How Many Different Plant Species Do You Eat in a Week?

They say you should aim for 30

I recently came across the idea of eating at least 30 different plants a week. The advice comes out of a 2018 study called the American Gut Project, where they found, through stool samples, that people who ate at least 30 different plants a week had better gut biome diversity. And diversity of beneficial bacteria in your intestine is linked to better overall health, even brain function and mental health. A diversity of plants also delivers a greater variety of nutrients.

What a healthy gut looks like.

The idea appealed to me, as diversity has always been one of my core principles in the kitchen (see Part 3 of my How to Eat Like a Farmer for more on this). Since even a tiny bit of a plant counts, it’s also simpler to track than trying to count servings (what is a serving, exactly?) or, god forbid, calories. I also just like thinking about my food not as dishes (guacamole, for instance) but as their constitutive parts (avocado, lemon, garlic, salt). Seeing the trees, not the forest. It feels more real and connected, and I’m all about keeping it real when it comes to food.

So, as something of a lark (how seriously can you take these food trends, anyway?), I kept track of each plant I ate for one week. As you’ll see, at first I thought I was rocking out this recommendation, but when I looked into it more, I wasn’t the rockstar I first thought I was. Here’s my list, in chronological order:

mint

coffee

wheat

maple

walnut

pecan

cacao

coconut

pumpkin

cucumber

mustard

apple

zucchini

cauliflower

garlic

lemon

dill

plum

broccoli

carrot

onion

celery

sunflower

haskap

banana

sumac

potato

cabbage

barley

hops

olive

kale

quinoa

tea

basil

sesame

almond

oat

honey

pepper

tomato

You probably noted the adjacent listing of barley and hops. You can guess what that was. I love any diet plan that beer counts towards!

I felt pretty smug that I hit the 30 mark after just two days, and coasted to a healthy 41 different plants by week’s end. But once again proving the adage that “ignorance is bliss”, when I looked in more detail at how this whole points system works, I found out that my results weren’t the slam dunk I thought they were.

You see, herbs only count for a quarter point. Ok, fine, that’s six points that now only count for 1.5. Still, I’m sitting pretty at 36.5.

Oh but wait, coffee and tea are also only a quarter point. No problem, I’m still at 35. Room to spare.

But then I read that processed plants don’t count for anything, so out goes my wheat from my white bread, and the barley, I suppose, from my beer (I knew it was too good to be true!). Still a pretty comfortable 33, though.

And sure, rob me for some reason of three-quarters of a point for the olive oil. I can take it! 32.25.

But now my self-righteousness gets dealt a devastating blow: apparently the high-priests of this diet have something against sugar. So out goes my maple syrup, honey, apple cider, sumac juice, and potatoes (too high on the glycemic index). Has anyone told them of the array of minerals and polyphenol antioxidants in maple syrup? Or how people apply honey to wounds (honey should count for several points, considering how many different flowers the bees put into it)? Or, despite their relatively high sugar and low fibre, how laden with nutrients my wild apple cider and sumac juice is? Or how the Irish literally survived off of nothing but milk and potatoes? Just because these foods come with a sugar baby, doesn’t mean we should throw out the bathwater of nutrients. (Or maybe that should read: “Just because these foods come with a bathwater of sugar, doesn’t mean we should throw out the baby of nutrition.” Take your pick.). If I follow their silly rules, my score has now fallen to 27.25.

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I think these guidelines have some merit, in that they get people to try to improve the diversity of what they eat – which is good – and get them to focus on eating more plants – which is also good, in the context of a culture that focuses too much on unhealthy animal products. But like most dietary prescriptions, in its focus on its narrow goal (promoting the gut microbiome, in this case), it does leave out some pieces of overall health puzzle.

As I already mentioned, while too much sugar is a bad thing, often sugar comes married to foods that contain a wealth of useful nutrients, and we shouldn’t be throwing out the baby or the bathwater. Mary Poppins was right: a spoonful of sugar does help the medicine go down.

Likewise, olive oil is really good for you. Even the fats in it are beneficial. Maybe it’s only assigned a quarter point because it’s assumed people use it sparingly, but I say, heap it on like the Greeks.

Your morning cup of coffee or tea can also be medicine! Coffee can even improve your sex life! And an abundant sex life in turn feeds back into more health! Now that’s what I call a positive feedback loop.

And while I fully agree that I should be eating more whole grains, I take exception to the claim that the barley in beer should count for nothing. Newsflash: sprouting grains, as is done when barley is malted for beer, greatly enhances their nutritive value. And don’t get me started about the benefits of fermented foods!

And of course this diet leaves out the benefits of healthy animal products altogether. Are not yogurt and kefir universally recognized for their positive contributions towards the gut microbiome? In your focus on plant diversity, don’t leave out the wide range of food diversity available to us.

Although even 30 plants a week is small potatoes compared to what non-agricultural societies ate/eat – 92 different plants consumed by the Alyawara of central Australia, for instance, or 126 by the Tlokwa of Botswana.

All that said, maybe one of the greatest benefits of this approach to eating is to simply get people thinking about where their food comes from. That sandwich you’re eating for lunch is actually made up of the seeds of a wheat plant, maybe a cut of ham from a pig, cheese from the udder of a dairy cow, leaves from a lettuce plant, the fruit of a tomato vine, egg from inside a chicken and oil from a seed to make the mayonnaise, and the pungent seeds of a mustard plant. Think about where all these ingredients might have come from, how far they might have travelled to come together into something delicious on your plate, and how they all ultimately sprung from this fertile, life-supporting Earth. Think about the stories of each of these plants and animals, their long evolutionary history, how each individual was just as alive as you feel today, and how they are sustaining your life.

When my son was young, we used to sing this song before every meal:

Earth who gives to us this food,

Sun who makes it ripe and good,

Dear Earth, dear Sun, by you we live,

Our loving thanks to you we give.

Aaaaaahmen.

Now that he’s older, we’ve fallen out of the habit. But it’s still good to be reminded sometimes.