Prebiotic Benefits, Best Foods and Dosage Recommendations - Dr. Axe

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Prebiotic Benefits for the Gut, Plus How They Work with Probiotics


Prebiotic benefits

By now, most people are well-aware that foods rich in dietary fiber and probiotic foods offer a long list of benefits and are essential to overall health. Nonetheless, prebiotics are still largely under-appreciated and often lacking in the typical American diet.

Unfortunately, this can result in serious issues like indigestion, inflammation, impaired immunity, weight gain and possibly even an increased risk for many chronic conditions.

Are prebiotics better than probiotics? Ideally you should get both. While probiotic foods play a key role in gut health and overall well-being, prebiotics help “feed” the probiotics to bump up the health benefits even more.

As explained more below, prebiotics and probiotics together amplify the incredible health-promoting properties of these powerful ingredients.

What Are Prebiotics?

By definition, prebiotics are non-digestible fiber compounds that are degraded by gut microbiota. What do prebiotics do? Just like other high-fiber foods, prebiotic compounds pass through the upper part of the gastrointestinal tract and remain undigested because the human body can’t fully break them down. Once they pass through the small intestine, they reach the colon, where they’re fermented by the gut microflora.


Today, when researchers refer to “fiber,” they’re speaking about not just one substance, but a whole group of different chemical compounds found in foods. Prebiotics are best known as types of dietary fibers called fructooligosaccharides, inulin and galactooligosaccharides.

Originally, prebiotics weren’t classified as prebiotic fiber compounds, but recent research has shown us that these compounds behave the same way as other forms of fiber. Today, prebiotic carbohydrates that have been evaluated in humans largely consist of fructans and galactans, both of which are fermented by anaerobic bacteria in the large intestine.

Certain foods function as natural prebiotics. Some examples of foods high in prebiotics include chicory root, dandelion greens, leeks and garlic.

What are the benefits of prebiotics? Upping your intake of prebiotics has been linked in studies to a long list of powerful benefits, including lower risk for cardiovascular disease, better gut health, lower stress response. better hormonal balance, higher immune function, lower risk for weight gain and lower inflammation.

Prebiotics vs. Probiotics vs. Postbiotics

What is the difference between prebiotics and probiotics? While prebiotics are substances that are fermented by the beneficial bacteria in the gut and used as a source of fuel to help enhance gut flora health, probiotics are defined as live microorganisms that can confer health benefits to the host, ranging from improved immunity to better brain function.

Postbiotics, meanwhile, are the byproducts of bacterial fermentation in the colon. To break down all the scientific jargon and put it simply: Prebiotics “feed” the probiotics, or beneficial bacteria in your gut, and end up producing a byproduct called postbiotics.

When it comes to supplementing, which is best: probiotics or prebiotics? All three boast an extensive array of health benefits and work together to boost both digestive and overall health. One is not necessarily “best,” since they work together to optimize things like nutrient absorption, appetite control, immune function, etc.


1. Work with Probiotics to Improve Overall Health

As prebiotics make their way through the stomach without being broken down by either gastric acids or digestive enzymes, they bring about positive changes in the digestive tract and organs. Essentially, prebiotic compounds become nutrient sources, or “fuel,” for the beneficial bacteria housed within your gut.

Prebiotics work together with probiotics (selectively fermented ingredients that produce gut-friendly bacteria) to allow specific changes to take place, both in the composition and activity of the gastrointestinal system. They play a fundamental role in preserving health by maintaining balance and diversity of intestinal bacteria, especially by increasing the presence of “good bacteria,” such as Lactobacilli and Bifidobacteria.

Because the health of the gut is closely tied to many other bodily functions, prebiotics and probiotics together are important for battling inflammation and lowering overall disease risk.

2. Better Gut Health and Improved Digestion

Prebiotics work to stimulate the growth of beneficial bacteria that colonize our gut microflora. Since they act like food for probiotics, prebiotic compounds help balance harmful bacteria and toxins living in the digestive tract.

This has numerous health implications, including improving digestion. Research shows that higher intakes of prebiotics foods can increase numerous probiotic microorganisms, including Lactobacillus rhamnosus GGL. reuteri, bifidobacteria, and certain strains of L. casei or the L. acidophilus-group.

The beneficial bacteria in your gut uses the indigestible fiber content from the foods that you eat as a source for their own survival. As your gut bacteria metabolize otherwise non-digestible fibers from foods, they produce short-chain fatty acids, which are compounds that boast a wide range of benefits.

