The number is usually traced back to the American Gut Project, a large citizen-science study of the microbiome. In a paper published in 2018, the researchers grouped thousands of participants by how many different plant types they reported eating per week. The two groups people quote are "more than 30" and "fewer than 10".
That's the origin. Thirty wasn't designed as a diet plan. It was a way of slicing survey data that happened to be very easy to remember.
How to treat the number
As a target, not a threshold. Nothing switches on at plant 30, and the number isn't a medical recommendation. It's a finish line for a habit a lot of people find worthwhile on its own: eating a wider range of foods than the same eight ingredients on rotation.
Since 2018, books, podcasts and food writers have run with the idea, and the rules have picked up local variations. Some people count herbs as a quarter. Some count red and green peppers separately. Some leave out white rice. None of these versions is official, so pick one you'll stick to.
Our position
Eating30 doesn't make health promises, and we're deliberate about that. The app counts variety. It shows how many different plants you've had this week and which colour groups you've covered. What you make of that is up to you, and if you have a medical condition, your doctor's view matters more than any app's.
The longer read
Where 30 Plants per Week Comes From: The Research Behind the Number
The 30 plants goal came from microbiome research, but what does it actually mean and how strong is the evidence?
Eating30 is an app for iPhone and Android that counts the different plants you eat each week, with 30 as the target. The core tracking is free. It's a habit tracker, not medical advice.
Count your plants with Eating30
Tap the plants you eat and watch your week fill up towards 30.