One of the most common arguments online about plant diversity goes something like this:
“One blueberry doesn’t count.”
And if we are talking purely about fibre fermentation, that is partly true.
Gut bacteria need actual fuel. A few crumbs of oats or a single bean will not suddenly transform the microbiome.
But biology is more complicated than that.
Fuel vs Signals
Some plant foods mainly work by feeding gut microbes.
This is the classic fibre story:
- resistant starch
- soluble fibre
- legumes
- oats
- vegetables
- whole grains
Bacteria ferment these foods and produce compounds linked to gut health, such as butyrate.
This process needs quantity.
So yes:
- one blueberry
- a basil leaf
- half a walnut
…probably contributes very little fibre fuel.
But plants also contain compounds that behave more like signals.
Tiny amounts can influence:
- immune signalling
- antioxidant systems
- gut barrier function
- bacterial competition
- cellular pathways
This is closer to a “lock and key” model of biology.
The key may be tiny, but unlocking the right pathway can still have large effects.
And the body is not controlled by one single lock. Different plants contain different compounds interacting with different systems in different ways.
That is one reason plant diversity may matter.
Tiny Things Can Matter
Humans already understand this principle when it comes to vitamins.
The body only needs tiny amounts of vitamin C, yet a lack of it once caused scurvy in sailors on long sea voyages.
A little citrus juice helped transform how the British Royal Navy operated around the world.
The amount was tiny.
The effect was enormous.
That does not mean a blueberry works like a vitamin tablet. But it shows how small compounds can sometimes have outsized biological effects.
Does It Count for 30 Plants a Week?
People following the “30 plants a week” approach often ask:
- do herbs count?
- do spices count?
- does garlic count?
- does coffee count?
There is no official perfect scoring system.
The goal is increasing plant diversity over time.
A teaspoon of parsley is obviously not nutritionally equivalent to a bowl of lentils. But herbs, spices, berries, teas and seeds still contribute chemical diversity.
And one thing appears consistently in research:
Greater plant diversity is linked with greater microbiome diversity.
That is why advice such as “eat the rainbow” keeps appearing in nutrition guidance.
Different coloured plants often contain different fibres and phytochemicals.
So instead of obsessing over one “superfood”, the evidence increasingly points toward something simpler:
Eat a wider variety of plants, regularly, over time.
Not perfection. Just more diversity than before.
Track Your Own Plant Diversity
Want to see how many different plants you eat each week?
The 30aweek app makes it easy to:
- track plant variety
- discover new foods
- complete weekly challenges
- build diversity over time
Available on iPhone and Android:
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