By now, health-savvy shoppers are familiar with probiotics—those friendly bacteria that inhabit our gastrointestinal tract, where they tackle digestive issues, from constipation and diarrhea to gas and bloating. 

Supporting gut health is the number-one reason people consume supplemental probiotics, but emerging research suggests a far broader range of health benefits beyond the belly. 

Just as mapping the human genome transformed the way we look at our bodies through the lens of DNA and genes, researchers are tantalizingly close to mapping the human microbiome—the more than 40 trillion microbes that live inside us. Microbiome researchers at the University of Colorado say the bacteria within us may influence obesity, diabetes, anxiety, depression, autism and even cancer. 

But it’s important to note that when we’re talking about probiotics, the specific probiotic strain matters—one acidophilus is not the same as another. For example, studies show that Lactobacillus acidophilus DDS-1 supports digestion by reducing diarrhea, cramping and vomiting among people who are lactose-intolerant. Other studies indicate that Lactobacillus acidophilus NCFM—same genus and species but a different strain—reduces fever, cough and runny noses. Supplement makers are starting to differentiate and specify their probiotics, with different bacterial strains showing benefit for different health needs. So if you’re looking for a specific benefit, seek out products that list the specific probiotic strain that has been linked to research. 

Here are six areas where probiotics benefit the body for more than digestive health and which strains to look for. 

Immunity 

About 70 percent of the body’s total number of immune cells reside in the gut. That’s why the second most popular use of probiotics is to support immune health. Lots of probiotic strains help. Let’s look at colds.

A recent analysis examined 20 published trials and concluded that, in general, Lactobacillus and Bifidobacterium probiotics cut the duration and severity of cold symptoms and lead to fewer missed days at work or school. 

Getting down to specific probiotic strains, Swedish researchers in one large study gave 272 people 1 billion CFUs per day of Lactobacillus plantarum HEAL9 (DSM 15312) and Lactobacillus paracasei 8700:2 (DSM 13434) for 12 weeks. The number of days with common cold symptoms dropped from 8.6 days in the control group to 6.2 days in the probiotic group. 

A large study in Germany gave 5 billion CFUs of Lactobacillus gasseri PA 16/8, Bifidobacterium longum SP 07/3 and Bifidobacterium bifidum MF 20/5 to participants for three months. The probiotic group had seven sick days versus nine for the control group. 

Another strain-specific probiotic supplement that’s backed with a human study is American Health Probiotic Kidstiks. Three strains (Lactobacillus helveticus Rosell-52, Bifidobacterium bifidum Rosell-71 and Bifidobacterium infantis Rosell-33) in individual serving-size packets make this an easy way to mix probiotics into a food or drink for your child. A study on 135 children ages 3 to 7 found that 25.8 percent of the children who took the probiotics had a sick day, but 42.8 percent of the children who did not take the probiotics missed school. 

Another promising option, Just Thrive is a supplement blend of four strains (Bacillus indicus HU36, Bacillus coagulans, Bacillus clausii, Bacillus subtilis HU58), licensed by the Royal Holloway, University of London, that encourage immune health but also produce antioxidants and support healthy cholesterol levels.

Weight control

Interesting recent research connects low-grade inflammation with the onset and progression of obesity-related conditions, such as diabetes. It turns out that the intestinal lining influences these conditions, including weight gain itself. 

One probiotic strain, called Lactobacillus gasseri SBT2055, makes sure the body excretes fat when you go number two, instead of absorbing it. A study among 30 healthy Japanese adults found 5 billion CFUs a day for just one week reduced belly fat and promoted weight loss. 

Garden of Life Dr. Formulated Probiotics Fitbiotic helps manage weight. It features the Lactobacillus gasseri strain, along with a baker’s dozen other probiotics. The total number of probiotics is 50 billion CFUs, and though the label does not tease out how much of each individual strain is included, the Lactobacillus gasseri strain is listed first, which means there’s more of it than any other. Swanson also offers a Lactobacillus gasseri line that contains 3 billion CFUs. 

In one study, 10 billion CFUs of a different strain, B. lactis 420 (B420), controlled body fat mass, trunk fat mass and waist circumference, and reduced calorie intake in overweight adults. It took six months, but subjects lost 3 pounds and tightened their belts by 1 inch. Metagenics sells an UltraFlora Control supplement with that strain and dose. So does Bariatric Advantage with its FloraVantage Control. 

Protein absorption 

One of the more popular probiotics found in foods and drinks is called GanedenBC30. More than two dozen published studies show it aids digestive health as well as immune health. New research indicates it also helps the body absorb amino acids and protein, so athletes taking BC30 can get the same protein effect with lower amounts of protein. One study found reduced muscle damage and faster recovery time among athletes taking 500 million CFUs of BC30. 

Early adopters in the supplement space are beginning to catch on. Gaspari Nutrition Real Mass Probiotic Series is an uber-athlete’s dream, containing the BC30 brand, along with a hefty 50 grams of whey and rice protein per serving. Six Star Pro Nutrition Instant Protein Smoothie also features the BC30 strain, along with 15 grams of plant protein. 

Stress relief  

Who would have thought the microbiota in your gut could affect what’s going on in your brain? The so-called gut-brain axis is an emerging area of microbiome science. Researchers fed mice a commercial probiotic product (Probio’Stick) and found it helped the mice deal with stress. The same product also helped people manage digestive problems when stressed.

Health Canada (our neighbor’s version of the FDA) has authorized the product for its benefits on stress, anxiety and mood balance. Jamieson Natural Sources has branded the “sticks.” Pure Encapsulations has also taken up the baton and offers ProbioMood, which contains the same strains. 

A new product on the market is the Fundamentals Pack from Amare Global. Inside the box are three bottles that address different aspects of the gut-brain axis. They do it with specific probiotic strains, prebiotic fibers that feed the pros and other ingredients that, combined, improve aspects of mental wellness, including elevated mood, reduced stress and enhanced focus. 

Fresh breath  

Did you realize your gastrointestinal tract is not just your intestines but includes your entire digestive tract from your mouth to your anus? That means bacteria reside inside your mouth, and it means probiotics can help. 

Researchers looking at the bacteria inside people with and without halitosis (a fancy word for chronic bad breath) found that the Streptococcus salivarius species was most associated with people with fresh breath. Researchers using 10 billion CFUs of the Streptococcus salivarius K12 strain found it was better than normal toothbrushing, flossing and mouthwashing in reducing the severity of bad breath in children. Because the ears, nose and throat are all related (and of course surround the mouth), other research using 5 billion CFUs found it reduced the incidence of strep throat in children by 90 percent and otitis media (ear infections) by 40 percent. 

NOW OralBiotic contains 1 billion CFUs of Streptococcus salivarius, while Nature’s Trove Oral Probiotic contains 2 billion CFUs and Solaray Oral Flora contains 5 billion CFUS. 

Moms and infants

New moms know how painful the otherwise joyous occasion of childbirth can be when they are racked with constipation or diarrhea. Probiotic strains like B. lactis can help with that. And B. infantis can help a baby more efficiently break down and use the sugars in breast milk for a more comfortable drinking experience. Great for moms, LoveBug Labor of Love has eight strains, including the two listed above—plus it contains folic acid, which can prevent neural tube birth defects. 

Colic—uncontrollable, intense crying by infants—can last minutes or hours, and from weeks to months (even though it seems like a hellacious eternity). Researchers found a difference in bacterial makeup between infants with and without colic. A 2018 study found Lactobacillus reuteri DSM 17938 supplementation resulted in 25 fewer minutes of crying—almost double the placebo group—but only among babies who were breast-fed.