Probiotics are microorganisms that have been found to confer a health benefit on their host organism. Currently, the media promotes the ingestion of probiotics as somewhat of a magic bullet helpful for everything from weight loss, to disease prevention, to stress relief. Probiotics are also often viewed as a natural solution to health problems. Many consumers find probiotics an attractive option for health promotion because they are readily available in fermented foods and in such foods have been consumed for years. Additionally, consumers may believe that supplementing their diets with probiotics will save them money by preventing the necessity for future doctor's visits or medications.

Probiotics are present in many forms and products. Probiotics may be found in a variety of fermented dairy products such as yogurt, kefir, milk, etc. There are also many probiotic supplements on the market that are readily available to consumers. But can consumers really depend on the touted health benefits of probiotics?

  • Antibiotics: Any substance that can destroy or inhibit the growth of bacteria and similar microorganisms.
  • Bacteria: Microscopic single-celled organisms lacking a nucleus. They are structured as either rod-shaped, sphere-shaped or spiral-shaped. They can be aerobic or anaerobic, or facultative anaerobic.
  • Bifidobacteria: A group of lactic acid producing microorganisms that constitutes a major part of the gastrointestinal microflora in humans.
  • Bile: thick, viscous fluid secreted from the liver, stored in the gallbladder, and released into the duodenum when fatty foods enter the duodenum; emulsifies fats in the intestine and forms compounds with fatty acids to facilitate their absorption (Mahan, 2008)
  • Common infectious diseases (CID): classified by category:
    • Upper respiratory tract infections: rhino-pharyngitis (runny nose, cold), sore throat, sinusitis, otitis (ear inflammation)
    • Lower respiratory tract infections: bronchitis, pneumonia, flu and flu-like syndromes
    • Gastrointestinal tract infections: gastro-enteritis (abdominal pain, diarrhea, vomiting) (Guillemard, 2009)
  • Flow cytometry: a technique for counting and examining microscopic particles, such as cells and chromosomes, by suspending them in a stream of fluid and passing them by an electronic detection apparatus.
  • In situ hybridization: The visualization of in vivo location of macromolecules by the histological staining of tissue sections or cytological preparations via labelled probes/antibodies.
  • Inflammation: A response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat.
  • Intestinal flora: Harmless microorganisms that inhabit the intestinal tract and are essential for its normal functioning.
  • Lactobacillus: Any of many rod-shaped, nonmotile, aerobic bacteria, of the genus Lactobacillus, that ferment sugars to form lactic acid.
  • Microbiota: The human flora is the assemblage of microorganisms that reside on the surface and in deep layers of skin, in the saliva and oral mucosa, and in the gastrointestinal tracts.
  • Neonates: A baby from birth to four weeks.
  • Probiotics: Live microorganisms which when administered in adequate amounts confer a health benefit on the host (FAO/WHO)

Hagloch; Yogurt Found to Reduce Children's Infections; abc news

Many believe that probiotics have the ability to prevent and cure some childhood infections; at least one article from abc News seems to think so. The article is titled “Yogurt Found to Reduce Children’s Infections”. The article leads readers to believe there is a yogurt that has the ability to “reduce [my] children’s infections.” As a consumer, I want to know where I can get this yogurt, how much it costs, whether or not the benefits outweigh the costs, and the big question— Is it "too good to be true?”

To answer these questions an analysis of the original article from which this headline came must be done. In the original article by Merenstein, the experiment was done very well, the population size was significant, careful controls were put into place, and the experiment ran for an adequate amount of time for this type of experiment. There was just one problem—while the headline said yogurt could reduce infections, research was not actually done on yogurt, but rather a fermented probiotic dairy drink containing 1x10^8 cfu/g of Lactobacillus Casei DN-114 001. And perhaps a greater disappointment to those looking to boost their children’s immune systems—the drink is not for sale (Merenstein, 2010).

