Are probiotics safe?

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Behind the probiotics trend – are there any side effects?

There is a new big trend in dietary supplements: probiotics. Stoked by more and more people paying attention to their health, you see many new products entering the market. Big brands and newcomers already offer probiotic supplements targeted at specific age groups. However, there is another intriguing development recently – customized probiotics and supplements targeting individual diseases and symptoms. Therefore it is no surprise that researchers are eager to assess the efficacy of probiotic strains, while consumers are interested in the potential preventive and therapeutic health benefits. Although there is a hype around probiotics recently, you should also be aware of potential side effects. 

What are probiotics?

Probiotics are living microorganisms (such as bacteria and yeast) that can improve your health given the right balance in your body.  Bacteria and yeast are naturally living in and on your body, but they can also be found in food and supplements. An imbalance of good bacteria, or excessive amounts of bad bacteria, for example in your gut, can lead to various health conditions.

What are probiotics used for?

Probiotics can alter your digestive microflora and are therefore used to improve symptoms of several health issues. Current research suggests that probiotics can help with digestive problems, diseases and skin conditions. They can also strengthen the immune system.

However, living microorganisms like probiotics differ from strain to strain and demonstrating their efficacy is thus harder than for other functional ingredients.

The suggested health benefits have been proven by some clinical studies, and probiotics research is advancing and promising.

Can probiotics cause gas and bloating?

Although probiotics are similar to the bacteria in our own body, you might suffer from side effects, as can happen with any other form of effective treatments or medications. At the same time, it must be said that healthy people usually only suffer from very mild symptoms like bloating and gas due to the die-off process of bad microorganisms. Sometimes trapped gas in your colon might be accompanied by light cramps, pain and acid reflux.

Can probiotics cause diarrhea?

Usually “bad” bacteria, yeast and viruses in your gut cause diarrhea. Recent research shows that probiotics are actually quite effective to treat diarrhea by balancing “good” and “bad” bacteria. However, probiotics also stimulate your digestive tract which can lead to mild diarrhea in the first 2 to 3 days of taking a new probiotic supplement.

Do probiotics cause skin problems?

Consuming probiotics can lead to skin rashes and mild acne. On the one hand, an allergic reaction to one of the ingredients can cause skin rashes. For example, if you take probiotics in the form of commercially fermented food, you are likely to consume biogenic amines like histamine. However, skin rashes can also be a sign that your body eliminates toxins and waste. On the other hand, specific bacteria on your skin or an imbalance of bacteria can cause acne. When you take probiotics, you add bacteria to your body which might at first cause pimples.

Why do these side effects occur?

These side effects can occur because taking probiotics influences the composition of microorganisms in your gut. Your body needs time to adjust to these changes. Thus, experts recommend to try one product at a time for at least four weeks. During this time you should monitor your intake and side effects to see potential improvements or deterioration of your health.

Can probiotics be harmful? Who should not take it?

Can Probiotics be harmful? While mild symptoms can signal that your body is adjusting, it is not advisable to take probiotics under certain conditions, because you might suffer from severe side effects. Firstly, you should not use probiotics when you are taking antibiotics or any other prescription drugs that weaken or suppress the immune system. This also applies if you  suffer from HIV, or any other condition that leads to weakened immune defenses. Furthermore, be careful with fungal infections as the probiotic supplement could accelerate the growth of yeasts.

Be aware of your allergies. In general, probiotics can help with lowering the symptoms of allergic reactions. On the other hand, probiotics may not only contain the probiotic strains, but also other active and inactive ingredients that you might be allergic to. Always remember: When planning to take a supplement, if you suffer from one of the mentioned conditions or any other chronic disease, please consult a doctor before taking probiotics.

What should I take into account when buying probiotics?

There is no legal definition of probiotics in the U.S. nor in any other country. So you should always investigate whether what you are buying is actually an effective and safe probiotic.

Additionally, the FDA can regulate probiotics as a drug, a food ingredient or as a dietary supplement, depending on the intended use. Most manfacturers sell their probiotics as dietary supplements which means that they not need to show their products are safe or that they work as claimed. Nevertheless, there are many good products on the market and here are some quality criteria to consider when buying your probiotic:

  • Potency: The potency of probiotics is measured in CFU (colony forming units) which refers to the individual colonies of bacteria or yeast. Depending on your condition and the strains used, the potency needed to show health benefits varies greatly. Generally, the higher the potency the better, because probiotics are living microorganisms and therefore susceptible to die-off during product storage.
  • Survivability: Look for probiotic supplements that survive the gastric and bile acid so that the probiotics actually reach your gut alive. If, for example, the probiotic capsule dissolves at an earlier stage in your digestive system, the probiotics die off and cannot colonize your gut.
  • Stability: In order to preserve the potency of some probiotics, they have to be kept cold during production, transportation, storage and sales. Other products, however, are more stable and tolerate warmer temperatures. You can find the best storage conditions for your product by checking the product label

Key takeaways

  • Mild probiotics side effects are normal for healthy people.
  • Be aware of interactions with other medications, your medical condition (impaired immune system) and allergies before taking probiotics. Consult your doctor for help when necessary.
  • Make sure you buy quality products.
  • Joint, F.A.O., 2002. WHO working group report on drafting guidelines for the evaluation of probiotics in food. London, Ontario, Canada, 30. (Retrieved: 25.07.2917)
  • Mayo Clinic. (2017) What are probiotics? In: (Retrieved: 25.07.2017)
  • McKenzie, Y.A., Thompson, J., Gulia, P. and Lomer, M.C.E., 2016. British Dietetic Association systematic review of systematic reviews and evidence‐based practice guidelines for the use of probiotics in the management of irritable bowel syndrome in adults (2016 update). Journal of Human Nutrition and Dietetics, 29(5), pp.576-592. (Retrieved: 07/25/2017)
  • Mayo Clinic. (2017) What are probiotics? In: (Retrieved: 25.07.2017)
  • National Center for Complementary and Integrative Health, 2016. Probiotics: In Depth. In: (Retrieved: 07/26/2017)
  • World Gastroenterology Organisation. (2017) World Gastroenterology Organisation Global Guidelines: Probiotics and prebiotics February 2017. In: (Retrieved: 07/26/2017)
  • Govender, M., Choonara, Y.E., Kumar, P., du Toit, L.C., van Vuuren, S. and Pillay, V., 2014. A review of the advancements in probiotic delivery: Conventional vs. non-conventional formulations for intestinal flora supplementation. AAPS PharmSciTech, 15(1), pp.29-43
  • Kechagia, M., Basoulis, D., Konstantopoulou, S., Dimitriadi, D., Gyftopoulou, K., Skarmoutsou, N. and Fakiri, E.M., 2013. Health benefits of probiotics: a review. ISRN nutrition, 2013
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