Why 30 plants a week?

You may have heard the target: eat 30 different plants a week. It sounds arbitrary, but it comes from the American Gut Project — one of the largest studies of the human microbiome — which found that people who ate 30+ different plant types per week had noticeably more diverse gut bacteria than those eating 10 or fewer.

Why diversity, not quantity?

Different plants feed different microbes. Each type of fibre, polyphenol and resistant starch is food for a different family of bacteria. The more varied your plants, the more varied — and resilient — your microbiome.

That’s why Biome Buddy counts unique plants, not portions or calories. Ten apples is one plant. An apple, a pear, some oats, a handful of walnuts and a few chickpeas is five.

What counts as a plant?

More than you’d think:

• Fruits and vegetables (obviously)
• Whole grains — oats, brown rice, quinoa, barley
• Legumes — lentils, chickpeas, beans
• Nuts and seeds
• Herbs and spices (yes, the basil on your pizza counts)

Getting started

Don’t overhaul your diet. Just start noticing variety. Add a new plant where you can — a different bean in the stew, seeds on the yoghurt, a herb you don’t usually reach for. Log it, watch the ring fill, and let a little friendly competition with yourself do the rest.