Look at the active fraction, not the compound weight
Garlic powder is standardised to alliin, and a 1.3% standard means 1,200 mg of powder yields roughly 3.6 mg to 5.4 mg of allicin once the enzyme does its work [1]. Two capsules totalling 1,800 mg of powder sound substantial. In active terms you're looking at single digit milligrams, and that contrast is the whole subject of this piece.
The same arithmetic runs through magnesium, zinc and iron. The elemental weight is what your body uses. The compound weight is what gets printed in large type.
Why labels quote the compound in the first place
Because the compound is what goes into the capsule. Magnesium never appears alone in a supplement, and neither does most zinc. It arrives bound to an oxide ion, a citrate molecule, an amino acid or a sulfur compound from garlic. Both figures are legitimate descriptions of the same physical object, which is exactly why they get used interchangeably in marketing and shouldn't be.
Take magnesium citrate. The compound is about 16.2% magnesium by weight, so 2,000 mg of it holds roughly 220 mg of the mineral. Read the front of the tub and you'd think you bought four days of magnesium. Read the fine print and you'd see about half a day. Two figures, one bottle, and no dishonesty required for the confusion to happen.
Where the real figure lives
Regulators require the elemental amount inside that box, and the percent Daily Value beside it refers to the elemental figure [2]. So the box is your cross check. If the front claims 1,800 mg and the fine print lists 220 mg, the fine print wins, because it is answering the question you're actually asking.
Look at something like our garlic
Our garlic is standardised to alliin and we print the allicin yield on the box rather than the powder weight, because the yield is the figure that tells you whether the product is worth swallowing. That single decision makes us easy to compare against anything else on the shelf, and it is the standard we would like to be held to.
Do the same check on everything else you buy. Find the word elemental, or find the compound name in brackets with a figure outside them. Then work out cost per elemental milligram rather than cost per gram of powder, because that ratio is where a cheap bottle stops being cheap. A 120 count bottle at 300 mg of the mineral per serving is not comparable to a 120 count bottle at 70 mg, even when both cost the same, and price per elemental milligram will show you that in about 30 seconds.
Strength also varies by form inside the same category. Our zinc, for instance, states 15 mg of the mineral per capsule, a figure that lines up with the 11 mg and 8 mg reference intakes for adult men and women, and leaves room for the zinc in your food without approaching the 40 mg upper limit. That is the comparison you want everywhere on your shelf. One number, same units, one clear answer. When a brand hides that one, the hiding is the message.
Two habits fix most of this. Photograph the fine print before you buy, so you can compare ratios at home instead of in the aisle with a phone in one hand. Check the serving size too, because the box can quote per capsule or per two capsules and that difference doubles your cost overnight. A 1800 mg claim and a 220 mg printed number can both be true, and only one of them answers the question you walked in with.
References
[1] Lawson LD, Wang ZJ. Allicin and total thiosulfinate content of garlic products. Journal of Agricultural and Food Chemistry, 2001. [2] US Food and Drug Administration. Dietary supplement labelling guide: Supplement Facts requirements.
Frequently asked questions
How do I find the elemental amount?Show answerHide answer
It is on the Supplement Facts panel, usually listed under the compound name.
Why do labels quote the compound?Show answerHide answer
Because that is what goes in the capsule. Both figures are legitimate, so read the one you are comparing.
Does % Daily Value refer to the elemental amount?Show answerHide answer
Yes, which is why it is a useful cross check.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
