L. acidophilus is a beneficial type of bacteria found in your intestines that helps protect against various illnesses. To boost levels, consume fermented goods or take supplements.

Probiotics are becoming popular food supplements.

Interestingly, each probiotic can have different effects on your body.

Lactobacillus acidophilus is one of the most common types of probiotics and can be found in fermented foods, yogurt and supplements.

What is Lactobacillus acidophilus?

Lactobacillus acidophilus is a type of bacteria found in your intestines.

It’s a member of the Lactobacillus genus of bacteria, and it plays an important role in human health.

Its name gives an indication of what it produces — lactic acid. It does this by producing an enzyme called lactase. Lactase breaks down lactose, a sugar found in milk, into lactic acid.

Lactobacillus acidophilus is also sometimes referred to as L. acidophilus or simply acidophilus.

Lactobacilli, particularly L. acidophilus, are often used as probiotics.

The International Scientific Association for Probiotics and Prebiotics defines probiotics as “live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host.”

Unfortunately, food manufacturers have overused the word “probiotic,” applying it to bacteria that haven’t been scientifically proven to have any specific health benefits.

This has led the European Food Safety Authority to ban the word “probiotic” on all foods in the EU.

L. acidophilus has been extensively studied as a probiotic, and evidence has shown that it may provide a number of health benefits. However, there are many different strains of L. acidophilus, and they can each have different effects on your body.

In addition to probiotic supplements, L. acidophilus can be found naturally in several fermented foods, including sauerkraut, miso, and tempeh.

Also, it’s added to other foods like cheese and yogurt as a probiotic.

Below are 9 ways in which Lactobacillus acidophilus may benefit your health.

High cholesterol levels may increase the risk of heart disease, especially for “bad” LDL cholesterol.

Fortunately, studies suggest that certain probiotics can help reduce cholesterol levels and that L. acidophilus may be more effective than other types of probiotics.

Some of these studies have examined probiotics on their own, while others have used milk drinks fermented by probiotics.

One study found that taking L. acidophilus and another probiotic for six weeks significantly lowered total and LDL cholesterol, but also “good” HDL cholesterol.

A similar six-week study found that L. acidophilus on its own had no effect.

However, there is evidence that combining L. acidophilus with prebiotics, or indigestible carbs that help good bacteria grow, can help increase HDL cholesterol and lower blood sugar.

Studies using probiotics and prebiotics, both as supplements and in fermented milk drinks, have demonstrated this.

Furthermore, other studies have shown that yogurt supplemented with L. acidophilus helped reduce cholesterol levels by up to nearly 7.5% more than ordinary yogurt.

This suggests that L. acidophilus — not another ingredient in the yogurt — was responsible for the beneficial effect.

Diarrhea affects people for a number of reasons, including bacterial infections.

It can be dangerous if it lasts a long time, as it results in fluid loss and, in some cases, dehydration.

A number of studies have shown that probiotics like L. acidophilus may help prevent and reduce diarrhea that’s associated with various diseases.

Evidence on the ability of L. acidophilus to treat acute diarrhea in children is mixed. Some studies have shown a beneficial effect, while others have shown no effect.

One meta-analysis involving more than 300 children found that L. acidophilus helped reduce diarrhea, but only in hospitalized children.

What’s more, when consumed in combination with another probiotic, L. acidophilus may help reduce diarrhea caused by radiotherapy in adult cancer patients.

Similarly, it may help reduce diarrhea associated with antibiotics and a common infection called Clostridium difficile, or C. diff.

Diarrhea is also common in people who travel to different countries and are exposed to new foods and environments.

A review of 12 studies found that probiotics are effective at preventing traveler’s diarrhea and that Lactobacillus acidophilus, in combination with another probiotic, was most effective at doing so.

Irritable bowel syndrome (IBS) affects up to one in five people in certain countries. Its symptoms include abdominal pain, bloating and unusual bowel movements.

While little is known about the cause of IBS, some research suggests it might be caused by certain types of bacteria in the intestines.

