B-complex
Sold for energy, stress and mood. Unless a test shows you are short of a B vitamin it does very little, and most Canadian products contain 50 mg or more of vitamin B6, enough to risk the nerves.
At a glance
| Our verdict | Gives no energy or calm unless you are short of a B vitamin, and 8 in 10 sold in Canada contain 10 mg or more of vitamin B6. |
| Sold for | Energy and stress (claimed) |
| How sure the evidence is | Low for any benefit |
| Cost a month | About $4 (a B-50 complex) |
Written for adults in Canada. It explains the evidence; it is not advice for you personally. Last reviewed 20 October 2026.
Supplement Check
Is it right for you?
Already taking a B-complex? Most contain far more B6 than our 10 mg limit, and some contain biotin that upsets blood tests. Your check counts what is in yours and tells you whether to stop it. Our Supplement Check looks at:
- Tingling, numbness or burning in the hands or feet
- Diabetic kidney disease
- Whether you smoke
- Pregnancy
- Any blood test you have booked (biotin can upset the results)
- Every medicine you take
- The total across everything you already take, against the safe upper limits
Coming soon. The Supplement Check and the Online Health Assessment open once our safety testing is complete.
$59 when it opens, paid once. Adults 18 and over, anywhere in Canada. While the service is new, Dr. French reads every report himself, and your report arrives within 3 working days. More about the Supplement Check
What it is
A combination of B1, B2, B3 (usually nicotinamide), B5, B6, biotin (B7), folic acid or methylfolate (B9) and B12, often named by dose: a “B-50” or “B-100” gives 50 or 100 mg each of B1, B2, B3, B5 and B6. Many add vitamin C, herbs such as rhodiola, or “stress” branding.
In Canada, the median B-complex gives 50 mg of B6 a day. Examples on sale: a common B-complex with 50 mg a caplet, up to 2 a day; an athlete's B-complex with 100 mg; another with 200 mg. Products under 10 mg exist (one has 5 mg). [1]
How it acts
B vitamins are helpers (coenzymes) for the body's energy reactions. In someone who is short of one, replacing it restores the reaction. In someone who is not, extra does nothing more: there is no drug-like action above what the body needs.
What it is used for, and what the evidence says
| Use | What the trials found | How sure we are |
|---|---|---|
| Stress, healthy and “at-risk” adults | In 16 trials (2,015 people) of at least 3 B vitamins for 4 weeks or more, self-rated stress improved by a small amount (a standardised effect of 0.23; range 0.02 to 0.45), from the 958 people with stress measured. Three of the authors were funded by the supplement industry. [2] | Low |
| Low mood | Same review: effect 0.15, which could be zero. [2] | Low |
| Anxiety | Same review: no effect (0.03). [2] | Low |
| Fatigue, memory and mood (B12 alone) | Without a deficiency, B12 had no effect on thinking, mood or fatigue. [3] | Moderate |
| Heart attack, stroke and death | All B vitamins together lowered stroke a little (4.3% against 5.1% over the trials) and did nothing for heart attack or death. [4] A larger stroke benefit with folic acid was seen in China, where flour is not fortified; [5] Canadian flour is, so it does not transfer here. | High |
| Diabetic kidney disease (harm) | In a Canadian trial, B6 25 mg, folic acid 2.5 mg and B12 1 mg a day made kidney function fall faster and doubled heart and blood-vessel events. [6] | One randomised trial |
How sure we are: High means further research is very unlikely to change the answer; Moderate, it might; Low, it may well change; Very low, we are very unsure. These follow the GRADE method that guideline panels use.
Benefits
- Self-rated stress: Small improvement (0.23); Low
- Low mood: 0.15, may be zero; Low
- Anxiety: None; Low
- Fatigue without a deficiency: None; Moderate
- Stroke: 4.3% against 5.1%; High
- Heart attack, death: No effect; High
Risks and side effects
- Too much vitamin B6. 79% of Canadian B-complex products give 10 mg a day or more, 59% give 50 mg or more, and 12 are licensed above Health Canada's 100 mg maximum. Only 6% carry the 2026 nerve warning in their licence record. [1] See vitamin B6.
