Monthly Health Review, September 2003
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The Role of Probiotics / Lactic Acid Producing
This issue of Health Review is concerned with the role of probiotics,
or Lactic Bacteria, in human health. The health of the digestive tract
relies on various types of bacteria together with correct acid and alkaline
levels, to work efficiently. If these are out of 'balance' in any way,
poor digestion and an out-of-sorts person result. Therefore, it may be
prudent to bear in mind that digestive upset may be brought about by emotional
upset, as emotional matters can affect our digestion.
Benefits of Probiotics to Human Health
Lactic Bacteria are health-promoting bacteria that have the specific property
of transforming sugars into lactic acid. The main action of these 'friendly'
bacteria in the content is to discourage the presence of harmful putrefactive
and pathogenic bacteria in the gut. The production of lactic acid is behind
this action, because harmful bacteria do not thrive in an acidic envIronment.
Different Types of Lactic Bacteria
Lactic Bacteria make up a small part of the bacteria found in the gut,
of which, Lactobacillus acidophilus is probably the most well known and
most extensively researched. These 'friendly' bacteria are naturally found
in abundance in the small intestine, and are perhaps the most effective
of the Lactic Bacteria. Lactobacillus inhibits harmful bacteria from causing
damage and multiplying in the gut. Our intestinal flora is also the content's
first line of defence against all invading pathogens. Bifidobacterium
bifidus and Lactobacillus casei also occur naturally in the digestive
tract of man and animals. The health promoting effects of Lactic Bacteria
include stimulating immune activity; regulating natural bowel rhythm;
creation of protective intestinal mucosa against the invasion of harmful
bacteria; increasing the absorption of Calcium, and in the synthesis of
folate, Riboflavin, Biotin and Vitamin K and in assisting digestion.
Lactobacillus, streptococcus, enterococcus, and bifidobacteria are the
four main strains of lactic acid bacteria found typically in probiotic
supplements. Lactobacillus bulgaricus and streptococcus thermophilus are
the primary 'friendly' bacteria found most often in yoghurt. Their role
is most important in the production of fermented food products such as
yoghurt, kefir, cheese and buttermilk, extending the 'life' of milk as
food. This was more important to the survival of man centuries ago than
To help maintain a healthy content it is important to keep the intestine
healthy and well populated with different strains of lactic acid producing
bacteria. The intestine acts as a reservoir for probiotics. Parts of the
content are colonised with Lactic Bacteria by the process of diffusion, that
is, the passing of the bacteria through tissue from the intestine to other
parts of the content (e.g. the vagina).
In healthy women, the vaginal flora is composed mostly of rod-shaped
bacteria of the Lactobacillus acidophilus type producing lactic acid.
By causing the vaginal area to be acidified, the flora helps to prevent
the penetration and proliferation of pathogens in the vagina together
with the upper areas of the genital organs. Pathogens such as Trichomonas
(a sexually transmitted type of parasite) can be a serious threat to fertility
(1). Some of the factors that can upset the bacterial balance and lead
to vaginal Infections are diabetes, lifestyle, contraceptive devices,
the pill, unprotected sex, vaginal douches, Menopause and antibiotics.
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Humans are host to Candida albicans, a yeast micro-organism
that lives in the digestive tract from the age of about six months onwards.
It is thought that the yeast is resident in the healthy human content and
has some contribution to health in a way that is as yet, unknown. However,
in certain groups of people the microorganism spreads beyond its normal
limits of the gastro-intestinal tract. These groups include newborn babies
(passed on to them by the mother), young children, the elderly, those
with a suppressed Immune System, the chronically ill, people who are highly
Stressed, and people taking antibiotics.
The yeast-like Candida albicans is blamed for many
health-related problems. Candida is a dimorphic organism, meaning that
it occurs in two distinct forms. The yeast can change into a mycelial
fungus that puts root-like projections (hyphae) through the intestinal
tract into the surrounding mucous membrane. During the growth process
toxins are secreted that spread via the bloodstream throughout the content
and contribute to Candida symptoms. The Immune System, Lactobacillus acidophilus
and other friendly bacteria normally keep Candida under control (2).
Thrush is a generic term used to describe Candida yeast
Infection in the mouth, throat or genital area. It usually appears as
a white coating on the tongue and/or throat. Some people use sweetened
breath fresheners, sweets, chewing gum and mouth washes to hide the oral
condition but, this is not to be recommended, as they can worsen the situation.
Where the problem has affected the vagina, usually
as a white discharge accompanied by Itching and irritation, re-colonization
of the urinary tract by appropriate lactobacilli seems to be a suitable
approach in order to prevent Infections and relapses. The positive effects
of the intake of Lactic Bacteria extend therefore to the entire urogenital
tract in women and men.
