Nutrition: The ins and outs of probiotics and prebiotics

Estimated Reading Time 3 Minutes

Antibiotics, probiotics, prebiotics and antibacterial – we’re pretty obsessed with bacteria these days. When it comes to antibiotics, like many parents, you’re probably concerned about their overuse. They not only kill off harmful illness-causing bacteria but the beneficial ones as well, potentially causing disturbances to our microbiota – the term used to describe the trillions of colonies of bacteria living in our intestines. For many years people simply thought of this in terms of bowel health, but research now shows that the balance – or imbalance – of different types of bacteria may be responsible for a growing list of illnesses through life.

Think of it as the body’s ecosystem. Scientists are now linking our microbiota not only to bowel disorders, but also to how our immune system functions when fighting off common infections, our risk of asthma and allergies, as well as conditions such as celiac disease, autism and depression. Even obesity has been to the list. 

In 1908, Russian scientist Eli Metchnikoff received the Nobel Prize for his contribution to science when he suggested that eating foods that promoted beneficial bacteria would increase longevity. He also believed the time to begin developing a healthy microbiota was in childhood. Yet here it is, more than 100 years later and we’re now just starting to pay attention to our gut instincts.

Cultivating a healthy microbiota can start right at birth. For example, it’s known that babies who are delivered vaginally get a head start on beneficial bacteria compared to those born via Caesarean section. A vaginal birth exposes a baby to bacteria and viruses as it passed through the birth canal. Breastfeeding also promotes a healthy range of bacteria in an infant.

Smart food choices can also lead to a healthy microbiota. This can involve both probiotics and prebiotics:

  • Probiotics are certain beneficial strains of bacteria found in foods or supplements.
  • Prebiotics are specific carbohydrates, resistant to human digestion, which stimulate and promote the growth of these beneficial bacteria. Simply put, they’re the food of choice for the good bacteria. So if you’re a welcoming host and looking to attract these microbes to make your gut their home, feed them well.

What’s best: Probiotics or Prebiotics?

The answer is both. Yogurt, cheese, milk, frozen desserts and even juices are now available with added probiotics, but not all products deliver on their probiotic promises. This may be because of the strain of bacteria, the numbers of bacteria in the food when it’s produced and whether those bitty bacteria survive in large numbers between the time the product lands on store shelves and when it goes into your tummy.

Dairy products such as yogurt and kefir can do a better job of delivering probiotics than supplements, because they may protect the bacteria from being killed off by stomach acids. Other fermented foods, such as miso (unpasteurized), tempeh (fermented soybeans), sauerkraut and kimchi (a Korean slaw), are loaded with the beneficial bacteria.

Check company websites of probiotic foods or supplements to see how the product performs. 

To get prebiotics on your family’s menu, include an assortment of whole plant foods rather than processed foods. This will likely provide an adequate supply. These bacteria are not fans of greasy, fatty fare.

Prebiotic Superstars

  • Legumes such as chickpeas, kidney beans and lentils
  • Members of the allium family – garlic, onions and leeks
  • Fruits and vegetables like bananas, berries, an assortment of dark greens, like chicory and spinach, as well as artichokes and asparagus 
  • Whole grains like barley, oatmeal and whole wheat


There’s a catch, though. Remember the ditty, “Beans, beans the musical fruit, the more you eat…” When you eat many of these prebiotic-laden foods, the probiotics feed on it, causing fermentation to happen in your gut, leading to a potentially unwelcome consequence: gas. To help manage symptoms, add these foods to your diet gradually along with plenty of fluids.


Rosie Schwartz is a Toronto-based consulting dietitian in private practice and author of The Enlightened Eater’s Whole Foods Guide (Viking Canada). Visit for more.

Originally published in ParentsCanada magazine, May 2014.

Related Articles

Made Possible With The Support Of Ontario Creates