Soon after the advent of the ‘germ theory of disease’ in the nineteenth century, the idea of voluntarily swallowing a pill full of bacteria would’ve sounded a little crazy. But as we learned more about the importance of the community of bacteria and other microorganisms occupying our intestines, eating probiotics has become the acceptable way to help re-populate our guts after courses of antibiotics or other stressors.

As we’ve continued to learn, it appears that our gut bugs influence far more than our digestive function and our ability to stay ‘regular.’ In fact, probiotics often aren’t that effective at re-populating the gut flora anyway. (Prebiotics tend to work better.) Our understanding of how probiotics work is evolving, and this is broadening the scope of health issues that probiotics can help treat.

We’re learning that the mechanisms behind the effect of probiotics are far more complicated than simply ‘topping off’ our supply of intestinal flora. Our gut bugs (even the transient ones) actually help modulate our immune system, and a robust immune system is necessary for the proper function of every other part of the body. Through the effect on immune regulation, probiotics can influence a number of conditions that may seem completely unrelated to the gut. In this post, I’ll describe five different uses for probiotics that are a bit unconventional but may be quite effective.

The benefits of probiotics go way beyond gut health.

Depression

If you’ve been following my blog for any length of time, using probiotics to treat depression probably seems reasonable. But for the average person whose only knowledge of probiotics was gleaned from an Activia commercial, taking probiotics to treat any sort of mental disorder could seem ridiculous. Unfortunately, the average psychiatrist likely feels the same way.

Despite a lack of accord from the medical community, there’s a lot of research to suggest that probiotics can be remarkably useful in treating depression. I’ve talked in the past about the ‘gut-brain axis,’ whereby the health of the brain and the health of the gut are inextricably linked. This relationship is important and can make a huge difference in the mental health of those with gut dysbiosis.

A basic explanation of the relationship is that imbalances in intestinal flora can lead to inflammation in the gut, causing inflammatory cytokines to be released into the blood. These cytokines can then cross the blood-brain barrier and cause inflammation in the brain, which can create symptoms of depression. Probiotics – even if they don’t colonize the intestinal lining – can reduce this gut inflammation and subsequently reduce the brain inflammation, improving symptoms of depression.

Preclinical and clinical studies have shown reductions in anxiety and depression from probiotic supplements, with a reduction in inflammatory cytokines as a likely mechanism. (1, 2) Another potential connection between the gut and brain is through neurotransmitters produced in the gut. This topic really deserves its own post, but for now, suffice it to say that probiotics are a promising treatment for depression and other mental disorders, especially when combined with other gut-healing therapies.

Nasal Congestion

A lesser-known use for probiotics could be in treating congestion and other sinus issues. Just like everywhere else in your body, your nasal passages are colonized by microorganisms that help maintain the health of their environment, and disrupting that balance of beneficial flora can cause problems. There’s not a whole lot of research on this topic yet, but one study showed that a probiotic supplement (in the form of a ‘fermented milk drink’) decreased the levels of pathogenic bacteria in the nasal passages. Other research indicates that probiotics could be helpful in reducing the congestion and other symptoms associated with seasonal allergies. (3, 4) This is especially interesting because in Chinese medicine, they believe sinus issues are almost always related to the gut. Now modern research is beginning to show a connection!

Oral Health

Probiotics can also play a role in maintaining oral health, which isn’t all that surprising once you consider that your mouth is part of your digestive tract. Although your dentist probably won’t be recommending sauerkraut as an adjunct therapy to basic oral hygiene anytime soon, the relationship between probiotics and oral health has been discussed somewhat extensively in the scientific literature.

The ‘good’ bacteria in the mouth help maintain oral health by producing substances (such as hydrogen peroxide and other antimicrobial substances) that inhibit the growth of pathogens, and by competing with these pathogens for space. (5) If those beneficial bacteria are disrupted, pathogenic bacteria can move in and cause a variety of oral and dental issues, including tooth decay, gingivitis, and halitosis (bad breath).

Numerous trials, both observational and clinical, have shown that supplementation with probiotics can reduce cavities and improve overall oral health by rebalancing the bacteria in the mouth. (6, 7, 8) Although probiotic pills taken internally may very well have a beneficial impact on oral health, the benefits shown by these studies are from probiotics that actually come into contact with and are able to colonize the mouth. This is another point in favor of getting probiotics from fermented foods, such as kimchi and kefir. Studies done with probiotic gum, mouthwash, and lozenges have also shown promise in treating oral conditions.

Acne

Acne is another common condition that can be influenced by probiotics, despite its seemingly distant relationship with the gut. In reality, the skin is very closely connected to the gut through the ‘gut-skin axis,’ which I’ve previously mentioned on the blog and podcast. (9, 10, 11) Just as inflammation in the gut can cause inflammation in the brain, it can also lead to inflammation in the skin. This inflammation can manifest as acne, psoriasis, eczema, dermatitis, or other skin conditions. So in the same way probiotics ameliorate symptoms of depression by reducing inflammation, they also improve skin disorders through a similar mechanism. (12)

In addition to taking probiotics internally, there’s some research showing that topical probiotics can reduce acne. (13, 14, 15) The skin is naturally home to beneficial flora that protect the skin from pathogens and regulate inflammation, but these friendly populations of bacteria can be disturbed through harsh soaps and other environmental toxins. Restoring beneficial bacteria through probiotic lotions or spot treatments appears to reduce skin inflammation from the outside, thus improving acne.

Household Cleaners

The last unconventional use for probiotics I’ll mention is in household cleaning products. Natural House is one company that produces these types of products, and they include probiotics in everything from toilet bowl cleaner to all-purpose cleaner. The theory is that while antimicrobial formulas might temporarily sterilize whatever surface you’re cleaning, the pathogenic bacteria will quickly return because there’s nothing to stop them. By using household cleaners containing probiotics, you’re inoculating your house with beneficial bacteria that should make the environment less hospitable to pathogens. It’s the same concept as following up a course of antibiotics with probiotics – antibiotics will likely wipe out a bacterial infection, but if we don’t encourage beneficial bacteria to grow in its place, there’s a strong likelihood that the pathogenic bacteria will return.

There really aren’t any studies proving the effectiveness of these products, but I’d say it’s worth a shot! At the very least, you’ll be avoiding the toxic chemicals that are found in most household cleaners, and that’s reason enough to seek out alternative cleaning solutions.

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