Method
Two upper limits
The same nutrient can have two different safe-intake ceilings depending on which side of the Atlantic you read. That is not a mistake by either body, and it is not a reason to ignore both. This piece explains where the two figures come from and what a reader should actually do with them.
An upper limit is a judgement, not a reading. This serving carries 13.8 mg of vitamin B6, printed at 812% of the US Daily Value, which is arithmetically correct. It sits at about 14% of the US limit of 100 mg a day and about 15% above the 12 mg limit EFSA set in 2023. Neither figure is a warning. Both matter if you are stacking supplements.
- Vitamin B6 printed
- 13.8 mg
- Printed as % of DV
- 812%
- Is the percentage right?
- Yes — 13.8 ÷ 1.7 = 811.8%
- US upper limit
- 100 mg a day
- EFSA limit, 2023
- 12 mg a day
- This serving against EFSA
- about 15% above
- Boron printed
- 10 mg
- Boron upper limit
- 20 mg a day
What an upper limit is, and what it is not
Three different kinds of number get printed near each other on supplement labels and in articles about them, and most confusion about safety comes from mixing them up. It is worth separating them before any figure is quoted.
A Daily Value is a labelling reference. It exists so that a percentage can be printed in the right-hand column of a panel and so that two products can be compared at a glance. It is derived from a recommended intake, which is an amount thought sufficient for most people. A Daily Value is a floor-ish figure, and exceeding it is ordinary — a multivitamin typically exceeds several.
A Tolerable Upper Intake Level, usually shortened to UL, is a different kind of number entirely. It is the highest average daily total intake judged unlikely to cause adverse effects in almost everybody in the general population. It is set by committee, from the published literature, with a deliberate margin. Six things follow from that definition, and all six are commonly lost.
- 01It describes a population, not a personA limit is set so that almost everybody in the general population can take that much every day without an adverse effect. It is a statement about a distribution, which is why it cannot tell any individual what will happen to them.
- 02It is a ceiling, not a targetNothing about a limit suggests that approaching it is desirable. A product at half a limit is not half as good as one at the whole of it.
- 03It applies to everything you take, added togetherThe limit is a figure for total daily intake from all sources: food, fortified food, and every supplement on the shelf. No single label can be checked against it in isolation, because no label knows what else is in the cupboard.
- 04It is built from the best no-effect intake, then stepped downA committee finds the highest intake at which an adverse effect has reliably not been seen, then divides by a margin to cover the people the studies did not include. The margin is a judgement, and judgements differ.
- 05Crossing it is not an injurySitting slightly above a limit is not the same as being harmed. It means the intake has left the range the committee set out to describe, so that committee's reassurance no longer covers it. A smaller statement than it sounds, and a real one.
- 06No figure at all is not the same as no limit neededWhere the data are too thin a body declines to set a figure rather than guessing. Boron has no Daily Value for exactly that reason, and it still has an upper limit.
The third is the one that does the most work on a page like this. A limit is a figure for the total, and a label can only ever show you one contribution to a total. That gap between what a limit measures and what a panel can tell you is the subject of this whole piece, and it is why the honest conclusion at the end is about stacking rather than about this bottle.
The B6 row: one amount, two ceilings
The panel prints Vitamin B6 (as pyridoxine hydrochloride) 13.8 mg, 812% DV. Start with the credit, because it is the only row on this panel where the printed percentage needs no correction at all: 13.8 divided by the 1.7 mg Daily Value is 811.8%, and the label prints 812%. The arithmetic is right, the form is named, and nothing on the row needs a footnote.
A figure in the hundreds of per cent looks alarming and is not, by itself, informative. Water-soluble B vitamins are routinely sold at large multiples of their Daily Values, and the Daily Value is a labelling reference rather than a ceiling. The question worth asking is the next one: where does 13.8 mg sit against a published limit? The answer depends on whose limit you read.
| US Food and Nutrition Board | EFSA, 2023 | |
|---|---|---|
| Adult upper limit | 100 mg a day | 12 mg a day |
| This serving | 13.8 mg | 13.8 mg |
| The division | 13.8 ÷ 100 | 13.8 ÷ 12 |
| Where that puts it | about 14% of the limit | about 15% above the limit |
| How to read it | Comfortably clear | Slightly over, from one serving alone |
Both columns are correct. That is the uncomfortable part and there is no way around it. A reader in Ohio and a reader in Antwerp can look at the same bottle, read the same 13.8 mg, consult the most authoritative body available to each of them, and come away with opposite impressions — one comfortably inside a limit, one fractionally outside a different one. Neither has made a mistake.
Notice also what the panel does for you here and what it cannot. It gives you the amount and the form, which is what makes the two divisions possible at all; the whole panel is transcribed row by row on the label page. What it cannot give you is the figure that both limits are actually about, which is your total.
