What Is Probiotic Acidophilus?

Lactobacillus acidophilus is a good bacteria that supports gut health and prevents infections

Lactobacillus acidophilus (L. acidophilus) is a type of good bacteria, sometimes called probiotic acidophilus, that’s found naturally in your gastrointestinal tract and other parts of your body.

Lactobacillus acidophilus belongs to the Lactobacillus family of bacteria. It occurs naturally in some foods but can also take the form of a supplement for various health conditions, including irritable bowel syndrome, diarrhea, high cholesterol, and bacterial vaginosis.

It often works as a probiotic. Like other probiotics, L. acidophilus may help balance bacteria in the gut so that potentially harmful strains will not flourish.

This article discusses the potential uses of L. acidophilus and the science behind them. It also covers its side effects, precautions, interactions, dosage, and how to store it properly.

Dietary supplements are not regulated like drugs in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before their makers market them. When possible, choose a supplement tested by a trusted third party, such as USP, ConsumerLab, or NSF. 

However, even if supplements are third-party tested, that doesn’t mean they are necessarily safe for all or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and check in about potential interactions with other supplements or medications.

Supplement Facts

  • Active ingredient(s): Lactobacillus acidophilus
  • Alternate name(s): L. acidophilus, Acidophilus, Acidophilus Bifidus
  • Legal status: Legal in the U.S. and available over the counter
  • Suggested dose: Dosage typically varies but may be as high as 60 billion colony-forming units (CFUs) per day for up to six months in adults.
  • Safety considerations: Side effects may include gas and bloating.
Sauerkraut, cucumber pickles and yogurt
L. acidophilus is added to foods like yogurt and is also found in fermented foods. marekuliasz / Getty Images

Benefits of Lactobacillus Acidophilus

In complementary alternative medicine, L. acidophilus has many uses and may prevent or treat several health conditions, like diarrhea, irritable bowel syndrome (IBS), high cholesterol, and bacterial vaginosis. Another of its common uses is as a probiotic for gut health.

Although L. acidophilus is one of the more extensively studied probiotics, findings have varied widely due to differences in patient populations, bacteria strains, and other factors. Consult a healthcare provider before using L. acidophilus to determine if it is an appropriate supplement for you.

Here are some health conditions that studies show can be improved with L. acidophilus.

Diarrhea

Your healthcare provider may recommend L. acidophilus to treat diarrhea.

A 2020 review on the use of L. acidophilus for digestive disorders found it to be both safe and effective in treating diarrhea. It can be useful as a complementary treatment for both acute diarrhea and chronic diarrhea, as well as diarrhea caused by antibiotics.

Another recent review showed L. acidophilus can reduce the duration of diarrhea in children. After looking at 15 trials, researchers from the review found that children who used L. acidophilus had shorter bouts of diarrhea compared to those who took a placebo.

Irritable Bowel Syndrome

Probiotics such as L. acidophilus can also help with irritable bowel syndrome (IBS).

A review of L. acidophilus found some evidence that the bacteria strain could reduce abdominal pain and discomfort in those with IBS. However, the review also noted that not all human trials on L. acidophilus for IBS could offer proven positive results. In fact, some studies have found L. acidophilus has unwanted side effects in those with IBS.

Additionally, a recent randomized controlled trial found L. acidophilus helped reduce IBS-associated abdominal pain and symptom severity more than a placebo.

Bacterial Vaginosis

L. acidophilus may help to prevent and treat vaginal infections, including bacterial vaginosis (BV) and yeast infections.

According to one review, daily intake of L. acidophilus supplements may help prevent and treat BV, a common vaginal infection that results from an imbalance in the types of bacteria in the vagina.

Like other strains of the Lactobacillus family, L. acidophilus may have antimicrobial properties that make it a potentially useful treatment for BV.

Yeast Infections

L. acidophilus may also have antifungal properties, making it a potential treatment for yeast infections. Laboratory research shows that L. acidophilus and other probiotics may inhibit the growth of the fungus Candida albicans, which is a common cause of yeast infections.

A 2015 clinical trial found L. acidophilus may help lower the risk of recurring yeast infections following standard medical treatment.

High Cholesterol

Several studies show that the probiotic L. acidophilus can reduce a person's total cholesterol levels. The probiotic plays a role in reducing the amount of cholesterol that is absorbed. Compared with other probiotic strains, L. acidophilus was more effective at lowering cholesterol levels than others.

Immune Health

L. acidophilus may also have antimicrobial and antiviral properties. These properties may make L. acidophilus a treatment option for respiratory infections. Although more research needs to be done, probiotic supplementation may also be one way to support immunity against COVID-19.

Food Sources

A food-first approach to nutrients (including probiotics) is always preferable. There is no solid evidence that probiotic foods are superior to probiotic supplements, but food forms of L. acidophilus may be preferred. While L. acidophilus is not widely found in foods, some products are fortified with the probiotic strain.

Food products that may be fortified with L. acidophilus include:

  • Yogurt
  • Fermented milk (acidophilus milk)
  • Feta cheese

Not all brands of these foods will contain L. acidophilus, so check the ingredient list on the nutrition label to see what is included.

L. acidophilus may also be present in additional fermented foods, like kimchi, kombucha, sauerkraut, and sourdough bread.

Supplements

L. acidophilus supplements are sold in various forms, including capsules, chewable tablets, beverages, powders, and suppositories.

L. acidophilus is sometimes combined with other probiotics and nutrients to make supplements. These products are available at health-food stores, supermarkets, drugstores, and online.

