PROBIOTIC DIET AS AN INTERVENTION
Probiotics are dietary supplements containing
potentially beneficial bacteria or yeast. As with many interventions
for Autism and
syndrome, use of probiotic diets has not been rigorously tested
and evidence appears to be largely anecdotal to date.
Probiotics are dietary supplements containing
potentially beneficial bacteria or yeast, with lactic acid bacteria
(LAB) as the most common microbes used. LAB have been used in the
food industry for many years, because they are able to convert sugars
(including lactose) and other carbohydrates into lactic acid. This
not only provides the characteristic sour taste of fermented dairy
foods such as yogurt, but acts as a preservative, by lowering the
pH and creating fewer opportunities for spoilage organisms to grow.
yeast and autism spectrum disorders
Some researchers believe there is evidence for
a yeast called candida albicans exacerbating many behavior
and health problems in autistic individuals, if not possibly an
actual cause of
Autism itself. Candida albicans is found in the digestive
tract and is normally kept under control unless antibiotics allow
an overgrowth. Proponents of this theory believe that behavior problems
include irritability, confusion, hyperactivity,
lethargy, short attention span and aggression. Research by a Dr.
William Shaw has discovered unusual microbial metabolites in the
urine of children on the autism spectrum who responded well to anti-fungal treatments, which
behavior, and increases in eye contact, vocalization, and concentration.
The rationale for probiotics is that the body
contains a miniature ecology of microbes, collectively known as
the gut flora. The number of bacterial types can be thrown out of
balance by a wide range of circumstances including the use of antibiotics
or other drugs, excess alcohol, stress, disease, exposure to toxic
substances, or even the use of antibacterial soap. In cases like
these, the bacteria that work well with our bodies may decrease
in number, an event which allows harmful competitors to thrive,
to the detriment of our health.
Maintenance of a healthy gut flora is, however,
dependent on many factors, especially the quality of food intake.
Supporters of the probiotic diet believe that including a significant
proportion of probiotic foods in the diet supports a healthy balance
of bacteria in the body.
What foods and supplements are used in a probiotic diet?
The most common form for probiotics are dairy
products, inulun, raw oats, unrefined wheat and probiotic-fortified
foods. However, tablets and capsules containing the bacteria in
freeze-dried form are also available. Some fermented products containing
similar (often not proven to have a probiotic or health effect)
lactic acid bacteria include kefir, yogurt, sauerkraut, kimchi and
Some common probiotics include various species of the genera Bifidobacterium
and Lactobacillus such as bifidobacterium bifidum, bifidobacterium
breve, bifidobacterium infantis, lactobacillus acidophilus, lactobacillus
casei, lactobacillus plantarum, lactobacillus reuteri, lactobacillus
rhamnosus and lactobacillus GG. Some other bacteria mentioned in
probiotic products are lactobacillus sporogenes, lactobacillus bifidus
-(became new genus bifidobacteria) and lactobacillus caucasicus.
The theory behind probiotic diets
Probiotic bacterial cultures are intended to assist
the body's naturally occurring flora within the digestive tract
to reestablish themselves, and may help children on the autism spectrum who have gastrointestinal
problems. They are sometimes recommended by doctors, and, more
frequently, by nutritionists, after a course of antibiotics, or
as part of the treatment for candidiasis. Many probiotics are present
in natural sources such as lactobacillus in yogurt and sauerkraut.
Claims are made that probiotics strengthen the immune system.
Effects of a probiotic diet
There is no published evidence that probiotic
supplements are able to replace the body's natural flora when these
have been killed off; indeed bacterial levels in feces disappear
within days when supplementation ceases. There is evidence, however,
that probiotics do form beneficial temporary colonies which may
assist the body in the same functions as the natural flora, while
allowing the natural flora time to recover from depletion. The probiotic
strains are then progressively replaced by a naturally developed
gut flora. Hence, probiotics have been defined as correctives of
the ecoorgan. If the conditions which originally caused damage to
the natural gut flora persist, the benefits obtained from probiotic
supplements will be short lived.
Potential benefits of a probiotic diet
Experiments into the benefits of probiotic therapies
suggest a range of potentially beneficial medicinal uses for probiotics.
