What a multi-strain probiotic is, and what a colony forming unit count actually tells you

Walk the aisle and the numbers climb. Ten billion. Fifty billion. A hundred billion, in bold, on the front.

Our Gut Health product says 27 billion, and we get asked about it.

So here is the honest version, which nobody selling probiotics tends to volunteer.

What a CFU is

A colony forming unit is one bacterium capable of multiplying into a visible colony on a plate. It's a count of things that are alive enough to reproduce.

That's a useful measure, and it's the right one. It counts living organisms rather than total cells, so it excludes anything that died on the way.

A close macro of the words 100 BILLION printed in heavy type on plain white carton board, near enough that the halftone dots of the ink and the fibre of the board are visible.

The part nobody says out loud

No probiotic company can tell you why their number is their number.

The definition of a probiotic, agreed by an international panel, requires live organisms “in adequate amounts.” That phrase has never been given an operational definition. There is no established figure for what adequate means, for most organisms or most purposes.

Which means the billions printed on a probiotic label, ours included, come from what a manufacturer can actually make and verify, and from what the rest of the shelf is printing. Not from a defined effective dose, because one doesn’t exist.

Once you know that, a bigger number stops being reassuring and starts being a design decision.

A sheet of laboratory paperwork on a clipboard on a steel bench, signed, with a pen beside it.

The questions we asked instead

Not how many. Who counted, and when.

Most CFU figures describe what went into the batch. That's an input, calculated by weight before anything is bottled, and nobody independent has looked at it.

Ours is different, and that part is deliberate. The cultures keep growing after the bottle is capped, and that number climbs quickly, so a count taken at bottling would not describe what reaches you. Every batch goes to an independent laboratory instead and is counted about a week later.

What we print is what a lab found in the bottle. Not what we put in it.

Five glass jars on a wooden shelf holding sauerkraut, kimchi, olives, pickles and a sourdough starter.

The fifteen

Ten Lactobacilli and five Bifidobacteria.

The Lactobacilli are food organisms. They are what has been working in fermented food for as long as people have been making it. Lactobacillus plantarum is in kimchi, sauerkraut, brined olives and sourdough starter. Lactobacillus bulgaricus is what turns milk into yogurt, and it’s named for Bulgaria, where a young scientist first described it in 1905. Lactobacillus brevis is in pickles. Lactobacillus casei is in aged cheese.

The Bifidobacteria are gut organisms, and among the most abundant in a healthy human gut.

The fifteen

What a multi-strain probiotic actually contains

Every batch is tested by an independent, accredited microbiology laboratory for safety and the absence of pathogens.

Open any of the fifteen. Where it comes from, who first described it, and what it is in plain words.

  • 27B CFU per shot
  • 15 Live strains
  • 2 oz Daily serving
  • 0g Added sugar

*at the time of manufacture
A petri dish of amber agar scattered with pale round bacterial colonies, photographed from directly above.
Twenty-five genera now, where the filing cabinet used to hold one.

One thing that changed recently

In 2020 the genus Lactobacillus was split into twenty-five separate genera. Genetic sequencing had shown it was less a family than a filing cabinet, holding organisms that weren’t closely related at all.

So more than half of these have a different official name than they did five years ago. Lactobacillus plantarum is now formally Lactiplantibacillus plantarum. Most labels still use the familiar names, because that’s what people recognize. Ours uses the updated ones where they changed, which is why the list below may not match what you are used to seeing.

Worth knowing if you ever compare two labels and the names don’t match.

What's in each bottle

Gut Health

Gut Health

Over 27 billion CFUs per serving, at the time of manufacture

Women's Health

Women's Health

15 billion CFUs per serving, at the time of manufacture

Fifteen strains in both. No gluten, no dairy, no added sugar. Pre-hydrated in juice, weeks before the bottle reaches you.

We tested ours in simulated stomach acid, see the results

See both blends

Questions

Is a higher CFU count better?

Not necessarily, and nobody can tell you where the threshold is. More organisms means more starting material, but survival, delivery, and what condition they arrive in all matter, and none of those show up in the number on the front.

Is a multi-strain probiotic better than a single strain?

It depends what you're comparing. More species means more variety. A single well-chosen organism at the right dose isn't automatically worse. The count of strains is another number that's easy to print and hard to interpret.

What does "at the time of manufacture" mean?

It means the count was taken at production rather than at the end of shelf life. It’s the industry convention. In our case the count is taken by an independent lab about a week after bottling, once the cultures are culturable.

Why do the strain names on different labels look different?

Because of the 2020 reclassification above. The same organism has two valid names, an older familiar one and a newer formal one.