HOW DO PROBIOTICS WORK? Posted on 24 Jan 17:08 , 0 comments

Dr. Melody Khorrami, PharmD, RPh, INHC


The human body isn’t just made up of our own cells. We host around 100 trillion microbes. Over 500 species of bacteria reside in the gut. The bacterial composition of each human is unique. Various factors can affect the composition of the gut, including lifestyle, diet, antibiotic use, exposure to toxins, and the initial colonization that occurs at birth. All these components affect the intestinal bacterial composition. 

Probiotics can help you get a healthy gut microbiome. There are many proven ways to support a healthy gut microbiome. Lifestyle methods include:

  • eating a balanced diet
  • increasing fiber consumption
  • reducing stress
  • managing emotional health
  • getting enough sleep
  • minimizing unnecessary exposure to antibiotics
  • using certain probiotics. 

 Probiotics are microscopic live organisms. When used correctly, they give their host health benefits. Probiotics work by competing with pathogens that try to enter the body. They produce anti-bacterial effects by making bacteriocins. Bacteriocins are antibiotics that are produced by certain bacterial species. Once produced for a particular strain of bacteria, bacteriocins can work on similar or related species. By producing bacteriocins, probiotics can:

  • destroy some toxins entering the body
  • strengthen your gut’s barrier
  • control muscle movements and sensations in the gut
  • enhance immunity
  • play a role in immune and cytokine modulation
  • help the metabolism function, including the drug metabolism
  • control the microbiota-gut-brain axis
  • break down food
  • produce usable nutrients in the form of vitamins and minerals for the body to use

What makes a good probiotic?

There are a couple of essential criteria to consider when choosing good probiotic products. They include:

  • showing a proven benefit—requesting clinical studies for the intended use(s)
  • proof that they survive the intestines after ingestion
  • no pathogenicity
  • no transmissible drug resistance
  • acid and bile resistance
  • defined antibiotic sensitivity

Additionally, there should always be 2 to 4 hours between administering antibiotics and ingestion of probiotics.

Generally, probiotics will not take up permanent residence in the gut after they are administered. Requesting clinical studies related to the exact probiotic product being used is important. Some observational studies have shown that within one to two weeks of stopping probiotics, they can no longer be found in the stool. Another study showed that after one month of discontinuing probiotics, fecal concentrations of lactobacilli, Bifidobacterium, and Streptococcus reached their original levels before probiotic consumption. However, this does not mean they are not beneficial to the host. As probiotics travel down the gastrointestinal tract they interact with the immune system. Probiotics also react with the variety of microbes that reside in the different parts of the body. Colonization is not required for health benefits to occur.

How do I know if I need probiotics?

As with all therapies, everyone may react differently when starting probiotics. It can take a few days up to a full month to notice the health benefits of probiotics.  Each person is unique and listening to your body and its responses is important. 

You can take some steps to determine whether probiotics are helping you. First, you should understand what symptoms you have and whether you want to see improvement in those symptoms with the probiotic you are using.

  • Do you have digestive issues?
  • Are you experiencing diarrhea with your IBS symptoms?
  • Do you have bloating and gas?
  • How severe are your symptoms?
  • Are you currently on antibiotics or have you just finished a course of antibiotics?
  • When did your symptoms start?
  • Do you want a daily use probiotic for general gut support?

It is important to notify your healthcare provider of unusual symptoms you may be experiencing. Pay attention once you start a probiotic. Only use the recommended amount. Notice how you are improving during the first couple of weeks. Some people may need to start at a lower dose due to side effects like bloating until the body adjusts. Listen to your body and its needs. Within about four weeks you should start seeing improvements. Although, it may take 12 weeks or longer to see to full benefits. 

Which probiotic is right for me?

When choosing a probiotic, it is important to look carefully at the product label. Probiotic labels should contain the genus, species, and strain designation, the number of CFUs (colony forming units), expiration date, recommended dosage, and storage requirements, according to guidelines issued by the Joint Food and Agriculture Organization of the United Nations and World Health Organization (2002) and the International Probiotics Association in its partnership with the Council for Responsible Nutrition (2017).

The side effects of probiotics are generally mild. Some of the common side effects associated with probiotic use include bloating and gas, but they typically disappear in the first couple of days. Adverse effects from probiotics are rare and typically limited to people with underlying diseases. If you have any underlying diseases, you should discuss whether probiotics are appropriate for you, with your licensed healthcare provider.  

Please note: This article is for educational purposes only. Always check with your licensed healthcare provider before starting any new therapies or changing your health plan.