What is a probiotic?

These days, the word ‘probiotic’ seems to be everywhere. But, what does it mean? Probiotic means ‘for life,’ but is used to refer to the ‘good bugs’ (bacteria and yeast) that live in our intestines.

“I have bacteria in my intestines??”

Yes- not all bugs are bad, and probiotics are good bugs given to replenish those that are killed off by antibiotics and those that are crowded out when the ‘bad bugs’ overpopulate creating something called ‘dysbiosis’ (an imbalance of good and bad bugs in the intestine).¹ In general, the mix of bacteria (good and bad) in the intestines is referred to as the ‘gut flora’ and these microorganisms serve a variety of purposes in maintaining good health.

Where did the bugs come from?

In a healthy intestine, there are a variety of good bug strains. The bugs most commonly researched are the Lactobacilli and Bifidobacteria species, as well as the yeast Saccharomyces boulardii.² The good bugs enter our bodies from the time we’re born (passing through our mom’s birth canal) and throughout our lifetime as a normal and natural part of our food. The diet that we eat can either help to maintain healthy levels and beneficial species in our intestines, or it can promote the growth of the ‘bad bugs’ which can crowd out the good bugs.

What do the bugs in my intestines do?

Normal gut flora live primarily in the intestines, where they ferment soluble dietary fiber and produce short chain fatty acids (SCFAs) and other substances which are absorbed into the body. SCFAs are the primary food for those cells lining the intestinal tract, and is a major reason why a healthy floral balance and proper dietary fiber intake is so important in maintaining the health of the intestines.¹ In the intestines, probiotics serve a variety of other functions as well.

Are there other functions of the microorganisms in my intestines?

One of the most important functions these microorganisms serve is to decrease the effect of bad bugs (pathogenic bacteria) on the system by:²

         Competing with pathogenic bacteria for nutrients

         Producing locally acting antibiotic substances

         Producing organic acids that decrease the intestinal pH making it more difficult for acid-sensitive pathogenic bacteria to survive⁴

         Secreting substances that help to decrease the virility of pathogenic bacteria such as E. coli

         Preventing pathogenic bacteria from sticking to the intestinal wall

         Inducing the production of the protective mucin coating by the cells of the intestinal wall, improving the barrier function of the intestine

Additional functions of the gut flora include decreasing the spasming of the colon (resulting in diarrhea) that can occur during gastrointestinal infections, and decreasing overall intestinal inflammation.² Healthy gut flora helps to decrease inflammation by decreasing the production of pro-inflammatory chemical signals from the immune system, and increase the production of anti-inflammatory signals.² Another important observation is that healthy gut flora shifts the balance of the immune system, mediating allergic/inflammatory response.³ The normal flora of the intestines also plays a role in the production of certain vitamins including folic acid, biotin, vitamin K, and other B vitamins.⁵

Why don’t I have enough of the good bugs?

As I mentioned, the good bugs can be killed off by antibiotic use, or crowded out by overpopulation of the bad bugs. Antibiotics can be extremely helpful when we need to take them for a bacterial infection, but they don’t discriminate about which bugs they kill in the body, making your healthy gut flora collateral damage. Unfortunately, antibiotics as medical treatment are not the only source of exposure. Antibiotics given to farm animals can be transmitted to humans when we eat the meat or milk of those animals, reeking havoc with our intestinal flora.

What else affects our gut flora?

Overpopulation of the bad bugs is another way that our gut flora is affected. Even if we seldom take antibiotics and only eat organic meats and dairy products, diets high in sugar and refined carbohydrates promote the growth and overpopulation of the bad bugs which crowd out the healthy gut flora. In addition, medications given for acid reflux and indigestion that work to buffer the stomach acid and relieve discomfort change the gut environment and make it easier for the bad bugs to survive the stomach and travel down to the intestine where they grow and proliferate.

Can supplementing with probiotics improve my health?

Recently, supplementing with probiotics has become very common in capsules, powders and even in yogurt. The health benefits claimed by the supplement companies are many and varied, but is there science to back this up? The answer is yes, but there are two questions that need to be addressed even before we can know if supplementing honestly does any good;

Are you supplementing with the right species to help your particular health

problem?, and

Are you supplementing with enough cultures to do any good?