In this particular study, researchers found a significant reduction in the prevalence of gastrointestinal and upper-respiratory tract infections in children ages 3-5 years in the active group, or in other words, the group that received the probiotic drink (Merenstein, 2010). However, existing research on probiotics is somewhat inconclusive. Even though there are numerous studies showing that probiotics help reduce children’s infections such as research done by Hatakka and Leyer, there are also just as many that show absolutely no benefit. In one such study done by the same research team headed by Merenstein, it was found that children given a probiotic-infused yogurt did not reduce the amount of sick days or improve any other childhood infection (Merenstein, 2010). In each case, a different probiotic was used. Data like this makes it impossible to say that probiotics in general help to reduce children’s infections. Probiotic research is all fairly recent, and there are millions of different probiotics to choose from. It is illogical to categorize all probiotics as having the same health benefits because health effects depend upon dose and type of probiotic consumed. For example, researchers from a study in Finland found that the probiotic Lactobacillus Rhamnosus GG reduced upper and lower respiratory tract infections by 17% among children ages 1-6 (Hatakka, 2001). However, in another study done in China, two different probiotics were used either by themselves or in combination with each other. In this particular study, research found that there was no reduction in the amount of lower respiratory tract infections, but there was a significant reduction in upper respiratory tract symptoms (Leyer, 2009).

There might be a day when the research that has been done to isolate certain strains and identify how they are beneficial to health will be available to consumers. Until then, probiotics shouldn't be classified as having health benefits. They can only be classified as potentially having health benefits. I found this headline to have a bit of noise as well as news. However, the headline that would best suit this research would be closer to “Probiotic Lactobacillus Casei Found to Potentially Help Reduce Children’s Infections.”

Holmgren: Probiotics May Help Ward Off Obesity: Study In Pregnant Women:Medical News Today

The news article Probiotics May Help Ward Off Obesity: Study In Pregnant Women states that probiotics are bacteria that help maintain a healthy bacterial balance in the digestive tract by reducing the growth of harmful bacteria. The study was designed to demonstrate the impact of probiotics-supplemented dietary counseling on adiposity. The published study reviewed in the news article reported that microbiota deviations were associated with the enhanced risk of excessive energy storage and obesity (Collado, 2008). Studies also suggest reduced number of bifidobacteria is associated with obesity and insulin resistance. Researchers found a significant increase in Bacteroides and Staphylococcus in women that were overweight rather than the women at a normal weight (Collado, 2008). In addition microbial counts increased from the first to third trimester of pregnancy and high Bacteroide concentrations were associated with excessive weight gain over pregnancy (Collado, 2008).

Gut microbiota may regulate obesity by increasing energy harvest and by regulating metabolism. Scientists used culture-independent microarray studies during the first year of life to determine the pattern of infant microbiota. They discuss how the gut microbiota regulates obesity and how environmental factors that affect the establishment of the gut microbiota during infancy may contribute to obesity later in life (Reinhardt, 2009). Studies suggest, “adult like,” gut microbiota have been identified after the introduction of adult food in infants as early as two. If the microbiota are altered to what the infant is not accustomed to, they may be a risk for obesity. The administration of probiotic, lactobacillus to mice has been shown to improve gut dysfunction (Reinhardt, 2009). The researchers indicate that intentional manipulation of the intestinal flora, even in neonates, may improve gut function and lower permeability, which may translate into lower serum endotoxin levels and protection against the development of metabolic disease (Cani, 2009). Experiments of the rodent model have shown a relationship in obesity and an altered gut microbiota. Researchers provided evidence that a subgroup of bacteroidetes was significantly enriched in the obese individuals including women who were pregnant. These studies support the gut microbiota profile may provide protection against overweight and obesity development (Cani, 2009).

The article titled Probiotics May Help Ward Off Obesity: Study In Pregnant Women is, in my opinion, both news and noise. In many of the studies I read, the women didn’t necessarily eat probiotics on its own to lose weight, they were given probiotics along with diet regulation, high fiber diets, and probiotics (Aaltonen, 2010). As healthy bacteria can be found in the gut of healthy woman, some studies suggest that taking a probiotic may influence the gut by causing a decrease in bad bacteria (Aaltonen, 2010), but this doesn’t necessarily make them lose weight. A higher number of probiotics were found in the gut of women who were healthier and had a normal weight (Kalliomaki, 2008). Gut microbiota and weight are linked and mother’s weight gain is affected by microbiota. There is indeed a difference between gut microbiota in normal weight and overweight people (Latinen, 2010). It may be important to keep in mind this is not the only way to lose weight but is a healthy choice when combined with diet and exercise.

