The Difference Between Prebiotics and Probiotics

When it comes to digestive health, you may have heard of “prebiotics” and “probiotics.” Both are important in supporting the health of your digestive system – particularly that of the microorganisms that live in your gut, also known as the microbiome.

In simple terms, probiotics are the “good” bacteria that keep your body healthy, while prebiotics are the foods that promote their growth.

Before we dive into the benefits of both, it helps to understand why these friendly microbes are so important.

Broadly speaking, prebiotics are the compounds in many of the high-fiber foods that you eat. While humans lack the ability to break down the certain carbohydrates and fiber that we consume in foods like fruits, vegetables, beans, and whole grains, the microbes in your gut are more than happy to do the job for you in a process referred to as fermentation. In fact, probiotics stimulate the growth and activity of the good bacteria in your digestive tract and can improve health.

Of the two general types of fiber – soluble and insoluble – it’s the soluble fibers (found in foods like oats, barley, and beans) that are considered to be prebiotic. Not only do they tend to thicken and swell when they come in contact with liquid, making foods tend to be filling, but soluble fibers also encourage the growth of the good bacteria in your digestive tract.

More specifically, you may hear about specific prebiotic compounds – such as resistant starches in underripe bananas – or compounds called fructooligosaccharides (found naturally in onions, garlic, asparagus and artichokes) that are known to stimulate bacterial production in the lower digestive tract.

Prebiotics serve as food for probiotics, but they potentially can affect other organs and systems in the body. Soluble fibers not only help to fill you up, but they also slow the absorption of sugar into the blood stream, so they can help to keep blood sugar levels more even throughout the day in normal, healthy people. These same fibers can also help keep blood cholesterol levels within a normal range.

In addition, prebiotics:

• Are broken down by the good bacteria, producing compounds that promote gut health, skin health and immune health
• May increase calcium absorption
• May help relieve certain digestive problems

The word “probiotic” derives from Greek, meaning “promoting life.” And probiotics certainly do just that in your digestive tract. Probiotics are the “good” bacteria (sometimes called live cultures) that you can consume from foods or supplements. Probiotics are the same bacteria that reside in your gut. Taking in probiotics can help to balance the populations of the various types of bacteria in your gut, which, in turn, promotes gut health.

While the idea of consuming bacteria may not sound appealing, it’s likely that you already consume them without realizing it. Probiotics are found in many fermented foods. Fermentation is a natural process in which bacteria convert sugars and other carbohydrates in foods into acids. That’s why many naturally fermented foods have a tangy taste.

There are many, many different microbes that live in your gut, and gut health relies on the right balance of the different types. The typical modern diet, with an abundance of sugar and highly processed foods, promotes the growth of certain bacteria that can lead to digestive discomfort – often in the form of bloating or irregularity.

But a diet rich in prebiotic fibers helps to promote the right balance in the digestive system. And, when you consume fermented foods that contain the live bacteria, you are introducing beneficial bacteria directly into your digestive tract.

While the benefits of probiotics to digestive function are well-documented, the list of additional health benefits of probiotics continues to grow and to be supported by scientific evidence. Aside from effects on intestinal health, probiotics appear to enhance the body’s immune response, reduce blood cholesterol levels, and may also play a role in cancer prevention. Evidence also suggests that probiotics may help with blood pressure control and may also have positive effects on mood.

Some benefits of probiotics include:

• Restores balance of gut bacteria
• Promotes regularity
• Keeps your immune system strong

For many people, the most common source of probiotics is fermented dairy products such as yogurt, kefir, and certain aged cheeses. In fact, one of the most common strains of probiotic bacteria that reside in your intestines is Lactobacillus acidophilus, which is found in yogurt.

Beneficial probiotics can also be found in:

• Fermented vegetables such as pickles, kimchi, olives, and sauerkraut (only when sold refrigerated; canned products are heated during processing, which destroys the beneficial bacteria.)
• Fermented soy products such as miso and tempeh
• Cultured non-dairy yogurts (look for “live active cultures” on the label)
• Kombucha beverages
• Other foods to which probiotics have been added such as cereals or protein bars

Adults should be eating in the neighborhood of 30 grams of fiber a day, but the average grownup only eats about a third of that. Our busy lifestyles contribute to the problem - when we’re on the go, we’re less likely to eat the high fiber fruits, vegetables and whole grains that are more typically found at home. So, many of us are lacking when it comes to good sources of prebiotics. And, unless you a regular consumer of fermented vegetables or dairy products, you might not be getting good sources of probiotics on a daily basis. Fiber supplements that contain both soluble and insoluble fibers, along with probiotic supplements can help to fill in gaps.

When adding fiber supplements to your diet, you may notice changes in your bowel function in just a couple of days. With probiotic supplements, a lot depends on the strain of the probiotic, the quality of the supplement and the dose, or simply to support general health – in which case it may be weeks to months before effects may be felt.

Supplements should be taken in amounts recommended on the product label, and can be used daily. However, when starting a fiber supplement, it’s often a good idea to start with a bit less than recommended and gradually increase the daily dose. That way, your digestive system has a chance to adjust.

The most important factor in taking supplements is taking them consistently. So choose a time of day when you will remember to take your supplements. You can take your prebiotics at any time – with food or without – but probiotics might be better taken on an empty stomach. That’s because stomach acid can degrade the probiotic bacteria, which means they may not survive the trip to the intestine. But an empty stomach provides less acidic conditions, which might be more favorable.

While it’s not necessary that you take your prebiotic and probiotic supplements at the same time, it might make it easier to get into the habit if you do. And there’s certainly no reason why you can’t take them at the same time – the combination is known as a symbiotic - since one acts as a food source for the other.