Bifidobacterium in the Gut Microbiota Declines in the Aging Adult: Guidance on How to Repopulate and Increase Bifidobacterium in the Gastrointestinal Tract

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Human Health Depends on a Beneficial and Diverse Gut Microbiota

In order to establish and maintain the health of the host, the intestinal microbiota in general and bifidobacterium in particular are very important.

Regardless of age, studies have determined that human health depends greatly on a beneficial gut microbiota.  1  One study from 2006 called the gut microbiota as the “forgotten organ.”  2 

The aging process can alter and affect the composition and functions of bacterial species in the gut microbiota.   A major consequence of the aging process, coupled with poor eating habits, extended use of antibiotics and stress is a loss of diversity in the gut microbiota.  In general a high diversity of gut organisms has been associated with states of relatively good health, while low diversity has been associated with states of disease or chronic dysfunction.  3 4

At the later stages of life the microbiota composition becomes less diverse, with a higher Bacteroides to Firmicutes ratio, an increase in Proteobacteria and decrease in Bifidobacterium.  5 

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Human microbiota: onset and shaping through life stages and perturbations. The graph provides a global overview of the relative abundance of key phyla of the human microbiota composition in different stages of life. Measured by either 16S RNA or metagenomic approaches (DNA). Data arriving from: Babies breast- and formula-fed (Schwartz et al., 2012), baby solid food (Koenig et al., 2011), toddler antibiotic treatment (Koenig et al., 2011), toddler healthy or malnourished (Monira et al., 2011), adult, elderly, and centenarian healthy (Biagi et al., 2010), and adult obese (Zhang et al., 2009).  Source:  The function of our microbiota: who is out there and what do they do?

The microbiota acclimates changes during the aging process as illustrated in the diagram below:

Development of human gut microbiota from prenatal to elderly. It is believed that infants are born with a sterile gastrointestinal track. During birth, the infant gut is exposed to microbes from the mother’s reproductive tract and environment and the gut microbiota starts colonizing. Up to the first two years of life, the composition of the gut microbiota often varies. After two years, when children are started to eat solid food (e.g. fibers and complex carbohydrates), the gut microbiota becomes more diverse and stable. In old age, the gut microbiota alters drastically and shows less diversity compared to younger age.

Development of human gut microbiota from prenatal to elderly. It is believed that infants are born with a sterile gastrointestinal track. During birth, the infant gut is exposed to microbes from the mother’s reproductive tract and environment and the gut microbiota starts colonizing. Up to the first two years of life, the composition of the gut microbiota often varies. After two years, when children are started to eat solid food (e.g. fibers and complex carbohydrates), the gut microbiota becomes more diverse and stable. In old age, the gut microbiota alters drastically and shows less diversity compared to younger age.  Source: Human gut microbiota and healthy aging: Recent developments and future prospective

Diversity Association is a proxy measure of gut biodiversity, which is defined as the number and abundance of distinct types of organisms present in the gut.  6  

The Diversity Association (DA) graphic is a global biomarker of overall gut health status and serves as a proxy measure of gut biodiversity. Specifically, the Diversity Association graphic represents the results of a proprietary algorithm based on selected commensal targets that appear to correlate with gut health status.

Diversity Association is graphically represented on a vertical ascending scale reflecting lower to higher overall diversity. In the gut, higher diversity is associated with gut health.

  • A Diversity Association indicator in the lower half of the graphical bar indicates a high likelihood that a patient’s gut is not healthy
  • A Diversity Association in the upper quartile of the graphical bar indicates high likelihood that a patient’s gut is healthy

The clinical utility of the Diversity Association is based on a growing body of research demonstrating that lower gut diversity is associated with clinical disease. As such, therapeutic interventions to restore gut balance (including dietary manipulation, prebiotics and/or probiotics, as well as other clinical strategies to heal the gut) are consistent with emerging clinical science on biodiversity.   7

 

Example of Diversity Association from Genova Diagnostics:

GI Effects® Comprehensive Profile – Stool

The prevalence of intestinal dysbiosis is the loss of microbiota diversity (LOMD).  8   This loss of microbiota diversity is in part due to the modern Western lifestyle.  9 

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Associative links between Western lifestyle, Human conditions, and loss of microbial diversity (LOMD). On one hand, most of the Human diseases affecting westernized countries are associated with LOMD and on the other hand, some western lifestyle patterns cause LOMD. Then, LOMD appears to play a central role linking western lifestyle and western chronic human conditions.  *LOMD not assessed.  Source:  Gut Microbiota Diversity and Human Diseases: Should We Reintroduce Key Predators in Our Ecosystem?

