“Doc, I read on the Internet that probiotics might help me. Is it true?”

Patrick Alexander Wachholz  is a Geriatrician, Research associate at Botucatu Medical School, São Paulo State University (UNESP). His paper Effectiveness of probiotics on the occurrence of infections in older people: systematic review and meta-analysis was recently published in Age and Ageing journal.

In 2001, an international Joint Expert Consultation of sci­entists working on behalf of the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) defined probiotics as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host”.

Probiotics are intended to have health benefits, and in some countries we can find a huge variety of products sold as probiotics including foods (such as yogurt and fermented milk), dietary supplements, and products that aren’t used orally, such as skin or vaginal creams.

Since the original report, medical databases (such as PubMed and EMBASE) have more than 14,000 research articles that use the term probiotic. Researchers have studied probiotics to find out whether they might help to reduce the occurrence or treat different health issues, including:

  • Digestive disorders, such as diarrhea caused by infections, antibiotic-associated diarrhea, irritable bowel syndrome, and inflammatory bowel disease;
  • Allergic disorders, such as atopic dermatitis (eczema) and allergic rhinitis;
  • Tooth decay, periodontal disease, and other oral health problems;
  • Liver disease;
  • Common cold;

In 2013, the International Scientific Association for Probiotics and Prebiotics (ISAPP) organized a meeting of clinical and scientific experts on probiotics (including  members of the original FAO/WHO Expert Panel). On the basis of the available literature (which includes well-designed clinical trials, systematic reviews and meta-analyses), the consensus panel concurred that certain effects could be ascribed to probiotics as a general class. In this context, however, they were only referring to strains of a number of well-studied microbial species delivered at a functional dose for use as foods or supplements in the general population.—not strains used as drugs.

“Drugs” are defined as “articles […] intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in man or other animals, and articles (other than food) intended to affect the structure or function of the body”. If a drug is “not generally recognized as safe and effective under the conditions prescribed, recommended, or suggested in the labeling,” it is a “new” drug, and so it must demonstrate both safety and efficacy in well controlled investigations, and most probiotics do not have such evidence.

Although some probiotics have shown promising results in research studies, strong scientific evidence to support specific uses of probiotics for most health conditions is lacking. The U.S. Food and Drug Administration (FDA) has not approved any probiotics for preventing or treating any health problem. Notwithstanding, it is easy to find advertisements on intended health benefits of consuming products containing probiotics, mainly related to the billionaire food and over-the-counter product market.

In healthy people, probiotics usually have only minor side effects, if any. However, in people with underlying health problems (for example, weakened immune systems), serious complications such as infections have occasionally been reported.

In our recent systematic review and meta-analysis, we assessed the effectiveness and safety of probiotics in comparison to placebo in the occurrence of infections in older adults. The current evidence, which is of low quality, does not support the use of probiotics for the reduction of the occurrence of infection in older people. It suggests that the mean duration of an infection episode is not affected by probiotics. The evidence suggests that probiotics have a safety profile similar to placebo.

We still don’t know which probiotics are helpful and which are not, and there is no scientific evidence on long-term safety. We also don’t know their effect on critically ill older patients, how much of the probiotic people would have to take or who would most likely benefit from taking probiotics. Even for the conditions that have been studied the most, researchers are still working toward finding the answers to these questions.

Read the Age and Ageing Paper: Effectiveness of probiotics on the occurrence of infections in older people: systematic review and meta-analysis

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