Why Prebiotics are Just as Important as Probiotics

While probiotics tend to get all the attention, prebiotics are just as important yet tend to get left in the shadows. And if you ask me, that’s pretty unfair. So to even out the playing field, we’ll discuss what prebiotics are, why they’re important, and what foods they’re in. If you haven’t read our previous post on probiotics yet, click here to get caught up!

What are prebiotics?

I like to think of prebiotics as the food for healthy bacteria in the gut. Prebiotics are natural, non-digestible carbohydrates called oligosaccharides that work in synergy with probiotics to keep our bodies running smoothly.

When looking at the benefits of prebiotics, it can seem like we’re talking about fiber and that’s because all prebiotics are fiber, but not all fibers are prebiotics (still with me?).

So what are these health benefits?

While the research on health benefits due to prebiotics, not just fiber, is still ongoing, it’s becoming clear that prebiotics play an important role in gut health and disease protection. 

Probiotic Fuel

As discussed in a previous post, we’re continuing to find out just how important probiotics are for overall health. From reduced anxiety and depression to decreased risk of disease and improved digestion, probiotics positively affect nearly all areas of the body. However, probiotics can’t work all on their own. Prebiotics get fermented in the colon by healthy bacteria, further promoting gut flora health.

Improved Digestion

When prebiotics are fermented by probiotics, one of the byproducts is a fatty acid called butyric acid. This beneficial fatty acid has been found to play a role in the health of intestinal lining, promote proper digestion, support regular bowel function, and treat diarrhea and constipation.

Prebiotics when combined with probiotics have also been shown to help manage many digestive diseases, including Crohn’s disease, ulcerative colitis, IBS, and leaky gut. 

Enhanced Immune Function

Due to the resulting changes in gut flora due to fermentation of prebiotics, there’s evidence to suggest that diets high in prebiotics (and probiotics) can reduce levels of certain cancer-promoting enzymes as well as decrease allergy symptoms.

Additionally, the fermentation of prebiotics also helps with the absorption of nutrients, many of which are essential to immune health. 

May Help Manage Stress

While we discussed the gut-brain axis and the beneficial effects of probiotics on mood and anxiety in a previous post, prebiotics have also been looked at on their role in cortisol secretion. Cortisol is our stress hormone, and a 2015 study of 45 healthy adults found that those given prebiotic supplements for 3 weeks had positive changes in cortisol levels.

Aids in Weight loss

A recent review published in 2018 found that multiple animal and human studies have found a relationship between pre- and probiotic intake with weight reduction. While the exact mechanisms are still being studied, the authors suggest the combination of short chain fatty acid production and changes in gut flora due to the fermentation of prebiotics likely plays a major role. 

A randomized, placebo-controlled trial of 7-12 year old kids with overweight or obesity found that after 16 weeks, kids taking a prebiotic supplement once a day had significant decreases in body weight and percent body fat compared to kids given the placebo.

Note for those with IBS

A side effect of many prebiotics is that they are fermented in the gut and can worsen symptoms of IBS. If you have IBS, it’s best to make an appointment with a registered dietitian to get a personalized plan for ways to incorporate more prebiotics while still managing symptoms.

12 Sources of Prebiotics

While there are many foods containing prebiotics, here are 12 that should be on your radar.

1. Chicory root and inulin – chicory root and inulin are probably the most common prebiotics that many of us don’t even realize that we’re eating. Inulin is a prebiotic fiber that is found in chicory root but is sometimes isolated from chicory root to be used on its own. Both inulin and chicory root are inexpensive, easy ways to add fiber to products, which is why you’ll often see one of them listed in the ingredient list on breakfast cereals, granola, and protein bars, and meal replacement shakes.
2. Jerusalem Artichoke – also called a “sunchoke,” Jerusalem artichokes are not actually artichokes at all. Instead, Jerusalem artichokes are tubers related to sunflowers. While you can eat them raw in salads (the consistency is similar to a water chestnut), they can also be cooked like a potato: boiled, roasted, mashed, or sauteed.
3. Asparagus – okay, now we’re getting to foods you’re likely more familiar with. Asparagus is a spring vegetable that’s rich in B vitamins, vitamin C, calcium, and iron. It can be eaten raw, but my personal favorite way to enjoy it is sauteed in a little avocado oil.
4. Cruciferous vegetables – this family of vegetables includes cauliflower, cabbage, bok choy, broccoli, and Brussels sprouts. Besides being a source of prebiotic fiber, they are also high in vitamin C, folate, and vitamin E.
5. Raw or cooked garlic – a cooking staple, garlic contains prebiotic fiber as well as iron, zinc, and potassium. Delicious raw or cooked garlic is often used to flavor dishes.
6. Raw or cooked onions – related to garlic, onions also contain iron and potassium as well as vitamins A, C, and E. There are many types of onions, each with slightly different tastes and uses in cooking.
7. Green bananas – when bananas still have green on them, it means they still contain mostly starch with very little sugar. As they ripen, the starches start to break down, and they become mostly sugar with a little starch. Prebiotics are found in resistant starch, so to get the most prebiotics, you’ll want to stick with bananas that still have quite a bit of green on them.
8. Apples – when I think fiber, apples usually come to mind first. Apples are packed with fiber, including prebiotic fiber, as well as are a good source of vitamin A, vitamin C, and antioxidants. While cooking does result in a loss of nutrients, especially vitamin C, by keeping the skin, you can retain most of the fiber.
9. Flax Seed – known for being a good source of healthy fats, flax seeds also contain prebiotic fibers as well as antioxidants. Note that to get all the benefits of flaxseed, it’s best to use ground rather than whole flax seeds. Add a tablespoon of ground flaxseeds to your oatmeal, baked goods, smoothies, or even condiments like mayo or mustard.
10. Barley – this chewy cereal grain contains a prebiotic fiber called beta-glucan, which in addition to promoting the growth of healthy bacteria, has also been shown to lower total and LDL cholesterol levels. Barley is delicious as a side dish or mixed into soups.
11. Wheat Bran – whole wheat grains are made up of three parts, with the wheat bran being the outer layer. Wheat bran is high in prebiotic fiber as well as antioxidants. Like ground flaxseed, wheat bran can be added to oatmeal, smoothies, or baked goods.
12. Oats – now there’s even more reason to eat oatmeal. Whole oats contain a large amount of beta-glucan prebiotic fiber as well as protein, healthy fats, and important minerals such as manganese, phosphorus, and iron. Not a fan of hot oatmeal? You can still get your oat fix with overnight oats, baked oatmeal, homemade granola or granola bars, oat muffins, oatmeal pancakes, or oatmeal bread.