During treatment for intestinal yeast and/or bacterial overgrowth it is essential that probiotic bacteria are consumed concurrently to restore the proper balance of organisms in the gut. When you undergo anti-fungal and/or anti-bacterial therapy when the pathogenic organisms are killed off space within the intestines and along the intestinal wall becomes available for colonization by other organisms. Taking probiotic supplements enhances the chances of these new colonies being made up of beneficial bacteria rather than more pathogenic types. Also of importance to sufferers of environmental illnesses is the fact that recent research has shown that the gut flora is directly linked to the development of allergies to both food and airborne allergens and that improving gut flora could potentially reduce the number and severity of allergies1, 2.
At first the range of probiotic products on the market will likely seem overwhelming and you won't know whether you are getting a good product or not until you learn a little bit more about the subject. The information below will explain a bit about probiotic bacteria, otherwise known as 'beneficial bacteria' or 'friendly bacteria', and provide some basic pointers on what to look for in a probiotic product.
Types of Probiotic Bacteria
The most numerous probiotic bacteria normally inhabiting the small intestine are species of Lactobacilli. In the colon the majority are mainly Bifidobacteria. Most probiotic products consist of one or more species of bacteria from one or both of these types. Some products available mainly in europe may also contain certain beneficial species of E.coli but these are rare at this time.
General Benefits of Lactobacilli:
- Prevent overgrowth of disease-causing microbes: Candida species, E. coli, Helicobacter pylori (H. pylori), and salmonella.
- Prevent and treat antibiotic-associated diarrhea
- Aid digestion of lactose and dairy products
- Improve nutrient absorption
- Maintain integrity of intestinal tract and protect against macromolecules entering bloodstream and causing antigenic response.
- Lessen intestinal stress from food poisoning
- Acidify intestinal tract. Low pH provides a hostile environment for pathogens and yeast.
- Helps prevent vaginal and urinary tract infections.
General Benefits of Bifidobacteria:
- Prevent colonization of the intestine by pathogenic bacteria and yeasts by protecting the integrity of the intestinal lining.
- Produce acids that keep the pH balance in the intestine. This acid environment prevents disease-producing microbes from getting a foothold.
- Decrease the side-effects of antibiotic therapy.
- Primary bacteria in infants, which help them grow.
- Inhibit growth of bacteria that produce nitrates in the bowel. Nitrates are bowel toxic and can cause cancer.
- Help prevent production and absorption of toxins produced by disease-causing bacteria, which reduces the toxic load on the liver.
- Manufacture B-complex vitamins.
- Help regulate peristalsis and bowel movements.
- Prevent and treat antibiotic-associated diarrhea.
(Source: Digestive Wellness by Liz Lipski, Ph.D., CCN)
Let's take a closer look at some of the most well researched probiotic bacteria and those found most commonly in probiotic supplements.
By far the most well known species of probiotic bacteria is Lactobacillus acidophilus which has led many people to refer to probiotics simply as "acidophilus". This status is not without reason as the acidophilus species is the most prevalent in the human intestine and has been the most widely studied probiotic bacteria with research starting on L.acidophilus as long ago as 1925. The best researched single strain of acidophilus is probably the DDS-1 strain. This strain amongst other benefits has been shown to stimulate the immune system, increasing levels of interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) which suppress cancerous tumour growth3. Other research has shown that L.acidophilus DDS-1 also alleviates lactose intolerance by producing significant amounts of the lactose digesting enzyme lactase, inhibits gastrointestinal pathogens by producing antimicrobial substances such as acidophilin and helps alleviate dermatitis and other skin conditions by altering gut flora amongst other things.
Lactobacillus rhamnosus is a probiotic bacteria that has been receiving a growing amount of attention as a treatment for many illnesses in the form of the GG strain. Lactobacillus rhamnosus GG (LGG) now has a wealth of research backing its use, particularly for infectious and allergic conditions. A 2001 study reviewing information regarding probiotics and infectious diseases found that there is a large amount of data showing that Lactobacillus GG is an effective treatment for diarrhea caused by Clostridium difficile infection4. Another study testing the effectiveness of probiotics in preventing allergic illness found that Lactobacillus GG given prenatally to mothers with at least 1 first-degree relative and postnatally for 6 months to their infants reduced the incidence of atopic eczema by half compared to controls5.