For many of the potential benefits, research is limited and only
preliminary results are available. Benefits regarding Autism and
Asperger's syndrome are not included due to a lack of evidence-based
Managing lactose intolerance
Because LAB convert lactose into lactic acid,
their ingestion may help lactose intolerant individuals tolerate
more lactose than what they would have otherwise.
Prevention of colon cancer
In laboratory investigations, LAB have demonstrated
anti-mutagenic effects thought to be due to their ability to bind
with heterocylic amines; carcinogenic substances formed in cooked
meat. Animal studies have demonstrated that LAB can protect against
colon cancer in rodents, though human data is limited and conflicting.
Most human trials have found that LAB may exert anti-carcinogenic
effects by decreasing the activity of an enzyme called ß-glucuronidase
(which can generate carcinogens in the digestive system). Lower
rates of colon cancer among higher consumers of fermented dairy
products have been observed in some population studies.
Animal studies have demonstrated the efficacy
of a range of LAB to be able to lower serum cholesterol levels,
presumably by breaking down bile in the gut, thus inhibiting its
reabsorption (which enters the blood as cholesterol).Some, but not
all human trials have shown that dairy foods fermented with LAB
can produce modest reductions in total and LDL cholesterol levels
in those with normal levels to begin with, however trials in hyperlipidemic
subjects are needed.
Lowering blood pressure
Several small clinical trials have shown that
consumption of milk fermented with various strains of LAB can result
in modest reductions in blood pressure. It is thought that this
is due to the ACE inhibitor like peptides produced during fermentation.
Improving immune function and preventing infections
LAB are thought to have several presumably beneficial
effects on immune function. They may protect against pathogens by
means of competitive inhibition (i.e., by competing for growth)
and there is evidence to suggest that they may improve immune function
by increasing the number of IgA-producing plasma cells , increasing
or improving phagocytosis as well as increasing the proportion of
T lymphocytes and Natural Killer cells. Clinical trials have demonstrated
that probiotics may decrease the incidence of respiratory tract
infections and dental caries in children as well as aid in the treatment
of Helicobacter pylori infections (which cause peptic ulcers) in
adults when used in combination with standard medical treatments.
LAB foods and supplements have been shown to be effective in the
treatment and prevention of acute diarrhea; decreasing the severity
and duration of rotavirus infections in children as well as antibiotic
associated and travelers diarrhea in adults.
LAB foods and supplements have been found to modulate
inflammatory and hypersensitivity responses, an observation thought
to be at least in part due to the regulation of cytokine function.
Clinical studies suggest that they can prevent reoccurrences of
inflammatory bowel disease in adults, as well as improve milk allergies
and decrease the risk of atopic eczema in children.
Improving mineral absorption
It is hypothesized that probiotic lactobacilli
may help correct malabsorption of trace minerals, found particularly
in those with diets high in phytate content from whole grains, nuts,
Prevents harmful bacterial growth under stress
In a study done to see the effects of stress on
intestinal flora, rats that were fed probiotics had no occurrence
of harmful bacteria latched onto their intestines compared to rats
that were fed sterile water.
Irritable bowel syndrome and colitis
B. infantis 35624, sold as Align, was found to
improve some symptoms of irritable bowel syndrome in women in a
recent study. Another probiotic bacterium, Lactobacillus plantarum
299V, was also found to be effective in reducing IBS symptoms. Additionally,
a probiotic formulation, VSL3, was found to be effective in treating
What does the research say?
To date there has not been rigorous research that
would qualify probiotics as an evidence-based
treatment. Research on yeast and Autism Spectrum Disorders
by a Dr. William Shaw reported unusual microbial metabolites in
the urine of children on the autism spectrum who responded well
to anti-fungal treatments. Reported benefits included increases
in eye contact, vocalization, and concentration, and decreases in
hyperactivity and self-stimulating behavior.
Long-term use of antifungal agents such as Fluconazole
should be monitored carefully as it can lead to liver toxicity and
exfoliative dermatitis. Nystatin is not systemically absorbed and
may result in diarrhea. Other research has noted that that the presence
of yeast is normal in both the bowel and stools, and to date candidal
overgrowth in the intestine has not been documented by endoscopy
(Wakefield, Murch, & Anthony 1998).
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