Probiotics aren’t just a popular buzzword in the wellness world; growing studies highlight the benefits of these healthy bacteria and living organisms in your digestive system. You can find them in fermented foods like kimchi, sauerkraut, yogurt, and kombucha, as well as in supplement form. Researchers have found that probiotics can improve or restore the gut microbiota, which in turn has been linked to better overall health.
It’s not just hype, and probiotics can definitely provide benefits. Even so, it’s easy to get lost and confused navigating the cluttered supplement industry to find the best ones that really work. I asked Dr. Ruvini Wijetilaka, MD, to answer our probiotic questions, dispel the myths, and break down the facts. It’s safe to say Dr. Wijetilaka knows a thing or two about the power of probiotics, and she’s an experienced board-certified internal medicine physician and medical advisor for VSL® Probiotics — the makers of VSL#3®, the top gastroenterologist-recommended multi-strain probiotic medical food intended to aid in the management of conditions like IBS.
What are probiotics?
The Manual: Could you explain exactly what probiotics are, and how they work?
Dr. Ruvini Wijetilaka: Probiotics are live microorganisms — most commonly bacteria — that, when taken in adequate amounts, confer health benefits. They work by supporting the gut microbiome, which plays a critical role in digestion, immune modulation, gut barrier integrity, and neurotransmitter production. High-quality probiotics can help crowd out harmful bacteria, produce beneficial metabolites like short-chain fatty acids, and improve communication between the gut and the rest of the body, including the brain and immune system.
My interest in probiotics grew out of both clinical frustration and curiosity. In traditional internal medicine training, we often focus on treating downstream symptoms such as bloating, IBS, and inflammation without fully addressing the gut ecosystem that drives them.
As I moved into longevity and concierge medicine, it became clear that gut health sits at the center of metabolic health, immune function, hormone regulation, and even mental performance. Clinically, I started seeing meaningful improvements in digestion, energy, inflammatory markers, and recovery when probiotics were used thoughtfully and strategically rather than as a one-size-fits-all supplement.”
Gut health, testosterone, brain power, and beyond
TM: The Manual is a publication for high-performing men living busy professional lives. What are the benefits of probiotics for men, specifically?
Dr. Ruvini Wijetilaka: For men juggling demanding careers, workouts, travel, and stress, probiotics can support several key performance pillars: improved digestion and nutrient absorption, better immune resilience, reduced systemic inflammation, and improved metabolic health. There’s also emerging evidence linking gut health to testosterone regulation, insulin sensitivity, and cognitive performance. In short, a healthier gut can translate to better energy, focus, recovery, and long-term health span.
Probiotics should be viewed as part of a larger gut-health strategy that includes diet, sleep, stress management, and movement. For high-performing men, optimizing gut health isn’t just about digestion; it’s about improving resilience, recovery, and long-term performance. When chosen and used correctly, probiotics can be a powerful, evidence-based tool in that equation.
Boosting athletic performance with probiotics
TM: Interestingly, researchers have found that taking probiotics can boost athletic performance and reduce muscle soreness and fatigue. As a physician, what benefits have you seen personally or with your patients with regard to athletic performance and probiotic supplementation? As this research shows, not all probiotics are the same.
Dr. Ruvini Wijetilaka: Clinically, I’ve seen probiotics support better recovery, less GI distress during training, fewer upper respiratory infections, and improved energy consistency in physically active patients. For athletes and high-performing professionals alike, reduced inflammation and improved nutrient absorption can translate into better training output and faster recovery. Importantly, these benefits tend to show up with specific strains and adequate dosing, not generic products.
When is the best time to take them?
TM: When is the best time to take probiotics and why?
Dr. Ruvini Wijetilaka: Generally, probiotics are best taken on an empty stomach or with a light meal, depending on the formulation. Many are designed to survive stomach acid, but consistency matters more than timing. Taking them at the same time daily improves adherence and supports more stable colonization effects.
TM: If you’re looking to get benefits from probiotics, how often should you take them?
Dr. Ruvini Wijetilaka: For most people, daily use is ideal—especially during periods of stress, travel, antibiotic exposure, or heavy training. Probiotics aren’t a quick fix; they work best when taken consistently over weeks to months, allowing the gut environment to shift in a favorable direction.
Not all probiotics are created equal
Not all probiotics are the same, and many of us have definitely scratched our heads in the past, wondering what works and what doesn’t, and what’s the difference. Personally, I’ve tried several brands over the years, and I have to say VSL#3® comes out on top for me. I asked Dr. Wijetilaka to shed some light on this.
TM: Why are some multi-strain probiotics superior to others?
Dr. Ruvini Wijetilaka: Not all strains perform the same function, and diversity matters. Multi-strain probiotics can target different mechanisms simultaneously, like immune modulation, barrier support, inflammation reduction, and microbial balance. That said, more strains aren’t always better; what matters is strain specificity, dose, survivability through the GI tract, and clinical evidence. A well-formulated multi-strain probiotic with proven strains and adequate colony counts will outperform generic blends.
TM: What are some of the best strains to look out for and why?
Dr. Ruvini Wijetilaka: The key is choosing strains backed by human clinical data, not just marketing claims. Some of the most studied and clinically relevant strains include:
- Lactobacillus plantarum for gut barrier integrity and inflammation.
- Lactobacillus rhamnosus for immune support.
- Bifidobacterium breve and Bifidobacterium longum for digestion and metabolic health.
- Streptococcus thermophilus for lactose digestion and gut resilience.
TM: What sets VSL#3® apart from other probiotic brands?
Dr. Ruvini Wijetilaka: VSL#3® is one of the most extensively studied high-potency probiotics available. What differentiates it is the combination of multiple clinically validated strains at a very high colony count, along with strong evidence in conditions involving inflammation and gut barrier dysfunction. It’s formulated more like a medical-grade probiotic than a lifestyle supplement, making it particularly useful for patients who need a more robust intervention.