This organism is slightly different to most probiotic bacteria in that it is a 'transient bacteria'. It is referred to in this way because unlike most probiotic bacteria it doesn't adhere to the intestinal wall and form colonies, rather it simply passes through the digestive system and leaves the body in the stool. It has many beneficial effects as it passes through the digestive tract, however. These include enhancing the digestibility of milk products and other proteins and producing natural antibiotic substances that specifically target pathogenic bacteria whilst sparing friendly species. In this sense L.bulgaricus can be thought of as a helper to colonizing bacteria just as the immune system has T helper cells to support other immune cells. A study published in the World Journal of Gastroenterology showed that L.bulgaricus could suppress inflammatory immune reactions in the intestinal wall thus preventing tissue damage6. In another study a substance produced by L.bulgaricus was shown to stimulate activity in part of the gut immune system called the Peyer's patches which provide defense against pathogenic organisms within the gut7.
L.salivarius has been repeatedly shown to inhibit the bacteria Helicobacter pylori (H.pylori) which is responsible for the creation of peptic ulcers8. H.pylori interferes with stomach acid production and/or produces a toxin that directly contributes to ulcer formation. The usual treatment involves taking antibiotics but H.pylori may become resistant to them and there are side effects of prolonged antibiotic use due to the eradication of beneficial bacteria along with the pathogenic bacteria. It has been discovered that L.salivarius produces large amounts of lactic acid that completely inhibits the growth of H.pylori and reduces the associated inflammatory response. The first bacteriocin (natural antibiotic substance) to be isolated and studied at the genetic level was taken from a strain of L.salivarius9.
This bacteria is the most prevalent species in most naturally fermented foods. It has the ability to block receptor sites for gram negative bacteria and so is effective as an antibiotic. It is an important player in antimicrobial defense and is effective against both extra and intracellular pathogens. L.plantarum is also capable of digesting semi-digestible fibres such as those found in onions, garlic, wheat, oats, rye and yeast. It may therefore help with digestive problems like gas and bloating. Recent research has shown that L.plantarum has the ability to break down bile acids and lower cholesterol10 and is extremely resistant to stress conditions including high temperature and concentrations of ethanol, extremes of pH and the freeze drying process that would normally kill lactic acid bacteria11.
This species is commonly found in probiotic dairy foods such as 'live yoghurt', hence the name 'casei' which relates to the milk protein casein. It was reported in Microbiology and Immunology to have the most potent protective activity against the Listeria bacteria. Listeria is potentially lethal with about 30% of victims dying. It is most commonly transmitted through consumption of dairy products and raw vegetables. Like L.salivarius, L.casei, in the form of the shirota strain found in Yakult probiotic yoghurt drinks, has been shown to significantly inhibit the growth of the peptic ulcer causing bacteria H.pylori12. A probiotic drink containing the shirota strain has also been shown to reduce the severity of constipation as evidenced by both patient response to questionnaires and physical examinations13. Finally, a study with malnourished mice showed that L.casei (combined with FOS), when given along with a re-nutrition diet, enhanced the immune response and increased resistance to certain pathogenic bacteria in the digestive tract14.
In a study at the G.B. Pant hospital in New Delhi, India, Lactobacillus sporogenes was able to lower cholesterol levels by 104 points. It produced a highly significant reduction in LDL cholesterol ('bad cholesterol) levels and a small but significant increase in HDL cholesterol ('good cholesterol'). This study offers the prospect of using L.sporogenes as a side-effect free alternative to drug therapy in the treatment of high cholesterol and heart disease. In a multi-centre double-blind placebo controlled trial, L.sporogenes was found to be nearly twice as effective as placebo in reducing the number of episodes and duration of diarrhea following antibiotic treatment in children15. As well as being used to lower cholesterol, Alternative Medical Review reports that L.sporogenes has been used in the treatment of gut dysbiosis, vaginitis and aphthous stomatitis16.
This bacteria is one of the major constituents of the normal flora in the colon and is the most common Bifidobacteria species found in probiotic products. It is reportedly well tolerated, reduces the inflammatory response in the colon and stimulates the body's fluid immunity. A study carried out at the Women and Children's Hospital of Buffalo, NY showed that B.bifidum can significantly reduce the intestinal concentration of endotoxin, which is made up of the cell walls of dead bacteria and is toxic if allowed to build up17. In another study B.bifidum of human origin was found to adhere well to the intestinal wall and significantly reduce the ability of pathogenic E.coli to do the same18. Research carried out by the Yakult company who manufacture probiotic drinks showed that their patented strain of B.bifidum had significant anti-oxidant action and was able to protect the intestinal lining from lipid peroxidation in iron overloaded mice19.
