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Probiotic health benefits and results of studies.

We know not everyone will want to read the more complex study data backing up probiotic health benefits, so we have a simpler "What brand for each condition or health problem" page HERE

Humans, like all animals, have large numbers of, and many types of, microbes on our skin, in our mouths, in women’s vaginal tracts, and in the whole length of our gastrointestinal tract. It has been estimated that there are more microbes associated with the human body (about 100,000 Billion bacterial cells) than there are human cells in it. As well as huge numbers, there is a huge variety of types of bacteria. (more than 1000 different species, or types, of bacteria make their homes on humans). Importantly, from a probiotic point of view, is than the numbers and types of microbes that colonize our bodies interact with each other and with our human cells. These colonizing microbes have been shown to have important roles in digestion, metabolism, vitamin synthesis, host cell development, immune system function, intestinal barrier function, defense against pathogens, and other activities that are critical to human health. Probiotics by directly and indirectly influencing the populations and activities of microbes inside us can improve human health.

The following describes some of the researched health benefits of consumption of probiotic cultures.
This info below comes from CDRF.org. We have put links to scientific referrence material and different studies backing up the claims made on a separate page HERE, simply because there is so much of it.

Allergy
Allergy is on the rise in industrialized nations. It is estimated that the incidence of asthma in the United States doubled between 1980 and 2000. Scientists have proposed a hypothesis known as the ‘hygiene hypothesis’ to explain the rise in allergic conditions such as asthma and eczema. This hypothesis is based on observations that lower allergy incidence is associated with environments that have greater numbers of microbes, such as day care centers, farms, or in homes with siblings or pets. Sanitary living environments and the consumption of processed foods have limited the number of microbes in the diet. The hypothesis suggests that the exposure of infants to microbes before the age of six months helps the immune system mature to be more tolerant of exposure to allergens later in life. Certainly, microbial colonization of the gut in early life is important to the development of a properly functioning immune system.

Of course, increasing exposure to microbes must be done safely. This hypothesis led researchers in Finland to conduct a study evaluating the effects of a Lactobacillus strain on incidence of atopic eczema in 132 infants at high risk of developing eczema. The study was double-blinded and placebo-controlled. Pregnant mothers two-to-four weeks before delivery and newborn babies through six months of age were given Lactobacillus rhamnosus GG. Infants were followed through two years of age and incidence of recurring atopic eczema was recorded. The study reported a 50% drop in incidence of recurring atopic eczema in the group receiving the probiotic supplement. A follow up study of these same children indicated that these same trends were still present at 4 years of age. However, no impact on other allergic conditions was observed through seven years of age. These results suggest that exposure to the right types of microbes early in life may decrease the risk of atopic dermatitis. However, a German research group using a very similar protocol and the same probiotic microbe as the Finnish group recently reported that no impact on incidence of atopic eczema was observed with supplementation with L. rhamnosus GG. In addition, the German study noted a statistically significant increase in wheezing in the probiotic group. This study calls into question the validity of the initial observation. An ongoing NIH-funded study in this same area will hopefully clarify a role of prevention of allergy in newborns by L. rhamnosus GG. The effects of probiotics on allergy have been reviewed.

Brain function
It may seem hard to believe, but evidence is emerging that the gut microbes can impact brain function. If we consider that the gut is known as our “second brain,” then perhaps this concept does not seem so far-fetched. The communication between the gut and the brain is bi-directional: the brain controls GI tract function (stress and emotions), but less obvious is that the gut can control pain and emotion. Of particular interest in the discussion of probiotics, is that gut microbes, and probiotics, have been shown to mediate some of this “bottom-up” communication.

For example, one study administered Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 for 30 days to healthy volunteers, who were assessed using validated questionnaires measuring different psychological scales in a randomized, double-blind, placebo-controlled design. The study found that the probiotic reduced somatisation, depression, anger–hostility, their self-blame and were more focused on the problem solving. Other studies showed probiotic impact on improved sleep in elderly volunteers, improved mood scores, and decreased anxiety in patients with chronic fatigue syndrome.

The role of probiotics on different aspects of brain function is an emerging area of research, and care should be taken not to over interpret early animal and pilot human studies, even though a plausible mechanism of action has been postulated.

