Probiotics are microorganisms that can improve a person's health.

By balancing intestinal microflora, probiotics play an important role in regulating intestinal function and digestion. Microflora are the microscopic algae and fungi already present in the digestive system.

The World Health Organization (WHO) define these "good" bacteria as "live microorganisms which when administered in adequate amounts confer a health benefit on the host."

The human body contains approximately 3.5 pounds (lb) of probiotic bacteria. This is more than the weight of the brain.

Probiotics are also consumed in fermented foods with active live cultures, such as yogurt. They are available in supplement form as capsules, liquids, and powders.

Fast facts on probiotics

  • Probiotics are microorganisms that actively provide health benefits to their host.
  • They have shown benefits for digestion, blood pressure, brain function, irritable bowel syndrome (IBS), and combating infection.
  • They are available as supplements or in fermented food products, such as yogurt, kimchi, miso, and aged cheeses.

Health benefits

Lactobacillus probioticShare on Pinterest
Lactobacillus is a probiotic strain found in yogurt.

It should be noted that many of the possible health benefits of probiotics still require further confirmation and research.

The effects of probiotics on the body vary between microorganisms and strains.

1) Treating diarrhea

Certain strains of probiotics have demonstrated positive results in treating diarrhea and gastroenteritis. According to a report published in the Journal of Pediatric Gastroenterology and Nutrition, probiotics are effective at combating different forms of diarrhea.

One study published in the Journal of Pediatrics concluded that Lactobacillus species are safe and effective for treating children with infectious diarrhea.

The researchers concluded that preventive consumption of Lactobacillus species could significantly reduce the risk of diarrhea, particularly nosocomial rotavirus gastroenteritis.

2) Brain function

Probiotics may be beneficial for brain function. Researchers at UCLA found that brain function improved among healthy women who regularly consumed yogurt containing probiotics.

"Our findings indicate that some of the contents of yogurt may actually change the way our brain responds to the environment."

Dr Kirsten Tillisch, study author, UCLA

Researchers have also suggested a connection between probiotics and anxiety. Studies have demonstrated the stress-reducing qualities of probiotics in mice. While this link remains untested in humans, the findings suggest possible ways in which probiotics can support the treatment of mental health problems.

3) Cholesterol

Research has also suggested that a formulation of Lactobacillus reuteri NCIMB 30242 can reduce levels of low-density lipoprotein (LDL) in the blood. LDL is sometimes referred to as "bad" cholesterol.

In the study, two daily doses of L. reuteri NCIMB 30242 lowered both "bad" and total cholesterol in the blood.

Dr. Mitchell Jones, one of the authors of the study, showed that probiotics can "in particular reduce the cholesterol esters associated with "bad" saturated fatty acids in the blood."

4) Blood pressure

One study has found that milk fermented with strains of Lactobacillus may help lower blood pressure.

In addition, this study shows that probiotics can increase vitamin D levels in the blood through their metabolic processes. Vitamin D also helps to prevent the increase of blood pressure. More clinical trials are required to confirm the blood pressure benefits of probiotics.

5) Irritable bowel syndrome

There is growing evidence that probiotics can help treat irritable bowel syndrome (IBS).

Two review articles, published in Nutrition in Clinical Practice, examined therapeutic approaches to IBS. They found that probiotics are highly effective at managing IBS, especially Bifidobacterium infantis.

6) Infection

Scientists found that probiotic bacteria can protect against infection by more harmful bacteria.

Lactobacillus paracasei offers significant protection against the foodborne Listeria infection. A special Listeria-adhesion protein is added to L. paracasei.

The probiotic microorganism will then latch on to the intestinal cells in place of Listeria, creating a competition between microorganisms that can prevent the harmful infection from finding a place to attach.

At this stage, only human cells have been tested, and more studies need to be carried out on living organisms to confirm the effects of L. paracasei on infection.

7) Psoriasis and chronic fatigue syndrome (CFS)

Scientists at University College Cork, Ireland, reported in the journal Gut Microbes that Bifidobacterium infantis 35624 may also have benefits for patients with psoriasis and chronic fatigue syndrome.

Bifidobacterium infantis 35624 is a probiotic available in the United States (U.S.) for fortifying the digestive system.

This study is significant, the authors added, because it shows that a single probiotic can affect the systemic immune system in humans, and not only the mucosal immune system. The mucosal immune system protects the respiratory system, the urogenital tract, and the lining of the stomach.

These are the first areas pathogens, or infectious microorganisms from outside the body, can infect.

Systemic immune defence, however, works throughout the body. If probiotics can act in support of systemic immunity, they can respond to conditions like psoriasis and chronic fatigue syndrome.

Foods that contain natural probiotics include:

  • yogurt
  • kefir
  • buttermilk
  • soft or aged cheeses
  • kimchi
  • unpasteurized sauerkraut
  • miso
  • tempeh
  • some soy beverages

Probiotic-fortified products are also available, such as juices, chocolates, flour, and cereal.

Always make sure that the probiotics you take are suitable for management of your condition.