B.longum is another species of Bifidobacteria commonly found in probiotic products. It is reportedly able to eliminate the nitrates commonly found in foods ingested by humans. Levels of nitrate commonly ingested by humans are unable to kill this species. B.longum has been shown to inhibit the action of vero cytotoxin produced by some strains of E.coli which can cause hemorrhagic colitis and hemolytic uremic syndrome in humans. It achieves this by producing substances that bind to the vero cytotoxins20. B.longum has also been shown to have a protective effect against infection with Salmonella Typhimurium, possibly due to an anti-inflammatory action21.
B.infantis is known to have an inhibitory action on invasive pathogenic bacteria such as E.coli. Research has shown that it achieves this inhibition through more than one mechanism which explains why it is effective against a range of pathogens. Inflammatory bowel disease (IBD) is thought to be caused by organisms called bacteroides which are a normal component of the gut flora. B.infantis has the ability to highly reduce the growth of bacteroides and also significantly inhibit the inflammatory response caused by them in the gut lining22. Other research using formulations containing B.infantis has found it to useful for treating irritable bowel syndrome (IBS) and diarrhea. Of all the strains of bacteria in the formulation B.infantis was found be one of the species that had colonized the intestines of patients to the highest degree23.
Like L.casei, this bacteria has been shown to aid recovery from malnutrition due to short-term fasting and reduce the associated intestinal atrophy in animal studies24. S.thermophilus is also known to have powerful antioxidant activity, protecting the body from dangerous free radicals which increase in the body due to aging, stress, sugar, antibiotics and other chemicals and toxins. It has also been shown to have anti-tumour activity which is especially effective against colon cancer cells.
Homeostatic Soil Organisms (HSO's)
In recent years a different sort of probiotics have become available known as homeostatic soil organisms. These are organisms that live naturally in the soil and used to be ingested regularly by humans before intensive farming methods removed them from the food supply. Most of the organisms found in HSO supplements are transient bacteria meaning they don't colonize the intestines but pass through, providing a number of benefits to us as they do so. Some of these benefits include aggressively killing pathogens, producing specific antigens that act to stimulate the immune system, create superoxide dismutase (SOD) a powerful antioxidant enzyme and help the body to metabolize proteins and eliminate toxins. Some of the benefits over traditional probiotic supplements that HSO's are said to have are there superior ability to survive stomach acid, ability to survive in any intestinal pH and their powerful ability to fight off infections in the GI tract. Many doctors and patients have reportedly had very good results using HSO's but as yet there is little good scientific research regarding their use.
Some studies have found that probiotic bacteria work best alone, suggesting that buying a probiotic supplement that contains only a single type of probiotic bacteria might be most effective. In one study, Finnish researchers tested the effects that 11 strains of bacteria (including lactobacillus and bifodobacterium) had on the production of cytokines by the immune system. Cytokines are chemical messengers which in healthy individuals control immune cells, coordinating the response to pathogens and keeping immune activity in check to avoid allergic reactions. The researchers found that all 11 probiotic bacteria strains had an effect on cytokine production when administered alone but had little or no effect when given in combination. So at least in terms of immune function it may be best to choose single strain probiotic products. Interestingly, the most effective probiotic in this study was Streptococcus thermophilus, a strain often found in combination probiotic products but rarely alone.
Currently the two single strain probiotic products with the most solid research to substantiate their health claims are Align and Culturelle.