One of these beneficial fatty acids is called butyric acid, which improves the health of the intestinal lining. Studies suggest that short-chain fatty acids also help regulate electrolyte levels in the body to promote proper digestion, support regularity, and relieve digestive issues like diarrhea and constipation.

Changes in the gut microbiota composition are classically considered as one of the many factors involved in the development of either inflammatory bowel disease or irritable bowel syndrome. A 2012 report published in the Journal of Nutrition reported that prebiotics, along with probiotics, can help treat many digestive problems, including diarrhea (especially after taking antibiotics), certain intestinal infections and chronic disorders, like Crohn’s disease and ulcerative colitis, symptoms of irritable bowel syndrome (IBS), inflammatory bowel disease and leaky gut.


3. Enhanced Immune Function

Many human studies have demonstrated that consuming prebiotic foods can result in significant changes in the composition of the gut microbiome that help improve immunity. This “prebiotic effect” has been associated with improvements in biomarkers and activities of the immune system, including reduced levels of certain cancer-promoting enzymes and bacterial metabolites in the gut.

According to a report in the British Journal of Nutrition, prebiotics can help improve stool frequency and consistency, reduce the risk of gastroenteritis and infections, enhance overall health, and decrease the incidence allergy symptoms. Prebiotics and probiotics also help boost immunity by improving nutrient absorption and lowering the pH in the gut to block the growth of potential pathogens and harmful bacteria.

Prebiotics may help enhance immunity by providing fuel for your gut bacteria. This could be beneficial in the treatment of a wide range of conditions, including viral infections, allergies, eczema and intestinal disorders. Plus, some studies have even reported a reduction in the incidence of tumors and cancer cells after eating foods high in prebiotics.

4. Lower Inflammation

Prebiotics can help lower inflammation, which is believed to be one of the root causes of many chronic diseases, including our nation’s No. 1 killer: heart disease. In fact, people consuming more prebiotics and fiber tend to have healthier cholesterol levels and lower risk markers for cardiovascular diseases.

Inflammation is also thought to contribute to many other chronic conditions as well, including diabetes, cancer and even obesity. Interestingly enough, it’s believed that prebiotics and probiotics contribute to improvements in metabolic processes that are tied to both obesity and type 2 diabetes.

Research also shows that a healthier gut environment can turn off autoimmune reactions, help the body metabolize nutrients more efficiently, and modulate immune functions that control how and where the body stores fats (including in the arteries).

5. Reduced Risk of Heart Disease

There’s evidence that consuming foods high in prebiotics can reduce glycation, which increases free radicals, triggers inflammation and lowers insulin resistance, all of which can contribute to heart disease.

Prebiotics have cholesterol-lowering properties, which can aid in the prevention of heart disease as well as autoimmune disorders like arthritis. They can also balance the body’s electrolyte and mineral levels, including potassium and sodium, which are responsible for controlling blood pressure.

6. Aid in Weight Loss

Do prebiotics help with weight loss? Data from both human and animal studies suggest there’s a connection between taking prebiotics and weight loss. Research notes there are beneficial effects of particular prebiotics on energy homeostasis and potentially increased weight loss.

Higher intakes of all types of fiber are, in fact, linked to lower body weight and protection against obesity. An animal study published in the British Journal of Nutrition found that prebiotic foods promote a feeling of fullness, prevent obesity and spur weight loss. Their effects on hormone levels are related to appetite regulation, with studies showing that animals given prebiotics produce less ghrelin, which is the the hormone responsible for stimulating hunger.

6. Protect Bone Health

A study published in the Journal of Nutrition found that prebiotics enhance the absorption of minerals in the body, including magnesium, possibly iron and calcium. All of these are crucial for retaining strong bone bones and preventing fractures or osteoporosis.

In one study, just eight grams of prebiotics a day was shown to have a big effect on the uptake of calcium in the body that led to an increase in bone density.

7. Regulate Hormone Levels and Mood

Research regarding the “gut-brain connection” is still in its infancy, but it’s becoming clear that mood-related disorders like anxiety or depression are closely linked to gut health. Research suggests that your mood and hormonal balance are affected by a combination of factors that most definitely includes the state of the bacterial inhabitants living inside of your body.

Your gut helps absorb and metabolize nutrients from the foods you eat that ultimately are used to support neurotransmitter functions that create the hormones (like serotonin) that control your mood and help relieve stress.

The final straw in triggering a mood-related disorder might be a series of misfiring neurotransmitters in parts of the brain that control fear and other emotions. These transmissions partly depend on the health of the human microbiome, so when the balance of gut bacteria isn’t working right, other biological pathways, including hormonal, immunological or neuronal, won’t work right either.

