How to tell if your probiotics are working

Probiotics are living microorganisms that scientists have linked to health benefits.

Some fermented foods like kimchi, kombucha, and yogurt contain these helpful bacteria. You can also take probiotics in the form of supplements

Probiotics can support your gut health and overall health in a variety of ways, but they may not be helpful for everyone. The evidence for most probiotics is limited, but it’s a growing area of research. 

At ZOE, we know how important the gut microbiome is for a healthy life. 

Our scientists run the largest nutrition study in the world and have identified 15 “good” bugs linked with good health and 15 “bad” bugs associated with worse health outcomes. 

With our at-home test, you learn which bugs you currently have in your gut, as well as which specific foods to eat for your overall health.

How to tell if your probiotics are working

The signs that probiotics are working for you will depend on which probiotics you are taking or adding to your diet and the reason why you’re consuming them in the first place. 

If you’re thinking of adding probiotics to your diet, speak with your doctor about the best options for you. 

This is particularly important if you're pregnant, elderly, or live with a chronic health condition, because there isn’t much data on how probiotics might affect you if you have a lower immune system. 

If you're considering probiotics for a child, it’s also best to speak with a healthcare professional.

Probiotic products vary in which bacteria they contain and how they affect your body. 

Also, not everyone will respond the same way to probiotics. But there are some common indicators that they may be working for you. 

1. Less stomach pain

For some people, certain probiotics can help with stomach pain and cramps. 

One review found that for some people with irregular bowel syndrome (IBS), certain probiotic supplements — including strains of Lactobacillus, Bifidobacterium, and Saccharomyces cerevisiae — can help with abdominal pain.  

2. More frequent poops 

If you’re prone to digestive issues like diarrhea or IBS, you may notice a reduction in irregular, loose poops with probiotics. 

Unpublished ZOE research also found that people who regularly consume probiotics have more frequent bowel movements. 

Individuals who consumed probiotics either as fermented dairy, other fermented foods, or from supplements, were 10% more likely to poop on most days than people who didn’t consume probiotics. 

But we don’t know if this was a direct effect of the probiotics themselves or due to other factors. 

3. Less bloating 

After starting some probiotics, you may see reduced bloating. There is evidence showing links between some Lactobacillus strains and less bloating.  

However, some studies suggest that probiotics in larger amounts may temporarily increase these symptoms, particularly while your gut adjusts to the bacteria you're consuming. 

The effectiveness of probiotics may also depend on what’s causing your bloating

4. Improved sleep

What’s happening in your gut can actually impact what’s happening in your brain and vice versa. This connection is called the gut-brain connection.

Through this pathway, disturbances in your gut may impact things like thinking skills, mental health, and sleep quality.

Your gut microbiome and ability to absorb nutrients impact the production of certain chemicals, hormones, and neurotransmitters that play a significant role in your sleep habits.

Probiotics may help:

However, much of this research stems from animal models, and more studies are needed to confirm if people would also experience these effects. 

5. Better mood, memory, and mental clarity

Your gut produces important mood- and focus-regulating neurotransmitters like serotonin, dopamine, and GABA.

However, research into how probiotics impact mental health and neurotransmitters is still a new field

Still, some studies have linked probiotics with:

Interestingly, this can occur even with limited, short-term use of probiotics. 

But it's important to note that these studies often involve participants with preexisting mental health conditions, and the evidence is limited.

So, it’s unclear whether it would be the same in people without these conditions.

Research has also linked certain probiotics to improved memory and cognitive function, though existing studies have focused on mice. 

6. Fewer vaginal infections

The vagina is also prone to bacterial imbalances. 

Women taking probiotics may see a reduction in the severity, frequency, and recurrence of bacterial vaginosis.

Probiotics may also be beneficial for someone taking antibiotics to fight one of these infections, as antibiotics can sometimes cause diarrhea or abdominal pain. 

However, research on this is mixed, as probiotics might also increase the risk of antibiotic resistance.

How long should it take to see improvements?

It can be difficult to predict what effects you'll see (if any), and when.

When you try a new probiotic, it may take 6–8 weeks before you notice any changes. If you don’t feel better, then stop taking it. 

Some factors that may influence when you see results from probiotic use include: 

  • The type and dosage of probiotics. Probiotics found in food and supplement forms vary in strains and dosages. Just because one works, this doesn’t mean they all will. Likewise, some strains may have counterproductive effects on symptoms like bloating and flatulence. 

  • The type of symptom. Some conditions may improve more quickly than others

As ZOE’s U.S. Medical Director and board-certified gastroenterologist Dr. Will Bulsiewicz says, it “depends on your individualized response to the probiotics and what happened when you started them in the first place.”

Dr. Bulsiewicz recommends having a specific goal in mind when you start consuming probiotics and discussing that goal with your doctor.

They can point you toward the probiotic that’s most likely to address the issue, and they can monitor how the condition responds over time. 

Which probiotics are best for you?

At ZOE, we believe it’s a good idea to get probiotics from foods that naturally contain them rather than from currently available supplements if you are generally well and healthy. 

Most supplements contain probiotic strains that are easy to manufacture. But this doesn’t necessarily mean they are the best for you and your unique health needs.  

Fermented foods like kombucha, sauerkraut, kefir, and certain dairy products are a great place to start for dietary probiotics. Make sure they're not pasteurized, though, as this kills the live probiotics.

Prof. Tim Spector recommends having a small amount of fermented foods regularly, rather than a large amount every now and then.

A healthy gut isn’t just about consuming probiotics, though. Eating a variety of colorful plants provides vital micronutrients and prebiotics that act as food for beneficial gut bacteria to thrive.

Some great prebiotic foods are asparagus, leeks, garlic, chickpeas, and whole grains.

Determining which probiotic is best for you and your gut can be a challenge. 

As Dr. Bulsiewic says, “Probiotics are […] a bit like a foreign exchange student arriving in a high school. The cliques are already established, and then this new person walks in, and it's possible that they change the dynamics, but it's also possible that nothing changes at all.”

With the ZOE program, you can learn what bacteria are living in your gut and find out which foods can improve your gut health.


Probiotics are health-promoting bacteria that promote a healthy gut and body. 

While you can find probiotics in supplements, we recommend getting probiotics from your food, if you are generally well and healthy.

Probiotics may benefit digestive issues, sleep quality, mood, and concentration. 

Unfortunately, it’s difficult to predict how, when, or if probiotics will help you. 

How fast and how well probiotics work for you will vary based on your symptoms and the type of probiotics you're taking.

It’s best to work with a healthcare professional, who can recommend the best evidence-based probiotic for your symptoms.

For general gut health, consider incorporating probiotics into your diet on a regular basis in the form of fermented foods. 


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