Bacteria have gotten a bad reputation, and for good reason. Bacteria are behind a number of serious diseases—including pneumonia (Streptococcus pneumoniae), meningitis (Haemophilus influenzae), strep throat (Group A Streptococcus), food poisoning (Escherichia coli and Salmonella) and a variety of other infections.
These “bad” bacteria are the reason why we diligently disinfect our hands and wipe down our kitchen and bathroom sinks, as well as any other places where germs tend to congregate. We also have developed a wide range of antibiotics, which are drugs designed to kill the bacteria that cause disease.
Yet not all bacteria are bad guys. In fact, our bodies are home to an estimated 100 trillion “good” bacteria, many of which reside in our gut. Not only do we live in harmony with these beneficial bacteria, but they are actually essential to our survival.
Good bacteria help our bodies digest food and absorb nutrients, and they produce several vitamins in the intestinal tract—including folic acid, niacin, and vitamins B6 and B12. According to research published in the journal Best Practice & Research Clinical Gastroenterology, beneficial bacteria may also protect us against their dangerous relatives that cause disease by crowding them out in the gut, producing acids that inhibit their growth, and stimulating the immune system to fight them off (BPRCG, 2003).
When helpful bacteria multiply and thrive in our bodies, they act as our protectors. But sometimes, we put the population of beneficial bacteria at risk. When we take antibiotics to treat an infection of harmful bacteria, we also kill helpful bacteria. This can cause an imbalance of bacteria in the body that can lead to diarrhea and other gastrointestinal problems.
Probiotics and Health
The idea that certain types of bacteria can improve our health has been around since the early 20th century, when Nobel prize-winning Russian biologist Elie Metchnikoff first proposed that eating bacteria similar to those living in the body could have health benefits. More recently, companies started marketing products containing these bacteria, called probiotics (which means “for life”).
Probiotics are available in many forms, including supplement pills, suppositories, and creams. Many foods contain friendly bacteria, such as yogurt, buttermilk, and cheeses with live active cultures. Other foods that contain friendly bacteria include fermented foods like miso, tempeh, sauerkraut, beer, sourdough bread, chocolate, and kimchi.
According to the National Center for Complementary and Alternative Medicine (NCCAM), probiotics are used to prevent and treat a variety of health conditions, such as:
- diarrhea (including diarrhea caused by antibiotics)
- irritable bowel syndrome
- ulcerative colitis and Crohn’s disease
- tooth decay, gingivitis, and periodontitis
- eczema (NCCAM, 2011)
Types of Probiotics and What They Do
Below are a few of the probiotics that are taken to treat or prevent disease, and how they’re thought to work.
In the body, lactobacillus bacteria are normally found in the digestive, urinary, and genital systems. You can also find them in yogurt and dietary supplements, as well as in suppositories.
More than 50 different species of lactobacillus exist, including:
- Lactobacillus acidophilus, one of the most commonly used probiotics. It’s found in yogurt and fermented soy products such as miso and tempeh. According to the University of Maryland Medical Center (UMMC), Lactobacillus acidophilus has been used (in suppository form) to treat bacterial infections of the vagina. In pill form, it can be taken to prevent and treat diarrhea, including traveler’s diarrhea in adults and diarrhea caused by rotavirus in children (UMMC, 2011).
- The National Institutes of Health (NIH) report that Lactobacillus rhamnosus GG may help treat traveler’s diarrhea, or diarrhea that’s caused by Clostridium difficile (C. difficile) bacteria or by antibiotics in children. It’s also been found to be helpful for preventing eczema in infants (NIH, 2011).
- Lactobacillus salivarius may help block the growth of Helicobacter pylori (H. pylori), the bacteria that cause peptic ulcers (Ryan et al., 2008).
- Lactobacillus plantarum can improve the immune system barrier against invading disease-causing bacteria (Anderson et al., 2010).
Other uses for lactobacillus include:
- preventing diarrhea caused by antibiotics and infection
- preventing colic (inconsolable crying) in babies
- preventing lung infections in young children
- preventing diarrhea in adults who are in the hospital or receiving chemotherapy treatment for cancer
- treating bowel conditions such as irritable bowel syndrome (IBS) and ulcerative colitis
Bifidobacteria make up most of the “good” bacteria living in the gut. These bacteria begin colonizing the gastrointestinal system almost immediately after we’re born.
Bifidobacteria come in about 30 different strains, including:
- Bifidobacteria bifidum may help protect against unhealthy bacteria. Research suggests they also can relieve IBS symptoms (Guglielmetti et al., 2011). When combined with Lactobacillus acidophilus, Bifidobacteria bifidum might help prevent eczema in newborns (Kim et al., 2010).
- Bifidobacteria infantis are thought to help relieve the symptoms (such as abdominal pain, gas, and bloating) of IBS (Kovacs & Stöppler).
- Bifidobacteria lactis has been reported to improve cholesterol levels in women and in people with type 2 diabetes.
These bacteria produce the enzyme lactase, which the body needs to digest the sugar in milk and other dairy products. Some studies suggest Streptococcus thermophilus can help prevent lactose intolerance (MedicineNet).
Saccharomyces boulardii is actually a type of yeast, but it acts as a probiotic. Some studies have found it helpful for preventing and treating traveler’s diarrhea, as well as diarrhea caused by antibiotics. It may also be useful for treating acne, and reducing the side effects of antibiotic treatment for H. pylori bacteria.
Cautions Regarding Use of Probiotics
Before you take any probiotic supplement, remember that the U.S. Food and Drug Administration (FDA) has not approved these products. That means you can’t be sure when you buy a product whether it’s safe and effective. There have been cases reported of people developing bacteria (bacteremia) or fungi (fungemia) in the blood after taking probiotics. More clinical studies are needed to confirm the benefits of probiotics, as well as the possible risks (NCCAM, 2011).
Let your doctor and pharmacist know before you take any probiotic supplement. Ask whether it’s safe for people with your health conditions, and if it will interact with other medications you are already taking. It’s especially important to tell your doctor before using these supplements if you are pregnant or nursing, you have a weakened immune system from a condition such as HIV/AIDS, or you’re taking drugs that suppress your immune system.