Contains the probiotic bacteria Bifantis (Bifidobacterium infantis 35624) and has been found in clinical studies to help build and maintain a healthy digestive system as well as benefitting those suffering from irritable bowel syndrome (IBS)31,32. Align is recommended for those with IBS as well as anyone who occassionally suffers from symptoms such as constipation, diarrhoea, abdominal discomfort, urgency, gas and bloating. (Ratings & Reviews of Align)
Contains the probiotic bacteria Lactobacillus GG, a subspecies of Lactobacillus casei. Lactobacillus GG is thought to be one of the best probiotic bacteria strains for surviving the harsh acidic environment of the stomach so it is subsequently able to colonize the lower gastrointestinal tract. Many research studies have been conducted using Lactobacillus GG with benefits discovered including the suppression of inflammatory changes in the intestine caused by E.coli33, direct effects on colonic smooth muscle cells34, and prevention of antibiotic-associated diarrhoea35. (Rating & Reviews of Culturelle)
There are also combination porbiotic products that have proved effective in clinical trials however. The most studied of which is VSL#3:
Contains eight different probiotic bacteria Bifidobacterium, Lactobacillus and Streptococcus species. What really distinguishes VSL#3 from other pobiotic products is the numbers of bacteria it contains. Each serving contains 450 billion bacteria where typically probiotic products contain only 5-30 billion. The manufacturer says that VSL#3 works by colonizing the GI tract with optimal quantities and types of probiotic bacteria and indeed studies have demonstrated good results in patients suffering from IBS, ulcerative colitis (UC), and ileal pouch (IP) (see manufacturer site for research data). (Ratings & Reviews of VSL#3)
Choosing a Probiotic Product
Unfortunately choosing a probiotic supplement is not as simple as just picking up the first bottle you find and assuming it will do the job. Some products contain bacteria that are not even known to be normal inhabitants of the human gastrointestinal tract and the bacteria in many have not undergone any testing with regards to their ability to colonize once they reach the intestines. There are a number of factors that will determine the effectiveness of a certain bacteria as a probiotic. Some of these are:
- Ability to survive the manufacturing process.
- Ability to survive heat, light, moisture etc during the time from packaging to use.
- Ability to survive stomach acid
- Ability to attach to the intestinal wall
- Ability to fend off other organisms, survive in the current intestinal environment and successfully colonize.
As you can see, the fragile probiotic bacteria have a lot to deal with if they are to eventually colonize your intestines. It would be naive to assume that every species and strain of Lactobacilli and Bifidobacteria would be equally effective as probiotics. As a result it is best to research a product before you buy. Look out for the species of bacteria covered on this page but if you see a species that isn't covered listed on a supplement bottle then do some research on that bacteria online yourself to make sure it will be effective. As a rule it is best to look for products that state the specific strains of the bacteria they contain such as L.acidophilus DDS-1 and L.rhamnosus GG, where the DDS-1 and GG respectively are the strains. You can then look for research carried out with that particular strain to assess its effectiveness. The best place online to look for scientific research on probiotic bacteria, or any subject, is the PubMed database which can be found here.
Also of importance is the ability of a products packaging to protect the bacteria from environmental factors such as light, heat, moisture and oxygen. Dark coloured glass bottles protect well from light and heat. Some products use rubber caps under the screw top of the bottle, this offers added protection from oxygen and moisture by providing an airtight seal. However the best protection is offered by products where each dose is individually packaged in a foil sachet. This avoids the situation with a bottle where all the capsules/tablets are exposed to the environment every time you take the top off. Also of importance is how the product is stored in the store. If a product says it needs to be refrigerated, make sure this is the case in the store.
Following these guidelines should increase your chances of purchasing an effective probiotic supplement.
Where probiotics are the beneficial bacteria found in the intestines 'prebiotics' are special indigestible carbohydrates known as oligosaccharides that feed probiotic bacteria and encourage their growth. Oligosaccharides are found naturally in certain fruit and vegetables, including bananas, asparagus, garlic, wheat, tomatoes, Jerusalem artichoke, onions and chicory. Because of the ability of prebiotics to encourage the growth of beneficial bacteria it is worth considering a supplement when there is a need to improve the gut flora. Prebiotics can be taken on their own or with a probiotic supplement. They have an advantage over probiotic supplements in that there is no concern about oligosaccharides being destroyed while in storage or en route to the intestines through the stomach acid and digestive enzymes.
The most common types of prebiotics available in supplements are fructooligosaccharides (FOS), inulin and galactooligosaccharides. As well as, or perhaps due to, encouraging the growth of beneficial bacteria in the intestines, prebiotics have been shown to have a number of other benefits.
FOS has been shown in one study in mice to increase intestinal Riga, the body's first line of defense against invaders25. In another study using pigs, FOS was shown to increase butyrate concentrations in the large intestine26. Butyrate is a short chain fatty acid (SCFA) that helps to maintain the health of the colon.
German research has shown that inulin is effective in improving the composition of the gut flora and reducing the severity of colitis symptoms when tested in rats27. In a study assessing the role of common foods in improving intestinal health cheese which contains inulin was found to have a beneficial effect, reducing bacteria and chance of infection28.
In animal studies galactooligosaccharides have shown very promising results increasing populations of both lactobacilli and bifidobacteria and increasing beneficial short chain fatty acids29. A mixture of galacto and fructooligosaccharides added to standard infant formulas has has also been shown to increase both lactobacilli and bifidobacteria species in human infants30.