What are Probiotics?

The natural microflora of the colon are abundant and diverse. There are over 500 species of bacteria that are living in the human gastrointestinal tract.^[1] The concentrations of these microflora amount of about 1 trillion cells per gram of colon content and approximately 60 percent of faecal solid mass is made up of these bacteria.^[5] Ninety-nine percent of the human intestinal flora is made up of anaerobic bacteria, principally Bacterioides, Bifidobacterium, Eubacterium, and Propionobacterium species.^[6]

The particular mix of bacteria in an individual’s intestine is influenced by the specific metabolic environment, depending on factors that include age, diet, pH, intestinal motility, secretions, mucus, and the immune system.^[7]

Important bacteria that reside in the gastrointestinal tract are lactic acid bacteria such as:^[8][9]

• Bifidobacteria, including B. longum, B. bifidum, B. infantis, and B. breve
• Lactobacilli, including L. rhamnosus and L. acidophilus.

The natural microflora used in probiotic preparations have been found to play a key role in improving digestive balance through their interaction in three main areas:

Metabolic

- The intestinal microflora contribute to the digestive process by secreting enzymes that help break down foods that are not digested in the stomach. They can also contribute to the breakdown of proteins and fats.^[10]

Pathogen inhibition

- Intestinal microflora limit the growth of harmful microorganisms in the intestinal tract by competing with them for nutrients and space. They also produce substances, including lactic acid and other organic acids that lower the pH of the intestine, creating a less hospitable environment for pathogens. Intestinal microflora produce substances that act like antibiotics, inhibiting the growth of harmful bacteria. There is also evidence to suggest that probiotic bacteria may send signals to intestinal cells to strengthen their barrier integrity to prevent the invasion of bad bacteria^[11][18]

Immunologic interactions

- The presence of probiotic bacteria is helpful for the maturing of the immune system and maintaining the balance between pro-inflammatory and anti-inflammatory factors at the intestinal mucosa.^[12] Probiotic bacteria have been shown to induce the production of interleukin-10, an important “chemical messenger” that suppresses inflammation.^[17]