One in 20 Adult B6 Supplements Directs at Least the Upper Limit. Most Aren't Sold as B6.

Vitamin B6 has an unusually well documented failure mode for a vitamin: taken in large enough amounts for long enough, it can damage the sensory nerves. What nobody had measured, product by product, was how close the doses printed on American supplement labels come to the limits regulators have set.

A census published on 20 October in Cureus did that. From a snapshot of the NIH Dietary Supplement Label Database taken on 4 October 2026, it merged 16,951 on-market label records into 11,913 products and calculated the largest daily dose each label’s own directions allow. Among the 11,367 adult products, 575 — 5.1%, with a 95% confidence interval of 4.7% to 5.5% — direct at least 100 mg a day, the US tolerable upper intake level.

Where those products sit on the shelf is the more useful finding. Only 252 of the 575 are sold as vitamin B6 or B-complex products. The other 323, or 56.2%, are multivitamins, sleep and mood formulas, women’s health products, energy lines and a long tail of items with no obvious B6 premise at all.

How the count was made

The database, run by the NIH Office of Dietary Supplements, transcribes each label’s Supplement Facts panel, serving size and printed directions. The census took every on-market label naming vitamin B6 under any of nine spellings and dropped match noise, products disclosing no B6 amount inside a proprietary blend, and records that contradicted their own percent daily value.

Dose meant what a buyer would meet: amount per serving, multiplied by the largest serving size and the most servings a day the directions permit. Median maximum directed dose was 10 mg a day, with an interquartile range of 2.2 to 25 mg.

The tail is steep. Of the 575 adult products at or above 100 mg a day, 408 direct exactly that and 167 direct more. Seventy reach at least 200 mg, twice the US limit; ten direct at least 500 mg. The share held between 3.5% and 5.6% under every alternative definition of a daily dose the author tried.

Why B6 keeps drawing regulators back

The recommended intake is small: MedlinePlus lists 1.3 mg a day for adults aged 19 to 50, 1.7 mg for men over 50 and 1.5 mg for women over 50, amounts a normal diet covers from fish, poultry, legumes, nuts and whole grains. Deficiency is uncommon.

The US upper limit of 100 mg a day was set by the Institute of Medicine in 1998 and never revised. It rests mainly on case reports of reversible sensory neuropathy after prolonged doses above 1,000 mg; the 100 mg figure itself is roughly 75 times the recommended intake, according to a 2025 review in Behavioural Neurology. MedlinePlus lists the effects of large doses as difficulty coordinating movement, numbness and sensory changes; the NHS puts the threshold for loss of feeling in the arms and legs at 200 mg a day or more, says it is permanent in a few cases, and calls the evidence between 10 mg and 200 mg unclear.

That review is narrative, built on case reports rather than trials, and it shows how uneven the harm can be. It cites a patient who took 6 mg a day in a multivitamin for ten years and developed three years of progressive peripheral neuropathy, which resolved after the supplement stopped. One hypothesis is that pyridoxine, the inactive form most used in supplements, accumulates and inhibits the enzymes that depend on its active form. Recovery is usual but not always clean: symptoms may worsen for two to three weeks, and persistent sensory deficits have been reported.

The dose is rarely on the front of the pack

Category by category, single-ingredient B6 products carried the highest share at or above the US limit: 113 of 244, or 46.3%. B-complex products followed at 139 of 597, or 23.3%. Together those two groups account for 43.8% of all high-dose products.

The rest are scattered. Fifty-one of 2,549 multivitamin and mineral products reach the limit, along with 29 of 703 sleep, mood, stress and brain products, 13 of 234 women’s health products and 200 that fit no named category. Against the much lower European limit described below — which 38.7% of adult products exceed — 86.2% of those above it were not sold as vitamin B6 or B-complex at all.

That matters because the upper limit covers total intake from food and supplements together. Food already supplies roughly 1.5 mg a day for women and 2 mg for men, the census notes, so a product directing exactly 100 mg pushes total intake past the limit on its own — inside a bottle bought for sleep, energy or general health rather than for B6.