Bifidobacterium is Critical to a Healthy Gut Microbiota

The most frequently observed intestinal microbiota alteration is the aberrant number or composition of bifidobacteria in the gut microbiota.  The population of bifidobacteria plays a very important role in intestinal homeostasis. 10

The NCBI data base, as of April 2016, holds 254 publicly available bifidobacterial genome sequences, of which sixty one represent complete genome sequences.  11  The Table below lists all the completely sequenced bifidobacterial genomes:  12

Table 1. Summary of all completely sequenced bifidobacterial genomes

A study from 2014 identified the most abundant bifidobacterial species present in the human gut, being represented by:  13

  • B. longum
  • B. pseudolongum
  • B. animalis subsp. lactis
  • B. adolescentis
  • B. bifidum
  • B. pseudocatenulatum
  • B. breve

Studies agree that the most abundant species of bifidobacteria is B. longum.  14  In adults, some studies have identified higher levels of B. adolescentis and B. catenulatum15  

The intestines of healthy breast fed infants are dominated by bifidobacterium. During the first three years of life, the fecal microbiota then gradually develops into the microbiota of adults. 

The strains commonly dominant in infants include:  16  17

  • B. longum
  • B. breve
  • B. bifidum subsp. infantis

However, by adulthood, bifidobacteria is lower but relatively stable and account for 10-20% of intestinal bacteria. 18  The presence of different species of bifidobacteria changes with age, from childhood to old age.

The strains commonly dominant in adults include:

  • B. catenulatum
  • B. adolescentis
  • B. longum

The intestinal flora then begins to again show changes during the transition from middle age to old age.  In old age (starting roughly at age 55), bifidobacterium decrease considerably.  19  20  The reported decline in bifidobacteria population with aging was accompanied by a decrease in species diversity.

FIGURE 1. At birth levels of bifidobacteria are found to be at their highest. In cases of natural childbirth the numbers are highest at birth. In contrast, they are lower in C sectioned babies. Various diseases such as obesity, diabetes and allergies have been associated with lower numbers of bifidobacteria at various stages of life. When weaned onto solid foods diet is more of an intervening factor and an adult-like (stable) microbiota develops. In this figure the authors hypothesize with regard to the relative abundance of bifidobacteria present at each stage of the life cycle, based on the literature cited in the following review by Voreades et al. (2014).  Source:  Gut Bifidobacteria Populations in Human Health and Aging

Certain research demonstrates that the decline in bifidobacteria in old age is associated with the reduction in adhesion to the intestinal mucosa.  21  However, an extrinsic factor, which is the extended use of antibiotics, may indirectly affect the bifidobacteria composition drastically. 22 

The Table below shows the distribution of the most abundant bifidobacterium species in the intestinal microbiota at different stages of life analyzed using different techniques:

Source: Gut Bifidobacteria Populations in Human Health and Aging

The three diagrams/figures below illustrate the fact that the intestinal flora begins to change during the transition from middle age to old age, with a reduction in the bifidobacterium. This reduction in the bifidobacterium has been claimed to be from the effect that aging of physiologic function in the host has on the intestinal bacterial microbiota; and due to this result can further accelerate the aging process.  23

Intestinal Flora and Age

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Changes in the fecal microbiota with increasing age.  Source:  Establishment of Intestinal Bacteriology

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Evolution of some representatives of the intestinal microbiota accordingly to age  Source:  Intestinal microbiota in health and disease: Role of bifidobacteria in gut homeostasis

Researchers have identified differences in the predominant bifidobacterium species or biotypes in different age groups of humans.  24

The Table below shows the frequency of occurrence of species and biotypes of bifidobacteria in feces of various age groups of humans:

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Source:  Establishment of Intestinal Bacteriology

Reduction in Bifidobacterium and Its Link to Various Diseases

Alterations in number and composition of the populations of bifidobacteria is one of the most frequent features present in various diseases.  This loss and reduction of bifidobacteria is called bifidobacterial dysbiosis.

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Bifidobacterial dysbiosis and its relationship with diseases: A target for probiotic intervention. IBD: Inflammatory bowel disease; IBS: Irritable bowel syndrome.   Source:  Intestinal microbiota in health and disease: Role of bifidobacteria in gut homeostasis

Bifidobacteria dysbiosis has been shown to lead to or be a cause of the following disease states:

  • allergy 25
  • atherosclerosis 26  27
  • atopic disease  28  29 
  • autism 30
  • celiac disease  31  32
  • colorectal cancer  33
  • diabetes – type 1 and type 2 34  35  36
  • inflammatory bowel disease 37  38  39
  • intestinal inflammation 40
  • irritable bowel syndrome 41  42  43  44
  • obesity 45  46

The Multiple Benefits of Bifidobacterium

Bifidobacterium has been studied extensively for its multiple benefits on human physiology.  Among the many benefits of bifidobacterium, the important ones include:

  • Bifidobacteria produces a number of potentially health promoting metabolites including:
    • short chain fatty acid acetic acid  47
    • conjugated linoleic acid  48 
    • bacteriocins  (Bacteriocins are an abundant and diverse group of ribosomally synthesized antimicrobial peptides)  49  
  • Bifidobacteria produce lactic acid (lactate) 50  51
  • Bifidobacteria detoxifies toxic substances
    • Bifidobacteria may lower blood ammonia levels  52
    • Bifidobacteria may reduce levels of beta-glucuronidase (activates various carcinogens and mutagens)  53 
    • Bifidobacteria may facilitate the detoxification and excretion of mercury 54
  • Bifidobacteria produce and synthesize B vitamins 55  56
  • Bifidobacteria do not produce the short-chain fatty acid butyrate directly, they do produce lactate that may be transformed in butyrate  57
  • Abundance  of bifidobacterium is associated with higher bacterial gene richness in the gut  58

Repopulating and Increasing Bifidobacterium in the Gastrointestinal Tract

As has been established, the colonic microbiota undergoes certain age related changes that may affect health. Above the age of 55-65 years, populations of bifidobacteria are known to decrease markedly.  59  It is important for persons at or above this age range to be proactive in replacing the lost bifidobacterium and to increase the population of bifidobacterium in the gastrointestinal tract. 