What the neuropathy literature actually shows
Both limits exist because of one documented effect: sensory peripheral neuropathy, a loss of sensation in the hands and feet, reported after prolonged high intakes of pyridoxine. It is worth setting out what the literature reports, at what intakes, because the numbers are a long way from the figure on this panel.
Reported cases start at around 500 mg a day — that is the intake range where the effect has actually been described. Meanwhile, studies of intakes averaging about 200 mg a day for up to five years found no evidence of it. Those two figures bracket the question: an effect seen at one intake, and no evidence of it at a considerably lower one maintained for years.
The US limit was built from the lower of those two. 100 mg a day is half of the 200 mg at which the long studies found nothing — a margin left to cover the people those studies did not include. That is the ordinary way a UL is constructed: find the most reliable no-effect intake available, then step down from it.
Set the panel figure against that scale. 13.8 mg is about a thirty-sixth of the 500 mg where cases have been described, and about a fourteenth of the intake the long studies used without finding anything. This is the paragraph to hold on to if the 812% on the panel was the thing that worried you.
None of which makes the EFSA figure irrelevant. A lower limit from a serious body is a serious statement, and the point of reporting both is not to pick the comforting one. It is to let a reader see that the distance between this serving and the documented effect is large, while the distance between this serving and one committee's line is small.
Why two expert bodies read one literature differently
This is the question readers actually have, and it has a plain answer: a limit is not measured, it is decided. The literature is one input. Everything else is a sequence of judgements, and each judgement is a place where two careful committees can part company.
- Which studies are admitted. Case reports, observational series and controlled trials carry different weight, and a committee has to decide how much. Admit a weaker study that reports an effect at a lower intake and the resulting limit falls.
- Which endpoint is protected. The same nutrient may have several reported effects at different intakes. Choosing the earliest-appearing one produces a stricter figure than choosing the best-characterised one.
- How large a margin to leave. The step down from a no-effect intake to a published limit is a deliberate factor, chosen to cover people the studies did not include. Two is a common choice; it is not the only defensible one.
- What the figure is for. A limit used to set fortification policy and one used to advise individuals are doing slightly different jobs, and a body may be more conservative where the figure will be applied to a whole population.
- When the review was done. Evidence accumulates. A 2023 review reads a literature that a review from an earlier year could not have seen, and that alone can move a figure in either direction.
Apply that to the case in hand. The Food and Nutrition Board set 100 mg a day. The European Food Safety Authority, reviewing the same question in 2023, set 12 mg a day, on reviews of sensory peripheral neuropathy. The gap between the two is wide in ratio and small in consequence at the intakes most people reach, and both bodies published their reasoning rather than a number alone.
The useful way to hold two limits at once
A disagreement between two expert bodies is not a sign that neither can be trusted. It is a sign that you are looking at a judgement rather than a constant — and that the honest summary of your position is a range, not a verdict. 13.8 mg is comfortably inside one published limit and fractionally outside another. That sentence is the whole of what the evidence supports, and it is more useful than either half of it alone.
One thing a reader can do with the disagreement, rather than about it: treat the lower figure as the cautious reading and the higher as the permissive one, and notice how much of your own total you would have to add before the two readings stopped agreeing on what to do. For most people taking one product, they agree.
Boron: half a limit, and seven to ten times a diet
The second row where a limit is the interesting figure is boron, and it works differently from B6 in a way worth following. The panel prints Boron (as boron amino acid chelate) 10 mg, with ** in the Daily Value column.
Both halves of that row are correct. The chemical form is named, which for a mineral does the job a standardisation does for a botanical. And the double asterisk is right: the Food and Nutrition Board found the data insufficient to set a Daily Value for boron, so there is none to print. A label that invented a percentage here would be worse, not better.
Boron does, however, have an upper limit, and the figure to set beside it is not a Daily Value but ordinary intake.
| Figure | Value | Where it comes from |
|---|---|---|
| Printed on the panel | 10 mg | The Supplement Facts panel, as boron amino acid chelate |
| Daily Value | None — ** on the row | The Food and Nutrition Board found the data insufficient to set one |
| Adult upper limit | 20 mg a day | NIH Office of Dietary Supplements, boron fact sheet |
| This serving against the limit | half of it | 10 ÷ 20 |
| Typical total daily intake | about 1 to 1.5 mg | NIH ODS, food and supplements together |
| This serving against that | about 6.7 to 10 times | 10 ÷ 1.5 and 10 ÷ 1 |
Two readings fall out of that table and they point in different directions. The reassuring one: NIH records no adverse effects from supplemental boron at doses within the upper limit, and no known clinically relevant drug interactions. The narrower one: one serving uses up half the available room, which is a different kind of fact from a safety concern. It is a fact about what else will fit.
