Colds and flu tend to rise sharply in the fall and winter months. This is largely because we spend more time indoors sharing air with others, while heating systems dry out the nasal passages that normally act as a frontline defense against viruses. Shorter days also mean reduced sunlight exposure, which can lead to lower Vitamin D levels - another factor that affects resilience. With these changes happening at the same time, the immune system often has to work harder to stay balanced.
This means that more attention has turned toward probiotic supplements, which have been shown to help strengthen the body from within. Here’s how they can protect your body during colder months and beyond.
Why the Gut Matters for Immune Health
Although we tend to think of immunity as something happening in the bloodstream or the lymph nodes, a large portion of the immune system is actually located in the gastrointestinal tract. Estimates suggest that about 70% of immune cells live in or around the gut. The gut microbiome - the network of bacteria, yeasts and microbes in the digestive system - plays a crucial role in how these immune cells communicate and how the body responds to external challenges.
When gut bacteria are in balance, the immune system is more likely to respond efficiently and appropriately. But when the microbiome is disrupted, something that can happen due to stress, travel, dietary changes, illness or simply the shift into winter, the immune response may become less stable. Supporting the microbiome during colder months can therefore be a meaningful way to help maintain immune readiness.
What Are Probiotics?
Probiotics are beneficial live bacteria that help maintain balance in the gut microbiome. While they are well-known for supporting digestion and general gut health, research also shows they play an important role in immune function - particularly during the colder months when the body is more exposed to seasonal viruses.
How Probiotics Protect Against Winter Illness
Because so much of the immune system is located in the gut, the balance of bacteria there can influence how effectively the body responds to potential threats. Probiotics help by reinforcing the gut barrier, supporting healthy inflammatory responses, and improving communication between immune cells. This creates a more prepared and well-regulated immune environment.
Various research suggest that probiotics can help reduce the likelihood of upper respiratory tract infections, and that people who do become unwell may experience milder symptoms and a shorter duration of illness. Strains such as Lactobacillus and Bifidobacterium are particularly well-studied in this area. They appear to enhance immune readiness - helping the body respond more efficiently to common pathogens like cold viruses. For this reason, it’s useful to look for probiotic formulas that include these strains, such as Dr. Ohhira’s Professional Formula.
You can find out more about how probiotic supplements help boost the immune system here.
How Long Does It Take to Notice Benefits?
Probiotic support doesn’t work overnight. Because probiotics work by influencing the microbiome, which then affects immune function, the benefits develop gradually. The key is consistency. Taking probiotics daily allows beneficial bacteria to establish themselves, helping the gut maintain a more stable environment over time.
This means that beginning probiotic supplementation before cold and flu season, or at the early signs of seasonal change, can be especially helpful. A steady routine allows the microbiome to adapt and support immunity in a sustained way, rather than only reacting when symptoms appear.
Choosing a Probiotic for Immune Support
Not all probiotics function the same way. Different strains have different effects, which is why multi-strain formulas are often recommended for immune support. A diverse blend more closely reflects the complexity of a healthy microbiome and provides a broader range of benefits.
Dr. Ohhira’s Probiotics are naturally fermented for three or five years, allowing multiple strains of beneficial bacteria to develop, mature, and stabilize within a whole-food environment. Because the bacteria remain active and are accompanied by prebiotic plant fibers, the formula is designed to integrate smoothly with the body’s existing microbial system rather than simply introducing isolated strains.
Supporting Immunity Through Winter
Supporting your immune system during colder months is most effective when done consistently and proactively. If you’re exploring probiotic support this season and beyond, you can learn more about Dr. Ohhira’s naturally fermented, multi-strain formulas here.