Tillotson/Hopkins: New study shows supplementing with probiotics may ease anxiety: Medical News Today

This headline certainly grabs the attention of a large audience. Who isn’t excited by the thought of reducing some of the stresses and anxieties of daily life? It may be disappointing to note that this headline was based on a scientific experiment of a small minority of people who had been diagnosed with chronic fatigue syndrome, CFS (Rao, et al, 2009). Researchers studied the effect of probiotic supplementation on gut microflora and anxiety symptoms of 35 CFS patients between the ages of 18-65 years old. Patients were randomly assigned to receive either a supplement containing 8 billion colony forming units (cfu) of Lactobacillus casei strain Shirota (LcS) or a placebo pill. After 8 weeks of treatment, the patients filled out anxiety questionnaires and gave stool samples. Analysis revealed that those who received the probiotic capsules experienced a 73.7% increase in gut bifidobacteria, a strain of healthful microorganisms. Review of the questionnaires showed that those receiving LcS claimed decreased symptoms of anxiety at the end of the study, though these claims are not quantifiable.

Additional research does not oppose the results found by Roa, but is not supportive of the general idea that probiotics decrease anxiety. Sullivan (2009) observed 15 subjects with CFS to obtain baseline measurements of their gut microflora. The patients were given a probiotic supplement containing 108 colony-forming units of three different strains of bacteria twice daily for four weeks. Final analysis revealed that levels of gut microflora were largely unaltered. No significant change occurred in the overall health and physical activity levels of the participants. Six patients reported that their CFS symptoms had “improved,” but not in terms that provide quantifiable evidence that probiotic supplementation decreases anxiety symptoms in people with CFS. The only study with potential to support this headline as it stands is a study performed on rats by Desbonnet, et al (2009). Desbonnet showed that rats given large daily doses of Bifidobacteria infantis for 14 days experienced an increase in their concentration of tryptophan. Tryptophan plays a part in mood elevation.

Though this article appropriately describes the research study about which it was written, the headline is misleading and causes readers to interpret its message to be that any probiotic supplement will help to decrease the anxiety in their own lives, which is simply not the case. Thus, it may be considered more of “noise” than “news.” The cited research has only shown a potential for probiotics to help decrease anxiety in people with CFS. The writer of this article would have been more correct to entitle it “New study show supplementing with probiotics may ease anxiety IN PEOPLE WITH CFS,” for that is in fact what the “new study” shows. Then we could accept the article as “news.” Additionally, the author would do well to point out that not all strains of bacteria are created equal – some have health benefits to humans and some do not. Simply consuming certain foods that contain probiotics is not a way to reduce anxiety, as this article implies.

Poulsen; New Study: Probiotic Strain Boosts Immune Response to Flu Virus;

The article New Study: Probiotic Strain Boosts Immune Response to Flu Virus, discusses findings from a human trial (with 9 participants) and states “that taking probiotics regularly can boost the immune system in a specific way which helps the body give influenza A the boot” (Baker, 09). This statement implies that taking any type of probiotics can help prevent and fight off the flu by strengthening the immune system. In the study the article is based upon, blood samples were obtained from participants at the beginning of the study (before probiotic treatment) and again after taking a probiotic supplement for 30 days (Baron, 2010). The blood samples were treated with antigens and examined; each participant’s baseline sample served as control. The study explained how conclusions from the specific supplement they used (GanedenBC) may be strain specific. Also, the supplement used was designed to survive heat, gastric acidity and bile in order to reach the intestinal tract intact; while not all probiotics sold are, as the article implies. The results from the study also relied solely on their specific antigens applied to the blood samples of only 9 people.

Recent research on probiotics preventing infection and boosting the immune system varies. One study, involving 326 children, found a combination of probiotic strains reduced incidence and duration of fever, coughing, runny nose, and reduced incidence of antibiotic use (Leyer, 09). Another study, with 1072 participants, found that common infectious disease (including the flu) duration was reduced, and the incidence and duration of upper respiratory tract infections were reduced in non-institutionalized elderly (Guillermard, 2010). Probiotic supplementation and the immune response to an influenza vaccination were examined by one study, finding that probiotics enhanced the immune response to the influenza vaccine (Olivares, 07). Another study concluded that the intake of certain strains of probiotics reduces the risk of acquiring common cold infections (Berggren, 2010). However, there are other studies in which probiotics did not have a significant reduction in common cold incidence or length (Baron, 2010).

In my opinion, the statement from the news article saying that taking probiotics can boost the immune system and help prevent and fight the flu, is over-generalized. Recent research supports the theory that probiotics can support a healthy immune system; however results vary and are strain and dose specific. Research often shows that probiotics can reduce the duration of colds and flu-like symptoms. However, reducing the incidence of the flu varies in studies. Few studies have examined probiotics effect on the influenza virus specifically, and further research is needed. While the article does have some nutrition truth to it (probiotics can strengthen an immune system), there is also a lot of “noise” in the article that sensationalizes and fails to mention that results are strain/dose specific, probiotics must be able to reach the colon intact (not all can), and the study the article is based on only tested two blood samples from 9 people which is not a large body of evidence.

