Which B vitamin is right for you?

What is vitamin B?

Vitamin B is a group of 8 water-soluble vitamins: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folic acid), and B12 (cobalamin). They act as cofactors in hundreds of enzymatic reactions — especially in energy metabolism, nervous system function, and blood formation.

The B vitamins were discovered one by one in the first half of the 20th century — first as a single "vitamin B," later separated when researchers found them to be multiple compounds. Today, we know that each of the eight B vitamins has its own role, but they also work closely together in metabolic networks. A deficiency in one B vitamin often affects the function of the others.

The most important distinction in modern B vitamin supplements is between synthetic precursors and bioactive forms. Folic acid (synthetic) must be converted by the body to 5-MTHF (methylfolate) before it can be used. Cyanocobalamin must be converted to methylcobalamin or adenosylcobalamin. Pyridoxine HCl to pyridoxal-5-phosphate (P5P). For people with an MTHFR gene variant (30-50% of the population), this conversion is less efficient — for them, bioactive forms are significantly more effective.

A specific point of attention: B12. Plant-based foods provide almost no biologically active B12 — vegans and vegetarians need targeted supplementation to prevent deficiency. Spirulina and certain algae contain "pseudo-B12" which is not recognized by the body as active B12 (See our spirulina category for the explanation). For vegans: choose methylcobalamin, not cyanocobalamin. Also, check our multivitamin category for complete-formula options.

Vitamin B and EFSA — what is scientifically recognized?

B vitamins have the most extensive range of recognized EFSA claims of all vitamins. Each individual B vitamin has its own claims; in summary:

"Thiamine (B1) contributes to normal energy-yielding metabolism and to the normal functioning of the nervous system."

"Riboflavin (B2) contributes to the protection of cells from oxidative stress and to normal energy-yielding metabolism."

"Niacin (B3) contributes to the normal functioning of the nervous system and to the reduction of tiredness and fatigue."

"Pantothenic acid (B5) contributes to normal mental performance."

"Vitamin B6 contributes to normal energy-yielding metabolism, to normal protein and glycogen metabolism, and to the reduction of fatigue."

"Biotin (B7) contributes to the maintenance of normal hair, normal mucous membranes and normal metabolism."

"Folic acid (B9) contributes to normal psychological function, to normal amino acid synthesis, to normal blood formation and, in pregnant women, to the growth of maternal tissue."

"Vitamin B12 contributes to normal energy-yielding metabolism, to the normal functioning of the nervous system, to normal red blood cell formation and to the reduction of fatigue."

Thresholds: claims apply with a daily intake of at least 15% RI per serving. Our B-complex formulas typically provide 100-200% RI per B vitamin, well above the threshold.

Synthetic vs. bioactive forms — what suits you?

B9 — folic acid vs. methylfolate (5-MTHF): Folic acid must be enzymatically converted. In MTHFR carriers (30-50% of the population), this conversion is less efficient. 5-MTHF (Quatrefolic, Metafolin) is directly absorbable.

B12 — cyanocobalamin vs. methylcobalamin: Cyanocobalamin: synthetic, cost-effective, needs to be converted. Methylcobalamin: bioactive, directly available for the nervous system. Adenosylcobalamin: for mitochondria.

B6 — pyridoxine HCl vs. P5P (pyridoxal-5-phosphate): Pyridoxine must be converted in the liver. P5P is directly biologically active. For liver burden or impaired liver function, P5P is the premium choice.

Riboflavin B2 — riboflavin vs. riboflavin-5-phosphate (R5P): R5P is directly absorbable; classic riboflavin needs to be converted.

Recommendation: For healthy non-MTHFR carriers <50: synthetic forms work fine. For MTHFR carriers, the elderly, or those with known B vitamin deficiencies: bioactive forms are beneficial. The NVWA indicates that high doses of certain B vitamins, especially B6, can carry risks.

The B vitamin forms at Plenthera

B-complex (synthetic forms)

Classic complete B formula with all 8 B vitamins. Cost-effective, for general supplementation.

B-complex (bioactive / methylated)

Premium version with methylcobalamin, methylfolate, P5P, and R5P. For MTHFR carriers, the elderly, or those who want maximum absorption.

Vitamin B12 (methylcobalamin)

Individual B12 in active form. For vegans, the elderly, people with absorption issues. Dosages 250-2,000 µg.

Folic acid / methylfolate

B9 individually — methylfolate for MTHFR, folic acid for general use. Crucial in preconception and pregnancy. See also the advice from the Health Council on folic acid supplementation.

Biotin (B7)

Individual biotin for hair/skin/nails concerns. Dosages 1,000-10,000 µg. See our biotin category for a specific focus.

Vitamin B6 (P5P)

Individual B6 in bioactive P5P form. For pyridoxine-targeted supplementation, high B6 needs.

