There's plenty of buzz about healthy bacteria in some yogurts, supplements, and other foods. The stories range from study results to scam warnings. Here, two NASM experts clear up confusion and offer a few surprising options of foods that contain probiotics. Spoiler: They're definitely worth eating!
Having a healthy gut or gastrointestinal (GI) tract is largely a numbers game, says Dr. Geoff Lecovin, MS, DC, ND, L.Ac., CSCS, CISSN, NASM-CPT (CES, PES, FNS) and an NASM Master Instructor, who holds master’s degrees in nutrition, exercise science, and acupuncture. In the adult gut, there are 100 trillion live microbes, also called microbiota. These bacteria outnumber our own body cells 10 to 1, but thankfully not all of these microbes are pathogenic. Some are not only beneficial but essential. (1)
When it comes to these bacteria, “you’re basically trying to outnumber the bad guys with the good guys,” says Dr. Lecovin, owner of Northwest Integrative Medicine in Redmond, Wash. “Probiotics are live food ingredients that can alter this microbiota and confer health benefits,” he says. “They are symbiotic organisms that are there to live--and to help us live.” (1, 4)
Other probiotics-related numbers are also impressive. In 2015, probiotics made up $36.6 billion of the market in terms of ingredient sales, according to Global Market Insights, Inc. And this organization expects that figure to surpass $64 billion by 2023. (9) That’s probably not a bad thing: Research shows that people in Western countries have less diversity among bacteria in their GI tract than in previous years. Antibiotic overuse, excessive hygiene, smaller family sizes, and dietary changes (fewer whole foods, more simple carbs) are some of the things that have shielded Westerners from exposure to bacteria which, it turns out, is not entirely a good thing. (2, 4)
To make a long story short: Given the rising popularity and myriad health benefits of probiotics, it’s a good idea to understand what these good microbes can do and how to add them to a healthy diet. Here’s a primer.
What Probiotics Can Do
Probiotics are important for digestion, including the processing of indigestible fiber and absorption of nutrients. A healthy gut microbiota also helps protect the lining of the digestive system from damage caused by its own acidic bile. People who don’t have enough beneficial bacteria in their system may develop “leaky gut syndrome,” in which food substances permeate the intestinal walls and leak into the bloodstream. This can trigger allergies like eczema and autoimmune diseases, such as Crohn’s disease, ulcerative colitis, and celiac disease. (1, 2, 4)
Our beneficial gut bacteria also are involved in the production of hormonal compounds. These compounds travel throughout the body, affecting other organs, including the brain. In fact, probiotics may help in the treatment of depression. (1, 10)
Also, gut bacteria can strengthen the immune system. “About 80 percent of our immunity comes from our gut,” says Emily Bailey, RD, CSSD, LD, NASM-CPT, and Director of Nutrition for NutriFormance in St. Louis, Mo. Probiotics even appear to play a role in reducing inflammation, which is a biomarker for many serious diseases. (2)
Bailey says that more studies are needed to determine their specific benefits, but “thankfully probiotics are not something that is going to harm you.” She adds: “The more important piece is paying attention to whether or not you have the variety of cultures and enough active living organisms to confer these benefits.” (2) (Read on for ways to do that.)
But first, let’s examine the role that probiotics may play in obesity and exercise recovery—two areas that are of particular importance to you and your clients. (4)
Probiotics and obesity
In “Microbiota: An Exercise Immunology Perspective,” researchers write, “Assuming that obesity is at least partly an immune-mediated disease, it has been shown that the gut microbiota plays an important role in weight control, in addition to diet, lifestyle, genetics, and the environment.” In studies of mice and humans, obese subjects had different gut bacteria than their “lean counterparts,” adds Dr. Lecovin. Additionally, when those obese rodents had the microbiota of the lean rodents transplanted into their gut, they lost weight. (4)
“There are so many factors going into obesity,” cautions Bailey. “Probiotics are not a magic bullet by any means. (2) But for clients who are trying to lose a significant amount of weight, increasing the amount and variety of probiotics in their diet is an easy addition to their daily meal plan.
Probiotics and exercise
Regular exercise is good for the gut—and not just because it can help burn off belly fat. “Research has definitely shown that athletes in general have a more diverse microbial system,” says Bailey. (2) Exercise also speeds digestion, which shuttles pathogenic bacteria through your system more quickly, before it can do harm. (4)
However, prolonged and intense exercise can disrupt the GI tract. Endurance athletes tend to suffer from more GI problems and upper respiratory tract infections than the general population. So probiotics may be particularly helpful to them. (7, 8) Gut microbes may also assist in regulating metabolism and hydration—two other key factors in the exercise equation. (8)
Few studies have examined exactly how exercise impacts gut microbiota, but preliminary findings indicate that exercise combined with food restriction (two things clients often do in tandem) seem to reduce the number of beneficial bacteria in the gut. (4) Adding probiotic foods, beverages, and supplements may help offset this reduction.
