Probiotic supplements contain a variety of potentially helpful bacteria and/or yeasts, typically sold in capsules or small packets. Sales have been strong for these products, reaching $1.4 billion last year in the U.S., up from $527 million five years earlier, according to Nutrition Business Journal. Sales have been driven by studies showing that certain probiotics reduce abdominal pain, lower the chance of developing antibiotic-associated diarrhea, reduce cold symptoms, and improve mood, as described in detail in the Review.
ConsumerLab.com’s tests showed that most of the probiotic supplements contained their claimed amounts of viable organisms—typically ranging from one billion to hundreds of billions. However, two products contained less than half of the amounts listed on their labels. In addition, a product for pets provided such a small number of organisms that it would seem unlikely to have any benefit.
Approximately half of the products claimed to be gluten-free, which tests confirmed to be true.
These cultured milk beverages (sometimes called “liquid yogurt”) have become increasingly popular in the U.S. and can be a major source of probiotic organisms. Like milk, they are rich in calcium and protein and some are fortified with vitamin D. They are also promoted for being easier to tolerate than milk for people with lactose intolerance, presumably due to lower amounts of lactose (milk sugar).
ConsumerLab.com tested three major products: Lifeway Lowfat Kefir, Latta Russian Kefir 2% fat, and Evolve Kefir. Each was teeming with live organisms, ranging from 140 billion to 950 billion per cup—far more than found in a serving of most probiotic supplements.
One of the products also claimed to be 99% lactose free, meaning that a one cup serving (about 240 grams) would contain less than 2.4 grams of lactose. However, tests showed that the kefir contained much more lactose than expected—8.2 grams, which is about two-thirds the amount in regular milk (about 12 grams). The other two kefirs contained 10.3 grams and 12.7 grams of lactose. Although this contradicts some promotional statements about kefir, it is consistent with other research which has found kefir to be about 4% lactose. Nevertheless, clinical research suggests that people with lactose-intolerance are better able to tolerate lactose from kefir (as well as from yogurt) than from milk. Researchers theorize that enzymes from bacteria in kefir and yogurt are active in the digestive system, breaking down lactose to more digestible glucose and galactose—similar to the effects of a lactase enzyme supplement.
Tests confirmed that all three kefirs were gluten-free and none was contaminated with pathogenic bacteria.
The test results appear online in ConsumerLab.com's “Probiotics and Kefirs Review.” The report covers the three kefir drinks noted above and 40 probiotic supplements, including those for women, adults in general, children, and pets. Nineteen of the probiotics were tested through ConsumerLab.com's voluntary Quality Certification Program. Also included in the report are two products similar to one which passed testing but which are sold under different brand names. In addition to the test results, the report includes the clinical evidence regarding probiotics as well as information about dosing, safety, and side-effects—including allergies.