Daily Consumption of Probiotics May Not Reduce Risk for Cold, Flu

Consuming probiotics on a daily basis may not reduce the risk of cold or flu in the elderly, according to a recent study.

Probiotics are beneficial bacteria (sometimes referred to as "friendly germs") that help to maintain the health of the intestinal tract and aid in digestion. They also help keep potentially harmful organisms in the gut (harmful bacteria and yeasts) under control. Most probiotics come from food sources, especially cultured milk products. Probiotics can be consumed as capsules, tablets, beverages, powders, yogurts and other foods.

Research suggests that probiotics, especially those in milk or food, may help boost the immune system. However, commercially produced yogurt may not be as effective. More studies are needed, particularly with yogurt, in order to reach a firm conclusion.

In a new study, researchers randomly assigned 737 healthy elderly individuals from 53 nursing homes to receive probiotics in the form of two bottles of fermented milk or a placebo drink containing no probiotics daily for 176 days. All participants also received a flu shot on day 21. Several outcome measures, including respiratory symptoms and immune response to the flu shot were evaluated.

The researchers found that the consumption of probiotics had no significant effect on respiratory symptoms or immune response to the flu shot. Additional research is necessary in this area.

For more information about probiotics, please visit Natural Standard's Health & Wellness Database.

For more information about integrative therapies for cold and flu prevention, please visit Natural Standard's Comparative Effectiveness Database.

Comments

[MS]

Probiotics may not be useful in the cold and flu but they do improve digestive health.
A recent review analysis showed that probiotics in elderly showed the following benefits: establishment of balanced intestinal microflora; improving colonization resistance and or prevention of diarrhea; reduction of fecal enzymes; reduction of serum cholesterol; reduction of potential mutagenes; reduction of lactose intolerance; synthesis of vitamins and predigestion of proteins. (http://www.ncbi.nlm.nih.gov/pubmed/22499466)

[ks]

It’s understandable that probiotics would’t reduce the risk of flu, since the flu is caused by viruses. However, the fact that it doesn’t decrease the risk of the common cold is interesting. According to Natural Standard databases, the best way to prevent colds are cleanliness, fluids, sufficient sleep, sleeping with a humidifier, and avoiding spreading the germs. I think getting a proper amount of vitamin C is also very helpful. I used to get colds all the time in the winter, but since taking vitamin C daily, I hardly ever do.

[Sal]

These other posts raise some really good points about probiotics. I especially enjoyed the one about cold and flu being caused by viruses, not by bacteria. So why would an ingested bacteria help the elderly respond better to a flu shot? I could see that possibility if the flu SHOT was a flu PILL, and probiotics could possibly aid the absorption or help in some other way, but it is not. It seems that the logic behind this study was ill-founded. I also agree with the comment that there are many types (or strains) of beneficial bacteria other than the one used in this study (Lactobacillus casei Shirota (LcS)), so another type may still be beneficial. The popular yogurt for digestive health these days, for example, contains a bacteria called Bifidobacterium lactis. The company claims that eating its product THREE TIMES A DAY for two weeks may help occasional irregularity. Three times a day! That amounts to 3g of saturated fat daily. Another product by the same company has 2.5g of saturated fat per serving, so that would be 7.5g daily, more than the recommended daily allowance. What about the cost? I say, if you want to try probiotics, then try them. An alternative to more expensive products is finding a store brand that states “contains live cultures” on the label. Most do.

[Empire Bakuba]

Introducing bacteria (either good or bad) can upset the environment in stomach. I'm curious to the ramifications of introducing too much probiotics? Is this possible?

[Virginia]

Very good points! It makes sense that probiotics may not affect viral symptoms. Also, different bacteria may have different benefits. I like the point Jennelle made that other strains of bacteria could still be studied.

[Marina]

I think it's really interesting that according to Natural Standard (NS), probiotics have Grade A evidence in the use for atopic dermatitis. Grade A evidence means that there's significant evidence of benefit from 2 or more properly randomized trials. They're also Grade A for acute diarrhea, but I was specifically surprised about the atopic dermatitis. As for safety, it has not been studied at great extent in scientific literature for probiotics, so they should be used with caution especially in immune-compromised, elderly and very young patients.

[Virginia]

First, why did the researchers choose to use fermented milk? eeewwww. There are much simpler and standardized forms of probiotics to take. Second, this study shouldn't be generalized to everyone since the study only evaluated the elderly.

[anonymous]

What a bummer? Well, by thinking about the MoA of probacteria, they are bacteria, of course they do not have anti-viral effects. the flu and common cold are caused by virus, which can only get cured on the body immune system. Although it may not have any effects for cold or flu, it still have good effects on the GI track, to increase motility and fight off bacteria.

[Jennelle]

The results of this study are certainly interesting and add to the existing “controversy” over whether or not probiotics can be used for flu prevention. The findings appear to conflict with a study published in 2009 conducted in children age 3-5 years that found that use of daily probiotic supplementation reduced episodes of fever, congestion, and cough, the incidence of antibiotic prescriptions, and the number of missed school days due to illness: http://www.ncbi.nlm.nih.gov/pubmed/19651563?dopt=Abstract
However, the study was conducted in children and used a different species of Lactobacillus, which likely helps to explain the divergent findings.

In addition, a Cochrane review in 2011 concluded that probiotics may be more beneficial than placebo for preventing acute upper respiratory tract infections. However, the studies used in the review lacked data for older people: http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD006895.pub2/abstract

Thus, additional studies are clearly needed to confirm the benefit (or lack thereof) of probiotic use for prevention of the common cold and flu.

One other issue that piqued my interest how the use of a different strain of organism would have impacted the results. In the aforementioned study conducted in children, Lactobacillus acidophilus and Bifidobacterium animalis subsp lactis were used while this study involved Lactobacillus casei Shirota.

In most cases, probiotic bacteria come from two separate groups – Lactobacillus or Bifidobacterium. These groups are further divided into different species, which contain varying strains of the organism. These different strains of the same probiotic species may be distinct from one another and used for completely different purposes, and not all probiotics are identical nor do they all work the same way. Consequently, it could prove beneficial to investigate if using a different strain of bacteria would yield different results.