- Biotin in some products can make blood tests wrong. See biotin.
- Flushing if the B3 is nicotinic acid rather than nicotinamide.
- Folic acid on top of fortified flour: 40% of Canadians already have a high red-cell folate. [7]
- Lung cancer signal in men who smoke and take single-vitamin B6 or B12 at high doses for years (observational; not seen with multivitamins). [8]
- Faster kidney decline in diabetic kidney disease. [6]
Interactions with medicines
None of the vitamins in a B-complex is known to speed up or block the liver enzymes (cytochrome P450) that clear most medicines. The interactions come from the individual vitamins.
| Medicine | What can happen | What to do |
|---|---|---|
| Phenytoin, phenobarbital | High-dose B6 lowers their levels; folic acid also interacts with phenytoin | Do not take; discuss with your doctor |
| Methotrexate | Folic acid interacts with it | Only the folic acid your doctor prescribes |
| Levodopa given without carbidopa (rare today) | High-dose B6 speeds its breakdown | Do not take |
| Blood tests (heart, thyroid and others) | Biotin can make results falsely high or low | Stop at least 3 days before; tell the laboratory |
| Prescribed B6 (Diclectin and generics, Pregvit, with isoniazid) | B6 adds up | Keep the prescribed one; stop the B-complex |
Who should not take it
- Tingling, numbness or burning in the hands or feet.
- Diabetic kidney disease: no B-vitamin combination. [6]
- Current smokers: no high-dose B6 or B12. [8]
- Pregnancy: a prenatal multivitamin instead.
- A blood test booked (biotin).
- Anyone already taking prescribed B6.
- Under 18: outside the Supplement Check.
Dose and timing
We do not recommend a dose. For reference, trials used at least 3 B vitamins daily for 4 weeks or more. [2]
If you want to keep one: choose a product with under 10 mg of B6 and under 1 mg of biotin a day, and count it with everything else you take. There is nothing to measure without a deficiency, so keep a 4-week diary of the symptom you bought it for, then stop if nothing has changed. Most Canadian licence records lack the B6 warning, so read the label.
What we know about Canadians
No Canadian survey reports B-complex use separately. Shortfalls of B1, B2, B6, niacin, B5 and biotin are rare in the general population, helped by fortified flour, though there are no Canadian figures for most. For the two that are measured nationally: 3.5% of adults are deficient in B12 and 17.8% marginal, [9] and folate deficiency is under 1%, with 40% having a high red-cell folate. [7]
On the shelf: of 731 licensed B-complex products, 580 (79%) give 10 mg of B6 a day or more, 431 (59%) give 50 mg or more, which will be pharmacist-only in Australia from June 2027, and only 32 of the 580 (6%) carry the nerve warning in their licence record. [1]
How sure are we: moderate. B12 and folate from the national measured health survey (Canadian Health Measures Survey); no Canadian data for the other B vitamins; product figures from a scan of every active licence, 20 Oct 2026.
An honest comparison: stress
Effects are standardised so different scales can be compared; 0.23 is a small effect. Cost a month in Canadian dollars.
| Option | Effect | How sure we are | Cost a month (CAD) |
|---|---|---|---|
| B-complex | Effect 0.23 (self-rated stress) [2] | Low | About $4 |
| Exercise | Effect about 0.4 | Not graded | $0 to $21 |
| Cognitive behavioural therapy | Effect 0.56 | Not graded | — |
| SSRI or SNRI antidepressant (for anxiety) | 2 to 3 points more than placebo on an anxiety rating scale | Moderate | $8 to $15 (estimated) |
Read honestly: exercise and talking therapy do roughly twice what a B-complex does, for little or no cost, and the B-complex effect comes from industry-linked trials. For low mood the B-complex effect may be zero.
