Lactobacillus Acidophilus: Benefits & Probiotic Characteristics

Lactobacillus Acidophilus: Benefits & Probiotic Characteristics

Acidophilus a common term used for the bacterium Lactobacillus acidophilus. The human body is host to more than 500 species of bacteria and lactobacilli plays a pivotal role in enteric flora. It is a gram-positive, non-motile, catalase-negative and non-spore forming bacterium. It produces a single end product through fermentation (homofermentative). It produces lactic acid by fermenting lactose, sucrose, glucose, fructose and other carbohydrates. It survives in lower oxygen levels (microaerophile) than in atmosphere (21%).

The gastric secretions are acidic in nature (low pH). It can survive in this low pH conditions making it one of the ideal probiotic. The name acidophilus is acquired from acido (acid) and philus (loving). Although extreme acidic conditions (< pH 5) will reduce the viability of this strain. Higher the pH (≥ 5), greater is the viability. It is also present in vaginal microbiota.

Along with other probiotics it will confer health benefits. It helps in reducing diabetes, reduction in symptoms of IBSanxiety disorders, helps in weight loss, prevents symptoms of leaky gut , acne and much more.

History of Fermentation

From time unknown mankind is consuming probiotics in the form of fermented foods. There is an ambiguity about which fermented food was first made by humans. Archeological evidence suggests that the first fermentation product was an alcoholic drink dated around 7000 BC to 6600 BC (1) in China. People used the process of fermentation since 6000 BC in several regions such as Eurasia, Egypt, and Babylon.

It was in Asia and/or North East Africa, man first started cultivation of animals between 8000 and 5000 BC. The usage of yogurt, butter, and cheese was very well documented in the Indian Vedas dated around 2000 BC. Sumerians carried bags of milk made from stomachs of sheep. The enzymes of in the stomach wall fermented milk into yogurt. This increased the shelf life of milk. The Old Testament states “Abraham offered to God, showed in an oak wood, fermented milk” (Genesis 18, 1–8). Almost every civilization used fermented milk. Hippocrates stated that the fermented milk is a good food and a medicine capable of curing gut disorders. He is the one to state “All diseases begin in the gut”.

Asian countries such as China, Japan, and Korea practiced fermentation of vegetables. They used this process for pickling of cabbage, cucumber, eggplant, turnip, and carrots. This process is documented for more than 6000 years.

Apart from fermented milk and alcohol (ale), bread is the most popular fermented food. The usage of bread was first documented in Egyptian hieroglyphs. They discovered that dough became fluffy and lighter if it is left unbaked for a few hours. They did not know that this is due to fermentation and attributed it as a divine process. Since ancient Egyptians conquered vast lands, the production of bread spread to other geographical locations.

All these pieces of evidence suggest that the process of fermentation and use of fermented foods was in practice since pre-historic civilization. The consumption of fermented milk is very well documented in various civilizations. Fermented milk is used to cure bowel disorders since the 13th century BC. Hence it is evident that Lacto-fermentation is an age-old practice and fermented milk is probably the first fermented food with probiotic value.

The consumption of fermented milk or yogurt continued until the present day. But the benefits were not well documented in the historical literature. In the 19th century, Russian Zoologist Elie Metchnikoff first time observed the relationship between human health and the consumption of yogurt. During his work at Pasteur Institute, Paris he observed that Bulgarian peasants who consumed yogurt daily were healthy and lived to a ripe old age (2).

The sour milk (the term for yogurt used before modern era) was considered as a byproduct due to the action of certain bacteria. The bacteria was initially named as Bulgarian bacillus. During the course of the history, it is later named as Bacillus bulgaricus and finally as Lactobacillus bulgaricus. The present research confirms that the yogurt is the result of fermentation by Lactobacillus delbrueckii subsp. bulgaricus and acts in concert with Streptococcus salivarius subsp. thermophilus.

Lactobacillus acidophilus is the most widely studied and commercially successful probiotic. It is first isolated by Austrian pediatrician Ernst Moro from the fecal samples of infants in the year 1900. It was initially named as Bacillus acidophilus. As there are many obstacles in differentiating different strains of Lactobacilli with similar observable characters (phenotypically similar), it has undergone huge changes in its taxonomic classification and nomenclature (3).

history of lactobacillus acidophilus

Major milestones in the development of Lactobacillus taxonomy, and the resulting effects on the taxonomic placement of Lactobacillus acidophilus.

