Making sense of the units on S-allyl cysteine

On an S-allyl cysteine label, 1,000 mcg equals 1 mg, and that single division explains why two bottles can look a thousand milligrams apart while carrying nearly the same amount. Divide the microgram figure by 1,000 and the comparison becomes ordinary arithmetic. I keep a note on my phone for this, because I get it wrong when I eyeball it.

Why the S-allyl cysteine mg vs mcg gap trips people up

A milligram is one thousandth of a gram. A microgram is one millionth. The two symbols differ by one letter, which is a poor design choice for something you swallow, and the failure mode is predictable: a label reading 800 mcg looks enormous next to one reading 0.8 mg, even though they are the same quantity written two ways.

Our own aged garlic gummies list S-allyl cysteine inside an aged garlic extract blend rather than as a standalone figure, so I won't invent a number for it here. What I can tell you is the arithmetic, and that's the part that travels between brands.

Run the conversion once, then stop thinking about it

Three lines cover almost every label. 1,000 mcg equals 1 mg. Move the decimal three places and you're done. Write 2,400 mcg as 2.4 mg, 350 mcg as 0.35 mg, and 15 mg as 15,000 mcg. Once both labels sit in the same unit, the bigger number really is the bigger dose.

You'll also see IU on older labels, mostly for vitamins A, D and E. IU measures biological activity, not weight, and the conversion factor depends on which nutrient you're looking at, so there's no single divisor that works across a whole panel. If a row mixes IU and mg, the two figures aren't comparable until you look up the nutrient-specific factor, and I treat those rows as a separate exercise.

Compare per serving, not per gummy

This is where I got burned. A bottle can state a dose per two gummies while the panel above it quotes a per-gummy figure, and both numbers are printed honestly. Our magnesium taurate gummies carry 1800 mg per serving, and that serving is two gummies rather than one. Someone reading the front of the bottle and the back in the same minute can walk away with a number that's off by half.

Check the column heading first. Per serving. Per capsule. Per 2 gummies. Then check how many pieces make that serving. Only after both are nailed down does the milligram count mean anything at all.

What the arithmetic can't tell you

A converted number tells you weight. It does not tell you how much of that weight is the compound you actually want. Aged garlic extract is standardised, meaning the maker sets a target for S-allyl cysteine, but the extract weight and the compound weight are different figures, and plenty of labels blur the two on purpose or by accident.

If a brand quotes 600 mg of extract without saying how much S-allyl cysteine sits inside it, you can't compare that bottle to one that names the compound. Ask the seller, and treat a vague answer as the answer. That's also why the CoQ10 figure on our label, 60 mg per serving, is printed as its own line while the garlic extract sits above it: one number you can check, one number you have to ask about.

My actual habit, which takes about a minute

Last Tuesday I stood in a kitchen with two bottles side by side, one quoting 1,200 mcg and the other 1 mg. Same ballpark, once divided. It took me longer to find the serving size than to do the division itself.

My partner had bought the louder label and was convinced it was a stronger product. It carried roughly a fifth more than the quiet one, which is a real difference and not the twentyfold difference the numbers suggested at a glance. We kept both.

I convert to milligrams, note the serving count, and write both on the bottle cap in marker. Two bottles from different brands then sit on the same scale in my head. It also stops me from double-dosing when I switch products mid-bottle, which is the more expensive of the two mistakes and the one nobody notices until the bottle empties early.

What I can't do for you is decide which dose is right, because that depends on what else is on your plate and what your clinician says. The arithmetic just keeps you from comparing two things that were never in the same unit.