Cancer
In general, cancer is caused by mutation or activation of abnormal genes that control cell growth and division. (A substance that causes a mistake in genes is known as a mutagen). Most of these abnormal cells do not result in cancer since normal cells usually out-compete abnormal ones. Also, the immune system recognizes and destroys most abnormal cells.

Many processes or exposures can increase the occurrence of abnormal cells. Precautions that minimize these exposures decrease the risk of cancer. Among the many potentially risky exposures are chemical exposures. Cancer-causing chemicals (carcinogens) can be ingested or generated by metabolic activity of microbes that live in the gastrointestinal tract. It has been hypothesized that probiotic cultures might decrease the exposure to chemical carcinogens by (1) detoxifying ingested carcinogens, (2) altering the environment of the intestine and thereby decreasing populations or metabolic activities of bacteria that may generate carcinogenic compounds, (3) producing metabolic products (e.g., butyrate) which improve a cell’s ability to die when it should die (a process known as apoptosis or programmed cell death), (4) producing compounds that inhibit the growth of tumor cells, or (5) stimulating the immune system to better defend against cancer cell proliferation.

Research suggests that the consumption of probiotic cultures may decrease cancer risk. Researchers testing the effect of the consumption of fermented milks, probiotic bacteria, components of bacteria or extracts of bacteria have found:

A reduction in the incidence of chemically induced tumors in rats.
A reduction of the activity of fecal enzymes (ß-glucuronidase, azoreductase, nitroreductase, and 7-a-dehydrogenase) postulated to play a role in colon cancer in human and animal subjects.
Degradation of nitrosamines.
A weakening of mutagenic activity of substances tested in the laboratory.
Prevention of damage to DNA in certain colonic cells.
In vitro binding of mutagens by cell wall components of probiotic bacteria.
Enhancement of immune system functioning.
Taken together, these results suggest that probiotic cultures may positively influence the gastrointestinal environment to decrease the risk of cancer. However, cancer reduction must be demonstrated in humans to confirm the significance of these observations. The impact of consumption of milk fermented by Lactobacillus caseiShirota on recurrence of superficial bladder cancer was tested. The recurrence-free period for the Lactobacillus-consuming group was found to be almost twice as long as the control group. In another study, this same strain was found to decrease atypical recurrent polyps in subjects with previous history of colonic polyp (Ishikawa et al. 2005). The European Union (EU)-sponsored Synbiotics and Cancer Prevention in Humans project tested a synbiotic (oligofructose plus L. rhamnosus GG and Bifidobacterium lactis Bb12) in patients at risk for colonic polyps and looked at intermediate end points that can be used as biomarkers of colon cancer risk. This study found that the synbiotic decreased uncontrolled growth of intestinal cells. These results must still be considered preliminary, but are encouraging that impacting the colonic environment may improve cancer occurrence.


Common infectious disease
Often people wonder if probiotics have any benefit for healthy people. Perhaps the most compelling line of research suggesting such benefit is with studies conducted on healthy subjects, such as children in school or day care, and tracking how often they experience symptoms associated with colds and mild flu. Numerous such studies have been conducted on a variety of different probiotic preparations. A meta-analysis was published on probiotics and preventing acute upper respiratory tract infections. After reviewing 14 human trials, it concluded that probiotics reduced episodes of acute upper respiratory tract infections and reduced antibiotic use.

Probiotics have also been evaluated in at-risk populations. For example, Saran et al. showed that a probiotic-containing food could improve growth parameters for undernourished children. Sur et al. showed that probiotics can help prevent acute diarrhoea in children in an urban slum in India.

Taken together, these controlled human studies provide support that certain probiotic strains can help avoid acute common infectious illnesses. This effect is likely mediated by immune enhancement functions or direct inhibition of pathogens, but mechanistic studies have not always accompanied positive clinical indications.

