Complete Guide to Probiotic Bacteria

The Right Probiotic Strains for You

Our body contains between 300 – 500 different strains of bacteria and microbes.  Two of the most well-known families or genus being Lactobacillus and Bifidobacteria – both essential for health, together with a number of other commensal or probiotic bacteria species and strains below – that help to treat a range of health ailments and conditions.

These probiotic bacteria help inhibit the growth of other harmful bacteria and pathogens, aid the digestion and production of important nutrients for our bodies, regulate and influence our metabolism, our immune system and immune response, fighting infections and even influencing our mood and mental health.

Lactobacillus Genus

The Lactobacillus family of bacteria are a major part of the lactic acid bacteria group and help to convert hexose sugars to lactic acid, which helps inhibits the growth of several species of harmful bacteria. In humans, Lactobacilli are normally present in the vagina, gastrointestinal tract, and together with the Bifidobacterium family are one of the first bacteria to colonize our gut at birth.

The Lactobacillus genus includes more than 80 different strains or species many of which line our intestines and help protect our gut from bad bacteria or pathogens such as Helicobacter pylori and Candida albicans (which causes vaginal thrush amongst other infections). They have a high tolerance to acid, bile and gastric juices, and able to colonise the gut lining where the lactic acid they produce helps inhibit the growth of pathogenic bacteria.

Strains of Lactobacillus are known to help maintain mental health; anxiety and mood. In combination with other probiotics, Lactobacillus strains can help treat IBS, Inflammatory bowel diseases; inflammation of the colon; and necrotizing enterocolitis (NEC) in babies born prematurely. Lactobacillus is also used to treat Helicobacter pylori infections, which cause ulcers, as well as urinary tract infections (UTIs) and vaginal yeast infections. 

Other treatments include skin disorders such eczema (atopic dermatitis) and acne, treating high cholesterol, lactose intolerance, Lyme disease, hives, and to boost the immune system and to ward off the common cold.

Lactobacillus Acidophilus

One of the most common is Lactobacillus acidophilus which you can supplement through regularly drinking milk kefir or yogurts that contains active cultures.

Species Treatments Side effects
L. Acidophilus
  • Travellers’ diarrhoea
  • Acute diarrhoea in children
  • Antifungal & Yeast infections
    (L. acidophilus ATCC-4495)

  • Bacterial Vaginosis (UTI)
  • C. difficile & associated diarrhoea 
  • Management of irritable bowel syndrome
  • Intestinal gas
  • bloating
  • Upset stomach
  • Diarrhea

Lactobacillus Rhamnosus

Lactobacillus rhamnosus shows some similar beneficial effects similar to its relative, L. acidophilus, but has not been subjected to the same amount of research.

Species Treatments Side effects
L. rhamnosus
  • Viral-associated pulmonary damage
    (L. rhamnosus CRL1505)
  • Prevention/ treatment of eczema (atopic dermatitis) in children (L. rhamnosus GG)
  • Treatment of diabetes
  • Necrotizing enterocolitis in newborns (L. rhamnosus GG)
  • Bacterial vaginosis/ UTI (L. rhamnosus GR-1)
  • Weight loss of obese women
    (L. rhamnosus CGMCC1.3724)
  • Acute gastroenteritis in children (L. rhamnosus GG)
  • reduction of risk for rhinovirus infections in preterm infants (L. rhamnosus GG, L. rhamnosus ATCC 53103)
  • Protection of human colonic muscle from lipopolysaccharide-induced damage (L. rhamnosus GG)
  • Intestinal gas
  • bloating
  • skin rashes, acne, and hives

Lactobacillus Reuteri

Sometimes called the universal probiotic, L. reuteri is found in the colons of most animals, where it can fight pathogenic bacteria. L. reuteri is found in human breast milk and may be responsible for some of the immunosupportive and anti-gas effects associated with breastfeeding.

Species Treatments Side effects
L. reuteri
  • Reduction of LDL cholesterol
    (L. reuteri NCIMB 30242)
  • Acute gastroenteritis in children
  • Management of infant colic
    (L. reuteri ATCC 55730 and L. reuteri DSM 17938)
  • Intestinal gas
  • bloating

Lactobacillus Casei

Found in the mouth and the gut, L. Casei produces lactic acid inhibiting the growth of pathogens and undesirable bacterial. It is a common bacteria found in raw and fermented dairy and plant products such as cheese, yogurt and fermented green olives.

Species Treatments Side effects
L. casei
  • Constipation in adults (L. casei Lcr35 and L. casei Shirota)
  • C. difficile-associated diarrhoea
  • Bacterial vaginosis (L. casei Lcr35)
  • Management of Irritable bowel syndrome symptoms
  • Treatment of antibiotic-associated diarrhoea in geriatric patients (L. casei Shirota)
  • Immunomodulatory mechanisms (L. casei Shirota)
  • Treatment of Rheumatoid arthritis (L. casei 01)
  • Protection against Salmonella infections (L. casei CRL-431)
  • Treatment of vaginal staphylococcosis (L. casei IMV B-7280)
  • gas and bloating
  • constipation
  • diarrhea
  • acne

Lactobacillus Lactis

L. Lactis is taken to boost immunity, aid digestion and combat cancer. Found in the intestines and the colon, it helps with digestion and produces essential vitamins and other nutrients for the body.

