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Diarrhea is a common and usually short-lived condition that many people experience a few times a year.

It’s defined as an increase in the frequency of bowel movements with at least 3 loose or liquid stools within a 24-hour period (1).

Diarrhea can be caused by a variety of factors, and certain foods — such as yogurt — may either alleviate or worsen it.

This article discusses how yogurt affects diarrhea.

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Certain types of yogurt contain friendly bacteria, also known as probiotics, which may help prevent or treat diarrhea.

Diarrhea related to infection

Studies show that consuming probiotics in the weeks leading up to a trip may reduce your risk of traveler’s diarrhea by up to 15% (2, 3).

A review of 63 randomized controlled trials further suggests that probiotics may shorten the length of diarrhea caused by bacterial, viral, or parasitic infections by around 25 hours (4).

The same review indicates that those given probiotics were 59% less likely, on average, to experience diarrhea lasting 4 or more days and had fewer bowel movements per day, compared with those given no probiotics (4).

Diarrhea related to antibiotics

Antibiotics are another common trigger for diarrhea. They disturb the balance of your gut bacteria, letting harmful, diarrhea-causing bacteria propagate.

Studies note that taking probiotics alongside antibiotics may help reduce your risk of diarrhea by up to 51% (5, 6).

However, their effectiveness may partly depend on your age. According to research, probiotics may be most effective in children and younger adults — but less so in individuals over 64 years of age (6, 7, 8).

Diarrhea related to other conditions

Finally, probiotics may reduce diarrhea caused by digestive disorders like irritable bowel syndrome (IBS) or ulcerative colitis (UC) (9, 10).

SUMMARY

Certain yogurts contain probiotics, which are beneficial bacteria that have been shown to help prevent or treat various types of diarrhea.

Bacteria are naturally found in all fermented milk products, including yogurt.

To make yogurt, specific bacterial cultures are added to milk to help convert its sugars into lactic acid. This fermentation process is what sets the yogurt.

To be considered a probiotic, bacteria need to be alive and able to provide health benefits. The starter bacteria cultures used to make yogurt aren’t considered probiotics, per se, as they often don’t survive digestion and thus don’t confer any therapeutic effects on your body (11, 12).

However, certain yogurt manufacturers include additional, digestion-withstanding probiotic strains in their products.

Amongst these strains, those effective at preventing or treating diarrhea include Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus rhamnosus, and Saccharomyces boulardii (13).

Which types of yogurt are considered rich in probiotics?

To provide gut benefits, experts suggest that a yogurt needs to fulfill two requirements (13):

  1. Provide over 10 billion colony-forming units (CFUs) of probiotics per serving
  2. Contain probiotic strains that can survive the acidic conditions of the human gut

Yet, few yogurt manufacturers list which probiotic strains they used, let alone the number of CFUs per serving.

Moreover, research shows that a large proportion of yogurts contain strains not listed on the label. In addition, up to 33% of commercial products provide fewer CFUs than necessary (12).

These factors make it difficult to pick the right yogurt based on the food label alone.

Still, some companies have their products analyzed by third-party labs to confirm the number of CFUs. Two such brands are Nancy’s and White Mountain Foods, both of which pack over 40 billion CFUs per serving.

Nancy’s also offers a dairy-free probiotic-rich yogurt made from oat milk.

If you can’t find third-party-tested probiotic yogurts, try picking a variety with a high number of CFUs that provides one of the strains listed above.

SUMMARY

Yogurts may contain varying types and amounts of probiotics. To help prevent diarrhea, opt for one with helpful probiotic strains and at least 10 billion CFUs per serving. Choose third-party tested yogurts whenever possible.

Yogurt contains lactose, a milk sugar that up to two-thirds of individuals cannot digest. People with lactose intolerance often experience diarrhea as a result of eating lactose-rich foods, including yogurt (14, 15).

That said, some evidence suggests that probiotic-rich foods may make it easier to digest lactose, in turn lessening unpleasant side effects like diarrhea (16, 17).

Therefore, if you find yourself experiencing diarrhea after eating conventional dairy yogurt, one option is to replace it with a probiotic-rich variety of either dairy or nondairy yogurt.

Yet, if you know you have lactose intolerance, it may be easiest to avoid dairy yogurt altogether.

SUMMARY

People with lactose intolerance may experience diarrhea after eating dairy yogurt. If this is the case for you, opt for a plant-based yogurt instead.

Probiotic-rich yogurts may protect against multiple types of diarrhea, including traveler’s diarrhea and those caused by infections, antibiotics, IBS, and Crohn’s disease.

For the strongest effects, choose a yogurt containing 10 billion CFUs or more per portion, as well as the probiotic strains Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus rhamnosus, or Saccharomyces boulardii.

However, if you have lactose intolerance, yogurt may cause diarrhea. In this case, go for probiotic-rich plant-based yogurts instead.