What some labels tell children to take

The snapshot held 541 children’s or teen products with an age band. Four exceeded the limit for the age stated at the smallest dose their directions allow, seven at the largest. Reading every label that supplied 30 mg a day or more and mentioned a child age turned up 22 products, carrying 28 age-specific directions, that send a stated child or teen age above the limit for that age.

The highest was 250 mg a day for “adults and children four years and older”, 6.2 times the 40 mg limit for ages four to eight. Ten of the 22 products, from one manufacturer, use that same one-dose-for-everyone-four-and-up pattern at 50 to 250 mg a day. Others include a weight-gain syrup directing 30 to 45 mg for ages two to 12 and 90 mg for ages 12 to 18, and a chewable at 60 mg for ages four to 11.

These are printed directions, not observed harm. The statutory bar on potency limits does not extend to products represented for use by children under 12.

Five regulators, five different answers

Only the United States uses 100 mg. The European Food Safety Authority set an adult limit of 12 mg a day in 2023, with peripheral neuropathy as the critical effect. The Netherlands capped B6 at 21 mg per daily dose from October 2018, after which neuropathy reports to its pharmacovigilance centre fell. Australia will require products above 50 mg a day to be sold behind the pharmacy counter from June 2027, and the NHS advises against more than 10 mg a day from supplements without a doctor’s advice.

The gap comes from different starting evidence. The 1998 US value drew on small clinical studies of pyridoxine treatment at 100 to 300 mg a day. EFSA worked from the 1987 case series, in which 48% of women who had taken less than 50 mg a day for more than six months had neuropathy symptoms, plus case reports and vigilance data; an uncertainty factor applied to a 50 mg reference point, and a midpoint rounded down, produced 12 mg.

Federal law has barred the FDA from setting maximum potencies for vitamins and minerals sold to adults since 1976, with narrow exceptions. The agency’s consumer page states that it has no authority to approve supplements for safety, effectiveness or labelling before sale, and that the firm is responsible for the product’s safety and claims. The census author’s proposal follows: a neuropathy warning on labels at or above the US limit, and a reassessment of the 1998 value. That is a recommendation, not policy.

What the census cannot show

It counts labels, not sales. A product that sells by the million counts once, exactly like one that sells by the dozen, so the percentages describe the market on offer rather than what people swallow. Linking the database to national dietary survey data would be needed to estimate how many adults take 100 mg a day or more, and nobody has done that here.

The database is not the market either. Its on-market flag can lag discontinuation, and it does not hold every product for sale. Labelled amounts are not measured content — manufacturers add overages, so a product tends to contain more than its label says, which makes the labelled dose more likely to understate than to overstate.

Nor is the upper limit a toxicity threshold for one person: it is a population safety benchmark, and exceeding it is not an overdose or evidence of harm. The maximum directed dose also overstates typical use. Verification was done by one reviewer working with a generative AI tool under his direction, disclosed in the paper, and the review lowered the estimate rather than raising it.

What we did not find

No national figures on high-dose B6 use. No trial, and no human dose-response curve, that would put a firm number on where neuropathy risk begins for a given person. No count of neuropathies attributable to the supplement aisle. And no agreement between regulators: a 100 mg ceiling and a 12 mg ceiling are 8.3-fold apart.

What it does establish is narrower. The dose is printed, in milligrams, on the Supplement Facts panel of products frequently bought for reasons unrelated to B6, and 5.1% of the adult market directs at least the US limit. For background on how far supplement marketing can run ahead of the evidence, our checks on collagen supplements and on a six-month greens-powder trial cover the same gap from other angles.

Unexplained numbness, tingling or unsteadiness is a symptom worth raising with a healthcare professional rather than self-managing, and a supplement history belongs in that conversation. Nothing here is medical advice or a reason to start or stop any product; see our medical disclaimer for how this site draws that line.