Why we don't recommend it
We do not sell B-complex products and our check never recommends one. Unless you are short of a B vitamin, they do not give energy or calm, and most sold in Canada contain enough vitamin B6 to risk the nerves in your hands and feet.
Already taking one? Check the B6 on the label. At 10 mg a day or more, stop it. If you want a B vitamin for a reason, we will choose a single product that does not overdose you; if you need B12 or folic acid, take that one vitamin.
The benefit is small and uncertain (a little less self-rated stress, nothing for mood, anxiety or fatigue), and the trials behind it were partly industry-funded. The risk is in the dose: 8 in 10 Canadian products give 10 mg of B6 a day or more, the median is 50 mg, and very few licences carry the new warning. Exercise does more for stress at little cost. Where there is a real need, such as low B12, one vitamin at the right dose does the job without the rest. So our current advice is not to sell B-complex products, and to stop one that gives 10 mg of B6 or more.
Supplement Check
Before you buy it, get it checked
Already taking a B-complex? Most contain far more B6 than our 10 mg limit, and some contain biotin that upsets blood tests. Your check counts what is in yours and tells you whether to stop it. Our Supplement Check looks at:
- Tingling, numbness or burning in the hands or feet
- Diabetic kidney disease
- Whether you smoke
- Pregnancy
- Any blood test you have booked (biotin can upset the results)
- Every medicine you take
- The total across everything you already take, against the safe upper limits
Coming soon. The Supplement Check and the Online Health Assessment open once our safety testing is complete.
$59 when it opens, paid once. Adults 18 and over, anywhere in Canada. While the service is new, Dr. French reads every report himself, and your report arrives within 3 working days. More about the Supplement Check
Disclosure of financial interest
White Pine Medical earns money from products bought through our Fullscript dispensary. Dr. French's Code of Ethics requires him to tell you this. You do not have to buy anything from us: every product is named by its ingredient and dose so you can buy it at any pharmacy, and the advice is the same wherever you buy it, or if you buy nothing.
References
- Health Canada. Licensed Natural Health Products Database, all active licences: daily vitamin B6 and biotin amounts and licence warnings, scanned 20 Oct 2026 (B-complex 744 licences; magnesium 2,238; biotin, hair and nail 827).
- Young LM, Pipingas A, White DJ, Gauci S, Scholey A. A Systematic Review and Meta-Analysis of B Vitamin Supplementation on Depressive Symptoms, Anxiety, and Stress: Effects on Healthy and 'At-Risk' Individuals. Nutrients. 2019;11(9):2232.
- Markun S, Gravestock I, Jäger L, Rosemann T, Pichierri G, Burgstaller JM. Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression. Nutrients. 2021;13(3):923.
- Martí-Carvajal AJ, Solà I, Lathyris D, Dayer M. Homocysteine-lowering interventions for preventing cardiovascular events. Cochrane Database Syst Rev. 2017;8(8):CD006612.
- Huo Y, Li J, Qin X, Huang Y, Wang X, Gottesman RF, et al. Efficacy of folic acid therapy in primary prevention of stroke among adults with hypertension in China: the CSPPT randomized clinical trial. JAMA. 2015;313(13):1325-35.
- House AA, Eliasziw M, Cattran DC, Churchill DN, Oliver MJ, Fine A, et al. Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial. JAMA. 2010;303(16):1603-9.
- Colapinto CK, O'Connor DL, Tremblay MS. Folate status of the population in the Canadian Health Measures Survey. CMAJ. 2011;183(2):E100-6.
- Brasky TM, White E, Chen CL. Long-Term, Supplemental, One-Carbon Metabolism-Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort. J Clin Oncol. 2017;35(30):3440-3448.
- Hopperton KE, Loukine L, Bonvalot Y, Esslinger K, McMillan HE, Greene-Finestone LS, et al. Vitamin B12 status of people living in Canada: results from the Canadian Health Measures Survey 2012-2019. Am J Clin Nutr. 2026:101540.
Costs marked as estimates are typical Canadian retail or pharmacy prices, before any drug plan. Certainty grades are ours unless the review gave its own.