Diarrhoea
Many types of diarrhoeal illnesses, with many different causes, disrupt intestinal function. The ability of probiotics to decrease the incidence or duration of certain diarrhoeal illnesses is perhaps the most substantiated of the health effects of probiotics. A paper published in 2002 reviewed nine studies on the effect of Lactobacillus as therapy for diarrhoea in children. This paper concluded that “Lactobacillus is safe and effective as a treatment for children with acute infectious diarrhoea.” Although this meta-analysis can be criticized for combining data from different species and strains of Lactobacillus into one analysis, the positive nature of the conclusion suggests that at least for this indication and for these strains, positive results have been obtained.

One common form of diarrhoea is that associated with the consumption of antibiotics. The purpose of antibiotics is to kill harmful bacteria. Unfortunately, they can kill normal bacteria as well, and consequently disturb normal intestinal function. (Note that it is certainly NOT true that antibiotics “wipe out” all your normal flora, but they can act broadly and exact a toll on your normal, non-pathogenic bacteria.) It is important to realize that the microbiota of the healthy person is quite resilient and will return to a pre-antibiotic status with no intervention. But it is hypothesized that supplementing the intestine with probiotics might help stabilize the antibiotic-induced dysbiosis and minimize disruptive effects. One recent study documented that a probiotic containing four Lactobacillus and Bifidobacterium strains did lead to a quicker return to normal microbiota in antibiotic-consuming adults. A paper published in 2002 reviewed seven studies (881 total patients) on the impact of probiotics (Lactobacillus rhamnosus GG or Saccharomyces boulardii) on antibiotic-associated diarrhoea. The paper concluded that probiotics can be used to prevent antibiotic-associated diarrhoea, but that no strong effect on the ability of probiotics to treat such diarrhoea exists. How these probiotics accomplish this task is not known. Not all studies have shown positive results in the prevention of antibiotic associated diarrhoea or other symptoms associated with antibiotic therapy..

A serious complication of antibiotic therapy can be the onset of colitis due to Clostridium difficile. This condition can be ractory to subsequent antibiotic treatment, resulting in ongoing recurrences. A few small studies have suggested that certain probiotics can prevent relapses of C. difficile colitis. A recent metaanalysis concluded that the probiotic yeast, Saccharomyces boulardii was the most effective probiotic treatment.

Another common form of diarrhoea is experienced by travellers. Studies evaluating the effect of probiotics on travellers’ diarrhoea are equivocal. There is a need for further research in this area for more convincing findings. One metaanalysis of 12 studies on travellers’ diarrhoea concluded that certain probiotic products may offer a safe and effective method to prevent traveller’s diarrhoea with no indication of serious adverse events.

Elevated Blood Cholesterol
Cholesterol is essential for many functions in the human body. It acts as a precursor to certain hormones and vitamins and it is a component of cell membranes and nerve cells. However, elevated levels of total blood cholesterol or other blood lipids are considered risk factors for developing coronary heart disease. Although humans synthesize cholesterol to maintain minimum levels for biological functioning, diet also is known to play a role in serum cholesterol levels. The extent of influence varies significantly from person to person. Probiotic cultures have been evaluated for their effect on serum cholesterol levels. Clinical studies on the effect of lowering cholesterol or low-density lipid levels in humans have not been conclusive. There have been some human studies that suggest that blood cholesterol levels can be reduced by consumption of probiotic-containing dairy foods by people with elevated blood cholesterol, but in general the evidence is not overwhelming. It is likely that some strains may demonstrate this property while others do not, or that only subsets of people with elevated cholesterol respond.

Helicobacter pylori
Helicobacter pylori is a bacterium which colonizes the stomach and can cause gastric ulcers and gastric cancer. The effect of probiotics on H. pylori has been studied. Mechanistic studies in laboratory assays or in animal models have shown that antibacterial substances including (but not limited to) organic acids produced by some lactobacilli inhibit the growth and survival of this pathogen. When tested in humans, results are mixed. Results in humans suggest that some probiotic strains or milk fermented with a probiotic strain can reduce metabolic activity or colonization by H. pylori but eradication has not been achieved. Probiotics have also been used to manage side effects of triple antibiotic therapy used to treat H. pylori infections. In these studies, the use of probiotics decreases the side effects of antibiotics, improves patient compliance with taking the prescribed therapy, and increases the rate at which H. pylori is eradicated..

