DAO enzyme units and milligrams measure different things, so a 500 mg figure on a kidney supplement can't be read as an activity number. Units describe how fast an enzyme works in a lab assay. Milligrams describe how much material went into the serving. Most labels give you one or the other, and knowing which one you're holding is the whole skill.
Where a DAO label gives you milligrams
Diamine oxidase, shortened to DAO, is an enzyme produced in the intestinal lining that is involved in breaking down histamine arriving with food. Supplemental versions come from animal kidney tissue, or from plant formulas that don't contain the enzyme at all.
The grass fed beef kidney gummies use the milligram style. Each two gummy serving delivers 500 mg of bovine kidney, and that figure is a weight of tissue, nothing more. The same copy calls the extract rich in DAO without attaching any unit value to the word, which is typical of a category where no unit has been standardized across brands.
What an activity unit measures instead
An enzyme unit is a rate, not an amount. It answers how much substrate a preparation converts per minute under fixed conditions of temperature, pH, and substrate concentration, so two samples of identical weight can return different unit values if one was heated harder, dried longer, or stored badly. Activity is fragile in a way that mass isn't.
Historically, diamine oxidase activity has been reported in units that some labels abbreviate as HDU, and readers assume those units sit on the same scale as a weight. They don't. A unit is defined by whoever ran the assay, and the assay belongs to that lab, not to the category.
Why 500 mg and an HDU number can't be converted
To move from weight to activity you need a specific activity: units per milligram, measured on a defined assay, usually printed on a certificate of analysis rather than on a bottle. Supplement panels don't carry that line, and the product copy that accompanies a bottle usually doesn't either. So when one product shows 500 mg and another shows a unit count, there is no arithmetic that puts them on one axis. Any page offering a conversion factor is inventing it.
That is the honest read, and it's the useful one. It tells you to stop comparing across those two numbers and start asking a different question: which material, how much of it, and when do you take it.
The 5:1 extract ratio is a third number
The kidney gummies also carry a 5:1 extract ratio next to the 500 mg. A ratio describes how much starting material was concentrated into the finished extract, and it works in one direction only: five parts of raw tissue reduced to one part of extract, or the opposite, and a printed ratio alone doesn't always say which direction was meant.
If the 500 mg is the concentrated extract and the ratio points back to raw tissue, the multiplication lands near 2,500 mg of starting kidney. That arithmetic belongs to you, not to the bottle. And concentration says nothing about whether the enzyme is still active, because activity is exactly what a hot or long extraction can cost you.
Reading a DAO formula that lists botanicals instead
The plant based DAO support gummies approach the same routine from another direction. There is no enzyme ingredient to weigh, so no milligram figure and no unit figure appear: the formula is pea sprout extract, quercetin, vitamin C, and bromelain, at two gummies per serving in a 60 count bottle.
A botanical formula and a kidney based formula aren't two strengths of one thing. They're two different approaches, and putting them on one scale by weight is like ranking a recipe against an ingredient. The DAO enzyme collection puts both styles side by side, which helps precisely because the labels themselves don't.
Timing the serving before a meal
Timing is where this label gets concrete. The plant based gummies ask for two gummies 5 to 15 minutes before a meal, a short window that matches the idea of the formula being present while food is arriving. That instruction is on the bottle, and it's the kind of detail worth copying exactly instead of improvising around it.
The kidney gummies state a serving without a timing window, which is common for tissue based products. If you want a before meal habit, follow the bottle that gives you a minute range. A slippery elm and marshmallow root drop adds a third reading problem, since liquids are measured in milliliters and the dropper is the measuring device you're trusting.
Format changes which number you even get. The digestive health collection mixes all three, gummies by count, liquids by volume, tissues by weight, and the gummies collection is the easiest place to compare serving counts, because count is the one number every gummy bottle has to print.
Is a higher milligram number more DAO activity?
Not necessarily. Milligrams measure material, not catalytic rate, and activity can differ between two batches of the same weight. Without a units per milligram figure, weight alone doesn't predict activity.
Do DAO supplements have to list activity units?
US supplement labels aren't required to report enzyme activity in units, which is why most bottles list weight or a blend instead. When a brand does publish activity, it's usually on a certificate of analysis rather than the panel.
Can I compare two DAO products by milligram alone?
Only if both are the same kind of material, and even then you're comparing weight rather than enzyme performance. Weight is a fair way to compare cost per serving, not a way to compare activity.