Research on probiotics has increased significantly in recent years, so much that today the therapeutic action of probiotics is a very widely studied and documented topic.

Some of the bacteria in our gut are capable of producing vitamin K and short-chain fatty acids, which are the main source of nutrients for the cells that line the colon. These cells promote a strong intestinal barrier that helps keep out harmful substances, viruses and other unwanted bacteria. They are also believed to have positive effects on modulating the immune system and strengthening it.


Lactobacillus and Bifidobacterium are among the most common probiotic bacteria. The first proliferate in our intestine, while the genus Bifidobacterium thrives in the colon. These “good” bacteria help the bacteria living in the intestine to process food improving digestion, as well as strengthen the immune system and prevent a number of diseases.

Many types of bacteria are classified as probiotics, most of them belong to these two species. All probiotics have different characteristics, and specifically offer different benefits. Let’s see some of the most common in more detail:

Representing the most important group of bacteria in our small intestine, the Lactobacillus genus groups over 80 recognized species and is characterized by a high level of diversity. These bacteria are found in yogurt and other fermented foods; they produce lactase, which breaks down the sugar in milk and ferments the carbohydrates you take in, to produce lactic acid. Lactic acid creates an acidic environment in the digestive tract, making it an inhospitable place for the proliferation of unhealthy microorganisms. It also helps our body absorb important minerals, such as iron, magnesium, copper and calcium.

Lactobacillus is useful for the treatment and prevention of irritable bowel syndrome, urinary tract infections, traveler’s diarrhea, antibiotic-related diarrhea, skin disorders such as acne and herpes, treatment of lactose intolerance and prevention of respiratory infections.

There are about 30 known species of bifidobacteria, some of them can be found in some dairy products. They make up most of the healthy bacteria in the colon. They appear in the intestinal tract within days of our birth, especially in breastfed babies, and are believed to be the best indicator of gut health. As probiotic agents, bifidobacteria have been studied for their efficacy in the prevention and treatment of a broad spectrum of human gastrointestinal disorders.

Some of the bifidobacteria commonly used as probiotics are Bifodobacterium bifidum, Bifodobacterium lactis, Bifodobacterium infantis, and Bifodobacterium thermophilum.

These bacteria produce lactic acid, which provides almost all of the energy needed by the cells to line the walls of the intestine, thus helping to enhance the natural protective barrier in our digestive tract. Lactic acid is useful for keeping the pH of the large intestine acidic and discouraging the proliferation of unhealthy bacteria and yeasts. A low pH environment also facilitates your body’s ability to absorb minerals such as iron, zinc, magnesium, copper, and calcium.

Bacilli are “good” bacteria that also produce lactic acid. They are very resistant bacteria that are able to work in the acidic environment of our stomach. When introduced, they readily colonize the small intestine and remain in our body for longer periods of time than many other bacteria. Bacillus includes parasitic and non-parasitic species. In addition to the few types in the human body, many bacillus bacteria grow in soil and are used as pesticides and plant growth additives.

This type has been used extensively in food processing throughout human history
Leuconostoc are traditionally found in association with vegetable substances, fermenting vegetables, milk, dairy products, wines and meats. This bacterium, together with other lactic bacteria, is the main responsible for the fermentation of the cabbage that takes place to obtain sauerkraut.

Saccharomyces boulardii
Saccharomyces boulardii is the only probiotic yeast, in fact not all probiotics are bacteria. Some studies have established that it is useful in the prevention and treatment of diarrhea associated with the use of antibiotics, and traveler’s diarrhea. It helps regulate the intestine and protect it from pathogens and other substances that can be harmful to the intestinal lining.

Streptococcus species incorporate numerous harmful and other beneficial bacteria. Probiotic bacteria of this species can help strengthen the immune system and prevent certain infections. They are lactic bacteria and ferment glucose into lactic acid. Streptococcal probiotics are found in mucous membranes and even on the skin. They can also move into the deeper tissues of the body.

Streptococcus thermophilus
This type of probiotic is also classified as a lactic acid bacterium; it is found in fermented milk products and is generally used in yogurt making. It is said to produce large quantities of the lactase enzyme, making it effective in preventing lactose intolerance.