":"chebi-30961","version_id":"57d1418b-0a23-4636-b807-c1f49501dc4b","name":"pyridoxine hydrochloride","definition":"The hydrochloride salt of pyridoxine."}

{"id":"chebi-18405","version_id":"944d94e9-40f6-4efc-a07b-c06b59e977cd","name":"pyridoxal 5'-phosphate","definition":"The monophosphate ester obtained by condensation of phosphoric acid with the primary hydroxy group of pyridoxal."}

{"id":"chebi-597326","version_id":"fa352dbb-997d-469a-9ff8-c6f8b59a5fea","name":"pyridoxal 5'-phosphate(2-)","definition":"The dianion resulting from the removal of two protons from the phosphate group of pyridoxal 5'-phosphate."}

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Supplement Facts
Serving Size: 1 Tablet
Servings Per Container: 180
	Amount Per Serving	%Daily Value
Vitamin B6 (as pyridoxine hydrochloride)	5 mg	294%
Folate (as 400 mcg folic acid)	667 mcg DFE	167%
Vitamin B12 (as cyanocobalamin)	1,000 mcg	41,667%

Xylitol, mannitol, citric acid, microcrystalline cellulose, natural berry flavor, silicon dioxide, sodium starch glycolate, croscarmellose sodium, sucralose, magnesium stearate. 
Free of sugar, yeast, wheat, egg, artificial colors, flavors, and preservatives.

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Germe de sarrasin, magnésium marin (oxyde de magnésium extrait d’eau de mer), gélule végétale (pullulan).Déclaration nutritionnelle pour 2 gélules :Germe de sarrasin : 712 mgdont vitamine B6 (pyridoxine) : 1,30 mg (93 % des VNR*)dont vitamine B9 (acide folique) : 238 µg (119 % des VNR*)dont vitamine B12 (cobalamine): 2,5 µg (100 % des VNR*).Magnésium : 273 mg (72 % des VNR*)*Valeurs Nutritionnelles de Référence.

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Magnesiumoxid, Füllstoff Cellulose, Füllstoff vernetzte Carboxymethylcellulose, Trennmittel Siliciumdioxid, Überzugsmittel Hydroxypropylmethylcellulose, Palmfett (ganz gehärtet), Trennmittel Talkum, Farbstoff , Trennmittel Calciumsalze der Speisefettsäuren, Überzugsmittel Schellack, Pyridoxinhydrochlorid, Emulgator Mono- und Diglyceride von Speisefettsäuren, Thiaminmononitrat, Olivenöl, Emulgator Polysorbat 80, Pteroylmonoglutaminsäure, Cyanocobalamin.