Vitamin B Complex

Eight vitamins grouped under one letter, taken in the morning, which help produce energy from what you eat. This section includes complete B complexes and B12 alone, the benchmark for vegan diets. Active forms, displayed dosages: we explain below how to compare them.

NOW Foods Vitamine B12 5000 µg avec acide folique — 60 pastilles
NOW Foods Vitamine B12 5000 µg 60 pastilles
Now Foods Vitamine B12 5000 mcg pastilles - vue de droite
Now Foods Vitamine B12 5000 mcg pastilles - vue de gauche
NOW Foods

NOW Foods Vitamine B12 5000 µg avec acide folique — 60 pastilles

(0)

12,96 €

NOW Foods Methyl B-12 1000 µg — méthylcobalamine, 100 pastilles
NOW Foods Methyl B-12 1000 µg 100 pastilles
Now Foods Methyl B-12 1000 mcg - vue de droite
Now Foods Methyl B-12 1000 mcg - vue de gauche
NOW Foods

NOW Foods Methyl B-12 1000 µg — méthylcobalamine, 100 pastilles

(0)

10,87 €

NOW Foods Acide folique 800 µg avec vitamine B12 — 250 comprimés
NOW Foods Acide folique 800 µg avec vitamine B12 250 comprimés
Now Foods Acide folique 800 mcg - vue de droite
Now Foods Acide folique 800 mcg - vue de gauche
NOW Foods

NOW Foods Acide folique 800 µg avec vitamine B12 — 250 comprimés

(0)

8,33 €

Now Foods Niacinamide 500 mg — Vitamine B3, 100 gélules
NOW Foods Niacinamide 500 mg, 100 gélules végétales
NOW Foods

Now Foods Niacinamide 500 mg — Vitamine B3, 100 gélules

(0)

13,28 €

NOW Foods Vitamine B1 Thiamine 100 mg — 100 comprimés
NOW Foods Vitamine B1 Thiamine 100 mg 100 comprimés
Now Foods Vitamine B1 Thiamine 100 mg - vue de droite
Now Foods Vitamine B1 Thiamine 100 mg - vue de gauche
NOW Foods

NOW Foods Vitamine B1 Thiamine 100 mg — 100 comprimés

(0)

10,39 €

NOW Foods Vitamine B2 Riboflavine 100 mg — 100 gélules
NOW Foods Vitamine B2 Riboflavine 100 mg 100 gélules
NOW Foods

NOW Foods Vitamine B2 Riboflavine 100 mg — 100 gélules

(0)

11,79 €

NOW Foods Spray liposomal B-12 — framboise, 59 ml
NOW Foods Spray liposomal B-12 framboise 59 ml
NOW Foods

NOW Foods Spray liposomal B-12 — framboise, 59 ml

(0)

17,62 €

NOW Foods Vitamine B12 2000 µg — pastilles trois formes, 100 pastilles
NOW Foods Vitamine B12 2000 µg 100 pastilles
NOW Foods

NOW Foods Vitamine B12 2000 µg — pastilles trois formes, 100 pastilles

(0)

14,47 €

NOW Foods Co-Enzyme B-Complex — vitamines B sous formes actives, 60 gélules
NOW Foods Co-Enzyme B-Complex 60 gélules
Now Foods Co-Enzyme B-Complex - vue de droite
Now Foods Co-Enzyme B-Complex - vue de gauche
NOW Foods

NOW Foods Co-Enzyme B-Complex — vitamines B sous formes actives, 60 gélules

(0)

22,72 €

NOW Foods Méthylfolate 1000 µg Quatrefolic — 90 comprimés
NOW Foods Méthylfolate 1000 µg 90 comprimés
NOW Foods

NOW Foods Méthylfolate 1000 µg Quatrefolic — 90 comprimés

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20,75 €

NOW Foods Vitamine B-50 — complexe des 8 vitamines B
NOW Foods Vitamine B-50 100 gélules
NOW Foods Vitamine B-50 250 gélules
NOW Foods Vitamine B-50 100 comprimés
NOW Foods

NOW Foods Vitamine B-50 — complexe des 8 vitamines B

(0)

From 17,26 €

Now Foods Levure Nutritionnelle en Paillettes — Vitamines B, 284 g
NOW Foods Levure nutritionnelle en paillettes, pot de 284 g
NOW Foods

