Also indexed as: Bifidobacterium
bifidum, Bifidobacterium longum, Intestinal Flora, Lactobacillus
acidophilus, Lactobacillus casei, Saccharomyces
What do they do?
Beneficial bacteria, such as
and Bifidobacterium bifidum,
are called probiotics. Probiotic bacteria favorably alter the intestinal
microflora balance, inhibit the growth of harmful bacteria, promote good
digestion, boost immune function, and increase resistance to infection.1
People with flourishing intestinal colonies of beneficial
bacteria are better equipped to fight the growth of disease-causing
Lactobacilli and bifidobacteria
maintain a healthy balance of intestinal flora by producing organic
compounds—such as lactic acid, hydrogen peroxide, and acetic acid—that
increase the acidity of the intestine and inhibit the reproduction of many
harmful bacteria.5 6
Probiotic bacteria also produce
substances called bacteriocins, which act as natural
to kill undesirable microorganisms.7
Immune function tends to decline with age. Twice daily supplementation
with Bifidobacterium lactis (a particular strain of
bifidobacteria) in milk was found in a double-blind trial to significantly
enhance various aspects of immune function in a group of healthy elderly
people.8 Benefits were apparent after only six weeks of
supplementation. Yogurt has been purported to support immune function, due
to its inclusion of lactic-acid bacteria.9 While B. lactis
is a different organism than that found in yogurt, effects on immunity may
Regular ingestion of probiotic bacteria may help prevent
.10 11 A review of the
research concluded that both topical and oral use of acidophilus can
prevent yeast infection caused by candida overgrowth.12
Diarrhea flushes intestinal microorganisms out of the gastrointestinal
tract, leaving the body vulnerable to opportunistic
. Replenishing the beneficial bacteria with probiotic
supplements can help prevent new infections. The incidence of “traveler’s
diarrhea,” caused by pathogenic bacteria in drinking water or undercooked
foods, can be reduced by the preventive use of probiotics.13
Most people associate lactobacilli with L. acidophilus, the
most popular species in this group of probiotic bacteria. However,
research shows that other Lactobacillus species may be beneficial
as well. For example, L. rhamnosus and L. plantarum
appear to be protective intestinal bacteria. They are involved in the
production of several “gut nutrients”, such as short-chain fatty acids,
and the amino acids, arginine, cysteine and glutamine.14 These
beneficial bacteria may also help remove toxins from the gut and exert a
beneficial effect on cholesterol levels.15
One probiotic, Saccharomyces boulardii, has prevented diarrhea
in several human trials.16 Double-blind research studying
critically ill patients found this strain of yeast to prevent diarrhea
when 500 mg is taken four times per day.17
Probiotics are important in recolonizing the intestine during and after
antibiotic use. Probiotic supplements replenish the beneficial bacteria,
preventing up to 50% of infections occurring after antibiotic use.18
Probiotics also promote healthy digestion. Enzymes secreted by
probiotic bacteria aid digestion. Acidophilus is a source of
, the enzyme needed to digest milk sugar, which is lacking in
Fructo-oligosaccharides (FOS) are naturally occurring carbohydrates
that cannot be digested or absorbed by humans. They support the growth of
bifidobacteria, one of the beneficial bacterial strains.20 Due
to this effect, some doctors recommend that patients taking bifidobacteria
also supplement with FOS. Several trials have used 8 grams per day.
However, a review of the research has suggested that 4 grams per day
appears to be enough to significantly increase the amount of
bifidobacteria in the gut.21
Where are they found? Beneficial bacteria
present in fermented dairy foods—namely live culture yogurt—have been used
as a folk remedy for hundreds, if not thousands of years. Yogurt is the
traditional source of beneficial bacteria. However, different brands of
yogurt can vary greatly in their bacteria strain and potency. Some
(particularly frozen) yogurts do not contain any live bacteria.
Supplements in powder, liquid extract, capsule, or tablet form containing
beneficial bacteria are other sources of probiotics.
Probiotics have been used in connection with the following conditions
(refer to the individual health concern for
Who is likely to be deficient? People using
antibiotics, eating a poor diet, or suffering from diarrhea are more
likely to have depleted colonies of friendly bacteria.
How much is usually taken? The amount of
probiotics necessary to replenish the intestine varies according to the
extent of microbial depletion and the presence of harmful bacteria. One to
two billion colony forming units (CFUs) per day of acidophilus is
considered to be the minimum amount for the healthy maintenance of
intestinal microflora. Some Saccharomyces boulardii research has
used 500 mg taken four times per day.
Are there any side effects or interactions?
There are at least nine case reports of severe, invasive (internal) fungal
developing in people treated with the yeast organism
. All of these people were debilitated or had
prior to receiving Saccharomyces boulardii
No such adverse reactions have been reported with other
probiotic supplements or in people with normal immune systems.
Acidophilus and bifidobacteria may manufacture B vitamins, including
niacin, folic acid, biotin, and vitamin B6.
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