Species Treatments Side effects
L. lactis
  • Restoration of Gut flora with antibiotics
  • Fighting infection from food borne pathogen such as E. coli or Salmonella
  • Treating acute stress
  • Regulating Immune response
  • Intestinal gas

Lactobacillus Paracasei

Lactobacillus paracasei is commonly used in dairy products and probiotics. Both L. paracasei  and its fermented products are effective immunomodulators, they alleviate allergies, prevent gastric mucosal lesions and inhibit fat tissue accumulation

Species Treatments Side effects
L. paracasei
  • Prevention of common infectious diseases in children
  • Boosts immunity through increased cytokine production
  • Reduces the symptoms of common allergies
  • Treats allergic Rhinitis
  • Helps reduce inflammation
  • unreported

Lactobacillus Plantarum

Also found in fermented foods aL. Plantarum helps treat infections from burns as well as strengthening the immune system.

Species Treatments Side effects
L. plantarum
  • Prevention of endotoxin production
  • Treatment of yeast infectionss (L. plantarum NRRL B-4496)
  • Management of irritable bowel syndrome
  • unreported

Lactobacillus Fermentum

L. Fermentum is found in fermented foods and sourdough, where it gets its name. It is also used to treat yeast and urogenital tract infections such as Bacterial vaginosis

Species Treatments Side effects
L. fermentum
  • Bacterial vaginosis (L. fermentum RC-14) [
  • Antistaphylococcal action (L. fermentum ATCC 11739)
  • Treatment of diabetes and insulin resistance and hypercholesterolemia (L. fermentum NCIMB 5221) [142].
  • unreported

Lactobacillus Bulgaricus

Lactobacillus Bulgaricus – a common form of bacteria present in sour fermented milk such as Kefir –  was one of the first of the lactic acid bacteria (LAB) discovered – by the Russian Nobel Prize winner, Ilya Mechnikov.

Species Treatments Side effects
L. bulgaris
  • Antibiotic resistance of yogurt starter culture
  • Boost Immune health in elderly (L. delbrueckii subsp. bulgaricus 8481)
  • Protection against pathogens such as a E. coli
    Modulation of brain activity
  • unreported

 Lactobacillus Gasserii

Species Treatments Side effects
L. gasserii
  • Travellers’ diarrhoea
  • Digestions
  • While relatively safe as a prebiotic in the gut, L. gasseri has been linked with “bacterial infection of the skin that affects the genitals and perineum


Bacteroidetes are one of the most dominant family of bacteria in the human gut and their proportion varies in lean and obese humans (Lean people have a higher proportion of Bacteroidetes bacteria to Firmicutes compared with overweight or obese people).

Commensal behaviour Bacteroidetes act as a probiotic bacteria in our gut – helping to reduce inflammation in the gut, regulating and informing our immune system, and producing butyrate – a very important chemical which helps maintain our gut wall – and keeping pathogens and toxins from getting into our blood.

Pathogenic behaviour: However, in unhealthy guts, when Bacteriodes themselves are able to escape into other parts of our body beyond our gut, they can act as pathogens and cause abscesses and other infections. This typically occurs when the integrity of the gut wall is compromised – known as leaky gut. From here they can cause infections in the central nervous system, the head, the neck, the chest, the abdomen, the pelvis, the skin, and the soft tissues.

Bacteroides probiotic supplements: Bacteroides are anaerobic bacteria that can only withstand temperatures of 25-40 degree – meaning that they can only survive outside the human body for a few minutes, so no Bacteroides supplements are viable. Therefor the best way to increase the number of bacteroidetes in your gut is to increase your intake of fibre and resistant starch – so eat more leafy vegetables, pulses, seeds, nuts and green bananas containing fructo-oligosaccharides .


Bifidobacteria are an important probiotic family of bacteria which includes many strains and can be found in the gut, the mouth and the vagina. In the gut it lines the walls of the colon protecting against undesirable bacteria, microbes and pathogens.  Bifidobacteria also produce vitamins and nutrients such as Vitamin B-complex, Vitamin K and lactic acid – helping protect the health of the lining of the colon. Bifidobacteria is thought to colonise your gut early in infancy through your mother’s breast milk.  Bifidobacteria boosts your immune health and includes several beneficial strains:

Bifidobacterium Adolescentis

Bifidobacterium adolescentis:   Bifidobacterium adolescentis are normal inhabitants of healthy human and animal intestinal tracts. Colonizing the gut immediately after birth but can be reduced by poor diet, stress, or courses of antibiotics

It can be used treating infant diarrhea by giving them large doses of bifidobacteria orally. Since their presence in the gut has been associated with a healthy microbiota they are commonly added to yoghurts and other dairy products as probiotics

Bifidobacterium Bifidum

At birth, B. Bifidum made up 95% of your intestines and protected you from germs. Bifidobacterium attaches to the lining of your colon to help you digest sugars. It also protects your blood from germs and toxins with nutrient absorption and overall digestion. Occasional diarrhea relief is also another benefit. Recent studies have shown this particular strain to reduce the incidences of colds and flu.