Niacin (B3)

Individual niacin — as nicotinic acid (flush effect) or niacinamide (no flush). Dosages 50-500 mg.

How to use vitamin B?

Simple basic approach for B vitamins:

1. Determine your goal: general supplementation (B-complex), MTHFR pathway (bioactive B-complex), specific focus (individual B12, B9, B7).
2. For general maintenance: one B-complex per day — preferably in the morning.
3. For vegans: at least 250 µg methylcobalamin daily, or 2,000 µg 2-3 times per week.
4. For MTHFR carriers and preconception: bioactive B-complex with methylfolate (400-800 µg/day).
5. Take B-complex in the morning — some B vitamins can be alerting (avoid late evening if sensitive).
6. B vitamins are water-soluble — not necessarily with a meal, but sensitive stomachs prefer with food.
7. For high doses of vitamin B6 (>25 mg/day): temporary use and consult with a therapist. UL EFSA: 25 mg/day.
8. For niacin flush with B3 forms: often normal, otherwise choose niacinamide (no flush).

Myths and misconceptions about vitamin B

Myth 1: "Everyone needs a methylated B-complex."

Incorrect. For 50-70% of the population without an MTHFR mutation, the body processes synthetic B vitamins perfectly well. Bioactive forms are useful for MTHFR carriers, the elderly, or with specific complaints.

Myth 2: "B12 can only be given by injection."

Incorrect for most people. Oral methylcobalamin in sufficient dosage (1,000-2,000 µg) achieves comparable blood levels to injections. Injection is only indicated for severe absorption disorders (pernicious anemia, gastric bypass).

Myth 3: "Spirulina provides enough B12 for vegans."

Incorrect. Spirulina contains pseudo-B12, which is not recognized by humans as active B12. Vegans need targeted methylcobalamin supplementation.

Myth 4: "High doses of B-complex provide energy faster."

The effect on energy is a function of correcting a deficiency, not of mega-dosing. Above the RI, extra B-complex does not provide extra energy. However, B6 above 25 mg/day can cause neuropathy in the long term.

Combining Vitamin B with other supplements

B vitamins work in a cofactor network with other nutrients. Commonly chosen combinations:

• Magnesium: cofactor in many B vitamin reactions.
• Vitamin D: for broad basic coverage.
• Iron: B12 and folic acid work together with iron for red blood cells.
• Q10: for mitochondrial energy cluster. See our Q10 category.
• Multivitamin: complete formula that incorporates B-complex.
• Choline: related to methylation cycle, often with B-complex.
• Lion's Mane: for brain concerns in combination with B-complex.

Frequently asked questions

What is vitamin B?

Group of 8 water-soluble vitamins: B1, B2, B3, B5, B6, B7 (biotin), B9 (folic acid), B12. Cofactors in energy metabolism and the nervous system.

What is a B-complex?

Supplement containing all 8 B vitamins. Premium versions contain bioactive forms (methylfolate, methylcobalamin, P5P).

What is methylfolate?

5-methyltetrahydrofolate — bioactive form of B9. Crucial for MTHFR carriers whose folic acid conversion is reduced.

What is methylcobalamin?

Bioactive form of B12 — directly absorbable for the nervous system. Better than cyanocobalamin for vegans, the elderly.

How many B vitamins per day?

Follow a good B-complex (100-200% RI per B). For individual B12 for vegans: 250-1,000 µg/day or 2,000 µg 2-3 times/week.

When to take B vitamins?

Preferably in the morning — some experience an alerting effect. Not right before bedtime.

Do I need an MTHFR test?

Not necessary. A safe strategy is to opt for a methylated B-complex as standard — no disadvantage for non-MTHFR carriers, advantage for carriers.

Vegans and B12 — how do I dose?

250-1,000 µg methylcobalamin per day, or 2,000 µg 2-3 times per week. Spirulina is NOT a source of B12.

What is the difference between folic acid and methylfolate?

Folic acid: synthetic, needs to be converted. Methylfolate: directly biologically active.

Does B6 have an upper limit?

Yes, EFSA-UL 25 mg/day for long-term use. Above this limit, reversible neuropathy can occur.

Sources

• EFSA Regulation (EU) 432/2012 — claims for B vitamins.
• Pietrzik K. et al., "Folic acid and L-5-methyltetrahydrofolate: comparison of clinical pharmacokinetics and pharmacodynamics", Clin Pharmacokinet (2010).
• Stover PJ. & Field MS., "Trafficking of intracellular folates", Adv Nutr (2011).
• Stabler SP., "Vitamin B12 deficiency", N Engl J Med (2013).
• EFSA NDA Panel — Tolerable Upper Intake Level for vitamin B6 (2023 update).