In order to do any good, a probiotic must be from a human source, be a safe species (won’t cause illness), be resistant to digestion in the stomach and intestines, and it has to be able to stick to and grow on the intestinal walls. If it’s not the right bug, one that won’t die, and one that is able to stay in the intestines, then it’s not going to provide any health benefits. If the probiotic is able to do all those things, then it also has to:

1. produce substances that help inhibit the growth of the ‘bad bugs,’
2. help control the immune system in a good way, and also
3. influence the breakdown and use of the foods we eat.²

A good probiotic has to do all that?

Yes! And if it doesn’t, then you’re wasting your money.

What kinds of conditions can supplementing with probiotics possibly help?

The conditions that have been studied demonstrating potential benefit from probiotic therapy include:

         Constipation¹

         Acute infectious diarrhea^1,2

         Antibiotic-associated diarrhea (Saccharomyces boulardii)^1,2

         Neonatal necrotizing enterocolitis (Bifidobacteria spp.)²

         Lactase deficiency²

         IBS (Bifidobacterium infantis¹)

         Ulcerative colitis (Lactobacillus GG^1,2, Saccharomyces boulardii¹, VSL#3:  high concentration mixture of B breve, Bifidobacterium longum, B infantis, L acidophilus, L plantarum, L casei, Lactobacillus bulgaricus, and Streptococcus thermophilus¹)

         Celiac disease²

         Food hypersensitivity (Bifidobacteria spp.)²

         H.Pylori infection²

         Pouchitis (VSL#3)¹

Is there any risk associated with using probiotics?

The potential risks that have been reported are generally very minor including temporary mild gastrointestinal (GI) complaints such as diarrhea, increased flatulence, and changes in bowel habits.² Rare, anecdotal risks reported include spread of bacteria in the blood in children treated with probiotics, primarily in those with poor immune function or underlying heart anomalies. Unhealthy spread was reported in several cases of adults in ICU care treated with the strain sacchacromyces cerevisia, and questions have been raised as to the safety of using probiotics in newborns with poor immune function based on the observation of one study using mice.²

Despite these potential risks, probiotics are generally quite safe. More and more research is demonstrating that using probiotics can be an effective way to help treat a variety of GI problems, and serve an important preventive role in immune function and general health.²

What is a prebiotic?

Many probiotic formulations also contain prebiotics. A prebiotic is a non-digestible part of food that selectively stimulates the growth of some good bugs in the intestines.¹ Some examples of prebiotics include oligosaccacharides, fructooligosaccharides (FOS) and inulin. So far, research indicates using prebiotics may help in the treatment of constipation, IBD, antibiotic-associated diarrhea, and hepatic encephalopathy (using lactulose in particular).¹

How do I know if a probiotic is of good quality?

These are some rough guidelines for selecting a safe and effective probiotic:²

 Live strains seem to be more effective; choose a probiotic that is refrigerated. If not, contact the company and ask for information regarding strain viability at room temperature.

        Choose a probiotic with a variety of strains, not just one or two. If you’re hoping to address a particular health condition, make sure the strains indicated for your condition are included in the product.

        The number of cultures is important: several billion to tens of billions per day depending on your health goals (preventive vs. therapeutic application)

Should everyone supplement with probiotics?

While we can’t yet say that everyone should supplement with probiotics, so far the research shows that the potential benefits vastly outweigh the risks in most people. As information continues to accumulate, more specific recommendations will be available including when to apply which strains, how many strains are necessary for treatment vs. maintenance goals, which combination of strains works the best, how and when to use prebiotics, etc. Until then, for most people the use of probiotics seems to be a reasonable and safe option for addressing some health concerns and possibly for good health maintenance, but working under the guidance of a knowledgeable health professional is still the best course of action.

References

1     Park, J., & Flock, M. H. (2007). Prebiotics, probiotics, and dietary fiber in gastrointestinal disease. Gastroenterology Clinics of North America. 36, 47-63.

2     Kliegman, R. M., Behrman, R. E., Jenson, H. B., Stanton, B. F., (2007). Nelson textbook of pediatrics (18^th ed.). Saunders; Philadelphia, PA.

3     Kidd, P. (2002). Th1/Th2 balance: The hypothesis, its limitations, and implications for health and disease. Alternative Medicine Reviews, 8,3, 223-246.

4     Percival, M. (1997). Choosing a probiotic supplement. Clinical nutrition insights, 6, 1, 1-4.

5     Haddad, P. S., Azar, G. A., Groom, S. & Boivin, M. (2005). Natural health productions, modulation of immune function and prevention of chronic diseases. eCAM, 2,4, 513-520.