For most healthy people, fermented foods are the better everyday choice: they are cheaper per serving, bring protein, fibre or calcium along with live microbes, and fit easily into meals. Probiotic capsules make more sense for a specific, short-term reason, ideally with a specific strain your healthcare provider recommends. Either way, feeding your gut with plenty of fibre from plants matters at least as much as adding microbes.
Ferments and probiotics are not the same thing
The two terms get used interchangeably, but they mean different things.
- Probiotics are live microorganisms intended to have a health benefit. The U.S. National Center for Complementary and Integrative Health explains in its overview of probiotics that they can be found in yogurt and other fermented foods, dietary supplements and even beauty products.
- Fermented foods are made by allowing microbes to grow and transform the food. An expert panel’s consensus statement on fermented foods defines them as “foods made through desired microbial growth and enzymatic conversions of food components.”
The key point from that consensus: not all fermented foods contain live microbes when you eat them. Baking, pasteurizing or heat-treating after fermentation kills the microbes. And some foods that taste “fermented,” like vinegar-brined pickles, were never fermented at all.
Which fermented foods actually have live microbes?
| Usually live microbes | Fermented but usually no live microbes | Not fermented |
|---|---|---|
| Yogurt, kefir, most cheeses, miso, tempeh, natto, unheated sauerkraut and kimchi | Sourdough and other bread (baked), shelf-stable sauerkraut or pickles (heat-treated), soy sauce, vinegar | Vegetables pickled in vinegar brine |
Shopping tips:
- Look for “live and active cultures” or “contains live cultures” on yogurt and kefir.
- Buy sauerkraut and kimchi from the refrigerated section; shelf-stable jars on the regular aisle have usually been heat-treated.
- Choose plain yogurt or kefir and add your own fruit to keep added sugar down.
The case for fermented foods
Fermented foods give you more than microbes. Yogurt and kefir provide protein and calcium; tempeh and miso add plant protein; kimchi and sauerkraut count toward your vegetables. A small but well-run 17-week study from Stanford, published in Cell, found that adults who ate a diet high in fermented foods steadily increased the diversity of their gut microbes and lowered several inflammatory markers. It was a small trial with 18 people per group, so treat it as encouraging rather than conclusive.
Easy ways to add one serving a day:
- Plain yogurt or kefir with berries and oats at breakfast.
- A forkful of kimchi or sauerkraut on eggs, rice bowls or sandwiches.
- Miso stirred into soup or salad dressing at the end of cooking (boiling reduces live cultures).
- Tempeh in a stir-fry or as a sandwich filling.
- A piece of aged cheese with an apple for a snack.
Start with small amounts. Some people get extra gas or bloating at first, which usually settles as you get used to them.
When a probiotic supplement might make sense
Probiotic effects depend on the specific strain. NCCIH notes that even for well-studied uses such as irritable bowel syndrome, reviews have not been able to identify which species or strains are most helpful. This is why a general “gut health” capsule is a gamble. Supplements may be worth discussing with your healthcare provider if:
- You are taking antibiotics and want to lower the chance of antibiotic-associated diarrhea. NCCIH reports moderate-quality evidence that probiotics had a protective effect in children for this purpose.
- You have a diagnosed condition, such as IBS, where your provider recommends a specific strain.
- You can’t or don’t eat any fermented foods.
How to choose a product
- In Canada, probiotics are regulated as natural health products. Health Canada says licensed products carry an eight-digit Natural Product Number (NPN) on the label.
- Look for the full strain name (genus, species and strain code), not just “probiotic blend.”
- Check that the amount is listed as guaranteed to the expiry date, not just “at time of manufacture.”
- Follow storage directions; some need refrigeration.
- Agree on a set trial period with your provider, track your symptoms, and stop if nothing changes.
The budget comparison
Prices vary widely by brand and province, so compare in your own store, but the pattern is usually clear:
- A large tub of plain yogurt or a bottle of kefir provides many servings plus protein and calcium.
- A jar of refrigerated sauerkraut or kimchi lasts for weeks when used a spoonful at a time.
- Making your own sauerkraut costs little more than cabbage and salt. Follow a tested recipe, keep the vegetables under the brine and discard anything that smells rotten or grows fuzzy mould.
- A month of a specialty probiotic capsule often costs more than all of the above combined, and provides microbes only.
For most people, the best value is a daily fermented food plus a fibre-rich diet, with supplements saved for a clear, specific reason.
Don’t forget prebiotics
Gut microbes need food. Prebiotic fibres in onions, garlic, leeks, asparagus, oats, bananas, beans and lentils help feed beneficial bacteria. Increase them gradually to avoid discomfort. Our guide to prebiotic variety explains how to rotate them, and fibre for digestion covers the basics.
When to check with a professional
NCCIH notes that the risk of harmful effects from probiotics is greater in people with severe illness or weakened immune systems, and advises not to use probiotics as a reason to delay seeing a healthcare provider. Talk with your doctor or pharmacist before taking a probiotic if you are immunocompromised, seriously ill, recently had surgery, have a central line, or are considering one for an infant. See your doctor about ongoing digestive symptoms, blood in stool, unexplained weight loss or symptoms that wake you at night.
Key takeaways
- Fermented foods and probiotics overlap but are not the same.
- Choose refrigerated, “live culture” ferments for live microbes.
- One serving a day of yogurt, kefir, kimchi, sauerkraut, miso or tempeh is an easy, affordable habit.
- Use probiotic capsules for a specific reason, a specific strain and a set trial period.
- In Canada, look for an NPN on supplements.
- Feed your microbes with fibre from a variety of plants.
Frequently asked questions
Can I get too many probiotics from food?
For most healthy people, normal servings of fermented foods are fine. If you notice gas or bloating, scale back to a small portion and build up slowly. Some fermented foods are high in salt, so keep portions of kimchi, sauerkraut and miso modest.
Is sourdough bread a probiotic food?
Sourdough is fermented, but baking kills the microbes. It can still be a tasty whole-grain choice; it just does not add live cultures.
Should I take a probiotic every day “just in case”?
There is not good evidence that healthy people need a daily capsule. A varied, fibre-rich diet with regular fermented foods is a sensible default, with supplements saved for specific situations your healthcare provider recommends.