PROBIOTIC DIET AS AN INTERVENTION

Probiotics are dietary supplements containing potentially beneficial bacteria or yeast. As with many interventions for Autism and Asperger's 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 lessened hyperactivity and self-stimulating 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 kombucha.

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 research.

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.

Cholesterol lowering

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.

Reducing inflammation

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, and legumes.

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 ulcerative colitis.

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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