Although probiotics have been around since the early 1900s, they have recently gained popularity due to their ability to treat a wide range of ailments. Research also suggests that probiotics can help you lose weight and maintain a healthy body-mass index, according to a meta-analysis that reviewed 20 studies that was published in May 2016 in the International Journal of Food Sciences and Nutrition. But what exactly are probiotics? In short, probiotics are live bacteria that help balance the bacteria in your gut, and keep your digestive system functioning properly. Your body’s bacterial balance may be thrown out of whack for a variety of reasons, such as long-term antibiotic use, illness, and more. While taking a daily probiotic supplement may seem like an easy answer to cure common gut ailments, it’s always best to try for a food first approach, since you can get probiotics from the foods you eat. Probiotics can be found in foods such as yogurt, cheese, miso, sauerkraut, and kimchi. But, adding a supplement into the mix if you haven’t achieved the desired effect through diet alone can be effective. A Seal of Approval When looking for a good probiotic, Gans advises consumers to buy from a trusted retailer and look for a seal from a third-party certifier. “Reputable probiotic supplements should list the genus, species, and strain, in addition to the number of organisms that will be alive by the use-by date and the dose on the label,” says Gans. This transparency will help consumers understand what’s in their supplement and how to best use it. What Form It Comes In You can choose from an array of tablets, powders, and liquids depending on which form you prefer. And one form isn’t necessarily better than another. The Number of CFUs The quality of a probiotic supplement has more to do with strains and how many CFUs it provides. (CFU stands for colony forming units, and it refers to the amount of live microorganisms in your supplement.) Although recommendations may vary, Gans says to look for probiotics with at least 1 billion CFUs: “Doses will typically range from 1 billion to 10 billion CFUs for adults; although doses for children are often under 1 billion.” If you are unsure about how many CFUs should be in your probiotic or which strain is best for your needs, ask your doctor for a recommendation. With so many options on the market, here are our top five picks to help get you started with probiotic supplements. As a disclaimer, the Food and Drug Administration (FDA) has not approved any health claims in regards to probiotics. If you are taking any prescribed medications or other supplements, be sure to consult a medical professional before adding a probiotic to your diet.