The Science Behind Prebiotics: What You Should Know

As we talked about last time, probiotics are seen to be effective in boosting the immune system and regulating digestion. It is still unclear if probiotics actually stick around in the gut after taking them. So, another way to boost the good bacteria that’s already in your gut is to eat prebiotics.

In this post, we’ll talk about what prebiotics are, what benefits research has shown them to have, where you can find prebiotics, and whether you should take prebiotic supplements or not. Let’s get to it!

Breaking Down Prebiotics

Last week we said probiotic means “for life.” That means that prebiotic means “before life.” AKA prebiotics are the foods that the probiotics eat to live.

Just like us, the living organisms (or microbes) in our gut need food to be able to do their thing. As we talked about a few weeks ago, what we eat determines which gut microbes dominate and which ones are quieted.

If we don’t eat food that will feed the good bacteria in our gut, our gut gets out of balance (AKA dysbiosis). This causes bad bacteria to overcome the good bacteria, which leads to many chronic diseases we have today.

So, to make sure the good bacteria dominate the bad, we have to eat food that will help the good bacteria thrive. These foods are called prebiotics.

Quick Fiber Guide

You may be more familiar with the term fiber. Prebiotics are simply the types of fiber that make it through the stomach and small intestine intact to be broken down in the colon by gut bacteria.

There are two main types of fiber – insoluble and soluble.

Soluble fiber is the fiber that makes into the colon intact and is broken down by gut bacteria.  Insoluble fiber cannot be broken down by gut bacteria, so it leaves the body still intact.

Soluble fiber helps the gut microbes to be diverse and the good microbes to thrive. Insoluble fiber helps make softer stools so removal of the stools is easier. Another type of fiber called resistant starch acts like both soluble and insoluble fiber.

Prebiotics are commonly soluble fiber and some resistant starches.

Proposed Benefits and What the Science Says

Before we get to how you can get more prebiotics in your diet, let’s talk about the benefits of eating them.

#1 All the Benefits of Having a Healthy Gut

Prebiotics are often given all the benefits of having a healthy gut because they help good bacteria thrive.

These benefits include boosting the immune system, helping with digestion, preventing and treating obesity, autoimmune diseases, autism, asthma, allergies, and food intolerances and allergies. Those with a healthy gut seem to avoid chronic diseases. But, we still have to be careful crediting a healthy gut with these benefits because research is not conclusive on these topics.

Also, we have to be careful with crediting healthy gut benefits to prebiotics since we don’t know which prebiotics feed the good gut bacteria. So, if you take a prebiotic supplement, there’s no sure evidence that the type of prebiotic in that supplement is one that feeds the microbes responsible for the above benefits.

#2 Increases Absorption of Minerals

Most of the studies I found that looked at the link between prebiotics and mineral absorption were done in animals. Though the studies mostly showed an increase in mineral absorption with increased prebiotic intake, this may not happen in humans.

More research is needed before this benefit is credited to prebiotics.

#3 Improves Mental Health

The gut plays a huge role in mental health. But, to say that prebiotics improve mental health is a far stretch.

But, little is known about which gut microbes are directly involved in depression, anxiety, and ability to handle stress.

So, how can we say that prebiotics improve mental health if we don’t know which microbes we need to increase in our gut? Unfortunately, we can’t.

If you want to know about the confirmed benefits of prebiotics, the section titled ‘Should I Take Prebiotic Supplements?’ below breaks down the benefits of different types of prebiotics.

Where to Find Prebiotics

I don’t mean to pop any prebiotic-bubbles, but I want to give you what the science says.

No matter what the opinions out there or what I say, science has to back it up.  And if it doesn’t, then you have a right to know.

There are always personal antidotes of different supplements working. That is wonderful if you experience benefits from taking prebiotic (or probiotic) supplements. And this is not to say that you’re crazy or a victim of the placebo effect.

Each person’s gut looks and can act differently from another’s gut. So, as I said last week, what works for one may or may not work for another.

This applies to prebiotics. Maybe your body needs a little more of a certain soluble fiber to get your GI on the right track. Maybe it needs a little more probiotics instead.

That’s why it’s important to try different things to see what works for you.

And that’s why I will always recommend getting prebiotics (and probiotics) from whole foods first.

Whole foods provide tons of benefits on top of being a source of prebiotics. For example, whole foods provide prebiotics in their natural environment (so they may be able to function better) as well as plenty of nutrients and insoluble fiber.

That being the case, let’s get to how you can get more prebiotics in your diet.

Here is a list of natural sources of soluble fiber…

• Raw garlic
• Under-ripe bananas
• Raw Jerusalem artichoke
• Onions
• Raw leeks
• Raw dandelion greens
• Jicama
• Raw chicory root
• Raw asparagus
• Wheat
• Fruits
• Vegetables

Soluble fiber can be sensitive to heat. So, most items on the list above have the highest amount of fiber when eaten raw.

You can put the raw ingredients above in a salad, pasta salad, chopped up in hummus, a cold dip, or a smoothie.

Here is a list of natural sources of resistant starch…

• Beans
• Whole grains
• Nuts
• Seeds
• Potatoes
• Under-ripe Bananas
• Oats
• Rice

Here is a list of natural sources of insoluble fiber…

• Whole grains
• Cocoa powder
• Oat
• Fruits
• Celery
• Cabbage
• Leafy greens
• Onions
• Bell peppers
• Other vegetables
• Popcorn
• Dried fruit
• Wheat Bran

As you can see, many whole foods have both soluble and insoluble fiber. This is why eating a diet that includes whole grains and lots of colorful vegetables and fruits is recommended by dietitians.

Fiber and nutrients all work together in these whole foods to help you achieve your best health and prevent your worst.

Should I take Prebiotic Supplements?

Sometimes cooking and preparing whole foods is just not practical with your schedule. This is where supplements can help.

If you have a busy schedule and need help getting a little extra prebiotics in your diet, then it might benefit to take a synbiotic. A synbiotic is a supplement that has probiotics and prebiotics. This way you can maximize the benefits of taking a prebiotic supplement.

Using the Natural Medicines Database, here are the common prebiotics put in supplements, their claimed benefits, and what the research shows as their potential benefits. Use the below information to choose which prebiotic ingredients you should look for in your supplement.

Fructo-oligosaccharides (FOS)

• Used for traveler’s diarrhea, constipation relief, and decreasing cholesterol levels
• Not enough research to prove effectiveness in these areas

Inulin

• Used for decreasing cholesterol, triglyceride, and lipid levels, weight loss, and improving digestion
• Research only shows it may be effective for lowering triglycerides levels and constipation relief
• Other claims don’t have enough research to support them

Galacto-oligosaccharides

• Used for allergies, asthma, colic, Crohn’s disease, dermatitis, colorectal cancer, flu, food allergies, IBS, osteoporosis, ulcerative colitis, and improving digestion
• Only enough research to show it to be possibly effective for colic and dermatitis (specifically, eczema)

Resistant Starch

• Several types of resistant starches and resistant dextrins
• Claimed benefits include helping with GI cancers, improving digestion, and preventing heavy metal toxicity, among others
• If you have a question about a specific one you are thinking about taking, comment below or shoot me an email with the specific supplement and I will get back to you on if the science backs up the claimed benefits