Probiotic: Live microorganisms which when administered in adequate amounts confer a health benefit on the host (WHO)

Probiotic properties of Lactobacillus acidophilus

L. acidophilus is known for its probiotic value since ages. With the development of microbiology and biochemistry, the actual probiotic functions of this strain are well established. Its major probiotic characteristics are:

  • Lactose metabolism.
  • Production of antimicrobial compounds.
  • Adherence to host (human) electrolytes.
  • Tolerant to fluctuation in pH levels (an important factor for the probiotics to colonize the lower GIT).
  • Generally Regarded As Safe (GRAS).
probiotic properties of lactobacillus acidophilus

The probiotic strains of L. acidophilus are first described by Shah in 2007 which includes LA-1 and LA-5 (Chr. Hansen, Denmark), NCFM (Dansico, Madison), DDS-1 (Nebraska Cultures, Nebraska) and SBT-2026 (Snow Brand Milk Products, Tokyo, Japan)

The success of this strain is based on two categories:

  • Desirable probiotic physiology demonstrable in vitro (tolerance to pH fluctuation, lactase activity etc.).
  • Observable probiotic effect on the host through feeding studies.

Why is Lactobacillus acidophilus a successful probiotic?

Of all Lactobacillus species, acidophilus is commercially successful because of its vast health benefits. The true probiotic nature of this strain was established after conducting countless researches and case studies.

Below are some of thethe proven benefits of:


An ideal probiotic’s first action is to stabilize a disturbed gut. Diarrhea is one such symptom which severely disturbs both gut and body. L. acidophilus may reduce various forms of diarrhea such as traveler’s diarrhea (4), antibiotic-induced diarrhea, infectious diarrhea (5), and diarrhea prominent irritable bowel syndrome (IBS).

A meta-analysis of masked, randomized and placebo-controlled trials has shown that L. acidophilus along with other probiotics significantly reduced the symptoms of acute diarrhea (6).

A combination of other probiotics with L. acidophilus is proved to be very effective in reducing diarrhea and associated symptoms.

The exact mechanism of action in preventing diarrhea is unknown. Some studies indicate that it helps in the expression of the SLC26A3 gene (7). The expression of this gene triggers manufacture of  protein (Solute carrier family 26, member 3 also known as CLD -Chloride anion exchanger) which helps in the regulation of ion absorption and secretion. This particular mechanism is known to reduce antibiotic-induced diarrhea. But it is also believed that the antimicrobial properties and its ability to induce multiplication of other probiotic bacteria help in reducing the symptoms of diarrhea.

Antibacterial Properties

Bacterial cells communicate with each other and the external environment through a series of signals known as autoinducers. This method of signaling is known as quorum sensing.

In a lab research, L. acidophilus inhibited quorum sensing in other bacterial cells (ex: E. coli). It secreted a molecule which directly interacted with the transcription of genes which are responsible for colonization (8). Thus it acts as a natural antibiotic preventing the toxic effects of other harmful types of bacteria.

In women it helps in preventing vaginal infections and urinary tract infections (UTI). It maintains ideal pH of vaginal fluids and fights opportunistic pathogens. Ex: yeast infections

Another important role of is the reduction of symptoms in H. pylori infection. H. pylori is associated with peptic ulcers, gastric cancer, and chronic gastritis.Along with other probiotics it acts as anti-microbial agents for H. pylori infection. They prevent the adherence of H. pylori cells and produce antimicrobial metabolites.

In a randomized case study, H. pylori positive and asymptomatic patients were given L. acidophilus along with other probiotics such as Lactobacillus rhamnosus GG (group I), Bifidobacterium lactis and Saccharomyces boulardii (group II) for 14 days. These probiotics greatly reduced the symptoms of the infection. However, there was no improvement in the symptoms of nausea and abdominal pain.

