The principal supplement for lactose intolerance is lactase enzyme, taken orally with lactose-containing foods. Supplementing with lactase enzyme has been shown to be clinically effective at reducing or eliminating the digestive symptoms of lactose intolerance.[1][2][3][4][5]
Probiotics have also been studied for lactose intolerance. Per a 2019 review, the probiotics that have been studied include Bifidobacterium longum, Bifidobacterium animalis, Lactobacillus bulgaricus, Lactobacillus reuteri, Lactobacillus acidophilus, Lactobacillus rhamnosus, Saccharomyces boulardii, and Streptococcus thermophilus. Of these, B. animalis had the best evidence for reducing symptoms of lactose intolerance.[6]
A promising, but less-studied and proprietary, probiotic is a genetically modified strain of L. acidophilus that produces mammalian lactase. However, no research on this probiotic strain has been published in a peer-reviewed journal, and clinical trials are still ongoing.[7]