Probiotics in 2017: What do we actually know?

Marketing is currently outpacing research on probiotics. Here’s what you need to know.

Even though probiotics is today’s trending “superfood”, research on the topic is actually pretty new. We’re here to help you find the facts and provide you with tips on how to shop for probiotics despite what seems like a lack of conclusive advice.

To help you shop smart for probiotics, we tested some of the top-selling brands in the US for label accuracy and common contaminants. For more information, check out Labdoor’s probiotics rankings here.

First, what are probiotics?

Probiotics are helpful, live bacteria. Although counterintuitive, our bodies need bacteria to stay healthy. Our intestines, for example, naturally host bacteria that help us digest food and make vitamins like vitamin K. Bacteria all over our bodies also kill other germs that would otherwise make us sick. Oftentimes, these “healthy” bacteria make up the probiotic supplements we see on store shelves.

What do probiotics do?

If you have too few “good” bacteria, your body can be overrun by “bad” bacteria, and that can lead to health problems ranging from mild constipation to chronic health conditions. In cases where you have an imbalance, probiotic supplements help by feeding your “good” bacteria pool. Here’s what we know so far about how probiotics do that and help with certain illnesses:

Gut Health

Most people use probiotics for gut-related issues, and there’s research to support this. For example, certain strains have been shown to help with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) (L. salivarius, E. coli strain Nissle, S. bouldarii) as well as lactose intolerance (L. bulgaricus, S. salivarius subsp. thermophilus). Probiotics can also help with short-term problems like traveler’s diarrhea (L. rhamnosus strain GG, L. reuteri, S. bouldarii) and diarrhea after antibiotics use (L. rhamnosus strain GG). There’s some evidence that even general fatigue and digestive dysregulation (constipation, diarrhea, bloating) caused by daily stress and common medications can also be mitigated with probiotics.

Immune Health

You may have heard that probiotics could be good for your immune system. There might be some truth to that. Researchers have found that probiotics can have an effect on allergies like hay fever. Some researchers are even looking at whether probiotics could help treat the common cold and for women, whether certain strains could help prevent vaginal infections. However, since the connection between our gut bacteria and immune systems is still unclear, scientists are still unsure if these findings are conclusive.

Other Proposed Health Benefits

Outside of gut health, many of the proposed health benefits of probiotics you see in ads and on labels are actually still unproven. Fortunately, research is now catching up. In fact, $500 million was just pledged to fund microbiome research for the next two years to see how bacteria in our bodies influence major diseases.

With this funding, researchers are looking into clues that probiotics might help chronic diseases like type 2 diabetes, obesity, and diseases of the heart and arteries. Autoimmune diseases like rheumatoid arthritis and cancers of the colon, bladder, and liver are also on the agenda. There’s even funding going into research on probiotics’ effects on oral health (tooth decay, gum disease) and mental health (anxiety, stress, depression, ADHD).

See our article on probiotics and mental health research here.

Are probiotics good for everyone?

As mentioned above, probiotics will mostly benefit those people with gut bacteria imbalances. You might want to consider this possibility for yourself if:

  1. you’re experiencing difficulties in your everyday digestive regulation (e.g. constipation, diarrhea, bloating, gas, indigestion),
  2. you’re of older age as our gut environments drastically change as we age,
  3. you recently took antibiotics or you’re taking other medications that affected your digestive system,
  4. you had a recent bout of gut trauma like diarrhea or constipation from a bug you caught traveling abroad,
  5. your body is under significant emotional or physical stress.

If your gut bacteria is in good shape and you’re trying to treat a health condition, probiotics are probably not the right approach for you.

Are probiotics safe?

We don’t know much yet about the long-term effects of probiotic supplements. For short-term use, probiotic safety really depends on the state of your health. At doses generally found in supplements, people with intact immune systems experience only minor side effects, if any. Gas, indigestion, and other mild stomach disturbances are all pretty common if you take a dose above 1–2 billion CFUs.

For people with weakened immune systems though, serious complications like life-threatening infections can occur. Critically ill patients, those who’ve had surgery recently, children, and those who are immunocompromised should be extra careful and consult a doctor before probiotic use.

For more information about dosing and safety: Can You Overdose on Probiotics?

What does this all mean for me?

It’s clear that probiotics research right now is both exciting and extremely new. For instance, we still don’t know much about long-term safety or how much you should take. We also don’t know for sure which bacteria to use for specific purposes.

We do know, however, that probiotics are generally safe for most people. So, if you’d like to try them, you can. Just do so wisely. In our testing of best-selling probiotics brands in the US, we found that the booming probiotics market is a breeding ground for unsavory sales and manufacturing practices. So, choose a product that’s been tested to be pure and has what it advertises, and check in with your doctor throughout the process.

Shop for top-selling probiotics at with detailed reports and rankings based on label claim and contamination testing performed in FDA-registered labs. Full reports and rankings available here.

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