Therefore, a number of studies have examined whether probiotics can help improve its symptoms.

In a study of 60 people with functional bowel disorders, including IBS, taking a combination of L. acidophilus and another probiotic for one to two months improved bloating.

A similar study found that L. acidophilus alone also reduced abdominal pain in IBS patients.

On the other hand, a study that examined a mixture of L. acidophilus and other probiotics found that it had no effect IBS symptoms.

This might be explained by another study suggesting that taking a low dose of single-strain probiotics for a short duration may improve IBS symptoms the most.

Specifically, the study indicates that the best way to take probiotics for IBS is to use single-strain probiotics, rather than a mix, for less than eight weeks, as well as a dose of less than 10 billion colony-forming units (CFUs) per day.

However, it’s important to choose a probiotic supplement that has been scientifically proven to benefit IBS.

Vaginosis and vulvovaginal candidiasis are common types of vaginal infections.

There is good evidence that L. acidophilus can help treat and prevent such infections.

Lactobacilli are typically the most common bacteria in the vagina. They produce lactic acid, which prevents the growth of other harmful bacteria.

However, in cases of certain vaginal disorders, other species of bacteria begin to outnumber lactobacilli.

A number of studies have found that taking L. acidophilus as a probiotic supplement can prevent and treat vaginal infections by increasing lactobacilli in the vagina.

Nevertheless, other studies have found no effect.

Eating yogurt that contains L. acidophilus may also prevent vaginal infections. However, more studies are needed before any conclusions can be drawn.

The bacteria in your intestines help control food digestion and a number of other bodily processes.

Therefore, they influence your weight.

There is some evidence that probiotics may help you lose weight, especially when multiple species are consumed together. However, the evidence on L. acidophilus alone is unclear.

A study that combined the results of 17 human studies and over 60 animal studies found that some lactobacilli species led to weight loss, while others may have contributed to weight gain.

It suggested that L. acidophilus was one of the species that led to weight gain. However, most of the studies were conducted in farm animals, not humans.

Furthermore, some of these older studies used probiotics that were originally thought to be L. acidophilus, but have since been identified as different species.

Therefore, the evidence on L. acidophilus affecting weight is unclear, and more rigorous studies are needed.

Healthy bacteria like L. acidophilus can boost the immune system and thus help reduce the risk of viral infections.

In fact, some studies have suggested that probiotics may prevent and improve symptoms of the common cold.

A few of these studies examined how effectively L. acidophilus treated colds in children.

In one study in 326 children, six months of daily L. acidophilus probiotics reduced fever by 53%, coughing by 41%, antibiotic use by 68% and days absent from school by 32%.

The same study found that combining L. acidophilus with another probiotic was even more effective.

A similar study on L. acidophilus and another probiotic also found similar positive results for reducing cold symptoms in children.

Allergies are common and can cause symptoms such as a runny nose or itchy eyes.

Nevertheless, some evidence suggests that certain probiotics can reduce the symptoms of some allergies.

One study showed that consuming a fermented milk drink containing L. acidophilus improved symptoms of Japanese cedar pollen allergy.

Similarly, taking L. acidophilus for four months reduced nasal swelling and other symptoms in children with perennial allergic rhinitis, a disorder that causes hay fever-like symptoms throughout the year.

A larger study in 47 children found similar results. It showed that taking a combination of L. acidophilus and another probiotic reduced runny nose, nasal blocking and other symptoms of pollen allergy.

Interestingly, the probiotics reduced the amount of an antibody called immunoglobulin A in the intestines, which is involved in these allergic reactions.

Another 2021 study found that probiotics can decrease the duration of allergy symptoms.

A 2024 study found that a probiotic blend including lactobacillus acidophilus could help with allergic rhinitis.

Eczema is a condition in which the skin becomes inflamed, resulting in itchiness and pain. The most common form is called atopic dermatitis.

Evidence suggests that probiotics can reduce the symptoms of this inflammatory condition in both adults and children.