There is a variety of L. acidophilus formulations. Because of this, you may benefit from reading labels and looking for two things in particular:

  • Strains: Some L. acidophilus products contain a single strain of the bacteria, while others contain several strains or species. Many different strains of probiotics can offer health benefits similar to those of L. acidophilus. Look for a broad-spectrum option that includes L. acidophilus.
  • Pectin: Some L. acidophilus supplements contain pectin, a soluble fiber in citrus and other fruits. Proponents claim that pectin is a prebiotic (a substance that promotes the growth of "good" bacteria in the gut).

Some probiotic supplements may contain milk allergens or traces of lactose. If you are allergic to milk proteins, lactose intolerant, or vegan, look for a supplement that is labeled dairy-free.

Unlike prescription and over-the-counter drugs, the FDA doesn't regulate probiotics or test them for safety. To ensure a quality product, look for a trusted, independent, third-party seal on the label, such as U.S. Pharmacopeia (USP), the National Science Foundation, or ConsumerLab. This can at least give you peace of mind that what is on the product label is what is in the product itself.

Dosage

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

Adults who take L. acidophilus often do so in doses of up to 60 billion colony-forming units (CFUs) per day. Typically, it's taken for up to six months.

Children should take smaller doses of up to 30 billion CFUs daily for no more than three months.

Please follow the directions on the supplement packaging or check with a healthcare provider for an appropriate L. acidophilus dosage.

What Happens if I Take Too Much Lactobacillus Acidophilus?

Although L. acidophilus is generally considered safe, there has not been sufficient testing for safety. Also, like most other supplements, the U.S. Food and Drug Administration (FDA) has not approved it as a treatment for health conditions.

Though there are no well-documented reports regarding the toxicity of L. acidophilus, taking too much of any supplement or probiotic could increase your risk of side effects.

If you take too much L. acidophilus, you may experience common side effects like gas and bloating.

What Are the Side Effects of Lactobacillus Acidophilus?

Although generally considered safe, using L. acidophilus may cause mild or severe side effects.

Common Side Effects

Many studies on L. acidophilus have reported little to no adverse events.

When side effects do occur, they tend to be mild. Side effects of L. acidophilus include digestive complaints, like gas and bloating.

If side effects do not improve or worsen, discontinue L. acidophilus and consult a healthcare provider.

Severe Side Effects

Although rare, severe side effects may occur when using L. acidophilus.

A minor risk of infection related to the use of L. acidophilus is also possible. Probiotics like L. acidophilus have caused blood infections in some people with weakened immune systems. There is also a low risk of infection of the inner lining of the heart (endocarditis) from taking probiotics, including L. acidophilus.

Always speak with a healthcare provider before starting a new supplement, especially if you have a weakened immune system or other health conditions. A healthcare provider can also help you determine the proper supplement dose, which may lower your risk of side effects.

Precautions

Some people may need to take special precautions when using L. acidophilus.

L. acidophilus is assumed safe for those who are pregnant or breastfeeding as long as it is used appropriately. For this reason, people who are pregnant or breastfeeding should speak to a healthcare provider before taking L. acidophilus.

Due to a greater risk of adverse events and complications, those with a weakened immune system should seek medical advice before taking L. acidophilus.

Likewise, you should seek guidance before taking L. acidophilus if you have a damaged heart valve. Although rare, there is a minimal risk of infection of the inner lining of the heart from taking L. acidophilus.

Interactions

It's important to be aware of medications, supplements, or foods that may negatively interact with L. acidophilus.

For the most part, L. acidophilus is thought to have few, if any, interactions.

Antibiotics may reduce the effectiveness of L. acidophilus. To avoid this interaction, antibiotics should be taken at least two hours before or after L. acidophilus.

Lab and animal studies have reported a potential interaction between L. acidophilus and sulfasalazine. Taking L. acidophilus and sulfasalazine may increase certain byproducts of the medication in your blood. However, no studies have reported this interaction in humans.

How to Store Lactobacillus Acidophilus

Depending on the manufacturing processes, some L. acidophilus products need refrigeration, while others are shelf-stable. Store probiotics as directed on the label and minimize contact with air. 

Store supplements in a cool, dry place and keep them out of direct sunlight. Also, keep them out of the reach of pets and small children.

Discard any remaining L. acidophilus supplements when they reach their expiration date.

Similar Supplements

Research suggests that L. acidophilus may help with gut health, vaginal health, and immune health. However, L. acidophilus is not the only supplement that may do so.

Supplements that are similar to L. acidophilus include:

  • Saccharomyces boulardii: Another probiotic, Saccharomyces boulardii (S. boulardii), has shown positive results when treating pediatric diarrhea. In infants and young children, S. boulardii supplementation may decrease the duration and severity of acute diarrhea.
  • Tea tree oil: Tea tree oil may possess anti-fungal properties, making it a possible option for fighting yeast infections. In one study, tea tree oil improved the effects of a conventional medication used to treat a yeast infection. However, studies have yet to prove these results in humans.
  • Vitamin D: Vitamin D, or the sunshine vitamin, may play a role in treating the common cold. Studies have linked vitamin D supplementation to the prevention of cold and respiratory tract infections. However, other studies have shown mixed results.

Consult your healthcare provider about which supplement is right for you.

Summary

L. acidophilus is a probiotic ("good" bacteria) that may benefit gut health, vaginal health, and immune health, as well as potentially lower cholesterol levels. Although, some research results on these and other uses are mixed. It is naturally found in some foods but is available in supplement form.

If you're considering taking L. acidophilus for any condition, consult a healthcare provider to confirm if it's appropriate and safe for you.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
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By Brittany Lubeck, MS, RDN
Brittany Lubeck, RD, is a nutrition writer and registered dietitian with a master's degree in clinical nutrition. 

Originally written by Cathy Wong