Bifidobacterium Breve

This powerhouse strain helps alleviate bloating, gas, diarrhea, and constipation. It also inhibits E. coli and suppresses candida (yeast) which can make you very sick.

Bifidobacterium Infantis

Bifidobacterium infantis inhabits the intestinal tract of both children and adults. Research has shown that increased numbers of B. infantis in the digestive track can boost women’s natural defense mechanisms against the common culprits of an IBS flare. This powerful probiotic has also been found to produce beneficial acids that have the potential to reduce the prevalence of harmful colon bacteria. This can be particularly useful for women who suffer from symptoms of Irritable Bowel Syndrome (IBS).

Bifidobacterium Lactis

This strain is one of the most versatile and hardest working as it supports healthy cholesterol levels, eases ulcerative colitis, and combats the effects of Celiac disease

Bifidobacterium Longum  

Impressively, Bifidobacterium Longum benefits your body by helping gastrointestinal discomfort caused by stress and attenuating anxiety.

Bifidobacterium Animalis

Bifidobacterium animalis is famed for its ability to improve digestive regularity. It is frequently used for people with irritable bowel syndrome or chronic constipation. One subspecies of B. animalis is used by the yogurt manufacturer Dannon, which markets strain under the patented name “Bifidus regularis.”

Bifidobacterium Pseudocatenulatum

Bifidobacterium Pseudolongum

Other Probiotic Bacteria


Streptococcus Thermophilus

Streptococcus thermophilus is a starter culture in the manufacturing process of yogurt, mozzarella cheese and other fermented dairy products. It is also used as a probiotic to help treat abdominal cramps, diarrhea, nausea and other gastrointestinal symptoms associated with lactose intolerance.

Streptococcus Salivarius

Another probiotic in the Streptococcus genus, Streptococcus salivarius, can be used to treat halitosis, the medical term for bad breath.

Streptococcus Faecium

Streptococcus faecium can also help treat or prevent diarrhea and maintain the health of the digestive system. They help alleviate symptoms of nasal cavity infections, irritable bowel syndrome, and baby colic. They even help manage symptoms of AIDS

Bacillus Coagulans

The Bacillus coagulans bacterium is a probiotic supplement that people use for various health concerns. Bacillus coagulans may be useful in the treatment of gastrointestinal disorders such as diarrhea associated with an antibiotic regimen, traveler’s and children’s diarrhea, inflammatory bowel disease and irritable bowel syndrome. The supplement may also be useful in preventing respiratory infections and enhancing their immune response.
However, Natural Medicines Comprehensive Database has concluded that there is “Insufficient Evidence to Rate the Effectiveness” of Bacillus coagulans for any of those therapeutic applications.

Escherichia Coli

While E. coli is rarely considered to be a “good” species of bacteria, some nonpathogenic strains actually hold therapeutic value. Escherichia coli bacteria synthesize the vital vitamin K in humans’ guts. Abundance of this vitamin allows humans’ blood clotting mechanisms to function properly.
One Japanese study, published in 2005 by the journal “Inflammatory Bowel Disease,” found that friendly strains of E. coli can actually prevent and treat ulcerative colitis.

Lactococcus Lactis

L. lactis has only limited medicinal value compared to other probiotic species, but it offers extensive commercial and culinary value. Almost all forms of cheese and buttermilk are manufactured using appropriate strains of L. lactis.

Other Notable Families of Bacteria:



Akkermansia feeds on mucus secreted by our gut lining to protect itself against invading bacteria. It also helps to strengthen the gut wall and reduce inflammation. Akkermansia is a desirable form of bacteria which has been shown to reduce obesity, diabetes and inflammation.

Akkermansia Muciniphila

A. muciniphila is the only currently known species within genus Akkermansia. Its understood to have anti-inflammatory properties, and tends to be found in greatly reduced quantities in patients with irritable bowel syndrome (IBS). In studies on mice it was also found to have a positive effect on obesity and diabetes, raising insulin sensitivity and metabolic health.
You can raise the amount of Akkermansia in your gut through intermittent fasting and by including foods high in polyphenols in your diet – such as chocolate, nuts, fruits and berries, teas and red wine.


Christensenella is a form of bacteria often found in lean people – particularly those who enjoy poor diets but seem able to effortlessly maintain their shape.  Christensenella appears to be hereditary and currently there is no evidence to suggest that consuming them as a probiotic will have any effect.


Firmicutes make up the largest portion of the human gut microbiome. They help digest the fat in our diet, and in times of scarcity having a large firmicute community was a good thing, allowing people to extract the most energy from their food. Now however larger numbers of Firmicutes are associated with poor diets high in fat and sugar and are linked with obesity and diabetes.
They are used commercially for a range of tasks, most notably to ferment beer and wine. To reduce the proportion of firmicutes in your gut you should cut down on sugars and processed or refined starches