The Nerve Supplement Guide

Numbness, burning, pins and needles and a loss of feeling that starts in the toes and works upwards are the classic presentation of distal symmetric polyneuropathy: the longest nerves in the body failing first, on both sides, in a pattern people describe as stockings and then gloves.

A JAMA review of the condition sets out how common it is and how varied the causes are. Diabetes is the largest single one in the United States. Others include B12 deficiency, thyroid disease, kidney disease, alcohol, several chemotherapies, a handful of inherited conditions, and a group that stays idiopathic after everything reasonable has been checked.

The National Library of Medicine's plain-language page is the best starting point for somebody who has just noticed it. It is short, it is free, and it says the same thing this guide is about to say at greater length.

Four rows, four dose columns you can actually use. Every figure here is the one a named trial ran, not a recommendation.

Read the dose column before the findings column. It is the part that transfers. Whatever you conclude about whether alpha-lipoic acid helps, you now know that the research on it ran at 600 mg once a day, and you can hold any label carrying it up against that number in a shop.

The pooled analysis of the intravenous trials is the older half of the alpha-lipoic acid story and is worth knowing about for one reason: the early work gave it by infusion, and an oral capsule is a different proposition from an infusion even at the same milligram figure.

A trial pairing acetyl-L-carnitine with methylcobalamin is the nearest thing in this list to a combination product, and it is instructive about what combination trials can and cannot tell you: it measured the pair, so neither component's own contribution was separated out.

The 2022 American Academy of Neurology guideline update covers oral and topical treatment of painful diabetic polyneuropathy. It is a guideline about medicines, and the honest summary of its position on supplements is that they are not what it recommends.

The American Diabetes Association position statement reaches the same place from the other direction: glucose control first, then the medicines with trial evidence for symptoms, and screening at diagnosis rather than when something already hurts.

The Academy's practice parameter on evaluation is the one worth reading if you have symptoms nobody has investigated. It sets out which laboratory tests have the highest yield, and B12 is among them.

This is not an argument that supplements are worthless. It is an argument about order. The guidelines put identifying the cause first because the causes differ enormously in what they respond to, and because two of the commonest are things you can do something about.

Vitamin B6 is the sharpest thing on any nerve supplement shelf and most shoppers have never been told about it. At ordinary dietary intakes it is a requirement. At high supplemental doses, sustained, it produces a sensory neuropathy — the same numbness and tingling the aisle is selling a fix for.

The European Food Safety Authority's 2023 opinion is the current upper-limit assessment and it is the document to read if you want the numbers rather than the summary.

A laboratory study of what high-dose pyridoxine does describes the mechanism that makes this more than a quantity problem: the form most supplements use, at high concentrations, appears to reduce B6 function rather than raise it. The paper calls it a paradox and the name has stuck.

The study of what happened when a regulator capped the dose is the strongest single piece of evidence here, because it is a natural experiment. A maximum was imposed on supplement B6, and the pattern of neuropathy reports changed.

For completeness: B6 is not on the label this website sells. Neither are the four ingredients in the previous section. The nine names on this panel are set out in full on the ingredients page, each beside the condition it was actually studied in.

Applied to the bottle this website sells: the panel is headed “Test Boost Proprietary Blend, 1000mg” with 9 names under it and no figure against any of them, the serving is two capsules, the bottle is 60 capsules and therefore thirty days, and the shell is gelatin. The panel page reproduces every row.

The practice parameter on evaluating this condition is unusually readable for a guideline, and its most useful section is about which tests have the highest yield. Blood glucose, B12 and a serum protein study are the ones it singles out.

The point of naming them is not to turn a reader into a diagnostician. It is that the list is short, the tests are ordinary, and the two commonest findings on it are both things that can be acted on.

An appointment also settles something a supplement cannot: whether the pattern you have is the pattern this whole category is aimed at. Several conditions produce similar sensations and respond to entirely different things.

Five things that make an appointment more urgent rather than optional. None of them is a reason to stop reading; all of them are a reason to stop waiting.

None of this argues against taking a supplement. It argues for knowing what you are taking it alongside, which is the difference between an informed purchase and a hopeful one.

A botanical blend is not competing with the four ingredients in the evidence-base table, because it does not contain them. It is a different proposition: a group of plants and an amino acid, most of which have their own research in something else.

That is worth saying without sneering, because it is how most of the supplement aisle works and the alternative reading — that every blend is a fraud — is both unfair and useless. What a reader needs is the ability to tell the two situations apart.

So: an ingredient with a trial in the condition you have, at a dose you can read on the panel, is one thing. An ingredient with a trial in a different condition, at an amount the panel does not print, is another. The ingredients page on this site puts every one of the nine names on this label into the second category, explicitly, with the condition each was actually studied in.

The other half of the honest answer is that NCCIH and the NIH Office of Dietary Supplements both publish the same guidance for this situation and it is not complicated: tell whoever is treating you what you are taking, read the panel rather than the front, and be suspicious of any product that promises what a medicine would have to prove.