TL;DR:
Probiotics are friendly microorganisms inhabiting our digestive tract that aid digestion and may confer additional health benefits.
Prebiotics are non-living, non-digestible carbs that serve as food for Probiotics.
Go deeper:
Probiotics are living microorganisms that are beneficial for our gut health. They include bacteria and yeast that naturally reside in our intestinal tract. We can obtain probiotics from the food we eat or supplements we take. Different types of probiotics have different effects on our gut microbiome. Although the term "probiotics" is relatively new, humans have been consuming them for thousands of years. Foods that are cultured or fermented are excellent sources of probiotics.
Examples of such foods include:
yogurt, kefir, and buttermilk
aged cheese such as cheddar, Gouda, or Parmesan
sauerkraut, kimchi and other pickled versions of veggies
sourdough bread
miso (fermented barley or soy or rice)
tempeh – fermented soy
kombucha – a fermented tea that is gaining in popularity in the US
beer, wine (yay!)
Probiotics have potential health benefits that are varied and wide-ranging, but scientists are still trying to understand the complex symbiosis between the gut, bacteria, and other parts of our body. Besides regulating bowel movement, probiotics may also help treat diarrhea, reduce lactose intolerance, boost the immune system, lower the risk of colon cancer, and decrease blood pressure and cholesterol levels. It is worth noting that when you take antibiotics while being sick, you not only kill off harmful bacteria but also the beneficial probiotics.
Don’t forget, when you are sick and take antibiotics, you’re killing off the germs that made you ill, but also the probiotics.
On to prebiotics.
Prebiotics are different from probiotics in that they are not living organisms. Instead, they are a type of fiber that our body cannot digest. However, the bacteria living in our gut, including the probiotics, can digest this fiber. By feeding these beneficial bacteria with prebiotics, we can help them maintain their ability to support our overall health.
Foods with prebiotics include:
raw chicory root – the top source, with almost 60% fiber
raw Jerusalem artichoke
raw garlic, leeks, and onions
whole wheat
fruits and vegetables
legumes
Each person's gut has its own unique set of bacteria. This means that the effects of consuming the same probiotics and prebiotics can vary greatly from person to person. It's a good idea to experiment with different foods to see which ones work best for you. The most effective way to consume probiotics and prebiotics is through food, not supplements.