One study found that giving a mix of L. acidophilus and other probiotics to pregnant women and their infants during the first three months of life reduced the prevalence of eczema by 22% by the time the infants reached one year of age.

A similar study found that L. acidophilus, in combination with traditional medical therapy, significantly improved atopic dermatitis symptoms in children.

A 2022 study found that probiotic supplementation, including Lactobacillus, in children with eczema showed clinical benefit.

However, not all studies have shown positive effects. A large study in 231 newborn children given L. acidophilus for the first six months of life found no beneficial effect in cases of atopic dermatosis. In fact, it increased sensitivity to allergens.

Your gut is lined with trillions of bacteria that play an important role in your health.

Generally, lactobacilli are very good for gut health.

They produce lactic acid, which may prevent harmful bacteria from colonizing the intestines. They also ensure the intestinal lining stays intact.

L. acidophilus can increase the amounts of other healthy bacteria in the gut, including other lactobacilli and Bifidobacteria.

It can also increase levels of short-chain fatty acids, such as butyrate, which promote gut health.

One study carefully examined the effects of L. acidophilus on the gut. It found that taking it as a probiotic increased the expression of genes in the intestines that are involved in immune response.

These results suggest that L. acidophilus may support a healthy immune system.

A 2020 randomized control trial looking at Lactobacillus acidophilus showed improved symptom severity scores and abdominal pain in IBS.

A separate study examined how the combination of L. acidophilus and a prebiotic affected human gut health.

It found that the combined supplement increased the amounts of lactobacilli and Bifidobacteria in the intestines, as well as branched-chain fatty acids, which are an important part of a healthy gut.

How to reap the most from L. acidophilus

L. acidophilus is a normal bacteria in healthy intestines, but you can reap a number of health benefits by taking it as a supplement or consuming foods that contain it.

L. acidophilus can be consumed in probiotic supplements, either on its own or in combination with other probiotics or prebiotics.

However, it’s also found in a number of foods, particularly fermented foods.

The best food sources of L. acidophilus are:

  • Yogurt: Yogurt is typically made from bacteria such as L. bulgaricus and S. thermophilus. Some yogurts also contain L. acidophilus, but only those that list it in the ingredients and state “live and active cultures.”
  • Kefir: Kefir is made of “grains” of bacteria and yeast, which can be added to milk or water to produce a healthy fermented drink. The types of bacteria and yeast in kefir can vary, but it commonly contains L. acidophilus, among others.
  • Miso: Miso is a paste originating from Japan that is made by fermenting soybeans. Although the primary microbe in miso is a fungus called Aspergillus oryzae, miso can also contain many bacteria, including L. acidophilus.
  • Tempeh: Tempeh is another food made from fermented soybeans. It can contain a number of different microorganisms, including L. acidophilus.
  • Cheese: Different varieties of cheese are produced by using different bacteria. L. acidophilus is not commonly used as a cheese starter culture, but a number of studies have examined the effects of adding it as a probiotic.
  • Sauerkraut: Sauerkraut is a fermented food made from cabbage. Most of the bacteria in sauerkraut are Lactobacillus species, including L. acidophilus.

Other than food, the best way to get L. acidophilus is directly through supplements.

A number of L. acidophilus probiotic supplements are available, either on their own or in combination with other probiotics. Aim for a probiotic with at least one billion CFUs per serving.

If taking a probiotic, it’s usually best to do so with a meal, ideally breakfast.

If you are new to probiotics, try taking them once daily for a week or two and then assess how you feel before continuing.

The bottom line

L. acidophilus is a probotic bacteria that’s normally found in your intestines and crucial to health.

Due to its ability to produce lactic acid and interact with your immune system, it may help prevent and treat symptoms of various diseases.

In order to increase L. acidophilus in your intestines, eat fermented foods, including those listed above.

Alternatively, L. acidophilus supplements can be beneficial, especially if you suffer from one of the disorders mentioned in this article.

Whether it’s obtained through foods or supplements, L. acidophilus can provide health benefits for everyone.