There are three ways in which to increase the population of bifidobacterium in the gastrointestinal tract.  These include:

  • Bifidogenic Factor
  • Bifidobacterium in food
  • Bifidobacterium in supplements (probiotics)

Bifidogenic Factor

A bifidogenic factor, also known as bifidus factor, is a compound that specifically enhances the growth of bifidobacteria in the gastrointestinal tract.  Most of the products available as bifidogenic factors consist of fibers and are known as prebiotics.  Fibrous substrates act as prebiotics for developing a beneficial gut microbiota.

It has been determined that elderly people consume low amounts of fibers which causes a negative impact on gut microbiota diversity.  60   

The following fibers are known to act as bifidogenic factors thus stimulating the growth of bifidobacteria:

  • Amylose  61
  • Apple Pectin  62
  • Fructo-oligosaccharides  63
  • Galactooligosaccharides  64
  • Gum Arabic  65
  • Inulin  66
  • Isomalto-oligosaccharide  67
  • Lactulose  68
  • Larch Arabinogalactan  69
  • Mannooligosaccharides 70
  • Resistant starch 71
  • Transgalactosylatedoligosaccharides  72
  • Xylooligosaccharides  73

In a study from 2010, done with human subjects, resistant starch showed significant growth of bifidobacteria in the gastrointestinal tract.  74  Resistant starch is starch and starch degradation products that avoid digestion in the small intestine and are fermented in the large intestine by beneficial bacteria.  Resistant starch occurs naturally in various foods.  The Table below list those foods in which resistant starch naturally occurs:

Examples of naturally occurring resistant starch*
Food Serving size Resistant starch
(grams)
Banana flour, from green bananas 1/4 cup, uncooked 10.5-13.2
Banana, raw, slightly green 1 medium, peeled 4.7
High amylose RS2 corn resistant starch 1 tablespoon (9.5 g) 4.5
Oats, rolled 1/4 cup, uncooked 4.4
Green peas, frozen 1 cup, cooked 4.0
White beans 1/2 cup, cooked 3.7
Lentils 1/2 cup cooked 2.5
Cold pasta 1 cup 1.9
Pearl barley 1/2 cup cooked 1.6
Cold potato 1/2″ diameter 0.6 – 0.8
Oatmeal 1 cup cooked 0.5

Source:  Wikipedia – Resistant Starch

Another bifidogenic factor, other than a specific fiber, is actually a beneficial bacteria found in the human gastrointestinal tract, called propionibacterium freudenreichii.  Propionibacterium freudenreichii produces a Bifidogenic Growth Stimulator (BGS) named ACNQ which selectively enhances the utilization of oligosaccharides by bifidobacteria.  75

Bifidobacterium in Food

Foods rich in bifidobacteria are not widespread and mostly include fermented dairy products.  The most common fermented dairy products that contain bifidobacteria include:

  • Yogurt (Cow and goat milk)
  • Kefir (Cow and goat milk)
  • Lassi (yogurt drink from the Indian subcontinent)

The Table below lists the various bifidobacterium strains found in each of the three fermented dairy products:

Bacteria

Yogurt

Kefir

Lassi

B. bifidus

X

X

 

B. animalis

X

 

 

B. animalis BB-12

 

X

 

B. lactis

 

X

X

B. lactis BB-12

X

 

 

B. breve

 

X

X

B. longum

 

X

X

B. regularis

X

 

 

Propionibacterium freudenreichii

 

 

X

Note:  Not all the commercially available products may contain all the listed bifidobacteria strains

Bifidobacterium in Supplements (Probiotics)

Other than the three fermented dairy products, no other foods contain bifidobacterium in any great quantities.  It therefore may be necessary to supplement with a combination of bifidobacterial strains in the form of a probiotic supplement in order to increase the gastrointestinal tract with bifidobacterium.

Consuming probiotic supplements that contain bifidobacteria can be very beneficial and efficient in obtaining proper quantities of bifidobacteria.  There are probiotic products that specifically contain only bifidobacteria strains and others that contain mixtures of bifidobacteria strains and lactobacillus strains.

Some of the more common strains of bifidobacterium species and strains found in probiotic products include:

  • B. adolescentis
  • B. animalis
  • B. bifidum
  • B. breve
  • B. infantis
  • B. lactis
  • B. lactis DN-173 010
  • B. lactis DR10
  • B. lactis HN019
  • B. longum
  • Bifantis
  • Bifidus DR10
  • Bifidus Regularis
  • HOWARU Bifido

Colon's friendly bifidobacteria population decreases from the age of 50

Bifidobacteria Levels Decline With Age How To Replace Bifidobacteria

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