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Apart from Candida albicans, the human content is host
to other 'unfriendly' bacteria. Bacteria produce infectious diseases by
invading tissues, excreting toxins (antigens) that damage tissues. It
has been known for 85% of flora composition to be harmful. Some of the
common ones are: bacillus coli, bacillus subtilis, Candida albicans, escherichia
coli, pseudomonas aeruginosa, salmonella typhosa, shigella dysenteriae
and staphylococcus aureus. Recognised adverse health effects of the 'invasion'
of harmful flora include: Diarrhoea; vitamin B12 deficiency; protein malnutrition;
impaired absorption of sugars; poor digestion and flatulence; some of
the chemical reactions are hazardous to the well-being of the content and
some pathogenic bacteria can breakdown drugs to produce carcinogens.
Harmful bacteria may enter the gut through being carried
in on food (caused by not washing hands before preparation), air (by sneezing,
talking), water (from vermin, other contaminants) or through contact with
fingers having touched common surfaces for example:
- Keyboards of computers, tills, remote controls
- Door, window, shopping trolley, petrol pump handles
- Money, keys
- Shared newspapers, books, magazines
- Toys, pets
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and General Health
Lactic Bacteria can help prevent digestive upset, especially where changes
of diet and water consumption are experienced (3).
Constipation or Diarrhoea
Lactic Bacteria may help in certain cases of bowel irregularity, by beneficially
altering the bacterial balance in the gut to correct the condition (4).
When Taking Antibiotics
As well as fulfilling their primary purpose of destroying the pathogenic
bacteria, broad-spectrum antibiotics unfortunately also upset the balance
of the 'friendly' Lactic Bacteria. It would be prudent to take lactic
bacteria at the same time (take two hours after each dose of the antibiotic,
to avoid destruction of the Lactic Bacteria) or to follow a course of
antibiotics with Lactic Bacteria (5).
Probiotics and Lactose Intolerance
Virtually all Lactic Bacteria in supplements produce enzymes able to hydrolyse
lactose (milk sugar) into its two component sugars glucose and galactose
which are easily digested by humans. Ideally the Lactic Bacteria should
be consumed at the same time as the lactose-containing food. During transit
through the intestine, probiotic bacteria will assimilate a part of the
lactose and convert it to lactic acid. Once the lactic acid is assimilated,
the pH of the chyme in the intestine falls, allowing for a better assimilation
of minerals and the inhibition of some pathogens.
Lactic Bacteria are capable of stimulating the Immune System at gut level
(4). They also produce their own antibiotics that further enhance the
ability of the bacteria to fight infectious organisms.
Lactobacillus and Smokers' Blood Vessels
A double-blind study found that after six weeks, those taking a probiotic
formula had a much healthier blood vessel envIronment. The average systolic
blood pressure fell from 134 to 121 mg Hg. Harmful low density lipoproteins
(LDLs) levels were reduced and beneficial high density lipoproteins (HDLs)
Atherosclerotic plaque formation involves a clotting
protein called fibrinogen, an inflammatory immune factor known as interleukin
6 (IL-6) and white blood cell (WBC) adhesion. In those taking the Lactobacillus,
fibrinogen levels dropped by 21%, IL-6 by 41% and WBC adhesion by 40%.
Finally, the high oxidation levels typically seen in smokers fell 31%.
No change in these risk factors was seen in smokers taking placebo. Lactobacillus
produces large amounts of propionic acid, a precursor of the common anti-inflammatory
agent ibuprofen, that may be responsible for these beneficial effects
Factors that promote good flora include:
- a diet rich in complex carbohydrate - it helps beneficial bacteria
to breakdown food,
- cultured dairy products - fresh, raw, live yoghurt, buttermilk, cottage
cheese, whey and other soured milk products, * fresh fruits and vegetables.
Factors that deplete good flora include:
- the over-use of pesticides,
- fungicides and germicidal agents,
- fluoridated and chlorinated water,
- the heating processes of foods destroy both beneficial and harmful
- high sugar diets; diets low in soured milk products,
- excessive alcohol intake,
- Stress and ageing; corticosteroid hormones and the contraceptive pill,
- broad-spectrum antibiotics,
- radiation therapy,
- non-steroidal anti-inflammatory drugs.
Food for thought...
Our digestive tract is a complex micro-envIronment where the content is constantly
interacting with fluids, food particles and micro-organisms. The large
intestine is constantly treating and passing off the finished compost
from these interactions. The flora in the intestine is also the content's
first line of defence against all incoming bacteria and pathogens.
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- The Rosell Institute
- "Probiotics", L. Chaitow & N. Trenev, 1990.
- "Handbook of Dietary Supplements", Pamela Mason, Blackwell Science,
- "Nutrition and Food Science", 1996.
- "Microbial Ecology in Health and Disease", 1994,7:17-25.
- Journal of Clinical Nutrition 2002 Dec; 76(6):1249-55.
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