Most people don’t realize it, but probiotics have a long history. Fermented products, such as kefir and miso, have been used therapeutically for 10,000 years or more. In the early 1900s, Russian scientist Elie Metchnikoff theorized friendly bacteria in yogurt enhanced physical and mental health and prevented aging, which sparked an uptick in yogurt consumption in Paris and other places.
As scientists have further uncovered the role of the human microbiome in health, and the development of various diseases in the past few decades, probiotics have become a hot health trend once again. Today, they’re added to everything from boxed cereal to tortilla chips, herbal tea, skin-care products, and even mattresses. The global market for probiotics exceeds $36 billion a year.
Not all probiotics are created equally. There are many different strains of beneficial bacteria and yeasts, and they’re not universally effective for all conditions. Moreover, because supplements aren’t regulated by the U.S. Food and Drug Administration, it’s hard to know what you’re really getting. Keep reading to find out which popular claims about probiotics are supported by evidence, and discover how to find the best probiotic supplement for your needs.
What Science Says About Probiotics
Probiotic supplements are sometimes touted as cure-alls that can prevent everything from anxiety to the flu. But not all the popular claims are supported by research. Studies suggest specific strains of probiotics are helpful for the following conditions.
Up to 35 percent of patients treated with antibiotics develop diarrhea. Worse, antibiotic treatment sometimes causes an overgrowth of the bacteria Colostrum difficile (C. diff) in the gut, which can lead to diarrhea, colitis, and even death. A Cochrane Collaboration review of 39 randomized trials suggests that when probiotics are taken at the same time as antibiotics, they reduce the risk of C. diff-associated diarrhea by 60 percent. In studies, the microorganism strains that have been most effective at preventing antibiotic side effects are mixtures containing Lactobacillus strains and Saccharomyces boulardii.
Between 25 and 45 million Americans suffer from Irritable Bowel Syndrome (IBS), a condition characterized by abdominal pain, bloating, cramping, and diarrhea or constipation. In a review of 43 studies, probiotics were found to be effective treatments for IBS. The following microorganism strains have been effective in studies: Lactobacillus plantarum 299v, Bacillus coagulans, and Lactobacillus rhamnosus GG.
About 900,000 Americans suffer from ulcerative colitis, an inflammatory bowel disease that causes inflammation and sores in the digestive track. Certain probiotic strains, including the strain Escherichia coli Nissle and the bacterial mixture VSL#3, have been shown to be effective in treating it.
Many people take probiotics to improve their general health or to boost the immune system. There’s not much evidence that probiotics benefit already healthy people. However, one randomized controlled trial suggests consuming certain probiotics for 12 weeks may reduce the risk of getting a cold. In the study, the microorganism strains found to be effective were Lactobacillus plantarum HEAL 9 and Lactobacillus paracasei 8700:2.
Researchers are studying whether probiotics may also be helpful for a wide range of other common conditions, including mood disorders, allergies, autism, high blood pressure, and periodontal and dental disease.
Choosing a Probiotic
Probiotics are only effective in adequate amounts. Ideally, adults should look for a probiotic supplement that contains more than 1 billion Colony-Forming Units (CFUs), a measurement of the total count of bacteria in the supplement. The label should specify the exact strains in the formula. The dosage will vary depending on the condition you’re treating.
Be forewarned: The label on your probiotic supplement may not match what’s inside. In one study of 14 probiotic supplements, the majority did not contain the exact microorganisms listed on the label. Look for a probiotic that’s been tested by an independent lab for purity and potency. And make sure the label specifies the microbes are viable through the end of its shelf life rather than just at the time it was manufactured. Look for a supplement that’s free of binders, fillers, and unnatural additives.
Most probiotic bacteria are sensitive to heat and moisture. Check the label to see if your probiotic supplement needs to be refrigerated. Probiotics with freeze-dried organisms, including most probiotics in tablet or capsule form, do not need refrigeration. However, they shouldn’t be exposed to temperatures above room temperature.
Eating a healthy real-food diet and getting plenty of sleep will help the ecosystems of microbiota in your gut thrive. Diets high in sugar and fat feed pathogenic bacteria while sleep disturbances are linked with changes in the microbiome. A probiotic supplement may also be helpful, especially if you target specific strains of bacteria for a condition. If you’re already healthy, the benefits are less clear. (However, a probiotic may lower your risk of catching a cold.) Follow the above guidelines to find the right probiotic for your needs.
Probiotic supplements have a good safety record for generally healthy people, although temporary stomach upset, gas, diarrhea, or bloating are common while adjusting to taking one. If you’re ill, have had surgery recently, or have a weakened immune system, talk to your doctor before taking a probiotic.