Now Foods Levure Nutritionnelle en Paillettes — Vitamines B, 284 g

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22,86 €

Now Foods P-5-P 50 mg — Vitamine B6 Active et Magnésium, 90 gélules
Now Foods P-5-P 50 mg — Vitamine B6 Active et Magnésium, 90 gélules
NOW Foods

Now Foods P-5-P 50 mg — Vitamine B6 Active et Magnésium, 90 gélules

(0)

17,98 €

NOW Foods Methyl B-12 5000 µg en gélules — méthylcobalamine, 90 gélules
NOW Foods Methyl B-12 5000 µg 90 gélules
NOW Foods

NOW Foods Methyl B-12 5000 µg en gélules — méthylcobalamine, 90 gélules

(0)

23,98 €

Now Foods Vitamine B6 100 mg — Pyridoxine, 100 gélules
Flacon de Now Foods Vitamine B6 100 mg, pyridoxine, 100 gélules végétales
NOW Foods

Now Foods Vitamine B6 100 mg — Pyridoxine, 100 gélules

(0)

8,90 €

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What do the eight B vitamins do?

"Vitamin B" does not exist in the singular. The B group brings together eight distinct vitamins, unrelated chemically, united by a common history: it was believed that a single water-soluble factor had been isolated before it was understood that it contained several. They share two practical properties: water-soluble, thus poorly stored and eliminated through urine, they almost all act as coenzymes in energy production.

Each carries its own European-authorized health claims, with wording regulated to the word, usable as soon as the product is a "source of" the vitamin concerned, meaning 15% of its nutritional reference value per serving.

  • B1, thiamine (NRV 1.1 mg) — coenzyme in carbohydrate metabolism. "Thiamine contributes to normal energy-yielding metabolism."
  • B2, riboflavin (NRV 1.4 mg) — FAD precursor, electron carrier. "Riboflavin contributes to normal iron metabolism."
  • B3, niacin (NRV 16 mg) — NAD precursor, present in hundreds of reactions. "Niacin contributes to the reduction of tiredness and fatigue."
  • B5, pantothenic acid (NRV 6 mg) — component of coenzyme A. "Pantothenic acid contributes to normal mental performance."
  • B6, pyridoxine (NRV 1.4 mg) — coenzyme in amino acid metabolism. "Vitamin B6 contributes to normal protein and glycogen metabolism."
  • B8, biotin (NRV 50 µg) — coenzyme of carboxylases. "Biotin contributes to the maintenance of normal hair."
  • B9, folate (NRV 200 µg) — one-carbon group transfer, DNA synthesis. "Folate has a role in the process of cell division."
  • B12, cobalamin (NRV 2.5 µg) — coenzyme for only two, but critical, reactions. "Vitamin B12 contributes to normal red blood cell formation."

Six of them — B2, B3, B5, B6, B9, and B12 — also carry the claim "contributes to the reduction of tiredness and fatigue." It means what it says: a contribution, for those who are deficient. It does not make a B complex a stimulant.

Why are they sold as a complex rather than individually?

Three reasons, only two of which are good.

Biochemistry first: these vitamins work in series on the same pathways. Pyruvate from carbohydrates needs B1, B2, B3, and B5 to be oxidized; homocysteine metabolism jointly mobilizes B6, B9, and B12. Providing one without the others only makes sense if a precise point is targeted.

Food sources then: they largely overlap. Offal, meats, eggs, dairy products, legumes, whole grains, green vegetables, and yeasts cover the group fairly homogeneously. A diet poor in one B vitamin is often poor in several — the major exception being B12.

The third reason is commercial: a complex sells better than a single capsule. A "B complex" at 500 or 1000% of NRVs offers nothing more than a reasonable dosage if your intake is adequate, as the excess water-soluble portion is excreted in the urine. The useful benchmark is not the percentage but the adequacy with what you are already taking: many multivitamins cover the entire B group, and combining the two is wasteful.

Why is B12 not optional in a vegan diet?

This is the only case in this entire catalog where we state that supplementation is necessary and not merely useful.

B12 is synthesized only by bacteria. It is found in animal products because these bacteria live in the digestive tract of ruminants, or because the animal has consumed it. No plant contains it in an active form: neither legumes, grains, vegetables, nor any fruit. A strict vegan diet therefore ultimately leads to zero intake.