Hypertension
About 50-60 million people in United States are estimated to have hypertension, or elevated blood pressure. Antihypertensive effects have been documented in animal models and in mildly hypertensive adults for three compounds derived from the growth of certain lactobacilli : 1) fermented milk containing two tripeptides derived from the proteolytic action of L. helveticus on casein in milk ; 2) bacterial cell wall components from cell extracts of lactobacilli; and 3) fermented milk containing fermentation-derived gamma-amino butyric acid. Systolic blood pressure was decreased on the order of 10-20 mm Hg. These results suggest that consumption of certain lactobacilli, or products made from them, may reduce blood pressure in mildly hypertensive people. Viability of the Lactobacillus is not required for the effect.

Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is a functional bowel disorder that can be characterized by symptoms of abdominal pain, cramps, gas, bloating, diarrhoea and constipation. Surveys estimate the prevalence rate ranging from 10-20% of the adult population and the condition is diagnosed 3 times more often in women than men. Only a few controlled studies have been conducted evaluating probiotics and IBS. Some symptom relief (primarily from diarrhoea or abdominal pain or bloating) has been reported in studies published to date.

Inflammatory Bowel Disease
Inflammatory bowel diseases such as ulcerative colitis and Crohn's disease, are serious intestinal diseases that can lead to the surgical removal of the colon. The cause of these diseases is not known but it has been hypothesized that an intolerance to the normal microbiota in the gut leads to inflammation and resulting pathology. Efforts to identify a single microbe associated with the disease has failed, leading some to suggest that it is a pathogenic microbial community, not a single microbe, that is responsible for IBD. The role of gut flora in the progression of these diseases has led some researchers to study the impact certain probiotic bacteria might have on maintaining the state of reduced inflammation that occurs during remission stages of the diseases. Several controlled, clinical trials have shown that high levels of certain probiotic strains can extend the disease-free remission period. Studies also have documented this effect on remission of pouchitis. But not all studies have shown benefits.

Immune System Modulation
The immune system defends against microbial pathogens that have entered our bodies. The immune system is extremely complex, involving both cell-based and antibody-based responses to potential infectious agents. Immunodeficiency can result from certain diseases (e.g., cancer, AIDS, leukemia) or, to a lesser extent, from more normal conditions such as old age, pregnancy, or stress. Autoimmune diseases (e.g., allergies, rheumatoid arthritis, inflammatory bowel diseases) also can occur due to misdirected immune system activity.

Probiotic cultures have been shown in a variety of test systems to stimulate certain cellular, biochemical and antibody functions of the immune system . Animal and some human studies have shown an effect of yogurt or lactic acid bacteria on enhancing levels of certain immunoreactive cells (e.g. macrophages, lymphocytes) or on regulation of immune factors (cytokines, immunoglobulins, interferon). In addition, some studies have shown improved survival of pathogen-infected laboratory animals consuming probiotic cultures as compared to animals consuming a control diet. Results accumulated so far suggest that probiotics may provide an additional tool to help your body protect itself.

An exciting area of research has been documenting the ability of certain probiotic bacteria to modulate immune dysregulation. Studies have shown that probiotics are effective in decreasing the development of allergy and relapse of inflammatory bowel disease.

Kidney Stones
High levels of oxalate in the urine is a risk factor for the development of kidney stones. Utilization of oxalate by intestinal microbes limits its absorption. A probiotic preparation that contained bacteria that were able to degrade oxalate in vitro was shown to reduce oxalate fecal excretion in six patients. These results suggest that manipulation of the gut flora with the right probiotic bacteria may have a positive impact on gastrointestinal tract oxalate levels and may decrease oxalate absorption . These results are intriguing, but preliminary.

Lactose Intolerance
The inability of adults to digest lactose, or milk sugar, is prevalent worldwide. People of northern European descent are unique in retaining the ability to produce the lactose-digesting enzyme, lactase, into adulthood. Consumption of lactose by those lacking adequate levels of lactase produced in the small intestine can result in symptoms of diarrhoea, bloating, abdominal pain and flatulence. These symptoms are due to undigested lactose reaching the large intestine and being fermented by the colonic microbes. These microbes can produce gases and products that lead to watery stool.

