Most people have heard that probiotics promote health, but the whole subject of these microorganisms is confusing to consumers for two reasons. First, there are over 20,000 medical articles written in the last 15 years referencing the multitude of different probiotics. And second, most probiotic supplements contain a long list of different probiotic species with nearly unpronounceable Latin names. Let’s try to simplify and elucidate this vast field. The human intestine contains an estimated 100 trillion microbes, made up of about 160 different species. These microbes serve the important direct functions of preventing infections, promoting healthy digestive function, and modulating the immune system. In addition they help balance other metabolic body systems.
What are probiotics?
Probiotics are live microorganisms that confer health benefits when consumed in adequate amounts. These microbes come in two common varieties: the genus Lactobacillus and Bifidobacterum. Other probiotics are used as well, but Lactobacillus species and Bifidobateria species comprise the majority of probiotic supplements. Most Lactobacillus species are transient, that is they do not persist unless they are replenished. There are more than 100 Lactobacillus species. They are plentiful in the intestines of people who eat a plant-based diet, but less than 25 percent of adults who eat a standard Western diet have any Lactobacillus bacteria. Bifidobacteria are natural residents of the large intestine that are plentiful in breastfed babies, but decrease with age.
Lactobacillus species have a variety of beneficial effects including:
- Help metabolize proteins and carbohydrates
- Fight pathogens including the bacteria Staphylococcus, Salmonella, and H. pylori, and the yeast Candida.
- Enhance the immune system
- Synthesize B vitamins and vitamin K
Bifidobacteria species have some similar and some unique effects:
- Inhibit pathogens
- Reduce intestinal barrier permeability
- Relieve constipation
- Prevent traveler’s diarrhea and antibiotic-associated diarrhea
- Metabolize lactose and ferment indigestible carbohydrates
- Synthesize B vitamins
Taking probiotics
It is better to take probiotic supplements with food since undiluted stomach acid tends to kill the bacteria before they reach the intestines. And second, it is best to take a variety of species in a supplement, but it is not necessary to rotate the probiotics that you take.
Specific species of probiotics
Lactobacilli
- L acidophilus is the most common probiotic contained in supplements. It is used to make fermented foods including yogurt. It is not a natural resident of the digestive tract in humans, but must be ingested. L acidophilus breaks down gluten and casein and ferments lactose and other sugars. It inhibits a wide range of pathogens including Candida species, rotavirus, and H pylori.
- L plantarum resides in the intestines if people eat a traditional plant-based diet. It promotes intestinal barrier function and prevents inflammation. It also supports normal bowel flora in people with irritable bowel syndrome.
- L rhamnosus enhances the immune system and inhibits inflammation by decreasing cytokine production. It antagonizes rotavirus, Candida, E coli, Staph, and many other pathogens.
- L fermentum helps reduce cholesterol levels and has been used to prevent and treat urinary tract infections in women.
- L reuteri prevents dental plaque and gum disease as well as allergies. It treats diarrhea and inhibits H pylori.
Bifidobacateria
- B bifidum populates the healthy colon. It has specific effects on allergies, boosting immune function and suppressing antigen-specific IgE production responsible for allergies. It also supports healthy intestinal bacteria during antibiotic therapy and antagonizes a wide range of pathogenic microbes including H pylori, Salmonella, and rotavirus.
- B longum has a wide range of anti-inflammatory effects including the inflammation in ulcerative colitis and in respiratory allergies. It is the dominant Bifidobacterium species in humans.
Other probiotics include L salivarius which supports intestinal barrier function while preventing leaky gut and Saccharomyces boulardii is not a bacterium, but a yeast that competes with candida and treats yeast overgrowth as well as improving intestinal barrier integrity. It successfully treats Crohn’s disease, ulcerative colitis, and parasites including amoebas and Giardia.
