Probiotics - what are they?

Probiotics are “good” bacteria that live in our digestive system and help to keep our digestive system and the rest of our bodies healthy.

We usually think of bacteria and fungi as being bad for us since some types can cause infection and illness. But, our bodies are covered in bacteria, most of which helps to keep the bad bacteria at bay (1). Probiotics is the term used to group together all the types of good bacteria and fungi that have important functions for promoting health, including forming part of our immune system and fighting off other bacteria and toxins that could make us ill, or helping to digest food into usable vitamins (2).

Some of the most studied strains of probiotics are from the Bifidobacterium, Lactobacillus, Enterococcus and Streptococcus genera.

Research-based benefits of probiotics

Research has demonstrated the following benefits of probiotics for health. Probiotics may help:

  • Reduce symptoms of gut disorders including
    • inflammatory bowel disease (3)
    • irritable bowel syndrome (4)
    • constipation (4)
    • diarrhea (4)
  • Treat infections (5)
    • Skin infections (topical probiotics) (6)
    • Vaginal, yeast, and urinary tract infections (7)
  • Prevent allergies (8)
  • Prevent autoimmune diseases (9)
  • Promote weight loss (10)
  • Protect against chronic diseases
    • Diabetes (11)
    • High cholesterol (12)
    • High blood pressure (13)
    • Heart disease (14)
  • Help prevent osteoporosis (15)
  • Help prevent colon cancer (16)
  • Improve migraines and headaches (17)
  • Prevent and treat mental disorders
    • Anxiety and depression (18, 19)
  • Manage symptoms of autism (20)
  • Improve exercise performance (21)
  • Protect from male infertility (22)
  • Improve symptoms of polycystic ovarian syndrome (23)

Recommended for:*

Many people may benefit from taking a probiotic, including people who want to support

  • Digestive health
  • Brain mental health
  • Bone health
  • Heart health
  • Reproductive health
  • Immune health
  • Healthy weight loss

*These are general recommendations and do not replace medical prescriptions or recommendations.

If you have an extremely weak immune system due to a particular illness, active autoimmune disease in the gut, or kidney disease, you should consult with your doctor before taking probiotics, as these pose an extra risk for you.


Research Summary




Study Reference

Multispecies probiotic supplementation reduced cognitive reactivity to sad mood.

Compared to participants who received the placebo intervention, participants who received the 4-week multispecies probiotics intervention showed a significantly reduced overall cognitive reactivity to sad mood, which was largely accounted for by reduced rumination and aggressive thoughts.

Multi-species probiotic:Bifidobacterium bifidum W23, Bifidobacterium lactis W52, Lactobacillus acidophilus W37, Lactobacillus brevis W63, Lactobacillus casei W56, Lactobacillus salivarius W24, andLactococcus lactis (W19 and W58), over 4 weeks


Probiotics and glutamine improve recovery of brain injury patients

An enteral formula containing glutamine and probiotics decreased the infection rate and shortened the stay in the intensive care unit of brain injury patients.

Not reported


Decrease in nasal symptoms in people with perennial allergies

These results suggest that oral administration of L-92 can alleviate the symptoms of perennial allergic rhinitis, however, statistically significant changes were not shown in blood parameters.

Lactobacillus acidophilus


Decrease in allergy stymptoms

omparison of subjective symptom scores indicated significant decreases in rhinorrhea, nasal blockage and composite scores in the BB536 group compared with the placebo group. Comparison of medical scores showed marked improvements in all symptoms on BB536 intake.

Bifidobacterium longum BB536


Decreased number of episodes of rhinitis in children, and duration of diarrhea episode is lower

In children with rhinitis or diarrhea, the annual number of rhinitis episodes was lower in the intervention group, when compared to the control group.

Lactobacillus casei


Decreased antigens, increased immune factors.

Volunteers treated with Lactobacillus casei Shirotashowed a significant reduction in levels of antigen-induced IL-5, IL-6 and IFN-gamma production compared with volunteers supplemented with placebo. Meanwhile, levels of specific IgG increased and IgE decreased in the probiotic group.

Lactobacillus casei Shirota (LcS)


Reduced dietary fat absorption

there was a statistically significant difference in the percentage change in body weight between the Lactobacillus JBD301 and the placebo group as well as in the BMI from the 0-week assessment to the 12-week assessment.

Lactobacillus JBD301


Reduced weight

Heat-killed LP28 reduced BMI, body fat percentage, body fat mass  and waist circumference when compared with a placebo group.

Pediococcus pentosaceus LP28


Reduced abdominal fat

The probiotic LG2055 showed lowering effects on abdominal adiposity, body weight and other measures, suggesting its beneficial influence on metabolic disorders.

Lactobacillus gasseri SBT2055 (LG2055)


Prevention of autoimmune diabetes and increases insulin sensitivity (animal trial)

Early oral administration of VSL#3 prevented diabetes development in non-diabetic mice. Protected mice showed reduced insulitis and a decreased rate of beta cell destruction.

VSL## (Bifidobacteriaand freeze-dried lactic acid)


Prevention of diabetes

Probiotic interventions resisted insulin resistance and development of diabetes in mice under high-fat diet feeding and beneficially modulated all the biochemical and molecular alterations in a mechanistic way in several tissues.

Lactobacillus plantarum MTCC5690 and Lactobacillus fermentum MTCC5689


Reduction in hypertension

After adjustment for potential confounders, the risk of developing hypertension is substantially lower in elderly people who take fermented milk products containing LcS at least 3 times a week.

Lactobacillus casei strain Shirota (LcS)


Normalized gut discomfort and psychiatric symptoms in people with schizophrenia

The administration of probiotics may help normalize C. albicans antibody levels and C. albicans-associated gut discomfort in many male individuals. Studies with larger sample sizes are warranted to address the role of probiotics in correcting C. albicans-associated psychiatric symptoms.

Candida albicans andSaccharomyces cerevisiae


Improvement in cognitive function and metabolic statuses of Alzheimer’s disease patients

After 12 weeks intervention, compared with the control group, the probiotic treated patients showed a significant improvement in the Mini-Mental State Exam (MMSE) score. In addition, changes in plasma malondialdehyde, serum high-sensitivity C-reactive protein, homeostasis model of assessment-estimated insulin resistance, Beta cell function, serum triglycerides, and quantitative insulin sensitivity check index in the probiotic group were significantly varied compared to the control group.

Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, andLactobacillus fermentum