Neilson; Preventive Probiotics Cut Cold Symptoms in Kids; Medpage Today

A recent news headline in Med Page Today titled “Preventive Probiotics Cut Cold Symptoms in Kids” reports on a study conducted on 326 children ages three to five years old in a daycare in Jinhua City, China (Leyer, 2010). The study examined the effects of probiotics on cold and flu symptoms and duration. The article reports on the three variables of the experiment- the control group that received plain milk, a variable group that received probiotic Lactobacillus Acidophilus twice per day mixed with milk, and another variable group that received a combination of probiotic strains L Acidophilus with Bifidobacterium Animalis mixed with milk. Supplementation showed a 53-73% reduction of fever incidence, a 41-62% reduction of coughing, and a 68-84% reduction of antibiotics use in regards to single strain and mix of strain probiotics, respectively. On average, probiotic intake decreased duration of illness by 32-48% (Leyer, 2010). Though results seem significant, researchers and reporter fail to address consistency of probiotic administration on days where the children weren’t at school (i.e. weekends, sick days, vacations) which may affect results. There also is no significant research besides this experiment to validate the results.

Few research studies have been conducted in regards to reducing cold symptoms in people by supplementation of probiotics. One experiment observed 479 adults, half of which were given strains of Lactobacillus gasseri, Bifidobacterium longum, and B. bifidum in a tablet, while the control group received a placebo tablet (De Vresea, 2006). Results showed a significant 21% reduction in duration of illness, but showed no evidence to support a decrease in incidence of illness. Another study conducted in a day care center supplemented milk with probiotic culture Lactobacillus Rhamnous (Hatakka, 2001). This study showed a 17% reduction in respiratory infections, a 19% reduction in antibiotic use, and a 16% reduction in duration of illness. Research consistently supports probiotic use may reduce duration of illness, but the effectiveness of reducing incidence of illness, types of probiotics, age of recipients, and single strains versus combination strains is still inconclusive, proving the need for more research on probiotics before any claims can be made.

The article titled “Preventive Probiotics Cut Cold Symptoms in Kids” is more news than noise, however, it still is not completely truthful. While that particular study and a few other studies show a reduction in incidence of cold symptoms (Leyer, 2010), several studies do not produce the same results (Szajewska, 2006). The article also does not address the significance in the specific strain of probiotic. Though research on probiotics and reducing illness is promising, nothing conclusive can be taken from this article (Szajewska, 2006). However, the significance and consistency in the result of decreasing illness and comparable results in other experiments makes the article news worthy and promotes probiotics as something to be mindful of in the next few years as more research is conducted. The article does not imply causation, and supplementing probiotics is not harmful. This article is mostly newsworthy from a scientific nutritional stand point.


Researchers have only recently begun to study probiotics, so the true effects of probiotics on human health remain largely unknown. Headlines often lead readers to believe that consuming probiotics will dramatically improve or eliminate many health problems. However, research reveals that these articles are most often misleading, delving into myths more than portraying facts. For example, healthy bacteria, or probiotics, are found naturally in higher levels in people who are at a healthy weight compared to those who are overweight. One myth claims that consuming probiotics will contribute to weight loss, while this is not necessarily true.The belief that probiotics have the ability to cure and/or prevent childhood infections has been controversial for many decades. Research is inconclusive about probiotics effects on preventing and reducing the duration of cold and flu symptoms. Much research leads us to believe that probiotics are helpful while others may not be helpful at all. Consumers must be informed that not all live bacterial strains are considered "probiotics," and the health benefit of any particular probiotic depends upon the strain, dosage, and even combination of the bacteria found in the food or supplement of interest. In addition, probiotics must be able to reach the colon intact to have a health effect. Not all food or supplement forms containing probiotics can survive the heat, acidity of the stomach, and bile to reach the colon; as news articles often fail to mention.

Current research now points us in the direction of understanding which bacterial strains are effective probiotics and which are not. Some research has also expressed the importance of genetics when looking at probiotics as a therapeutic treatment for infections. Until we fully understand probiotics and their role in the human body, claims that probiotics "prevent" or "cure" any condition cannot be used and are much more noise than news.


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