The inability to comfortably consume dairy products not only limits people's freedom to choose preferred foods, but also potentially compromises calcium intake, threatening bone health. It has been documented scientifically that many lactose intolerant individuals are better able to consume fermented dairy products, such as yogurt, with fewer symptoms than the same amount of unfermented milk, even though yogurt contains about the same amount of lactose as milk . Yogurt was found to aid digestion of lactose because the lactic acid bacteria used to make yogurt deliver lactase to the small intestine, where it breaks down the lactose before it reaches the colon. In addition to yogurt starter bacteria, L. acidophilus and bifidobacteria have been shown by several studies to improve digestion of lactose, although generally to a lesser extent than the yogurt starter cultures, Lactobacillus bulgaricus and Streptococcus thermophilus.


Obesity and metabolic syndrome
Perhaps one of the most fascinating areas of research on the gut microbiota and health is how colonizing microbes might impact the onset of obesity and metabolic syndrome. Disrupted patterns of colonization are associated, for example, with obesity and diabetes, but what is not clear is if strategies to alter the disrupted microbiota can impact the course of these conditions. Microbes may directly impact energy harvest from foods due to bacterial metabolism in the gut. But microbes or their products may also act as metabolic regulators through interacting with host cellular targets. Some experimental animal model studies have looked at the effect of probiotics on obesity. In humans, a strain of Lactobacillus gasseri was shown to decrease fat mass (visceral and subcutaneous) and BMI in diabetic patients . In another human study, a probiotic preserved insulin sensitivity. This is a field of research with promise, but still in its infancy.

Necrotizing enterocolitis
Necrotizing enterocolitis (NEC) is a gastrointestinal disease that mostly affects premature infants. It is characterized by infection and inflammation leading to death of tissue of the large intestine. Probiotic supplementation may reduce the risk of NEC in preterm infants. A recent review of studies targeting efficacy and safety of probiotics for infants at risk for developing NEC was conducted . Taken together, studies suggest that probiotics lower the risk of mortality in preterm infants, but additional studies on best strains for this application, short- and long-term safety and required dose must be conducted.

Oral health.
One study conducted with children aged 3-6 years in day care centers evaluated the ability of milk containing L. rhamnosus GG to reduce the incidence of dental caries . Only a subset of the study group, children aged 3-4 years, showed any statistically significant reduction in dental caries incidence. Other studies have documented that other probiotics, e.g., L. reuteri or Bifidobacterium animalis DN173 010, can reduce salivary levels of cariogenic Streptococcus mutans in young adults .

Small Bowel Bacterial Overgrowth
Under certain conditions (production of low stomach acid, kidney dialysis and others), microbial populations in the small intestine can increase beyond normal levels. This is termed small bowel bacterial overgrowth. The misplaced microbes can produce byproducts from their growth that can be toxic. Researchers have found that feeding high levels of certain probiotic strains can control the toxic effects of these microbes . This is another example of the ability of probiotic strains fed in high numbers to modulate the activity of other intestinal bacteria.

Vaginosis
The vagina and its microbiota form a finely balanced ecosystem. Disruption of this ecosystem can lead to a microbiological imbalance and symptoms of vaginosis. Vaginosis used to be considered a mere annoyance, but now is being examined for a role in serious conditions including pelvic inflammatory disease, pregnancy-related complications (such as low birth weight babies), and increased susceptibility to AIDS infection. Vaginosis can be caused by several different organisms, and in many cases, the causative agent may not be identified. What is known is that lactobacilli predominate in the healthy vagina, and a lack of lactobacilli is a risk factor for vaginosis. The lactobacilli are thought to maintain a favorable vaginal pH in the acidic range and to inhibit pathogens, possibly through the production of hydrogen peroxide and other antimicrobial factors. The most conclusive human studies to date on the impact of lactobacilli on bacterial vaginosis showed that Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 administered in milk could pass through the intestine, ascend to the vagina and restore a normal lactobacilli microbiota in women prone to infections . These strains were delivered in yogurt to African women with bacterial vaginosis and shown to improve therapeutic outcome . These studies have provided the best evidence to date for successful probiotic intervention to improve vaginal health. Some other recent studies have not shown positive results , highlighting the importance of use of effective strains and delivery systems.

Our scientific probiotic study referrence page is HERE

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