Two misleading ideas circulate. Spirulina and several algae show "B12" contents that mainly correspond to inactive analogues: these molecules resemble B12 without having its activity and can occupy the same transporters. Spirulina is interesting for other reasons, but it is not a source of B12. Plant proteins, unenriched nutritional yeast, and fermented foods are also not reliable sources.

Key implementation point: B12 absorption is saturable. Active transport, which depends on intrinsic factor secreted by the stomach, only handles a very small amount per intake; the rest only passes through passive diffusion, at about 1% of the dose. Hence, supplements are dosed well above the NRV of 2.5 µg, and weekly high-dose intake is common. The precise regimen—dose, frequency, biological control—should be decided with a doctor.

Methylcobalamin, methylfolate, P5P: Are active forms worth their price?

The commercial argument is always the same: the form sold would be "already active," hence superior to what the body must convert. What can be said honestly:

Methylcobalamin versus cyanocobalamin. Cyanocobalamin is the most stable and well-documented; the body detaches the cyanide group from it, in negligible quantity, and converts it into active forms—including methylcobalamin. The latter is perfectly valid but less stable to light, and no European claim distinguishes it: both carry the same wording.

Methylfolate versus folic acid. Same logic: 5-methyltetrahydrofolate is the circulating form; folic acid must be reduced then methylated, a conversion that MTHFR gene variants slow down in a portion of the population. Methylfolate is a good choice, but folic acid carries most of the available data.

P5P versus pyridoxine. Pyridoxal 5-phosphate (P5P) is the coenzymatic form of B6. A rarely mentioned detail: ingested P5P is in any case dephosphorylated in the intestine before being absorbed, then rephosphorylated in the liver. The theoretical advantage is therefore thinner than advertised, except in specific situations requiring a doctor's advice.

Active forms are therefore not an empty argument, but neither are they the revolution that the price suggests: they do not render classic forms ineffective.

What dose, and what are the safety limits?

Water solubility reassuringly misleads. Three B vitamins have a European upper safety limit, and these are precisely the ones often overdosed in high-percentage complexes.

Vitamin B6 is the most monitored: the European safety limit has been revised downwards and is set at 12 mg per day for adults, from all sources combined. High and prolonged intake of B6 is associated with peripheral nerve damage. However, many B complexes display 25 mg or 50 mg of B6 without any justification — and ZMA formulas also contain it.

Niacin comes in two forms: nicotinic acid, whose limit is very low due to the flushing it causes, and nicotinamide, which is much better tolerated and by far the most commonly used. The mention of the form on the label is therefore important.

Folic acid has a limit set at 1,000 µg per day for adults. High intake can mask a B12 deficiency biologically, which is a serious reason not to stack sources.

Medical advice is essential before any supplementation during pregnancy or breastfeeding — recommendations on folate around conception are precise and fall under the purview of a healthcare professional — for children and adolescents, in cases of kidney failure, during long-term treatment, or in cases of chronic illness.

Frequently Asked Questions

What are B vitamins?

Eight distinct vitamins, chemically unrelated, grouped under the same letter by historical accident: it was long believed that a single water-soluble factor had been isolated before it was discovered that it contained several, hence the gapped numbering we know — B1, B2, B3, B5, B6, B8, B9, B12. They have only two things in common. They are water-soluble, therefore poorly stored and eliminated through urine, requiring regular intake. And almost all act as coenzymes: they provide no energy themselves; they enable enzymes to extract energy from food. This is why a B complex is not a stimulant.

What is the role of B vitamins?

Three main roles, distributed differently depending on the vitamin. First, energy metabolism: B1, B2, B3, and B5 enable the oxidation of carbohydrates, fats, and proteins to produce ATP. Second, DNA synthesis and repair, carried out by folates (B9) and B12, which explains their importance in cell division and red blood cell formation. Finally, the functioning of the nervous system, where B6 is involved in the production of several neurotransmitters and B12 in the maintenance of the myelin sheath. Additionally, B6 plays a role in protein metabolism, particularly stressed in athletes with high protein intake.

How to take a B vitamin complex?