Probiotics form a physical barrier, adhering themselves to the epithelial cells of the intestine. This barrier prevents the invasion of opportunistic pathogens. Along with this, probiotics will stimulate the host immune response by secreting antimicrobial agents.


Coronary heart disease (CHD) is directly attributed to an increase in plasma cholesterol levels. An increase in low-density lipoproteins (LPL) is directly associated in predisposing CHD. It has the ability to reduce the cholesterol levels and has grabbed the attention of medical media.

Recent studies suggest that gene ccpA which encodes catabolite Control Protein A in the presence of probiotics play a significant role in the reduction of cholesterol (9). It is also believed that it will absorb the cholesterol into its cell wall membranes thereby reducing the serum cholesterol levels.

In a case study, 15 men and 15 women (age range 42 to 53) with hypercholesterolemia were given L. acidophilus supplements for a period of 60 days. The test subjects were divided into 3 groups of 10 members each. The third group was not given any probiotic supplements. Cholesterol levels were compared at 0, 30 and 60 days of the trial. The comparison showed a significant reduction in LDL, serum triglycerides and an increase in HDL.


The most common cause of allergy is the exposure of antigen (foreign body) to the host cells. When the antigen is exposed to the immune system by dendric cells, the immune system triggers the production of helper cells 1 and 2 (Th1 and Th2). Two types of immune response come into action:

Cellular immunity – Mediated by inflammatory cytokines such as interleukin (IL)-2, interferon (IFN)-γ, and tumor necrosis factor (TNF)-α

Humoral immunity – Carried by Th2 cells by inducing Immunoglobulin E (IgE).

A balance between Th1 and Th2 cells brings homeostasis of allergic response. Increase in Th1 cells will trigger autoimmune disorders where an increase in Th2 cells will cause allergic conditions.

Exposure to allergic stimulants from early childhood plays an important role in the development of the immune system to these conditions. According to ‘Hygiene hypothesis’, excessive cleanliness and over usage of sterile conditions will reduce the human exposure to foreign particles and hinders the development of immunity. This will result in Th2 dominance in adults when exposed to stimuli.

L- 92 regulates the allergic reactions by its influence on dendric cells (10). Dendric cells trigger Th1 response to antigens by secreting IL -12. In the presence of L. acidophilus, the immune response is directed towards Th1 response thus suppressing allergic reactions caused by Th2 cells. It is also believed that L – 92 strain will regulate the balance between Th1 and Th2 cells by stimulating the secretion of T – regulatory (Treg)cells. These regulatory cells prevent excessive immune reactions.

Allergic rhinitis, an IgE mediated allergic reaction (called as Hay fever) affects nearly 50 million people in the USA. In a randomized, double-blind, placebo-controlled study, L. acidophilus (L – 92) supplementation was given to test subjects with allergic rhinitis. There was a significant reduction in nasal inflammation after 6 to 8 weeks.

L – 92 was able to reduce other allergic symptoms such as pollen induced allergy and atopic dermatitis (AD). Studies are still required to firmly establish the relationship between probiotics and allergic symptoms. L – 92 is known to reduce allergies by reduction or causing the death of Th2 cells, influence on the function of dendritic cells, regulation of Th1 and Th2 cytokines, activation of Treg cells, and immunomodulatory genes.

Irritable Bowel Syndrome (IBS)

Irritable bowel syndrome (IBS) is a disease with a group of symptoms. Depending on the predominant symptom, IBS is categorized into IBS – D (diarrhea), IBS – C (constipation), IBS – M/A (abdominal pain and diarrhea), IBS – PI (post-infectious IBS) and IBS – U (unspecified).

The major causes of IBS are:

  • Disturbance in gut motility
  • Infection by opportunistic pathogens such as E. coli and helminth parasites
  • Sensitivity to certain foods (lactose, gluten)
  • Fermented oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs).

Lactobacillus acidophilus along with other probiotics significantly reduces the symptoms of IBS by the following methods:

  • Prevents the invasion of opportunistic pathogens.
  • Help tight junction proteins in preventing toxins from entering the bloodstream.
  • Metabolizes lactose.
  • Forms a physical barrier preventing the excess stimulus of the immune system.

