What makes a supplement high quality?

Most of quality is decided before the tub exists: the four formulation decisions a buyer reads off the label, form, dose, excipients and format, and what each looks like when made for the person swallowing it

What makes a supplement high quality is a question most answers locate in the factory, and most of the answer was decided before the factory was involved, at the moment the product was formulated, in four decisions that a buyer can read off the label in a minute. A brand sitting down to make a magnesium, a vitamin D or a creatine makes the same four choices every time, and each can be made for the person who will swallow the product or for the spreadsheet, and the label records which. The four manufacturing decisions that follow, read from documents rather than the label, are the second half of the page; the first half is the four that most buyers never see as decisions at all.

The first is the form of the nutrient. Most nutrients come in several chemical forms that differ in absorption, in tolerance and in cost, and the choice is made at formulation: magnesium as the oxide, cheap and poorly tolerated, or as the bisglycinate, dearer and gentler on the gut; vitamin D as D3 or D2; iron as the sulphate or the bisglycinate; B12 as cyanocobalamin or the methyl form; creatine as the monohydrate every trial used or as a dearer form with fewer trials. A form chosen for the person is the one the absorption and tolerance evidence supports for that nutrient, and a form chosen for cost is the cheapest that can carry the name; the label states the form in the ingredient list, and a buyer who knows the forms reads the decision there. The second is the dose, and it has a reference point most labels ignore: the intake an authorised claim is conditioned on. The register's claims are granted for a nutrient at a stated intake, and a dose set at that intake is a dose that earns its claim, while a dose set far above it is a number chosen to look large, often above the upper level, and a dose set below it is a product that cannot lawfully make the claim it implies. A mineral stated as elemental content with its percentage of the reference value beside it is a dose stated for the person; a mineral stated as the compound weight, which can be several times the elemental figure, is a dose stated to look large, and the two most common formulation errors on the shelf are the cheap form and the compound-weight dose.

The third is the excipients, the materials after the active that make the product fillable or pressable, and the decision is between the fewest the fill needs, a capsule shell and one flow agent for a machine-filled capsule, and a list for appearance, a coating, a colour, a glaze and a sweetener; the label's ingredient list, in descending order of weight, records the choice. The fourth is the format: a capsule, which disintegrates in the stomach within the time the pharmacopoeial test allows and delivers the dose, or a tablet, cheaper to make and pressed hard enough that some pass through intact, which a kitchen can test in a glass of warm water. A tablet is not a wrong decision, a well-made tablet disintegrates, but it is a decision made for the machine's speed that has to be checked, and a capsule is a decision made for the dose that rarely needs to be.

Four decisions on the label and what each looks like made for the person, and the four decisions in the documents, the facility, the release, the stability and the operator, with the worked example's eight read and the verdict, which is the next section.

The four decisions in the documents: the facility's standard, the release testing, the stability behind the shelf life and the named operator; how each is read; the worked example's eight decisions; and the verdict

The four decisions in the documents follow the four on the label, and they are read from documents a buyer asks for rather than from the tub. The fifth decision is the facility: where the product is made and to which audited standard, good manufacturing practice certification and, for many UK facilities, the retail consortium's standard, named and verifiable with the certifier, against a facility the brand will not name or a standard described as high; the decision was the brand's choice of manufacturer, and it is read from the brand's statement and the certifier's register. The sixth is release testing: whether each batch is tested against a specification before sale, for the assay of the active within a tolerance and for heavy metals and microbes against limits, at an accredited laboratory for the tests that need one, with a certificate of analysis by lot, against a brand that buys finished product and never sees a result; it is read from the certificate the brand sends on request, and its absence is the commonest quality gap in the market.

The seventh is stability: whether the shelf life printed on the tub was set from stability data, the testing of the product over time that shows the declared content lasts to expiry, with an overage for a vitamin that degrades and a stated release range for a mineral that does not, against a date chosen because other brands print it; it is read, in practice, from an expiry that fits the fill date and a brand that can say how its shelf life was set. The eighth is the operator: a named food business operator with a UK or EU address on the label, answering for the product in law and checkable in the company register for a trading history, against a tub with no address, which was imported by the buyer and is answered for by nobody.

The eight decisions read together are the whole of quality in a form a buyer can use: the four on the label say whether the product was formulated for the person swallowing it, and the four in the documents say whether the formulation was then made, tested, kept and answered for. A product with the cheap form, a compound-weight dose, a coated tablet and a list of six, made in an unnamed facility without release testing, with an arbitrary date and no address, has made all eight decisions the other way, and the label alone reveals four of them before any email is sent. A buyer who reads the four label decisions in the shop and asks for the four document decisions afterwards has done the whole of the quality check, and the page's claim is that the first four are the half most buyers skip and the half that was decided first.