Once a day, with a meal and preferably in the morning or at noon. Taking it with a meal reduces nausea that some formulas cause on an empty stomach; taking it in the morning avoids sleep disturbances reported by some people with highly dosed complexes. Three practical points are more important than the timing. Add up your sources: if you already take a multivitamin or ZMA, a B complex is redundant and increases B6 intake. Check the B6 dose, the only truly sensitive line of a complex. And don't rely on percentages: 1000% of NRVs doesn't make it ten times better, the excess water-soluble portion is excreted in the urine.

Why does urine become bright yellow?

It's riboflavin, vitamin B2: a fluorescent yellow pigment, hence its old name lactoflavin. The unused excess is filtered by the kidneys and colors the urine within a few hours. The phenomenon is harmless and does not indicate a problem or good assimilation: it signals that the dose exceeded what your body could use. Persistent discoloration without supplement intake, however, should be reported to a doctor.

What are the symptoms of a B vitamin deficiency?

First, it must be said why the question is poorly phrased: the eight B vitamins have different roles, and a lack of B1 is not like a lack of B12. Furthermore, proven deficiencies have become rare in France, except in specific situations — vegan diet without supplementation, chronic alcoholism, malabsorption, digestive surgery, malnutrition. The manifestations described in medical literature are severe and specific: anemia and neurological disorders for B12 and folate, nerve damage for B1, skin and mucous membrane lesions for B2 and B3. Vague symptoms often invoked online — fatigue, low mood, dull hair — do not allow for any conclusions: they are shared with dozens of other situations. Doubt is raised by a blood test prescribed by a doctor, not by a purchase.

In which foods are B vitamins found?

Offal and liver cover almost the entire group. Then come meats, fish, eggs and dairy products for B2, B3, B6 and B12; legumes, whole grains and seeds for B1, B6 and B9; leafy green vegetables for folate, whose name comes from the Latin folium, the leaf; brewer's yeast for the entire group except B12.

Which fruit is richest in vitamin B12?

None, and that's the complete answer: B12 is bacterial in origin and is not present in any fruit or vegetable. The richest foods are liver, offal, shellfish and fish, then meat, eggs, and dairy products. For folate (B9), however, citrus fruits, leafy green vegetables, and legumes are good sources.

What are the reasons for a vitamin B12 deficiency?

Two very different mechanisms, which do not call for the same response. The first is insufficient intake: a vegan diet without supplementation, or a diet very low in animal products — this is the only situation where an over-the-counter supplement directly addresses the problem. The second is defective absorption, and it is medical: B12 needs gastric acid to be released from food proteins, then intrinsic factor secreted by the stomach to be absorbed in the ileum. Anything that disrupts this chain causes it to drop: age, which reduces gastric secretion, certain long-term treatments, stomach or intestinal surgeries, inflammatory bowel diseases, and pernicious anemia. In this second case, increasing dietary intake does not solve anything: a blood test and a doctor are needed.

How to detect a vitamin B12 deficiency?

By a blood test prescribed and interpreted by a doctor, and by nothing else. Serum B12 levels are the first test, but they are imperfect: a "borderline" level has no clear meaning, and the doctor may request additional markers — homocysteine, methylmalonic acid — as well as a blood count. Two pitfalls are worth knowing. A high intake of folic acid can correct anemia while allowing neurological damage to progress, which masks the problem. And starting to supplement before testing skews the result: if you suspect a deficiency, get tested first. No symptom, no self-test, and no web page can replace this approach.

How to raise B12 levels?

This question is for a doctor, not a dietary supplement: depending on the cause, high-dose oral and injectable routes do not have the same place, and biological monitoring is part of the treatment. A general public supplement ensures intake for a healthy person; it does not correct a diagnosed anomaly.

How long does a course of B vitamins last?

One to three months is the common duration for a complex, to be reconsidered afterwards. The case of B12 in a vegan diet is different: it is not a course but a permanent intake, as long as the diet continues.

Do B vitamins affect hair?

Only one claim allows this, that of biotin: "Biotin contributes to the maintenance of normal hair," from 7.5 µg per serving. It concerns the maintenance of normal function, not regrowth or density, and does not concern any scalp conditions. A little-known point: high-dose biotin intake can skew certain blood test results—report it before a blood test.

Should I take more after 50?

The relevant question at this age concerns B12, whose absorption from food becomes less efficient, and not the entire group. This is a point to discuss during a check-up, along with vitamin D — not a reason to proactively increase an already highly dosed B6 complex.