That is the whole of the boron finding, and it is deliberately unexciting. The side-effects page carries the documented cautions for every row on this panel, including the places where nothing is documented at all.
The situation a label cannot see
Both limits in this piece are figures for total daily intake from all sources. Every panel in the world reports one contribution to that total. The gap between those two sentences is where the only real risk in this material lives, and it is not a risk about this product.
Work it through. A man takes this product at its printed serving. He also takes a men's multivitamin, because the two are sold to the same person by the same kind of page. Multivitamins commonly carry B6, and some carry boron. Neither label is wrong, neither seller has done anything improper, and nobody along the chain is in a position to see the sum — because the sum exists only in that man's cupboard.
What a panel can tell you
- The amount of each ingredient in one serving of one product, which this label gives for all 9 rows.
- The chemical form, which decides how a figure converts and what a limit applies to.
- The serving size and the servings per container, so a daily figure can be worked out.
- Enough to let a pharmacist read the product in under a minute and ask the right next question.
- Enough to be checked by a stranger, which is the whole function of a printed panel.
What no panel can tell you
- Your total intake of any nutrient, which is the figure both upper limits are about.
- What else is in your cupboard, or how much B6 or boron the multivitamin beside it carries.
- Whether you have been taking any of it for a week or for five years, which is the variable the neuropathy literature turns on.
- Anything about you: your weight, your kidneys, your prescriptions or your diet.
- Whether a second product you are about to buy would push a total past a limit.
So the practical question is never “is 13.8 mg of B6 safe”. It is “what is my total, and what else is adding to it”. One serving of this product is a knowable contribution to an unknown sum, and the only person who can close that gap is the reader with the cupboard. The fit check asks whether you already take a multivitamin or a second men's supplement, and it asks first for this reason.
Why neither figure is a warning on its own
Time to say the conclusion plainly, because a piece about upper limits that leaves a reader uneasy has failed even if every figure in it is correct.
Neither the B6 figure nor the boron figure is a warning about this product. The B6 serving sits at about 14% of the US limit and about 15% above a stricter European one, while the intakes at which the documented effect has actually been reported are roughly thirty-six times larger. The boron serving sits at half a limit, under which NIH records no adverse effects and no known clinically relevant interactions. Those are the facts, in their proportions.
What both figures are is worth seeing, and the reason is arithmetic rather than alarm. A serving at half a limit leaves half the room. A serving slightly above one committee's line leaves none of that committee's room. Those are statements about headroom, and headroom only matters to somebody adding something else.
There is a fairness point to print here too. This label is the reason either figure is available to you. It prints an amount for every one of its 9 rows, names the chemical form on both of the rows discussed in this piece, and carries a complete caution block naming a dose limit and the groups who should ask a physician first. A product that printed Prostate Blend 808 mg would have hidden both figures and nothing in this piece could have been written.
The honest summary, then, is a conditional rather than a verdict. If this is the only thing you take, the two figures are background. If it is the third bottle on the shelf, they are the two numbers to add up first — and the situation that makes them matter is exactly the one no label can see.
What to do with two different limits
Six steps, written to be run on any supplement and any nutrient rather than on this one. None of them requires a view about which committee is right.
- 01Write down the total, not the labelAdd the same nutrient across everything you take, the multivitamin and the fortified cereal included. A limit is a figure for the total, so one panel can never be measured against it.
- 02Find out whether a limit exists at allSome nutrients have one, some have none because the evidence is too thin, and some have different ones in different places. “No published limit” is a finding to write down rather than a gap to fill with reassurance.
- 03Put the printed percentage of the Daily Value to one sideA Daily Value is a reference intake for labelling, not a limit. A figure in the hundreds of per cent says the serving is a large multiple of a labelling reference, and on its own it says nothing at all about safety in either direction.
- 04Note which body set the figure you are using, and whenA limit has an author and a date. Quoting one without them is how a reader ends up arguing with somebody quoting the other.
- 05Take the panel to a pharmacist rather than a search engineThis product has a panel to take, which is more than most in this series offer: nine rows, nine amounts, forms named. A pharmacist can read it in under a minute.
- 06Decide once, in writing, and keep the note with the bottleThe useful output is a sentence, not a feeling: what you take, what it adds up to, and which limit you measured it against. Written down, it survives until the next bottle.
The first step is the one that does almost all of the work, and it is the one nobody does. A limit is a figure for a total; a label is a figure for a contribution. Until the contributions have been added up, no comparison with a limit means anything, in either direction. Five minutes with the cupboard door open beats any amount of reading about committees.
