General information, checked against the regulations and trials cited below. Not medical advice.
Most people compare supplements the way they compare cereal: by the front of the box. The front of a supplement bottle is advertising. The back — the Supplement Facts panel — is the only part a regulator requires to be true. Learning how to read a supplement label takes about ten minutes, and it changes what you buy for the rest of your life, because most of the tricks in this industry are not lies. They are true statements placed where you will misread them.
This guide walks through the five places where a label can mislead you, with real examples — including our own labels, and including the places where our doses sit below the studies we cite. If a brand will not do that arithmetic on its own products, it should not be asking you to trust its arithmetic on anyone else’s.
How we put this guide together
We read the US labelling regulation for dietary supplements (21 CFR 101.36), the NIH Office of Dietary Supplements fact sheets for the minerals discussed, and the human trials behind every ingredient we sell. We then took the Supplement Facts panels for our eight formulas and checked each line against the dose used in the study we cite for it. Where our number is lower, we say so. Where the label convention could be misread, we say that too. No independent lab was involved in writing this page; the certificates of analysis referenced are those our contract laboratory issues per lot.
1. Serving size: the number every other number depends on
Every Supplement Facts panel in the United States must state a serving size, and every amount on the panel is per serving — not per capsule. That single convention is responsible for more misreading than anything else on a label.
A bottle that says “1,000 mg per serving” with a serving size of four capsules delivers 250 mg per capsule. If you take two, you are getting half of what the front of the bottle implied. Serving size also decides the real price: a “30-day supply” of 120 capsules at four per serving is 30 days; at two per serving it is 60.
On our labels: NAD+ is two capsules per serving, magnesium is three, DIM is one, Cortisol Health is two. The “cost per serving” figure on each product page is calculated on those serving sizes, not per capsule. Check the same thing on every competitor’s page before comparing prices.
2. Compound weight versus elemental mineral: the magnesium problem
Minerals never arrive alone. Magnesium is bound to something — oxide, citrate, glycinate, malate — and the carrier molecule has weight. Pure magnesium bisglycinate is about 14 % magnesium by weight; the other 86 % is glycine. Published composition data put anhydrous magnesium citrate at 16.2 % elemental magnesium, and the hydrated form is closer to 12 %. Magnesium oxide, by contrast, is roughly 60 % magnesium — which is why a cheap oxide capsule can honestly print a much larger number than a premium chelate.
The same arithmetic decides which magnesium is worth buying, which we worked through in Magnesium Glycinate vs Citrate.
This creates two label conventions that look identical and mean very different things:
- “Magnesium (as magnesium bisglycinate) — 140 mg”: the 140 mg is elemental magnesium. This is the number that counts toward the 310–420 mg daily reference intake.
- “Magnesium bisglycinate — 1,000 mg”: the 1,000 mg is the weight of the whole compound. The actual magnesium is about 140 mg.
A 2018 randomised trial of 264 stressed adults with low serum magnesium used 300 mg of elemental magnesium a day (Pouteau et al., PMID 30562392). To match that with a pure glycinate chelate you would need over two grams of compound — roughly four large capsules. If a label offers you “300 mg magnesium glycinate” in one capsule and implies it matches the trial, the chemistry says it cannot.
How to check any magnesium label in ten seconds: find the word “Magnesium” on its own line with a % Daily Value beside it. If there is a %DV, the figure is elemental. If the line reads “magnesium glycinate” with a number and no %DV, you are probably looking at compound weight — divide by seven for glycinate, by six for citrate. Then compare it with the elemental dose in the trial the brand cites.
The same logic applies to zinc (zinc picolinate is about 20 % zinc), calcium and iron. Ask which number you are reading before you ask whether it is enough.
3. Form of the substance versus name of the substance
Two products can both say “NAD+” on the front and contain completely different things. That matters, because the human absorption evidence is attached to specific molecules, not to a category.
On our NAD+ label: the front of the jar says “NAD+ 1400 mg Complex”. The panel shows what that 1,400 mg is: 400 mg of NAD (β-nicotinamide adenine dinucleotide), 250 mg of nicotinamide riboside chloride, and 750 mg of hydrolysed fish collagen. The headline number is a total of three ingredients, one of which is a skin-and-joint ingredient with its own literature.
