Vitamin B

Best for

Sharpen focus and mental stamina

Not enough research for 5 weeks · 1 meta-analysis , n=3.9k

19 papers · 3 claims · 51 outcomes scored · 2 positive

Outcomes

What vitamin b actually does, by outcome

Each row is one outcome with effect size, evidence base, the dose that worked in trials, and time to first effect. Magnitude tiers come from native-unit MCID where available, Cohen's d otherwise.

Outcome Effect size Evidence Dose Weeks Rank

Sharpen focus and mental stamina Not enough research

Concentrate longer, resist distraction, and stay mentally sharp through demanding tasks.

3 meta-analyses n=3.9k — 5 wk

32331312·20454891·24465438

trivial

3 meta-analyses n=3.9k Meta-analyzed

—

5 wk

—

Reduce everyday fatigue Likely real but unnoticeable

Less of that heavy, worn-out feeling that makes simple tasks feel like a chore.

2 RCTs n=308 — 5–26 wk

20454891·31612139

trivial

2 RCTs n=308

—

5–26 wk

—

Lift mood and reduce negativity Probably doesn't help

Fewer dark stretches and more spontaneous positive moments through the day.

1 RCT n=152 55.4 mg 52 wk

17616840

trivial

1 RCT n=152

55.4 mg

52 wk

—

Outcome	Effect	Evidence	Dose	Weeks	Rank
Sharpen focus and mental stamina Not enough research	trivial	3 meta-analyses n=3.9k Meta-analyzed	—	5 wk	—
Reduce everyday fatigue Likely real but unnoticeable	trivial	2 RCTs n=308	—	5–26 wk	—
Lift mood and reduce negativity Probably doesn't help	trivial	1 RCT n=152	55.4 mg	52 wk	—

Risk profile

Adverse events and known drug interactions

Safety events

Urine discoloration (yellowish) mild

Vitamin B12 deficiency diagnosed during follow-up

Peripheral neuropathy (suspected vitamin B6 toxicity)

flush

vomiting

rash

nausea

constipation

Drug interactions

Metformin major decreases concentration

Aspirin major decreases effect

Co-studied with

Supplements that share evidence with vitamin b

Sources

Generated August 14, 2026

Vitamin B

What vitamin b actually does, by outcome

Adverse events and known drug interactions

Supplements that share evidence with vitamin b

More evidence for Vitamin B

Best Supplements to Protect Brain Tissue as You Age (2026)

Focus & memory: evidence map across 45 supplements

Stress: evidence map across 46 supplements

Clinical trials found many null results for vitamin B

lemon balm

Saffron

Vitamin B

More evidence for Vitamin B

NewBest Supplements to Protect Brain Tissue as You Age (2026)

NewFocus & memory: evidence map across 45 supplements

NewStress: evidence map across 46 supplements

NewClinical trials found many null results for vitamin B

Newlemon balm

NewSaffron

Best Supplements to Protect Brain Tissue as You Age (2026)

Focus & memory: evidence map across 45 supplements

Stress: evidence map across 46 supplements

Clinical trials found many null results for vitamin B

lemon balm

Saffron