By Katherine Giles, Registered Dietitian & Group Exercise Instructor

If your GI health could use a boost, stay tuned for the next few minutes. Prebiotics and probiotics have been known to work wonders.

Even if you’ve already heard of them, further understanding of their function can provide a useful tool to help maximize your nutrition. Research shows promising links between adequate probiotic levels and the improvement of many health conditions such as migraines, inflammatory bowel disease, chronic inflammation, hypertension and even certain cancers.


With a few small adjustments to your diet, probiotics can improve the well-being of most systems of the body. That's major health benefit, wrapped in a tiny package!


What are they?

Prebiotics: Natural, non-digestible fiber compounds in foods that pass undigested through the upper sections of the GI (gastrointestinal) tract and assist in the growth of beneficial bacteria in the lower GI tract. Simply put, prebiotics are the “food” necessary to promote “good” bacteria growth in the gut.

Probiotics: Live, active micro-organisms living in our gut that, when present in adequate amounts, provide health benefits. In other words, probiotics are the “good” bacteria or live cultures that naturally live in our digestive tract.

When these components exist in adequate (but not excessive) amounts in our gut, we get the benefit of better GI health, which may lead to improvements in overall health, improved immunity and reduced inflammation. While probiotic supplements are commercially available, there are also many readily available food sources of both pre- and probiotics.

Where are they?

Prebiotics are commonly found in fruits, vegetables and whole grains such as: bananas, onions, garlic, leeks, asparagus, artichokes, soybeans and whole-wheat foods. The 2015-2020 Dietary Guidelines recommend filling half your plate at each meal with fruits and vegetables and making half of the grains you consume each day whole-grain products.

Consuming adequate amounts of a variety of fruits, veggies and whole grains provides the amount of prebiotics necessary for probiotic growth and function.

Probiotics (in Greek, “for life”) were first discovered in the 19th century by Elie Metchnikoff, who believed that the healthy lives of Bulgarian peasants were related to their consumption of fermented milks containing Lactobacillus. We now know that Lactobacilli and Bifidobacterium are two of the most common strains of probiotics found in fermented dairy and non-dairy foods. Consuming adequate amounts of these foods helps to increase the amount “friendly bacteria” in our GI tract.

Dairy (fermented) sources of probiotics: yogurt, kefir, aged cheeses, buttermilk and acidophilus milk

Non-dairy sources of probiotics: kombucha, kimchi, sauerkraut, green olives, miso, and tempeh

How can I incorporate them into my diet?

Since probiotics are living micro-organisms, they require prebiotics as their “food source.” Combining both pre- and probiotics will help improve your GI health. Putting bananas on top of your yogurt or cooking asparagus with tempeh allows the health-promoting components of both pre- and probiotics to work together.

While foods like kefir and kombucha can sound, smell and taste unfamiliar to you, there are many food sources that can provide adequate amounts of both prebiotics and probiotics when consumed regularly. Be adventurous, and try something new!

Recipes to try:

Kefir Smoothie: Combine the following in a stick blender or food processor: 2 bananas, 2 oranges, 2 cups mixed berries, ¼ cup coconut oil, 2 tbsp. chia seeds, 2 cups milk kefir, ½ cup yogurt. If the taste of the kefir is too “tangy,” add a teaspoon of sugar. Pour into a glass, add a straw and enjoy!

Miso Soup: Heat 1 qt. vegetable or chicken stock and 2 cups water until simmering. Add 4-5oz. firm tofu (cut into small cubes) and 2 cups of assorted mushrooms (sliced). Simmer until mushrooms are cooked. Add 4-5 scallions (thinly sliced) and remove soup from heat. In a small bowl, whisk 2-3 tbsp. miso paste with ¼ cup of the hot broth to form a paste. Stir the paste back into the soup. Serve immediately.

A note about probiotic supplements

When shopping for a probiotic supplement, take note of the number of CFUs (colony forming units) present in each capsule. Remember, probiotics are live organisms. Lots of research is devoted to studying how many of the live cultures in probiotic supplements are still alive and beneficial once the bottle of capsules is purchased by a consumer. You may want to consult your doctor to find the right dosage for your body.

Research also shows that different strains of “friendly” bacteria can benefit varying conditions in different areas of the body. If you choose to use a probiotic supplement, make sure it contains a variety of probiotic strains (ex. Lactobacillus, L. acidophilus, Bifidobacterium). 

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