The human trials that show blood NAD+ rising are trials of the precursor nicotinamide riboside: 100, 300 and 1,000 mg a day raised whole-blood NAD+ by 22 %, 51 % and 142 % over eight weeks (Conze et al., PMID 31278280). Our serving carries 250 mg of NR chloride — below the 300 mg arm that produced the 51 % result. We publish that comparison on the product page rather than hoping you will not do the division.
The general rule: find the exact molecule the study used, then find that exact molecule on the panel with its own milligram figure. “Complex”, “matrix” and “formula” are words for the front of the jar. They do not appear in trial registrations.
4. Standardisation: what “extract” actually promises
A botanical extract is only comparable to a trial if it is standardised to the same marker compound at the same percentage, ideally from the same plant part. Otherwise “ashwagandha 600 mg” tells you the weight of dried plant material, not how much of anything active is in it.
Three questions for any herbal line on a label:
- Which part of the plant? Ashwagandha trials overwhelmingly use root extract. Leaf material is cheaper and contains a different withanolide profile. A label that does not say “root” has not told you.
- Standardised to what? KSM-66® is a root-only extract standardised to 5 % withanolides; a typical rhodiola standard is 3 % rosavins and 1 % salidroside. A label that says “extract” with no percentage is not standardised, or is not telling you.
- What was the extract ratio? “10:1” means ten kilograms of raw herb produced one kilogram of extract. Higher is not automatically better — it depends what was concentrated — but it should be stated.
On our Cortisol Health label: 300 mg of KSM-66® root extract per two-capsule serving. The most-cited cortisol trial of this extract gave 300 mg twice daily, for a total of 600 mg, and reported a 27.9 % fall in serum cortisol over 60 days (Chandrasekhar et al., PMID 23439798). Our morning serving is half that trial’s daily dose. It is the same extract at the same standardisation, which makes the comparison honest — and it is a lower dose, which we would rather you learn here than in a review.
5. Proprietary blends: the dose that cannot be checked
Under 21 CFR 101.36, a manufacturer may group ingredients into a “proprietary blend” and declare only the blend’s total weight, with the ingredients listed in descending order by weight. Every ingredient must be named. No individual amount has to be.
That is the entire problem. A “Stress Support Blend 800 mg” containing ashwagandha, rhodiola, L-theanine, holy basil and phosphatidylserine could legally be 700 mg of the cheapest herb and 25 mg of each of the others. The descending-order rule gives you one clue — whatever is listed first is the largest — and nothing else. You cannot compare a blend to a trial, because you do not know the dose.
The honest reasons brands give for blends are real but rare: protecting a formulation ratio from copying. Reviewers of the category put it bluntly: in practice, most proprietary blends exist to obscure underdosing. Our position is simple: none of our eight formulas uses one, and the individual milligram figure for every active is printed on the panel. If you find an active on any 4Well label without its own number, email us and we will publish it.
6. The lines people skip: “Other ingredients” and the allergen statement
Below the panel sits the list of everything that is not a dietary ingredient — capsule material, flow agents, fillers. It is where you find out whether the capsule is gelatin or cellulose, whether there is titanium dioxide, and, critically, where allergens hide.
On our NAD+ label: the collagen is hydrolysed fish collagen from cod and tilapia. That one line makes the product unsuitable for anyone with a fish allergy and for vegetarians, regardless of the vegetable capsule. It is printed on the panel and in the product description because it is the single most important line on that label for a meaningful number of people.
7. “Lab tested”: what was tested, by whom, and can you see it?
“Third-party tested” on a jar is a claim, not evidence. A certificate of analysis (CoA) is evidence, and a useful one has four features:
- A lot number that matches the one printed on your bottle.
- The laboratory’s name and, ideally, its ISO 17025 accreditation.
- The tests performed — identity, potency, heavy metals and microbials are four separate assays, and a certificate can cover one without the others.
