Why don't meat and fish count towards 30 plants a week?

Meat and fish do not count towards 30 plants a week, and that is not an oversight. The 30 plants a week guideline counts plants because it is about feeding the bacteria in your gut, and what they live on is fibre. Meat has none. The chicken is still welcome on the plate. It just does not get a card.

What the count is for

The guideline comes from the American Gut Project, in which adults who ate more than 30 different plants a week had a more varied gut flora than adults who ate 10 or fewer (McDonald, 2018). It is an observation in adults, and it is about variety of plants, not about meat. Nobody in that study was asked to eat less of anything.

Plants are the unit because of what happens after a meal. Protein, fat and sugar are taken up in the small intestine. Most plant fibre is not. It travels on to the large intestine, where the gut bacteria live, and there it becomes their food. Different plants carry different fibres, and different fibres feed different bacteria (Koh, 2016). That is why 30 different plants says more than 30 portions of the same one.

Why meat and fish do not count

Meat and fish contain no fibre. The protein and fat are absorbed long before the large intestine, so almost nothing of a steak or a piece of salmon reaches the bacteria. That makes them a different kind of food from a lentil or an apple: good to eat, not part of this count.

It shows quickly, too. In a small study, adults ate only animal foods for 5 days, and within those days the bacteria that live on plant fibre dropped while others rose (David, 2014). An ordinary plate with chicken and two vegetables is not that diet. It only shows which side of the plate the bacteria are watching.

So the count is not a verdict on meat. It leaves meat out of the sum, the way a step counter leaves out how long you sat.

Do we need bacteria from meat

No. Meat does not bring useful bacteria with it, and the bacteria you have do not need any. They need feeding. The kinds that live on fibre are already there in most adults. What changes with the week's plants is how many kinds get something to eat.

There is one group of foods that does bring bacteria along: ferments. Yoghurt, kefir, sauerkraut, kimchi, miso, tempeh, kombucha and sourdough bread are made with live cultures. In one trial, adults who ate several portions of fermented food a day for 10 weeks saw the variety of their gut bacteria rise steadily (Wastyk, 2021). That is why ferments count in the app, each as its own plant, next to the fruit, vegetables, legumes, grains, nuts, seeds and herbs. The full list of what counts, cheese and eggs included, is in what counts as a plant.

What a plate with meat adds to the count

A plate with meat usually scores well. It is just the rest of the plate that scores. Chicken with rice, broccoli and a tomato salad is 3 plants: rice, broccoli, tomato. Add the onion and garlic from the sauce and the parsley on top and it is 6. The chicken was the part everyone liked. The count was already running around it.

That is the easiest way to grow the number without changing what you cook:

• Keep the meat, add a second vegetable.
• Stir a tin of beans or lentils through the mince.
• Let herbs and spices count: oregano on the pizza, cumin in the chili, each is 1.
• Put a ferment on the table: a spoon of sauerkraut, yoghurt with the fruit.
• Change the grain: barley or bulgur instead of rice, one night.

None of this is less meat. It is more plants next to it, and the count rises by itself. How a week like that adds up for a household of four is in 30 plants a week as a family.

What backfires

• A meat debate at the table. The count is not a case for or against meat, and a child does not need to hear one. The plants beside the meat are the whole story.
• "Good" and "bad" foods. A steak is not a lost point and a lentil is not a virtue. Name the food, count the plant, and leave it there.
• A child measured against the number. The 30 belongs to the adults. A child's game is tasting, one lick at a time, and that counts for the household whatever else is on the plate.

How Project Food does this

Project Food is an app on your phone that counts plants for everyone at your table. After a meal you tap what was on the table, per person. Every plant is a card, and a card fills by tasting. The catalogue holds over 200 plants, ferments included, and no meat, fish, eggs or cheese, because they do not add to the count. The app gives no advice on what to eat or how much, and promises nothing for a child. It keeps the shared count and gives you something to talk about at the table.

To remember

• Meat and fish do not count. They contain no fibre, and fibre is what the count is about.
• Your gut bacteria do not need bacteria from meat. They need feeding, with different plants.
• Ferments count: yoghurt, kefir, sauerkraut, kimchi, miso, tempeh, kombucha, sourdough.
• A plate with meat still scores, through everything next to it.