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Bifidobacteria levels in the gut being supported by the prebiotic XOS

Feed Your Beneficial Bacteria

With age, beneficial gut bacteria sharply decline to just 5% of youthful levels. A unique prebiotic repopulated bifidobacteria levels within weeks

Scientifically reviewed by: Dr. Gary Gonzalez, MD, in October 2021. Written by: Marina MacDonald, MS, PHD.

One of the most exciting areas of health research is the microbiome, the trillions of healthy bacteria and other microbes that live in and on us.

The National Institutes of Health saw this as so important that it launched the Human Microbiome Project to encourage advancement in the knowledge and application of the human microbiome for healthy longevity.1

Among the most beneficial gut bacteria are those belonging to the group called bifidobacteria.2

Research shows that bifidobacteria have wide-ranging potential health benefits, from immunity to cancer.3-5

During adulthood, the abundant bifidobacteria that was present in early childhood dramatically declines. By old age, it has been estimated to be just 5% of original youthful levels.4

Prebiotics are a source of food for bifidobacteria, allowing them to grow and multiply.

In a clinical trial at UCLA School of Medicine, researchers found that a prebiotic significantly increased bifidobacteria levels in the gastro-intestinal tract.6

This same prebiotic has been shown to restore youthful levels of bifidobacteria in several human studies.

Importance of Bifidobacteria

Lab researcher pointing to culture of bifidobacteria apart of the gut microbiome

Bifidobacteria are an important part of the gut microbiome and play a valuable role in whole-body health.

Healthy bifidobacteria are estimated to account for about 60% of gut microbes in infancy.4

Researchers have suggested that by adulthood, bifidobacteria levels decline to 30%-40% of total gut microbes, then to about 10% in late middle age, and drop to less than 5% by old age.4

This is where prebiotics play an important role. Replenishing intestinal bifidobacteria restores their multiple healthful effects, while limiting room for harmful bacteria to live and grow.7

Bifidobacteria have been of great interest to researchers due to their ability to modulate so many areas of health, particularly immunity.8

A variety of research models, from animal to clinical trials, have found that bifidobacteria levels are reduced in some digestive disorders, infections, and in auto-immune arthritis.9

Bifidobacteria may be protective against an underlying mechanism of diabetes and obesity, along with improving blood sugar metabolism. An animal model found that bifidobacteria supplementation suppressed colon cancer.9

Just as bifidobacteria levels decrease over time, the incidence of degenerative diseases increases with age.

Scientists have discovered a prebiotic called xylo-oligosaccharide or XOS that increases the bifidobacteria population, helping to support a healthy gut microbiome and all the benefits that come with it.

What are Prebiotics?

The gut microbiota is made up of the trillions of microorganisms in your digestive tract. They impact immunity, metabolism, the endocrine system, mood, and cardiovascular health.10-14

Foods that specifically nourish and promote healthy gut flora are called prebiotics.15,16 Very few people ingest enough prebiotics from food sources to help foster a healthy gut microbiota filled with bifidobacteria.

For a food ingredient to be classified as a prebiotic, it must:17

  • Resist digestion,
  • Be fermented by intestinal microorganisms,
  • Stimulate growth and/or activity of beneficial bacteria, and
  • Enable healthy bacteria to grow and thrive.

Most commercial prebiotics require large doses to provide optimal digestive health support. This can cause excessive flatulence, bloating and general digestive discomfort.18

The XOS prebiotic is different, requiring only small doses.

Advantages of XOS

Xylooligosaccharides (XOS) are prebiotics usually made from corn cobs. They feed healthy bifidobacteria and help them grow and multiply.

XOS has demonstrated the following advantages:

  • Human studies: XOS consumption created rapid increases in bifidobacteria in as little as two weeks.6,19
  • Culture studies: Fermentation of XOS by bifidobacteria inhibited the growth of harmful bacteria Clostridium difficile, which can cause fever, diarrhea, and serious or fatal gastro-intestinal disease.20
  • XOS works at lower doses, minimizing gastrointestinal discomforts like gas and bloating that are often associated with other prebiotics that require higher doses.6,18
  • Taking XOS daily increased levels of butyrate in human subjects.21 Butyrate is a short-chain fatty acid that is the food for the cells that line the colon. In animal models, butyrate has been linked with gut and brain health.22
  • In a study of type II diabetics, taking XOS daily for eight weeks modestly improved blood sugar and cholesterol levels.23

What you need to know

Researcher holding screen with intestine being boosted by XOS

Nourish Bifidobacteria with XOS

  • The gut microbiota plays a pivotal role in gut, immune, and overall health.
  • Lower levels of bifidobacteria have been associated, in a range of research models, with characteristics of several age-related diseases, and in many cases with the diseases themselves.
  • Xylooligosaccharide or XOS is a prebiotic that specifically targets and boosts bifidobacteria. It has been validated in human studies to work in relatively low doses, without side effects, in as little as two weeks.
  • XOS has also been shown to lower cholesterol, triglycerides, and blood sugar–risk factors for cardiovascular disease and diabetes, respectively.

Boosting Bifidobacteria with XOS

In an eight-week study conducted at UCLA School of Medicine, XOS significantly boosted levels of bifidobacteria.6

Researchers divided 32 healthy subjects into one of three groups:

  • Placebo
  • Low-dose XOS
  • High-dose XOS

The preparation contained 70% XOS, so that the total amount of XOS ingested in the two study groups was one gram or two grams, respectively.

Both treatment groups had increases in bifido-bacteria, but those taking two grams daily of XOS had significantly larger increases than the lower-dose group.

To achieve similar increases using another common prebiotic, FOS (fructooligosaccharides), you’d have to take 10 to 20 grams, which could cause cramps and other digestive problems.6

What the study showed was that XOS is an effective way to repopulate the gut with healthy bifidobacteria. By using the prebiotic XOS, researchers showed that they could rejuvenate an aging gut microbiome.

In another study using the same dose, those taking two grams of XOS daily achieved rapid increases in bifidobacteria in just 14 days.19

A 2020 rat study found that XOS supplementation modulates gut flora and reduces colon inflammation caused by high-fat-diet-induced obesity.24

Wide-Ranging Health Benefits

XOS in vials linked with improving bifidobacteria levels in the gut

XOS provides a way to improve bifidobacteria levels in the gut without the digestive discomforts often associated with other common prebiotics. One study found that taking two grams of XOS:19

  • Increased fecal acidity, likely reflecting the presence of higher amounts of beneficial short chain fatty acids, produced by beneficial intestinal microbes including bifidobacteria.9
  • Decreased blood sugar, an effect which could reduce the risk of metabolic syndrome and type II diabetes.
  • Decreased blood cholesterol and triglycerides, while these were increased in stool, suggesting that excess lipids were removed from blood and transferred to the feces for excretion.

Research shows that bifidobacteria feed on precisely the types of carbohydrates that humans cannot digest, especially the group known as oligosaccharides. XOS (xylooligosaccharide) is an example of this oligosaccharide group of prebiotics.25

These findings add up to a viable method to rejuvenate the bifidobacteria of the gut microbiome.


The health benefits of bifidobacteria are well-known.

By the time we reach an advanced age, however, this beneficial organism will have declined to just 5% of youthful levels.

Xylooligosaccharides (XOS) are prebiotics that can boost bifidobacteria populations.

In human studies, daily consumption of XOS increased numbers of bifidobacteria in as little as two weeks.

If you have any questions on the scientific content of this article, please call a Life Extension Wellness Specialist at 1-866-864-3027.


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