The worked example's eight decisions are read in the open: {FL} uses the bisglycinate form, chosen for absorption and tolerance over the oxide; states its dose as 300mg elemental at 80% NRV, the intake its authorised claims are conditioned on, rather than as the 1500mg of compound that would look larger; lists three ingredients, the bisglycinate, an HPMC capsule and rice flour as the one flow agent the fill needs; and uses a capsule that disintegrates. In the documents, it is made in a UK facility certified to GMP and BRC; each batch is released against a specification with lead, mercury, arsenic and cadmium tested at an accredited UK laboratory and the certificate by lot on request; the mineral is stable with an expiry set from the fill date; and a UK operator's address is on the tub with a UK company on the register behind it. Two capsules with the evening meal, 180 capsules for £19.99 at 22p a day. The full label breakdown is here.

The verdict: a supplement is made high quality by eight decisions, four on the label that were made before the tub existed, the form chosen for absorption and tolerance, the dose set at the claim's conditioned intake and stated as elemental, the fewest excipients the fill needs, and a format that disintegrates, and four in the documents, a named and audited facility, release testing by lot, stability behind the shelf life and a named operator with an address. The label reveals half the answer in a minute, the documents reveal the other half on request, and the two decisions most brands get wrong, the cheap form and the compound-weight dose, are the two the label shows first.

What to check on the label

Questions people also ask

What should I look for in a high quality supplement?

Eight decisions, four on the label made before the tub existed and four in the documents: the form of the nutrient chosen for absorption and tolerance rather than cost, the dose set at the intake the authorised claim is conditioned on and stated as elemental with its reference value percentage, the fewest excipients the fill needs, and a format that disintegrates; then a named and audited facility, release testing of each batch with a certificate by lot, a shelf life set from stability data, and a named operator with a UK or EU address; the label reveals the first four in a minute.

Why does the form of a nutrient matter for quality?

Because most nutrients come in several chemical forms that differ in absorption, tolerance and cost, and the choice was made at formulation: magnesium as the oxide is cheap and poorly tolerated while the bisglycinate is dearer and gentler on the gut, iron as the bisglycinate is better tolerated than the sulphate, B12's methyl form matters to the few who absorb cyanocobalamin poorly, and creatine's monohydrate is the form every trial used; a form chosen for the person is the one the evidence supports for that nutrient, and the ingredient list records which choice the brand made.

What is the most common quality mistake on supplement labels?

Two that travel together: the cheap form, chosen for cost rather than absorption or tolerance, and the dose stated as the compound weight rather than the elemental content, so that a magnesium label reading 1500mg looks larger than one reading 300mg elemental when they are the same product, and so that the dose is not set at the intake the authorised claim is conditioned on; a label that states the elemental amount with its reference value percentage has made the decision for the person, and one that leads with the compound weight has made it for the shelf.

How can I test a supplement's quality at home?

One of the eight decisions can be checked in a kitchen: drop a capsule or tablet into a glass of warm water, swirl it, and watch whether it breaks apart within the time the pharmacopoeial disintegration test allows; a capsule should open within minutes and a well-made tablet within the hour, and a tablet still intact after an hour was pressed for the machine's speed and may pass through a person the same way; the other seven decisions are read from the label's form, dose and excipients and from the documents a brand sends on request.

How does this site's magnesium make the eight decisions?

On the label: the bisglycinate form for absorption and tolerance, a dose of 300mg elemental at 80% NRV stated as elemental rather than as the 1500mg of compound, three ingredients with an HPMC capsule and rice flour as the one flow agent, and a capsule that disintegrates; in the documents: a UK facility certified to GMP and BRC, each batch released against a specification with four metals tested at an accredited UK laboratory and the certificate by lot on request, a stable mineral with an expiry set from the fill date, and a UK operator's address with a UK company on the register; two capsules with the evening meal at 22p a day.

Sources

1. The vitamin and mineral form literature: magnesium oxide has lower fractional absorption than citrate or glycinate; synthetic DL-alpha-tocopherol has about half the biological activity of the natural RRR form per milligram; cyanocobalamin and methylcobalamin both correct B12 deficiency; form changes absorption or activity per milligram rather than whether a nutrient works. PubMed record
2. Retained Regulation (EC) No 1924/2006 on nutrition and health claims made on foods, and the Great Britain nutrition and health claims register. https://www.gov.uk/government/publications/great-britain-nutrition-and-health-claims-nhc-register
3. The pharmaceutical excipient literature: capsule shells, bulking agents, glidants and anti-caking agents, binders, disintegrants and coatings are functional non-active ingredients whose purpose is manufacturability, stability and dosing accuracy rather than effect. PubMed record
4. The pharmacopoeial disintegration test: uncoated tablets and hard capsules are required to disintegrate in warm aqueous medium within a set time, typically 30 minutes for uncoated tablets and shorter for capsules, the test a tablet pressed too hard to dissolve fails and a kitchen glass of warm water crudely imitates. PubMed record

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