And when the two figures disagree, carry both. 13.8 mg of vitamin B6 is about 14% of one published adult limit and about 15% above another. A reader holding that sentence is better informed than one holding either half, and far better informed than one holding the 812% from the panel on its own. The companion piece in this journal does the same kind of work on two standardised rows, where the bigger printed figure turns out to deliver less.
Questions people type about this
Six queries, answered off the panel and the two cited fact sheets. Where a question is about a person rather than a figure, the answer says so.
vitamin b6 812 percent daily value too much
The percentage is arithmetically correct — 13.8 divided by the 1.7 mg Daily Value is 811.8% — and by itself it says nothing about safety. A Daily Value is a labelling reference, not a ceiling. The figures that bear on safety are the upper limits: 100 mg a day in the United States, which this serving is about 14% of, and 12 mg a day from EFSA in 2023, which it is about 15% above.
is 10 mg boron a day safe
This desk does not answer safety questions about individuals, and no body it cites does either. What is publishable: the adult Tolerable Upper Intake Level for boron is 20 mg a day, this serving is 10 mg, and NIH records no adverse effects from supplemental doses within the limit and no known clinically relevant drug interactions. Typical total intake from food and supplements is about 1 to 1.5 mg a day, so the serving is roughly 6.7 to 10 times that.
boron 10 mg supplement safe
The same two figures do the work: 10 mg printed, against an adult upper limit of 20 mg a day for total intake from all sources. One serving is half the limit, which leaves no room for a second boron-containing product without crossing it. That is the practical reading, and it is about stacking rather than about this bottle on its own.
Why do the United States and Europe disagree about vitamin B6?
Because a limit is a judgement applied to evidence, not a reading taken off it. Two committees choose which studies to admit, which effect to protect against, and how large a margin to leave for the people the studies did not include. The Food and Nutrition Board landed on 100 mg a day; EFSA, reviewing the question in 2023, landed on 12 mg. Both are real figures from serious bodies, and a reader is better off knowing both than picking one.
can i take prostacyl with prescription medication
That is a question for the person who prescribed the medication, and this product gives you an unusually good document to take to them: a complete nine-row panel with every amount printed and the chemical forms named. The label itself says that anyone with a known medical condition should consult a physician first.
prostacyl side effects
No adverse-event data for this product exists in any material supplied to this desk, so none is published here. What can be reported is what the amounts are and where they sit against published limits, which is what this piece does for two rows.
References
Two sources carry this piece, both opened and read: the NIH Office of Dietary Supplements fact sheet for vitamin B6, which gives the Daily Value, the US upper limit, the EFSA figure and the neuropathy literature behind all three, and the equivalent fact sheet for boron, which gives the adult upper limit, the absence of a Daily Value and the typical-intake figures.
- National Institutes of Health, Office of Dietary Supplements (2026). Vitamin B6: Fact Sheet for Health Professionals.
- National Institutes of Health, Office of Dietary Supplements (2026). Boron: Fact Sheet for Health Professionals.
Neither was written about this product and neither mentions it. They are cited for what a limit is and what each figure is, which is the only thing a fact sheet can be cited for. The divisions on this page — 13.8 into 100, 13.8 into 12, 10 into 20 — use the panel's own printed amounts and need no citation.
Read the panel before you decide
Sixty capsules, two a day, thirty days a bottle. The Supplement Facts panel declares nine ingredients and nine amounts, with no proprietary blend — the most transparent label in this series. Four of those nine rows change meaning once the arithmetic is done, and all four sums are shown in full. One bottle is $69; six are $49 each. The refund window is printed as 60 days in one place and 90 in another.
- 60 or 90 days — the page prints both
- Nine ingredients, nine printed amounts, no blend
- Returns to 1370 Avenue of the Americas, Floor 4, New York, NY 10019, USA
Prices as printed on the sales page, as of October 12, 2026: one bottle $69, six bottles $49 each with free shipping. The three-bottle total is not published, so it is left blank rather than estimated. The refund window is printed as 60 days in one place and 90 in another — confirm it at the checkout. Questions first? Every published contact route is here.
Keep reading
Authorship and review
Who wrote and checked this page
What this page was checked against
- The label artwork, read at 2× and transcribed character for character. Where the label and the marketing disagree, the label is printed.
- The seller pack, quoted rather than paraphrased, and identified as marketing wherever it is used.
- The published sources listed in the references on this page. Every one was opened and read; none is cited from memory.
- The arithmetic, shown in full. Every amount on this panel is printed, so the figures here are conversions of printed amounts with the working given, never ceilings and never estimates.
- Nothing else. Any fact that was not supplied is recorded as not published rather than filled in.
Last updated October 12, 2026. A highlighted slot is a value no human has supplied yet. Who reviews these pages?