Prebiotics and Probiotics: Do You Need Them?

April 2, 2019
| Created by Hannah Langley, MS, RDN, CD

There is a lot of talk about prebiotics and probiotics-whether it’s on the news, on social media, or down the aisles of the grocery store. It’s always coupled with talk of digestive bacteria or the “gut microbiome” and often in the form of “you need more good bacteria and fewer bad bacteria.” But what does that mean and what, if anything, should you do about it?

Gut Microbiome Basics

The gut microbiome (the community of bacteria in your digestive tract) and research on how it impacts health is a very exciting and relatively new realm in nutrition. The bacteria in your digestive tract are living organisms and there are anywhere from 10 trillion to 100 trillion living in there. That is 10 times the number of human cells you have!

We are just beginning to understand how these bacteria affect health. In reality, we understand very little about them. We know they play some type of role in:

Making neurotransmitters, enzymes, vitamins, phytochemicals, and antioxidants
Supporting the immune system
Feeding intestinal cells
Breaking down toxins and carcinogens
Maintaining healthy digestion
Moderating general inflammation
Weight management and insulin sensitivity
Emotional health and mental illness
Cardiovascular disease, irritable bowel diseases and Clostridium difficile


While we don’t fully understand the impact that these bacteria have, we do know that supporting the growth of “good” bacteria is a good idea. The best way to do this is by enjoying prebiotic and probiotic foods.

Prebiotic Foods

Why eat them?

One of the ways scientists measure healthy digestive bacteria is through “richness.” Richness refers to the number of different bacterial species. Eating prebiotic foods increases richness by acting as food for the friendly bacteria. You want to eat a variety of prebiotic foods because different bacteria prefer different types. These are our top picks for prebiotic foods:

Onions, garlic, asparagus, and jicama
Apples, bananas, peaches, and watermelon
Beans (all types including lentils)
Flax seeds and chia seeds

Probiotic Foods

Probiotic foods actually contain living bacteria that provide health benefits. Eating probiotic foods is a great way to promote healthy digestive bacteria. Here at Harmons we think that prebiotics are actually more important. Why? Eating prebiotics could support the growth of hundreds of different types of bacteria. Probiotic foods and supplements usually contain just three or four species. So, focus on the prebiotic foods and include probiotic foods for a little extra boost. These are our favorite probiotic foods:

Yogurt and kefir
Unpasteurized sauerkraut and kimchi
Refrigerated miso paste

A Word on Supplements

You might be thinking that a supplement could be an easy way to get what you need. Unfortunately, it’s not so simple.  Why? Not all strains of bacteria and yeast are created equal. The quality of the supplement matters and the reputability of the place where you purchase the supplement is important too. Our general recommendation is to eat food first and then check with your doctor, pharmacist, or Harmons dietitian to see if you are a good candidate for supplementation.