Best Probiotics for Constipation
Not All Strains Are Created Equal
You've probably heard the standard advice for constipation: drink more water, eat more fiber, and exercise regularly. While these lifestyle changes can certainly help, constipation isn't always that simple.
For many people, chronic constipation has multiple underlying causes, and simply adding more fiber may not solve the problem. That's why people often turn to herbal supplements and probiotics in search of relief.
But here's something many people don't know: not all probiotics work the same way. Their effects are strain-specific, meaning one probiotic strain may improve constipation while another has little or no effect.
In this article, we'll look at why probiotics may help constipation, which strains have the strongest evidence, and how to choose a probiotic based on science rather than marketing.
Imagine Your Gut Is a Conveyor Belt
I like explaining body systems with simple analogies, so imagine your digestive tract as a conveyor belt running from your mouth to your anus. Its job is to move food, fluids, and gas smoothly from one end to the other.
When that conveyor belt slows down, stool remains in the colon for longer. During that time, the colon absorbs more water, making the stool drier, harder, and more difficult to pass. This is one of the main reasons constipation develops.
But the conveyor belt doesn't work on its own—it depends on several systems working together.
The intestinal muscles are the engine, pushing stool forward through coordinated contractions called peristalsis.
The enteric nervous system (ENS) is the electrician. Often called the body's "second brain," it controls gut movement independently of the brain, although stress and emotions can still influence how well it functions.
The gut microbiome is the factory workforce. Gut bacteria ferment dietary fiber and produce short-chain fatty acids (SCFAs), which help regulate gut movement, fluid secretion, and serotonin signaling.
The immune system acts as the factory's security team. When inflammation or immune dysregulation is present, normal communication between the gut, nerves, and muscles may be disrupted.
Finally, mucus and bile acids help lubricate the conveyor belt, allowing stool to move more easily through the intestine.
So, Where Do Probiotics Fit In?
The idea behind probiotics is surprisingly simple.
Rather than forcing the conveyor belt to move—as stimulant laxatives do—certain probiotic strains may help the systems that regulate gut movement work more efficiently.
Depending on the strain, probiotics may:
Help restore a healthier gut microbiome
Increase the production of beneficial short-chain fatty acids (SCFAs)
Communicate with the enteric nervous system
Influence serotonin signaling involved in gut motility
Support a balanced immune response
Modify bile acid metabolism
Improve mucus production
None of these mechanisms guarantees relief, and not every probiotic works the same way. But together, they help explain why some probiotic strains have shown benefits for constipation while others have not.
Which Probiotic Strains Have the Best Evidence?
One of the biggest misconceptions about probiotics is that they all work the same way. In reality, their benefits are strain-specific, meaning that even two probiotics belonging to the same species can produce different effects.
Although hundreds of probiotic products are available, only a handful of strains have been studied extensively for constipation.
1. Bifidobacterium animalis subsp. lactis HN019
HN019 has one of the strongest bodies of evidence for constipation. Multiple randomized controlled trials have shown that it may:
Increase bowel movement frequency
Shorten whole-gut transit time
Improve symptoms of functional constipation
Although not every study has demonstrated significant benefits, HN019 remains one of the most extensively researched probiotic strains for constipation.
2. Bifidobacterium animalis subsp. lactis BB-12
BB-12 is another well-studied strain with encouraging evidence.
Clinical studies suggest that it may:
Increase bowel movement frequency
Improve bowel regularity
Support a healthy gut microbiome
Its effects appear to be more modest than those reported for HN019, but BB-12 remains one of the probiotic strains most frequently investigated for constipation.
3. Bifidobacterium animalis subsp. lactis DN-173 010 (CNCM I-2494)
This strain is best known as the probiotic used in Activia®.
Research suggests that it may:
Reduce colonic transit time
Increase stool frequency
Improve overall bowel regularity
It has been studied particularly in people with slow intestinal transit and has shown promising results in several clinical trials.
4. Lactobacillus reuteri DSM 17938
Lactobacillus reuteri DSM 17938 has also demonstrated promising results, particularly in people with functional constipation.
Studies suggest that it may:
Increase the number of weekly bowel movements
Reduce bloating and abdominal discomfort
Improve constipation-related quality of life
Although its evidence base is smaller than that of HN019, it remains one of the better-studied probiotic strains for constipation.
So...Should You Try a Probiotic?
A probiotic isn't a magic cure for constipation.
In most clinical trials, participants took probiotics for 4–8 weeks, and the improvements were generally modest rather than dramatic. Some people notice meaningful benefits, while others experience little change.
If you're considering a probiotic, don't choose the product with the highest CFU count or the longest list of bacteria. Instead, look for a product that clearly lists the strain designation—for example, HN019, BB-12, or DSM 17938—because research shows that the strain, not just the species, determines whether a probiotic is likely to be effective.
Finally, remember that constipation has many possible causes, including pelvic floor dysfunction, IBS-C, medications, neurological disorders, and metabolic conditions. If constipation is persistent, severe, or accompanied by alarm symptoms, it's important to seek evaluation from a qualified healthcare professional rather than relying on supplements alone.
References
Dimidi E, Christodoulides S, Scott SM, Whelan K. Mechanisms of Action of Probiotics and the Gastrointestinal Microbiota on Gut Motility and Constipation. Adv Nutr. 2017;8(3):484–494.
Miller LE, Ouwehand AC. Probiotic supplementation decreases intestinal transit time: A meta-analysis of randomized controlled trials. World J Gastroenterol. 2013;19:4718–4725.
Black CJ, Ford AC, et al. British Dietetic Association Guidelines for the Dietary Management of Chronic Constipation in Adults. J Hum Nutr Diet. 2025.