Photo by Brooke Lark on Unsplash
In short: Prebiotics are food for your gut bacteria, mostly special kinds of fibre in plants like leeks, onions, oats and lentils. Probiotics are live friendly bacteria. Fermented foods are foods made with the help of microbes, and some of them still carry live bacteria when you eat them. The simplest way to use all three is to build meals around a variety of plants and add a spoonful of something live and fermented now and then.
You’re standing in the supermarket in front of the chilled shelf. One yoghurt says “with probiotics”. A box of cereal says “with prebiotic fibre”. A jar of sauerkraut on the next aisle says nothing at all. They all sound like they’re good for your gut, but what’s the difference, and do you need all three?
The words are confusing because they sound so alike. Once you see how they fit together, it becomes very simple, and you’ll find that most of what your gut needs is already in a good French market basket.
What are prebiotics?
Prebiotics are food for the friendly bacteria in your gut. They’re mostly particular kinds of fibre that you can’t digest yourself. They pass through your stomach and small intestine untouched and arrive in your large intestine, where your gut bacteria feast on them.
When the bacteria eat this fibre, they make substances that nourish the cells lining your gut and help keep it in good shape. So when you feed them, they look after you in return.
You’ll find prebiotic fibre in leeks, onions, garlic, chicory, artichokes, asparagus, slightly green bananas, oats, barley, lentils, chickpeas and beans. Apples and pears play their part too. Notice how ordinary these are. A leek and potato soup is a prebiotic meal; so is a bowl of porridge.
What are probiotics?
Probiotics are live friendly microbes, mostly bacteria and a few yeasts. Strictly speaking, the word is used for particular live microbes that have been shown to do something useful, but in everyday life people use it for any friendly live bacteria in food or in a capsule.
Most of them don’t move in for good. They pass through, a bit like visitors to your gut garden, and while they’re there they interact with the bacteria who already live there. That’s one reason why variety and regularity matter more than any single product.
Are all fermented foods probiotic?
No, and this surprises many people. Fermented foods are foods that microbes have helped to make: yoghurt, kefir, sauerkraut, kimchi, miso, some cheeses, sourdough bread, even wine and chocolate.
But only some of them still contain live bacteria when they reach your plate. Bread is baked, so the microbes are gone. Sauerkraut in a tin or a jar from a warm shelf has usually been heated. Pickles made with vinegar were never fermented at all. The live ones are usually in the chilled section and say “live”, “raw” or “unpasteurised”. I explain how to choose them, and share my easy homemade sauerkraut, in Fermented foods for beginners.
How do the three work together?
Think of your gut as a garden. Prebiotic fibre is the compost: it feeds the plants that already grow there. Live fermented foods are visitors bringing a few new seeds and some news from outside. And probiotic supplements are a particular packet of seeds, chosen for a particular purpose.
A garden with lots of seeds and no compost doesn’t do well. That’s why, when I work with someone on their digestion, I always start with the compost: plenty of plants and fibre, in many colours, every day. Fermented foods come second, as a pleasure and a bonus. Your gut and your brain are also in constant conversation, and I wrote about that in The hidden connection: how your gut and brain communicate.
What helps?
1. Put a prebiotic plant in every meal
Sautéed leeks with your eggs in the morning. Oats with a grated apple. Lentils or chickpeas at lunch. Onion and garlic as the base of your evening soup. It doesn’t have to be fancy; it just has to be there. You’ll find more ideas for colourful plates in Colour your plate with nutrients.
2. Add a spoonful of something live
A spoonful of raw sauerkraut beside your lunch, a bowl of plain live yoghurt with walnuts, a glass of kefir, a little miso stirred into soup at the end, once it’s off the heat. Small and regular is better than a big bowl once a week. My overnight oats bring prebiotic oats and live yoghurt together in one jar.
3. Go slowly
If you suddenly add a lot of beans, onions and artichokes, your gut bacteria will throw a party and you’ll feel it: wind and bloating. Add one new food at a time, in small amounts, and drink a little more water as you go, because fibre needs water to do its work.
4. Eat them calmly
The same bowl of soup eaten in five minutes at the desk and eaten slowly at the table is, for your gut, two different meals. Sit down, take a few slow breaths, and chew. Digestion works best when your body feels safe.
What doesn’t help?
Relying on a capsule. No supplement can replace a varied plate full of plants.
Thinking “fermented” always means “live”. Check the label and the shelf it’s on.
Doing everything at once. A gut that’s used to little fibre needs time to adapt.
Cooking the live ones. Heat kills the friendly bacteria, so add yoghurt, miso or sauerkraut at the end.
Try this for one week
Each day, make sure one meal contains a prebiotic plant and one spoonful of a live fermented food. A leek soup with a spoonful of yoghurt on top counts for both. Keep a little note each evening of what you ate and how your digestion felt. At the end of the week, look back: which foods did your gut enjoy, and which made it grumble? That’s your own map.
Frequently asked questions
What’s the difference between prebiotics and probiotics?
Prebiotics are fibre that feeds your gut bacteria; probiotics are live friendly bacteria themselves. You need the first to make the most of the second.
Which foods contain both?
Very few foods contain both on their own, but you can easily combine them: yoghurt with oats and apple, or lentil soup with a spoonful of raw sauerkraut on the side.
Should I take a probiotic or prebiotic supplement?
I don’t recommend supplements myself, and food is the place to start for most people. If you’re thinking about one, please talk to your doctor or pharmacist first, especially if your immune system is weakened, you’re seriously ill or you take regular medicines.
When should I talk to my doctor?
If more fibre or fermented food gives you strong pain or bloating, or if your digestion has changed and doesn’t settle, please see your doctor rather than trying more products. Blood in your stools, weight loss you can’t explain or ongoing diarrhoea always need checking. My frequently asked questions on gut health answer many other questions too.
Would you like some help?
Knowing the difference between prebiotics and probiotics is one thing; finding the foods your own gut enjoys is another. That’s the kind of thing we work out together in my group programmes in nutrition and health, such as Six Tuesdays in Montignac. Write to me at hello@catherinepolet.coach if you’d like to hear when the next group opens.
If you’d prefer to work one to one, from anywhere, I coach online as well. Book a free 20-minute call and we’ll look at what’s on your plate and how your gut is feeling.
About Catherine
I’m Catherine Polet, a holistic nutrition health coach, yoga and autogenic training teacher for more than 30 years, author and speaker. I help people find a way of eating and living that suits their own body, online in English, French, Spanish and German, and in person in Southwest France.