Recent studies have demonstrated that prebiotics have significant neurobiological effects in the human brain, including lowering cortisol levels and the body’s stress response.

For example, a 2015 study published in Psychopharmacology explored the effects of two prebiotics on the secretion of the stress hormone cortisol and emotional processing in healthy adult volunteers. After volunteers received one of two prebiotics or a placebo daily for three weeks, the group receiving prebiotics showed positive changes in levels of cortisol, suggesting that it may be beneficial in the treatment of stress-related disorders.

Prebiotic Foods

What foods are prebiotics? While probiotics are typically found in cultured and fermented foods like yogurt, kefir, kimchi and kombucha, prebiotics are typically found in certain vegetables (especially when eaten raw), whole grains and sources of resistant starch, such as under-ripe bananas.

A few of the best prebiotic foods that you can add to your diet include acacia gum, raw chicory root, raw Jerusalem artichoke, raw garlic, raw leeks, raw or cooked onions, raw jicama, raw asparagus, quinoa, under-ripe bananas and yacon syrup.

Some other sources include apples with skin and foods that contain isolated carbohydrates (oligosaccharides such as galactooligosaccharides and transgalactooligosaccharides), such as raw honey, wheat dextrin, psyllium husk, whole-grain wheat, barley, oatmeal and whole-grain corn.

Supplements and Dosage Recommendations

Some prebiotics are added to some foods artificially and can often be found as dietary supplements. The best prebiotics come from whole food sources and foods containing prebiotics, like raw chicory root or onions. Not only do these foods supply a concentrated amount of prebiotics, but they are also rich in other important vitamins, minerals and antioxidants that can help optimize your health.

Focus on eating plenty of fiber-rich foods, aiming to get 25 to 30 grams of fiber each day from a variety of whole foods.

That said, if you’re unable to meet your needs through food alone, you may want to consider prebiotics and probiotics supplements. Look for a supplement that contains real prebiotics instead of compounds with prebiotic-like effects, and be sure to buy from a reputable retailer with high-quality standards as well.

Additionally, it’s important to stick to the recommended dosage to avoid adverse symptoms and gastrointestinal problems. You may also want to start with a low dose and gradually increase your intake to assess your tolerance and minimize the risk of side effects.

Prebiotics and probiotics can be taken at the same time, or use a supplement that combines both (along with postbiotics). Ideally, take them daily around at the same time each day in order to establish a consistent routine.

How long do prebiotics take to work? This really depends on the individual. Like other dietary changes, you may notice some benefits within several days or need to be consistent for several weeks before experiencing changes like improved digestion.

Risks, Side Effects and Interactions

Are prebiotics safe? Yes, but because prebiotics are fermented in the gut, increasing your intake of prebiotics too quickly may lead to some side effects. Possible prebiotic side effects can include abdominal pain, gas, bloating and diarrhea.

Starting with a small amount and increasing gradually is the best way to assess your tolerance and sidestep negative symptoms. If you have IBS, SIBO (small intestinal bacterial overgrowth) or FODMAPs intolerance, then be careful about consuming lots of prebiotics, since this may trigger symptoms.

Additionally, be sure to increase your water intake as well. Fiber-rich foods like prebiotics can absorb water in the colon, which can slow down digestion and cause adverse side effects like dehydration.

Staying well-hydrated while eating plenty of prebiotics can help prevent constipation and promote regularity to keep your digestive tract running smoothly.

Are prebiotics for kids safe? Generally speaking, prebiotics and probiotics are safe for kids, unless your child has a compromised immune system, cancer or is a premature infant. Some experts believe that for children, it’s generally better to get probiotics and prebiotics through foods instead of supplements.

Some studies have found that eating fibrous foods helps children regulate their appetite and lowers risk for obesity. If you’re unsure of whether your child can tolerate these types of supplements, when in doubt talk to your family’s pediatrician.

Final Thoughts

  • What are prebiotics? They’re non-digestible fiber compounds that pass through the upper part of the gastrointestinal tract and end up in the colon, where they’re fermented by the gut microflora
  • Benefits of prebiotics include better gut health and improved digestion, enhanced immune function, lower inflammation, reduced risk of heart disease, aid in weight loss, protect bone health, and regulate hormone levels and mood.
  • Foods with prebiotics include many fruits, vegetables and whole grains, such as under-ripe bananas, raw garlic, onions and acacia gum. They can be found in supplement form as well.

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