What brands are found in this section?

We prioritize labels that name the form of each vitamin rather than those that stack percentages. IO.Genix covers both needs of the section: a complete B complex, and a vegan 1,000 µg sustained-release B12. Now Foods offers a highly dosed methylated B12, a format consistent with the saturable absorption logic described above. Since a multivitamin often duplicates a B complex, choose one or the other. The rest of our micronutrition is in the vitamin C, vitamin E, zinc, magnesium, iron, and omega 3 sections; our sports nutrition guide explains each category, and the complete catalog is under sports nutrition.

Need advice at a store near Montpellier?

Our store in Vendargues, about ten minutes from Montpellier, is where we turn a box over to look at the only line that matters on a B complex: the vitamin B6 dosage. It's also where we most often advise against a purchase, because the person is already taking a multivitamin that covers the group. We ship everywhere in France and Europe. We will explain what a product contains; we will not tell you if you are lacking anything, as that question belongs to your doctor.

Sources: ANSES for nutritional references, Ciqual for food composition, EFSA for authorized claims and upper safety limits.

To go further: the role of vitamin B12 and signs of deficiency.

Sources

À intégrer dans une alimentation variée et équilibrée et un mode de vie sain.

Questions fréquentes — Vitamin B Complex

Les vitamines B, c'est quoi ?

Huit vitamines distinctes, sans parenté chimique entre elles, regroupées sous une même lettre par accident historique : on a longtemps cru avoir isolé un seul facteur hydrosoluble avant de découvrir qu'il en contenait plusieurs, d'où la numérotation trouée que l'on connaît — B1, B2, B3, B5, B6, B8, B9, B12. Elles ont deux points communs seulement. Elles sont hydrosolubles, donc peu stockées et éliminées par les urines, ce qui impose un apport régulier. Et elles agissent presque toutes comme coenzymes : elles ne fournissent aucune énergie par elles-mêmes, elles permettent aux enzymes d'extraire celle des aliments. C'est pourquoi un complexe B n'est pas un stimulant.

Quel est le rôle des vitamines B ?

Trois grands rôles, répartis différemment selon la vitamine. Le métabolisme énergétique d'abord : B1, B2, B3 et B5 permettent d'oxyder glucides, lipides et protéines pour en tirer de l'ATP. La synthèse et la réparation de l'ADN ensuite, portées par les folates (B9) et la B12, ce qui explique leur importance dans la division cellulaire et la formation des globules rouges. Le fonctionnement du système nerveux enfin, où la B6 intervient dans la fabrication de plusieurs neurotransmetteurs et la B12 dans le maintien de la gaine de myéline. S'y ajoute le rôle de la B6 dans le métabolisme des protéines, particulièrement sollicité chez les sportifs à apport protéique élevé.

Comment prendre un complexe de vitamines B ?

Une prise par jour, au cours d'un repas et de préférence le matin ou à midi. Le repas limite les nausées que provoquent certaines formules à jeun ; le matin évite la gêne à l'endormissement que rapportent certaines personnes avec les complexes fortement dosés. Trois points pratiques valent plus que l'horaire. Additionnez vos sources : une multivitamine ou un ZMA couvre déjà une partie du groupe, donc choisissez l'un ou l'autre et suivez le total de B6. Vérifiez la dose de B6, la ligne sensible d'un complexe. Et lisez les milligrammes plutôt que les pourcentages : l'excédent hydrosoluble part dans les urines, un dosage mesuré suffit.

Pourquoi les urines deviennent-elles jaune vif ?

C'est la riboflavine, la vitamine B2 : un pigment jaune fluorescent, d'où son ancien nom de lactoflavine. L'excédent non utilisé est filtré par le rein et colore les urines en quelques heures. Le phénomène est sans gravité et n'annonce ni un problème ni une bonne assimilation : il signale que la dose dépassait ce que votre organisme pouvait employer. Une coloration qui persiste sans prise de complément, elle, se signale à un médecin.

Quels sont les symptômes d'un manque de vitamine B ?

