What is Lactobacillus Acidophilus?

Benefits, Uses, Side Effects & More

Yogurt is a source of probiotics
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A type of bacteria found naturally in your intestines, Lactobacillus acidophilus, also known as L. acidophilus or acidophilus, is one of the best-known probiotics (beneficial microorganisms that may promote health and protect against infections).

Uses for Acidophilus

Acidophilus belongs to a group of bacteria called lactic acid bacteria (or Lactobacillus) for their ability to convert sugars into lactic acid and hydrogen peroxide, substances that inhibit the growth of undesirable bacteria in the intestines.

Foods and supplements made with acidophilus are said to help balance potentially harmful bacteria that can otherwise flourish in the gut due to illness or antibiotics.

In addition, acidophilus is sometimes used to prevent and/or treat the following health conditions:

  • Acne
  • Bacterial vaginosis
  • C. difficile infection
  • Candida infection
  • Diabetes
  • Diarrhea
  • E. coli infection
  • Eczema
  • Irritable bowel syndrome (IBS)
  • Lactose intolerance
  • Urinary tract infection (UTI)
  • Yeast infection

Some proponents also claim that acidophilus can promote weight loss and strengthen the immune system.

The Benefits of Acidophilus

Although acidophilus is one of the more extensively studied probiotics, findings have varied widely due to differences in patient populations, acidophilus strains, and other factors. Here's a look at some findings from the available research:

1) High Cholesterol

Studies suggest that probiotics may help to cut cholesterol levels, and acidophilus appears to be more effective than other species. For a report published in the Annals of Medicine in 2015, for instance, researchers reviewed previously published studies on the effects of probiotics on lipids and cardiovascular disease risk factors.

Their analysis found that probiotic supplements were effective in lowering total cholesterol and LDL cholesterol levels ("bad cholesterol") and factors associated with cardiovascular disease (such as body mass index, waist circumference, and inflammatory markers). A significant reduction in LDL was found in trials containing Lactobacillus Acidophilus compared to other probiotics.

2) Diarrhea

While acidophilus has been explored as a potential treatment for diarrhea, recent evidence has been mixed on whether it can help prevent C. difficile-associated diarrhea, a type of severe diarrhea that often affects older adults in medical care who require broad-spectrum antibiotic treatment.

In a research review published in the Cochrane Database of Systematic Reviews in 2013, for instance, scientists analyzed 23 previously published trials on the use of various types of probiotics to prevent C. difficile-associated diarrhea and concluded that the short-term use of probiotics is safe and effective for preventing C. diff-associated diarrhea in people who do not have weakened immune systems or are severely debilitated.

A later study published in The Lancet, however, found no evidence that a probiotic supplement containing two strains of Lactobacillus acidophilus (and two strains of Bifidobacterium) could prevent antibiotic-associated diarrhea or Clostridium difficile-associated diarrhea.

3) Bacterial Vaginosis

Bacterial vaginosis is a common vaginal infection that results from an imbalance in the types of bacteria in the vagina. According to a 2014 review, Lactobacillus (including acidophilus) supplements taken daily may help prevent and treat bacterial vaginosis.

Sources of Acidophilus

Lactic acid bacteria are used in the making of many foods, including yogurt, kefir, and buttermilk. Acidophilus, in particular, can be found in yogurt that is made with live acidophilus cultures, other fermented milk products such as kefir, and fermented soy products such as miso and tempeh. The number of live organisms varies greatly from product to product due to differences in processing methods.

Acidophilus supplements come in many forms. Some contain a single strain, while others contain a number of different strains or species of bacteria. They can be found in capsule, caplet, drink, pearls, chewable wafers, or liquid form. Some are available in suppository form.

Non-dairy or dairy-free acidophilus supplements are available.

Some acidophilus supplements contain pectin, a soluble fiber found in citrus and other fruit. Proponents claim that the pectin is a prebiotic (a substance that promotes the growth of probiotic bacteria).

Acidophilus milk can be found in health food stores and some grocery stores and Asian grocers.

Possible Side Effects

Common side effects include digestive complaints, such as gas, bloating, upset stomach, or diarrhea. Although most digestive side effects decrease with use, if they do not improve or worsen, you should discontinue use and consult your health care provider.

If you experience hives, skin rash, itching, difficulty breathing, vomiting, or swelling of your face, lips, tongue, or throat, discontinue use and seek immediate medical attention.

While many people can tolerate acidophilus, it isn't right for everyone.

If you have a weak or impaired immune system (due to a medical condition or immune-suppressing treatment or medication), you may not be able to take acidophilus.

There may be milk allergens or traces of lactose in dairy-derived acidophilus products.

There's some concern that acidophilus can raise the risk of D-lactate toxicity. People who have short bowel syndrome, small intestine bacterial overgrowth, thiamine deficiency, kidney failure, diabetes, or have had gastric bypass surgery may be at greater risk. 

Avoid acidophilus if you have a condition resulting in intestinal damage, due to the risk that the bacteria could escape into other parts of the body and potentially cause serious complications such as bacteremia or sepsis. There have been reports of other lactobacillus species being involved in infections, such as abscess and meningitis.

You shouldn't take acidophilus if you have an artificial heart valve, heart valve disorder, or central venous catheter due to the risk of an infection.

Acidophilus may weaken tooth enamel over time when exposed to teeth.

If you are pregnant or breastfeeding, speak to your doctor before taking acidophilus. You should consult your pediatrician before giving acidophilus to children, babies, or infants. Children who are ill, premature infants, and children with weakened immune systems are at a greater risk for adverse events and complications.

Unlike prescription and over-the-counter drugs, the U.S. Food and Drug Administration (FDA) doesn't regulate probiotics (or other dietary supplements) or test them for safety. Some products may contain fewer than the stated number of live organisms. Other products may be contaminated with other bacterial strains or ingredients.

You can get tips on using supplements here.

The Bottom Line

Despite the research that has been done on acidophilus, most studies have used a unique combination of probiotics or different doses, making it difficult to compare the results.

While acidophilus may seem harmless (because it is found naturally in the body and in many common foods), it isn't right for everyone. If you're considering taking acidophilus for any condition, it's a good idea to consult your health care provider first to see if it's appropriate (and safe) for you.

Eating certain types of yogurt and kefir can boost your intake of acidophilus. You can check the label to see if it contains acidophilus. Other sources of acidophilus include kimchi (a traditional fermented cabbage dish), sour pickles, sauerkraut, sourdough bread, and miso paste.

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Article Sources

  • Goldenberg JZ, Ma SS, Saxton JD, et al. Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children. Cochrane Database Syst Rev. 2013 May 31;(5):CD006095.
  • Sun J, Buys N. Effects of probiotics consumption on lowering lipids and CVD risk factors: a systematic review and meta-analysis of randomized controlled trials. Ann Med. 2015;47(6):430-40.