What Do Probiotics Do? Exploring Their Benefits for Health

Your body is home to trillions of bacteria. Some are beneficial, and some are not. The right balance of these bacteria can provide ample benefits. However, modern diets, stress, and medications may disrupt this balance and affect your health. I’ve experienced this firsthand - after taking antibiotics, my doctor recommended adding “good” bacteria to support my gut health. Including them in my diet once a day for 1–2 months helped me avoid disruptive effects.

I’m talking about probiotics. These beneficial bacteria play a key role in keeping your gut running smoothly. But what exactly do they do, and how can they benefit your health?

To explore this topic, I teamed up with Sandra Vigelienė, a nutrition specialist, to break down the science behind probiotics and their potential role in your well-being.

What are probiotics?

Probiotics are live bacteria and yeasts that support gut health and overall well-being. They naturally exist in fermented foods like yogurt, kimchi, sauerkraut, and kefir.

Probiotic supplements, on the other hand, provide concentrated doses of beneficial bacteria in capsules, powders, or gummies, often containing specific strains targeted for digestion, immunity, or vaginal health.

Both work by replenishing ‘good’ bacteria in the gut, competing with harmful microbes, and supporting a balanced microbiome. Common probiotic species include Lactobacillus and Bifidobacterium, found in both supplements and foods, while Saccharomyces boulardii (a beneficial yeast) is popular in supplements.

People may need probiotics after antibiotic use, digestive issues, certain recurrent infections, or bloating and irregularity. Those with specific health concerns, like irritable bowel syndrome (IBS), may benefit from targeted probiotic strains. However, make sure to consult a doctor to choose the right strains for your individual needs.

Probiotics in health

Probiotics are more than just beneficial bacteria — they’re allies that can impact your overall health. Let's dive deeper into two key areas where probiotics show clear potential:

Probiotics and digestive health

Your digestive tract partially relies on a delicate balance of gut bacteria to function effectively.

Probiotics may play a role in maintaining this balance by supporting healthy digestion, easing bloating, and reducing constipation or antibiotic-associated diarrhea symptoms.

Certain strains, such as Bifidobacterium lactis and Lactobacillus acidophilus, have been studied for their potential to reduce the symptoms of digestive conditions like irritable bowel syndrome and low-grade gut inflammation and support certain nutrient absorption.

Probiotics and immune system health

A large portion of your immune system is housed in your gut.

Probiotics may support immunity by helping ‘good’ bacteria thrive, making it harder for harmful germs to take hold. Specific probiotic strains like Lactobacillus rhamnosus GG and Bifidobacterium bifidum are studied for their potential to reduce the risk of upper respiratory infections, shorten their duration, and even reduce allergy symptoms.

It’s important to note that probiotics have strain-specific effects, meaning their benefits can vary. However, this variability is even greater in natural sources since the exact strains and amounts in food are unknown. Evidence on probiotics for allergy symptoms is inconsistent. Their long-term effects remain unclear. While the gut-immune system connection is well established, the overall impact of probiotics — especially for allergies — is still uncertain.

All in all, supporting a balanced gut microbiome with probiotics may still be one of the ways to reinforce your body's natural defenses.

Other probiotic benefits and their limitations

Beyond digestion and immunity, probiotics might offer additional health benefits.

Some emerging evidence suggests probiotics may positively influence mental health by impacting gut-brain communication, potentially reducing mild anxiety or depression symptoms in some people. This concept, known as psychobiotics, explores the gut-brain axis, but as health researcher Sandra Vigelienė notes, the evidence is limited. While certain strains may offer some short-term benefits for specific individuals, probiotics should not replace standard therapies or medications.

Similarly, probiotics may also support skin health by addressing conditions like eczema or acne, likely due to their anti-inflammatory effects. However, the gut-skin connection is complex, and research in this area remains inconsistent. As Vigelienė highlights, individual response, strain selection, and dose all play a role, meaning probiotics are not a universal solution for skin health.

While probiotics show some positive associations with mental and skin health, their impact is likely limited, and no large-scale studies confirm their effectiveness in these areas. Due to these uncertainties, they can’t be recommended as a primary approach for mental health or in dermatology.

Keep in mind that probiotics aren't a cure-all. Results can vary significantly based on the specific strain, dose, and individual health status. Some people may experience no noticeable benefits at all. Additionally, probiotics usually provide temporary benefits. Regular intake may be necessary to maintain positive effects.

Understanding these limitations helps set realistic expectations about what probiotics can and can't achieve for your general health.

A guide on how to take probiotics properly

Knowing how to take probiotics the right way can support their potential benefits for your health. Here’s what you need to consider:

How to know if probiotics are working

Probiotics don’t work overnight, but signs of improvement can appear within days or weeks.

The most noticeable effects are better digestion — less bloating, gas, or constipation. If you struggle with irregular bowel movements, probiotics may help promote consistency. However, as nutrition specialist Sandra Vigelienė points out, the effectiveness of probiotics varies from person to person, and their impact is often subtle and gradual. Tracking specific symptoms, such as changes in digestion or reduced bloating, can help you understand if they are working.

If you don’t notice any changes after a few weeks, it could mean the specific probiotic strains aren’t the best fit for your body. It could also mean that you may need to address other underlying health factors. In that case, consult with a healthcare specialist to help tailor your strains and dose based on your needs.

Safety, side effects, and contraindications of probiotics

Probiotics are generally safe for most people, but some may experience mild side effects, especially when first starting. These can include bloating, gas, or mild digestive discomfort as the gut adjusts. Symptoms usually resolve within a few days.

In rare cases, probiotics may not be suitable for individuals with weakened immune systems, severe illnesses, or those recovering from major surgery, as there’s a small risk of infection. People with conditions like small intestinal bacterial overgrowth (SIBO) may also experience worsened symptoms.

If you have a medical condition or take immunosuppressants, consult a healthcare provider before using probiotics to ensure they’re safe for you.

Choosing the right probiotic supplement

There are several factors you need to consider when choosing a probiotic supplement:

Probiotic strains for specific conditions

Targeted probiotics are designed to address particular concerns, but according to researcher Sandra Vigelienė, their effectiveness depends on multiple factors. These include the strains used, the dose, and individual responses.

While some strains provide broader benefits across multiple body systems, others have highly specific effects. It’s always worth double-checking the list of strains presented, especially in probiotic supplements advertised as targeted probiotic formulas or multi-strain formulas.