La réponse se décline par vitamine : les huit ont des rôles différents, et un manque de B1 ne ressemble pas à un manque de B12. Les carences avérées sont par ailleurs devenues rares en France, hors situations particulières — régime végétalien sans supplémentation, alcoolisme chronique, malabsorption, chirurgie digestive, dénutrition. Les manifestations décrites dans la littérature médicale sont sévères et spécifiques : anémie et troubles neurologiques pour la B12 et les folates, atteintes nerveuses pour la B1, lésions cutanées et des muqueuses pour la B2 et la B3. Les symptômes vagues souvent invoqués en ligne — fatigue, moral bas, cheveux ternes — sont partagés avec des dizaines d'autres situations : une prise de sang prescrite par un médecin est ce qui permet de conclure.

Dans quels aliments trouve-t-on les vitamines B ?

Les abats et le foie couvrent presque tout le groupe. Viennent les viandes, poissons, œufs et produits laitiers pour B2, B3, B6 et B12 ; les légumineuses, céréales complètes et graines pour B1, B6 et B9 ; les légumes verts à feuilles pour les folates, dont le nom vient du latin folium, la feuille ; la levure de bière pour tout le groupe hors B12.

Quel fruit est le plus riche en vitamine B12 ?

Aucun, et c'est la réponse complète : la B12 est d'origine bactérienne et n'est présente dans aucun fruit ni aucun légume. Les aliments les plus riches sont le foie, les abats, les coquillages et les poissons, puis les viandes, les œufs et les produits laitiers. Pour les folates (B9), les agrumes, les légumes verts à feuilles et les légumineuses sont en revanche de bonnes sources.

Quelles sont les raisons d'un manque de vitamine B12 ?

Deux mécanismes très différents, qui n'appellent pas la même réponse. Le premier est un apport insuffisant : régime végétalien sans supplémentation, ou alimentation très pauvre en produits animaux — c'est la seule situation où un complément grand public répond directement au problème. Le second est une absorption défaillante, et il est médical : la B12 a besoin de l'acidité gastrique pour être libérée des protéines alimentaires, puis du facteur intrinsèque sécrété par l'estomac pour être absorbée dans l'iléon. Tout ce qui perturbe cette chaîne la fait chuter : l'âge, qui réduit la sécrétion gastrique, certains traitements au long cours, les chirurgies de l'estomac ou de l'intestin, les maladies inflammatoires digestives et la maladie de Biermer. Dans ce second cas, augmenter les apports alimentaires ne résout rien : c'est une prise de sang et un médecin qu'il faut.

Comment détecter une carence en vitamine B12 ?

Par une prise de sang prescrite et interprétée par un médecin. Le dosage de la B12 sérique est le premier examen ; un taux dit « limite » n'a pas de signification claire, et le médecin peut demander des marqueurs complémentaires — homocystéine, acide méthylmalonique — ainsi qu'une numération sanguine. Deux points pratiques méritent d'être connus. Un apport élevé en acide folique peut corriger l'anémie tout en laissant progresser l'atteinte neurologique. Et commencer une supplémentation avant le dosage fausse le résultat : le bilan se fait d'abord.

Comment faire remonter un taux de B12 ?

Cette question se règle avec un médecin : selon la cause, la voie orale à forte dose et la voie injectable n'ont pas la même place, et le suivi biologique fait partie du traitement. Un complément alimentaire sécurise un apport chez une personne en bonne santé, ce qui est son rôle.

Combien de temps dure une cure de vitamines B ?

Un à trois mois est la durée courante pour un complexe, à reconsidérer ensuite. Le cas de la B12 en régime végétalien est différent : il ne s'agit pas d'une cure mais d'un apport permanent, aussi longtemps que dure le régime.

Les vitamines B agissent-elles sur les cheveux ?

Une seule allégation le permet, celle de la biotine : « La biotine contribue au maintien de cheveux normaux », à partir de 7,5 µg par portion. Elle porte sur le maintien d'une fonction normale, pas sur la repousse ni la densité, et ne concerne aucune affection du cuir chevelu. Point peu connu : une prise de biotine à forte dose peut fausser certains dosages sanguins — signalez-la avant une prise de sang.

Faut-il en prendre davantage après 50 ans ?

La question pertinente à cet âge porte sur la B12, dont l'absorption à partir des aliments devient moins efficace, et non sur le groupe entier. C'est un point à évoquer lors d'un bilan, en même temps que la vitamine D : la B12 se complète alors à part, plutôt qu'en augmentant un complexe entier.