In a case study on Korean and Iranian adults with IBS, L. acidophilus along with other probiotics significantly reduced abdominal pain and bloating (11, 12).

Symptoms of IBS were reduced to a great extent when it is used along with other probiotics (multi-strain probiotic therapy). 


Probiotics are known to play a key role in the development of immunity since birth. These probiotics are closely associated with Peyer’s patches present in the lower gut of infants. These patches are a group of the gut-associated lymphoid tissue (GALT) which form the first line of defense of the human body.

In a case study, L. acidophilus (along with other lactic acid bacteria) were fed to mice to test its effect on immune system.  The analysis of macrophages from Peyer’s patches showed an increase in TNFα and INFγ (13). Further, there was a significant induction of interleukins IL – 2 and IL – 12. Deeper analysis showed that along with other lactic acid bacteria (LAB) it increased IgG1 response which favors Th1 balance. They also enhanced IgG2a response favoring Th2 balance.

In another case study, L. acidophilus modulated the immune response towards breast cancer (14). This study indicated that oral administration of L. acidophilus was able to alter the cytokine production into a Th1 protective pattern, favorable to anti-tumor immunity.

L .acidophilus may also induce immunity against viruses by a Toll-like receptor-2-dependent mechanism in dendric cells (15).

Its drug interactions may effect the outcome of the immune response to various stimulants (citation needed). 

Lactose intolerance

Lactose intolerance is the inability to digest lactose present in milk and dairy products (not to be confused with milk intolerance). The primary cause of lactose intolerance is the lack of enzyme lactase (lactase-phlorizin hydrolase, or LPH) in small intestine. Depending on cause and degree of intolerance, lactose intolerance is classified into four types:

  • Primary – Decrease in lactase with age resulting in progressive lactose intolerance.
  • Secondary – Caused due infection or injury to small intestine.
  • Developmental – Seen in premature babies but the condition improves over time
  • Congenital – Rare genetic disease resulting in very little or no lactase.

Lactobacillus acidophilus is lactose digesting bacteria. Supplements may improve the condition of lactose intolerance. But it depends on the colonization of bacteria in the lower gut. Since it can survive acid fluctuations as well as bile, its chances of colonizing in lower gut is more.

An article published in Journal of Daily Science (1995), researches stated that it can reduce the symptoms of lactose intolerance.

In a randomized test, 42 subjects with lactose intolerance were given Lactobacillus acidophilus BG2FO4 for 7 days. There was no difference in hydrogen – breath analysis and there were no changes in symptoms compared to baseline (16).

How to get daily dose of probiotics?

There are plenty of fermented foods which can pe prepared at home or available at grocery stores. You can take them on a daily basis. Some fermented foods such as kefir, kombucha, sauerkraut, miso and tempeh contain diverse strains of probiotics.

You can also have dietary supplements. There are many dietary supplements available in market and make sure you read the label. The manufacturer must mention the number of probiotic strains, shelf life and colony forming units. A simple term ‘live and probiotic’ need not make the supplement a probiotic.

Don’t overdose yourself with either fermented foods or supplements. Seek medical advice if you are using any prescription drugs. Check the drug information (if you are using any) and their interactions with other drugs or food supplements. Initial dosage may result in side effects such as bloating or diarrhea and/or constipation. Don’t worry about it. It is common a phenomenon after an initial dose when you are deprived of probiotics or there is a decrease in their numbers.

Wrapping up

Having probiotics in your daily diet is always healthy. These probiotics are normally found in our body. They are constantly depleted in their numbers. Rebalancing their numbers can prevent us from many health conditions or they can improve if you are having an existing condition.

Eating probiotic foods or supplements early in morning (before breakfast) or before sleeping gives maximum results. Make sure you include them in your daily food menu.

The information provided here is for educational purposes only. 

Talking to your doctor before starting any remedy (if you are suffering from any medical ailment) is strictly advised. Seek medical assistance if you see any adverse effects. 

Dr.Shashikanth Vydyula is founder of Pocket Reviewer. He is a vivid health enthusiast with a passion for beauty, wellness and nutrition.

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Last update on 2018-09-19 at 05:09 / Affiliate links / Images from Amazon Product Advertising API

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