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What Are Probiotics and Which Ones Should You Take?

The basics of good gut bugs.

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Why should you take probiotics? The answer is simple: Without a healthy gut, the body simply cannot receive the nourishment it needs to function. Your gut is home to billions of bacteria (known collectively as the microbiome) that play a key role in everything from belly bliss to your mood.

“There are hundreds of known uses for probiotics that include not only digestive help, but also benefits against many health conditions, from the common cold and asthma to certain forms of cancer,” says Jo A. Panyko, BS, MNT, author of Probiotics for Health. “Probiotics can help with your external health as well. They have been shown to help reduce the signs of aging, improve nails and hair, and even fight bad breath and acne.”

How Much Do You Need?

Research suggests that you need a minimum of 1 billion live probiotic bacteria, measured in colony forming units (CFUs). Many people find that taking more—5 to 50 billion CFUs—is beneficial, especially for gastrointestinal conditions such as irritable bowel syndrome.

Sorting Out Probiotic Strains

Convinced that you need to be taking probiotics, but don’t know where to start? Use this guide to common strains—and their key benefits—to help you find a formula that meets your needs.

Lactobacillus acidophilus (L. acidophilus) and Bifidobacterium bifidum (B. bifidum)

Help enhance digestive and immune system health. Use L. acidophilus to ease lactose intolerance and B. bifidum for relief from irritable bowel syndrome. L. acidophilus is also great to take if you’re coming down with a cold. Try: American Health Chewable Probiotic.

chewable probiotic

Bacillus subtilis (B. subtilis)

Is a spore probiotic—a robust strain that stands up to heat, sunlight, and stomach acid. Research on B. subtilis shows that it helps alleviate diarrhea, vaginitis, allergic skin conditions, high cholesterol, gas, and constipation. Try: Arthur Andrew Syntol AMD.

Arthur Andrew Medical Syntol AMD

Lactobacillus casei (L. casei)

This probiotic strain is noted for alleviating antibiotic-induced diarrhea and Clostridium difficile (C. diff) infections, as well as inflammation in patients with rheumatoid arthritis. One study showed that L. casei lessened anxiety and promoted gut health in chronic fatigue sufferers. Try: Dr. Mercola 100 Billion CFU Complete Probiotics.

Dr. Mercola Complete Probiotics

Enterococcus faecalis TH10

This probiotic strain comes from lactic acid bacteria (LAB). Recent studies have found that this novel form of LAB shows immune-boosting activity that is more than six times greater than traditional LAB. Try: Dr. Ohhira’s Probiotics Original Formula.

Essential Formulas Dr. Ohhira’s Probiotics

Lactobacillus plantarum (L. plantarum)

Has been shown in studies to enhance immune function and overall health, especially among elderly people. Other research supports its use for improving memory and age-related memory loss. Try: Flora Udo’s Choice Super 8 Hi-Potency Probiotic.

Flora Udo’s Choice Super 8 Hi-Potency Probiotic

Bifidobacterium longum (B. longum)

Helps tame inflammation and lessen food allergies. Other research shows that B. longum eases depression and anxiety, while also helping the body handle stress more effectively. B. longum helps increase the amount of available tryptophan, which is a precursor to serotonin. Try: Garden of Life Dr. Formulated Probiotics Mood+.

Garden of Life Dr. Formulated Probiotics Mood+

Lactobacillus reuteri (L. reuteri)

This probiotic strain is known to reduce symptoms associated with gastroenteritis (stomach flu). It also colonizes the vaginal environment and fights off unwelcome bacteria and yeast. Use it to help restore vaginal health. Try: Jarrow Formulas Fem Dophilus.

Jarrow Formulas Women's Fem-Dophilus

Lactobacillus rhamnosus (L. rhamnosus)

Useful for treating a variety of health issues, including dermatitis, obesity, diarrhea, digestive gas and bloating, vaginal yeast infections, depression, and anxiety. Try: Natural Factors Relief Biotic.

Natural Factors Relief Biotic

Xylooligosaccharides (XOS)

This isn’t a probiotic strain, but a type of prebiotic fiber that feeds your gut’s good bacteria and improves digestive health. Take it with probiotics to improve their effects. Try: LifeExtension Florassist Prebiotic Chewable.

Life Extension Florassist Prebiotic Chewable Natural Strawberry Flavor