What are probiotics?

Probiotics are living bacteria and yeast that have health benefits, particularly for the digestive system, when consumed in sufficient quantities (1).

Probiotics can be found in supplements (in capsule, pill, powder, or liquid form) and in some fermented foods, such as yoghurt, kefir, sauerkraut, kimchi, miso, tempeh, and kombucha.

Probiotics are classified by their genus (e.g., Lactobacillus), species (e.g., plantarum), and strain (e.g., 299v). It is important to select the right strain to align with your desired benefits, as the effects can differ significantly between strains (2).

The two most common probiotics found in supplements and food are Lactobacillus and Bifidobacterium (3). Saccharomyces Boulardii is a beneficial yeast that is commonly used in probiotic products (3).  

What are the benefits of probiotics?

Probiotics offer a range of benefits, such as the regulation of digestion, the restoration of a healthy balance of gut bacteria, the renewal of intestinal cells, the prevention of harmful pathogen growth, and the production of helpful substances like short-chain fatty acids (SCFAs)(4,5). These shared benefits, known as "core benefits," are common among most probiotic species.

In contrast, certain effects are unique to specific probiotic species. These effects include vitamin synthesis, amino acid generation, protection of gut barrier integrity, microbiota alteration, hormone regulation, bile salt production, enzymatic support, carcinogen neutralisation, and regulation of metabolic processes like cholesterol absorption, blood pressure, and glucose metabolism (4,5,6).

Some of the conditions that respond well to probiotics include (5,6,7,8):

• Diarrhoea and constipation
• Irritable bowel syndrome (IBS)
• Inflammatory bowel disease (IBD)
• Infant colic
• Anxiety and depression
• Infections, including urinary tract and respiratory tract infections
• Bacterial vaginosis
• Allergies
• Gum disease
• Eczema
• Acne
• Insulin resistance
• Type 2 diabetes
• Non-alcoholic fatty liver disease (NAFLD)
  
  

How do probiotics work?

Probiotics work via five main mechanisms (4,6):

Strengthening the gut barrier: Through promoting mucous production and tightening junction proteins, probiotics seal gaps between intestinal cells, preventing harmful substances from entering the bloodstream from the intestine.

Balancing gut bacteria: Probiotics help maintain a healthy balance of bacteria in the gut, known as the gut microbiome, by promoting diversity and beneficial bacterial populations.

Regulating the immune system: Probiotics stimulate the production of immune cells that reduce inflammation, balance immune function, and enhance the body’s defence mechanisms.

Promoting antimicrobial activity: Certain probiotics produce antimicrobial substances that can inhibit the growth of harmful bacteria and pathogens in the gut.

Competitive exclusion: Probiotics outcompete harmful bacteria for nutrients and space, inhibiting their growth in the gut.

When is the ideal time to take probiotics?

You can choose when to take probiotics, but it is important to be consistent. Follow the product's guidelines and allow time to observe its impact on your gut health and well-being. Taking your probiotic at a specific time, such as before bed or in the morning, may suit you better.

Can I take probiotics with antibiotics?

Taking probiotics alongside antibiotics can prevent or lessen some of the less desirable effects of antibiotics on your gut microbiome, such as diarrhoea (9,10).

Lactobacillus rhamnosus GG and Saccharomyces boulardii appear to be the most effective probiotics for preventing antibiotic-associated diarrhoea (11).

Key take-away

Probiotics are living microorganisms with health benefits, particularly for the digestive system. They regulate digestion, restore gut balance, and offer unique effects such as vitamin synthesis and hormone regulation.

Probiotics work by strengthening the gut barrier, balancing bacteria, regulating the immune system, promoting antimicrobial activity, and outcompeting harmful bacteria.

Choosing the right probiotic strain to align with your desired benefits is crucial, as the effects can vary significantly.

While probiotics are generally considered safe, always consult a healthcare provider before starting any new supplement, including probiotics.