- The result against a specification — for example, “NAD assayed by HPLC at 462.58 mg against a 400–500 mg specification” (that is the actual figure from one of our released NAD+ lots).
If a brand says “every batch tested” but the certificate is available “on request”, request it before buying. If it never arrives, you have your answer.
Putting it together: a 60-second label check
- Find the serving size. Convert every number to per-capsule and to your actual daily intake.
- For minerals, decide whether the figure is elemental or compound weight. If in doubt, assume compound.
- Find the exact molecule the brand’s cited study used, and find it on the panel with its own milligram figure.
- For herbs: plant part, standardisation percentage, extract ratio.
- If there is a proprietary blend, stop comparing — you cannot.
- Read “other ingredients” for allergens and capsule material.
- Ask for the certificate of analysis by lot number.
A product that passes all seven may still not be the right product for you. A product that fails two or three is not worth the arithmetic.
Frequently asked questions
What does % Daily Value mean on a supplement label?
The percentage of the FDA reference daily intake supplied by one serving. It exists only for vitamins and minerals with an established value; a double asterisk means no daily value has been set, which is the case for most herbs, amino acids and compounds like NAD+.
Is a higher milligram number always better?
No. It can mean compound weight rather than elemental mineral, a total of several ingredients, or a dose above what the trials used with no added evidence of benefit. The right number is the one the relevant human study used.
Why do brands use proprietary blends?
Legally, to protect a formulation. In practice, usually so that individual doses cannot be checked against the research. Either way the effect on you is the same: you cannot verify the dose.
Does “clinically studied ingredient” mean the product was studied?
No. It means the ingredient was, often at a different dose, in a different form, in a different population. Look for the words “not conducted on this finished product” — brands that write them are at least being clear.
How much elemental magnesium is in magnesium glycinate?
About 14 % by weight for the pure chelate. 1,000 mg of magnesium bisglycinate provides roughly 140 mg of magnesium.
Conclusion
The front of a supplement bottle is written by marketing; the back is written under regulation. Read the back first. Convert to per-capsule, separate mineral from carrier, match the molecule to the study, check the plant part and standardisation, refuse to compare anything inside a proprietary blend, and ask for the lot-specific certificate. Do that, and most of what is on the shelf sorts itself into two piles in under a minute. If our own labels ever fail that check, we would rather you tell us than a review site.
Related reading: NAD+ Supplements: What Raises It, What It Changes, and What It Does Not · DIM Supplements: Estrogen Metabolism, Dosage and How to Choose One · Adaptogens for Stress: The Real Clinical Evidence
Labels discussed: NAD+ Supplement Facts · Cortisol Health for Women · DIM Complex 370 mg · Berberine Triple Strength · Saw Palmetto for Women · Saw Palmetto for Men · Resveratrol 1800 mg
References
- US FDA. 21 CFR §101.36 — Nutrition labeling of dietary supplements. Electronic Code of Federal Regulations.
- Pouteau E et al. Superiority of magnesium and vitamin B6 over magnesium alone on severe stress in healthy adults with low magnesemia. PLoS One 2018;13(12):e0208454. PMID 30562392
- Conze D et al. Safety and metabolism of long-term administration of NIAGEN. Sci Rep 2019;9:9772. PMID 31278280
- Chandrasekhar K et al. A prospective, randomized double-blind, placebo-controlled study of a high-concentration full-spectrum ashwagandha root extract. Indian J Psychol Med 2012;34(3):255–62. PMID 23439798
- Magnesium citrate (3:2) — composition data. Wikipedia
- WBCIL. Identifying magnesium bisglycinate: quality and testing guide (14.1 % elemental Mg). wbcil.com
- NIH Office of Dietary Supplements. Magnesium — Fact Sheet for Health Professionals.
These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.
References
- Pouteau E et al. PLoS One 2018;13(12):e0208454. PMID: 30562392
- Conze D et al. Sci Rep 2019;9(1):9772. PMID: 31278280
- Chandrasekhar K et al. Indian J Psychol Med 2012;34(3):255-62. PMID: 23439798
