As a practicing physician and nutritionist, I hear that
question at least three times a day. The good news is we
can strengthen the immune system’s resistance to infection
by taking supplements of Lactobacillus acidophilus or Bifidobacterium
bifidum, two breeds of “friendly” bacteria that
normally live in the human gastrointestinal (G.I.) tract.
Lactobacillus attaches itself mainly in
the upper G.I. tract (small intestine); bifidobacterium
resides mainly in the lower G.I. tract (large intestine).
Research shows that these friendly bacteria strengthen the
ability of the immune cells surrounding the G.I. tract to
defend the body against toxins, bacteria and allergens.
It is thought that the G.I. tract’s immune cells, a
type of lymphocyte, in turn signal immune cells elsewhere
in the body to increase or decrease activity.
Researchers from the departments of immunology
and biochemistry at the University of Paris tested the effect
of oral supplements of friendly bacteria on the ability
of white blood cells to attack and destroy hostile microorganisms.
In one study, 28 healthy adult human volunteers
took one of three fermented milk supplements: those with
no friendly bacteria added, those with L. acidophilus or
those with B. bifidum. The supplementation amounted to a
daily dose of 70 billion colony-forming units (cfu) of L.
acidophilus or 10 billion cfu of B. bifidum
Scientists examined volunteers’ blood
samples after three weeks and checked the phagocytic activity
of each person’s white blood cells by gauging the cells’
ability to attack and ingest E. Coli, a bacteria with moderately
high potential for causing disease.
The percentage of white blood cells that
were able to attack and “eat up” E. Coli doubled
in volunteers taking either L. acidophilus or B. bifidum-an
increase from 40 percent to 80 percent. Even better, six
weeks after stopping the bacteria supplements phagocytic
activity was still much higher than at the start of the
study, although it had fallen off from its peak during supplementation.
With fermented milk alone there was no increase in phagocytic
ability.
The native bacteria living within the
G.I. tract play an important role in protecting us from
intestinal infections caused by “unfriendly” gut
organisms such as candida (Candida albicans) or the diarrhea-causing
bacteria Clostridium difficile. This may be caused by crowding
the undesirable organisms out of their potential biological
niche.
Whole Body Protection
The current study breaks new ground because
it shows that lactobacillus and bifidobacterium supplements
caused sustained immunological protection-both stimulated
immune cells that were outside the G.I. tract, i.e. white
cells in the blood.
Bacteria-containing supplements, called
probiotics, are only one of many natural substances being
studied for their ability to improve our overall resistance
to infection. Vitamins C and A, selenium, zinc, echinacea
(Echinacea angustifolia or purpurea), aloe(Aloe vera), garlic(Allium
sativum), silymarin(from milk thistle, Silybum marianum)
and cow’s milk whey also improve the body’s natural
resistance to infection. Probiotics are especially intriguing
because of growing evidence that connects bacterial action
within the G.I. tract to a number of body processes.
It is estimated there are more bacteria
in the gut than cells in the body or stars in the sky. In
addition to the immune system effects, gut bacteria manufacture
vitamins, detoxify environmental chemicals and metabolize
hormones and other substances. Unfriendly organisms in the
G.I. tract, however, not only can cause infections, but
can produce toxic products including a host of carcinogens.
Beta glucuronidase, for example, is an
enzyme produced by certain unfriendly gut bacteria. High
levels of beta glucuronidase disrupt the body’s ability
to detoxify both natural hormones and environmental chemicals.
People who have high levels of beta glucuronidase in their
stool may be at increased risk for breast and colon cancer.
Because beta glucuronidase in the stool is easily measured,
it may help assess a person’s cancer risk.
Can we reduce our exposure to beta
glucuronidase? Taking probiotic supplements increases the
proportion of lactobacillus and bifidobacterium in the G.I.
tract, which thereby decreases the number of beta-glucuronidase-producing
bacteria. A diet that reduces red meat and emphasizes plenty
of vegetables and fruits, whole grains and fermented milk
products containing live organisms also promotes a healthy
population of friendly bacteria.
