We’ve talked on our blog about how important the gut is to overall health, so much so that some talk about the gut as a “second brain.” There are numerous claims about how probiotics can help your digestive health, but there’s not a lot that explains exactly what probiotics are, or how you can know whether they might help you. In this post and our next one, we’ll take you through you the basics on these microorganisms.
What are probiotics?
Probiotics are bacteria that are similar to, or in some cases the same as, microorganisms that are naturally found within the human body. That’s why they’re sometimes called “good bacteria.” Though the benefits of foods containing live bacteria have been noted for centuries, it wasn’t until the beginning of the 20th century that scientists realized how probiotics might work. It’s generally proposed that these good bacteria can replace harmful microbes, aiding in digestion and promoting health. The term “probiotic” was coined in the 60s, derived from a Greek word meaning “for life.”
Probiotics are just some of what lives in your gut. The human gastrointestinal tract is home to over 500 bacterial species—in fact, bacterial cells outnumber human cells by a factor of 10 to 1! These bacteria are like factory workers within your gut helping to acidify the colon (which sounds scary but is a good thing), facilitate digestion, provide your body with nutrients, and support your immune system. They produce nutrients including vitamin K, several B vitamins, folate, and short-chain fatty acids. The byproducts of bacterial fermentation in your gut can provide up to 10% of your daily energy needs, making them quite powerful indeed.
You may also have heard of prebiotics, which aren’t the same as probiotics. Prebiotics are a special type of soluble fiber that is mainly used by “good bacteria” (aka probiotics) as fuel. There are two main types of prebiotics: Fructo-oligosaccharides (FOS) and inulin. FOS are made up of plant sugars linked in chains, and can be used to make medicines. They can be taken from asparagus, Jerusalem artichokes, and soybeans, or produced in the laboratory. Inulin has been found in over 36,000 varieties of plants (leaving little doubt that it’s been part of diets for many years), but today we get inulin from a fairly limited range of sources. Most Americans get very little of this important fiber (on the order of only 2-3 grams daily), mainly from wheat and onions. In contrast, Europeans average 3 to 5 times as much daily consumption of inulin! How can you get more of this valuable prebiotic? In addition to onions and wheat (which many try to avoid for gut health), bananas, garlic, leeks, chicory root, jicama, agave, wild yams, and Jerusalem artichokes are also good sources of inulin.
Are there different kinds of probiotics?
The kinds of probiotics you get in foods and supplements consist of yeast and bacteria. Probiotic products might have a single kind of microorganism, or a mix of multiple species. The most common kinds of probiotics include lactic acid bacteria (especially the species lactobacillus and bifidobacterium) and the yeast saccharomyces boulardii.
Not all probiotics are created equal. First, they need to be safe and effective in humans (though they’re generally safe, not every bacteria is a “good” one). Second, the probiotics need to be able to remain viable — in other words, stay alive — for the shelf life of the product. Last, they face many hurdles getting into your gut. The probiotics need to be able to survive acid and bile to be able to adhere to the epithelium, colonize and reproduce, and live alongside the existing gut flora.
This means that you can’t really generalize about the health benefits of all probiotics. The effects tend to be specific to particular strains. Even within a species, one strain may have health benefits while another does not. The effects can also vary from person to person, so products boasting more than one kind of organism often have a better chance of being effective.
What are the benefits of probiotics?
The main reason for using probiotics is to restore microbial balance in the gut. For most healthy adults, this isn’t an issue, but antibiotics, some medications (particularly those that suppress the immune system), surgery, and irradiation can let the levels of “bad” bacteria grow. This can cause an imbalance that probiotics can aid in correcting.
Though probiotics have been used for years to support general wellness and to treat different conditions, the evidence supporting their efficacy has varied. Part of the reason for this is the variation in strains, differences between probiotic products, and the difficulty of quality control with live organisms. Additionally, since many probiotics are most effective in combination, it can be hard to identify exactly which are providing health benefits. As a result, the FDA has not officially approved probiotics for the treatment of any specific disease or condition, though they are regularly used by complementary and alternative health practitioners, and anecdotally many people have found symptom relief from them.
A large volume of research on probiotics continues to accumulate, and studies have found that they can be effective in treating various ailments. Here’s a summary of some of the latest research on probiotics:
- Probiotics are sometimes used to treat diarrhea associated with irritable bowel disease and irritable bowel syndrome. Here, the jury’s out — some studies have shown that probiotics provide relief, while others have not found a significant difference between patients who consume probiotics and those who do not.
- A 2013 review looking at 23 different studies of clostridium difficile-associated diarrhea (CDAD) that enrolled more than 4,200 participants found that overall, probiotic use was associated with a 64% reduction of risk. CDAD occurs when antibiotics have reduced the healthy gut flora, allowing “bad” bacteria like clostridium to take over. Probiotics seemed to mitigate this risk, bolstering the “good” bacteria, keeping the “bad guys” in check, and reducing the chances that adults and children taking antibiotics would contract CDAD.
- An October 2012 study in the Journal of Allergy and Clinical Immunology found that mothers with a history of allergies who took probiotics during pregnancy and while breastfeeding had children who were less likely to develop eczema. A separate 2013 review of studies on the topic also found that most showed probiotics helped to reduce the incidence of eczema in infants.
- A 2013 study used functional MRI to assess whether probiotics can modulate brain activity. Sponsored by Danone (the company that makes Activia yogurt, among other products), the researchers found that women who regularly consumed yogurt that contained probiotics showed altered activity in the brain regions that control central processing of emotion and sensation. Though more research is needed, it does show that probiotics may impact the brain.
- While the exact mechanisms are not yet understood, research has shown that probiotics may lower cholesterol. They seem to regulate the expression of some proteins that affect lipid profiles.
Probiotics are also being studied in many more areas, including allergic rhinitis, hepatic encephalopathy, and post-surgical infections. Adverse effects from probiotics are rare, plus they’re generally mild and subside with time, making them a potentially safe treatment for many conditions. Though there are some concerns about more troublesome side effects, at this point these are theoretical. For healthy people, probiotics should be tolerated well. People who are taking antifungal or immunosuppressant medications, or who are undergoing chemotherapy, should consult a doctor before taking probiotics. In some cases, staggering the timing of the supplements and the medications can enable both to be effective, but it’s important to talk to a professional first.
Want to learn more about what probiotics are the most effective, and how you can ensure you’re giving your gut bacteria the support they need? In our next post, we’ll tackle those questions — and let you know whether yogurt is really an effective way to get probiotics. Have questions about your gut health, and whether probiotics can help you? Dr. Tang can help you with individualized advice. Call Rejuvé today at 408-740-5320 to schedule a consultation.