Yogurts that contain live probiotic cultures, particularly strains of Bifidobacterium, are the most likely to help you have more regular bowel movements. Not all yogurts are equal here. The strain, the sugar content, and whether the cultures survived processing all determine whether a yogurt will actually make a difference in your gut.
Why Yogurt Can Help You Poop
Your gut bacteria play a direct role in how fast food moves through your colon. Probiotics in yogurt contribute to this process by influencing the balance of microbes in your digestive tract, which in turn affects colonic motility, fluid secretion, and absorption. The bacteria ferment fiber and produce compounds called short-chain fatty acids, which interact with the cells lining your colon. A systematic review and meta-analysis found that probiotics increase stool frequency and decrease intestinal transit time in people with constipation, with one study showing reduced transit time in both the small bowel and colon.
The key word is “live.” Yogurt that’s been heat-treated after fermentation may taste the same but contain few or no living bacteria. If you’re eating yogurt specifically to get things moving, you need cultures that are still alive when you eat them.
Which Strains Work Best
The strain with the strongest track record for constipation is Bifidobacterium animalis subsp. lactis, sold under various trade names. In a double-blind, placebo-controlled trial of 228 adults with functional constipation, participants who had fewer than three bowel movements per week saw a meaningful increase of about 1.7 to 2.0 additional bowel movements per week when supplementing with this strain. The benefit was most pronounced in people who were genuinely constipated rather than just slightly irregular.
Activia is the most widely recognized yogurt brand built around this type of strain. It contains Bifidobacterium animalis DN-173 010, and five clinical trials have examined it. Four of those trials found that dairy products containing this bacterium shorten intestinal transit time. That said, the research shows Activia shortens transit but hasn’t been definitively proven to increase the number of times you go. For many people, faster transit alone is enough to make a noticeable difference.
Another strain worth knowing is Lactobacillus casei Shirota, found in Yakult (a fermented milk drink, not technically yogurt). Research suggests it may be more effective than some other strains at improving stool consistency and reducing the feeling of incomplete evacuation.
Greek Yogurt vs. Regular Yogurt
Greek yogurt and regular yogurt both start with the same bacterial cultures (typically Lactobacillus bulgaricus and Streptococcus thermophilus). The straining process that makes Greek yogurt thicker doesn’t kill the bacteria, so both types can contain live cultures. Neither one is inherently better for constipation based on that alone.
What matters more than the yogurt style is whether the product includes additional probiotic strains beyond the two starter cultures. Many regular and Greek yogurts now add Bifidobacterium or Lactobacillus acidophilus. Check the label for these additions rather than choosing based on thickness or protein content. The delivery matrix (yogurt vs. capsule vs. fermented milk) can affect how well probiotics work, but research hasn’t found a consistent advantage for one yogurt type over another.
Kefir: A Stronger Option
If yogurt alone isn’t doing much for you, kefir is worth trying. It contains a wider variety of bacteria than yogurt, plus beneficial yeasts like Saccharomyces cerevisiae that yogurt doesn’t have. This broader microbial diversity means kefir colonizes the gut differently. A 2019 study of people who drank kefir for 12 weeks found favorable shifts in their gut bacteria, though the research on kefir specifically for constipation is still limited. Many people who don’t notice results from yogurt report better outcomes with kefir, likely because of that wider range of organisms.
How to Read the Label
Look for the “Live & Active Cultures” seal from the National Yogurt Association. This voluntary certification means the product contains at least 100 million cultures per gram at the time of manufacturing. For frozen yogurt, the threshold is lower: just 10 million cultures per gram. The seal also confirms the yogurt was actually fermented rather than made with acidifiers that mimic the taste.
Beyond the seal, check the ingredient list for specific strain names. Generic “live cultures” usually refers to the two starter bacteria needed to make any yogurt. You want to see additional strains listed, especially Bifidobacterium. One clinical trial that showed improvement in constipation symptoms used yogurt containing 48 billion CFU of Bifidobacterium and Lactobacillus acidophilus in a 300-gram daily serving. You don’t necessarily need that high a count, but more is generally better than less.
Watch the Sugar Content
Flavored yogurts can quietly undermine the benefits you’re after. High amounts of added sugar can cause digestive discomfort on their own, and sugar alcohols (common in “light” or sugar-free versions) can produce bloating and gas that makes constipation feel worse. All yogurt naturally contains some sugar from lactose, and that’s fine. The problem is the added sugars in flavored varieties, which can reach 15 to 20 grams per serving.
Your best bet is plain yogurt. If that’s too tart, add your own fruit or a small drizzle of honey. You’ll get the probiotic benefit without the sugar load that can irritate a sensitive gut.
How Much to Eat and How Long to Wait
Most studies showing a benefit used daily consumption for at least two to four weeks. One trial had participants eating 300 grams (roughly 1.25 cups) of probiotic yogurt per day for four weeks. That’s a reasonable target, though even a single 150-gram serving daily can make a difference over time.
Don’t expect overnight results. Some people notice changes within a few days, but for constipation specifically, most research suggests two to four weeks of consistent daily intake before the effect becomes reliable. If you’ve been eating probiotic yogurt daily for a month and notice no change, the strain in that product may not be the right fit for your gut. Switching brands or trying kefir is a reasonable next step.
Plant-Based Yogurt Alternatives
Dairy-free yogurts made from soy, coconut, or almond milk can contain probiotics, but many don’t. The fermentation process for plant-based yogurts often uses different bacterial strains, and some products skip fermentation entirely, relying on thickeners and acids to mimic the texture. If you’re dairy-free, look specifically for products that list live probiotic strains on the label and carry the Live & Active Cultures seal. Some research has explored yogurt formulations using Lactobacillus plantarum isolated from fermented soybean, which showed promise for slow-transit constipation by shifting gut bacteria composition. But the commercial plant-based yogurt in your grocery store may or may not contain strains at useful levels, so label reading is especially important here.