Talking to clients about probiotics
Recommending specific probiotic products is technically outside of scope for personal trainers who don’t hold additional medical or nutrition certifications, notes Bailey. “I’m leery of personal trainers recommending specific supplements or foods,” she says. “There are so many factors that can affect health and weight.” If a symptom is affecting the day-in-day-out life of a client, it’s definitely time to refer out to a dietitian, physician, or other qualified party. (2)
Still, both experts agree that probiotics are generally a smart addition to most people’s diets. (1, 2) “Thankfully probiotics are not something that is going to harm you, so it’s more important to pay attention to making sure you have a variety of cultures. And enough of these active, living organisms,” says Bailey. (2)
Dr. Lecovin agrees. Research has shown that having a greater variety of bacterial species in the gut is associated with better overall health. “Studies show different strains target health for specific reasons,” says Dr. Lecovin. So trying different sources of probiotics—which will expose you to more bacterial strains—is a good idea. (1)
Probiotic foods and beverages
“For people who are lactose intolerant, like myself, yogurt is not really a great choice,” says Dr. Lecovin. (1) Fortunately, there are many products that contain probiotics:
- Yogurt and yogurt-based products. Don’t assume that all yogurt products contain live microbes. Read labels to find ones that contain live, active cultures and that list the strains of bacteria that are inside. You may want to try a different option if you are lactose intolerant. (1, 2)
- Pickled foods such as sauerkraut, pickles, and pickled vegetables. Processed versions won’t do the trick; pasteurization kills the bacteria used in the pickling process. Instead, look for locally produced products labeled “raw fermented”—or find a recipe and make your own. (1, 2, 10)
- Fermented foods such as:
- Kefir, dairy and non-dairy versions (a beverage made with kefir grains and milk, sugary water, coconut water, or fruit juice)
- KeVita (a fermented drink made with coconut water)
- Kimchee (a Korean vegetable side dish)
- Kombucha (a bubbly tea-based beverage)
- Miso and tempeh (both made from fermented soybeans) (1,2)
- Sourdough bread (look for fresh-baked, not something that’s been on a shelf for a long time) (2)
While most experts agree it’s ideal to take in probiotics from food sources, rather than supplements, sometimes supplementation is helpful. This is particularly true if a person has very low levels of GI bacteria (say, because they’re taking antibiotics) or they can’t or won’t consume foods and beverages that contain live, active cultures. (1, 2) Some things to look for when choosing a probiotic supplement:
- Refrigeration. Probiotic supplements should be kept refrigerated because their bacteria need cool temperatures to live. (2, 10)
- Expiration dates. Probiotic supplements won’t “go bad” (as in “spoil”), but the bacteria will die off as they age, reducing their effectiveness. (2, 10)
- Microencapsulated. This type of supplement is coated so it will be sure to survive the trip through the stomach to the intestines, where it’s needed. (2, 10)
- CFUs. Between 15 and 25 billion colony forming units (CFUs) has been shown to be most effective, says Bailey. (2)
- Multiple strains. The more strains, the better. Look for a supplement that contains at least one Lactobacillus and one Bifidobacterium. (10) Dr. Lecovin notes that if you’re looking for a probiotic to help with a certain concern such as diarrhea or eczema, you can search Google Scholar for studies that will tell you which bacterial strains may be most helpful. (1) Again, this is for personal use; don’t suggest specific products to your clients unless you are legally qualified to do so.
- Dr. Geoff Lecovin, MS, DC, ND, L.Ac., CSCS, CISSN, NASM-CPT (CES, PES, FNS) and a NASM Master Instructor, who holds master’s degrees in nutrition, exercise science, and acupuncture, and is owner of Northwest Integrative Medicine in Redmond, Wash.
- Emily Bailey, RD, CSSD, LD, NASM-CPT, Director of Nutrition for NutriFormance in St. Louis, Mo.
- West, N. P., D. B. Pyne, J. M. Peake, and A. W. Cripps. “Probiotics, Immunity and Exercise: A Review.” National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 15 June 2016.
- Bermon, Stéphane, Bernardo A. Petriz, Alma Kajėnienė, Jonato Prestes, Lindy Castell, and Octavio L. Franco. “The Microbiota: An Exercise Immunology Perspective” ResearchGate, n.d. Web. 15 June 2016.
- Cox, A. J., D. B. Byrne, P. U. Saunders, and P. A. Fricker. "Oral Administration of the Probiotic Lactobacillus Fermentum VRI-003 and Mucosal Immunity in Endurance Athletes." British Journal of Sports Medicine. British Association of Sport & Exercise Medicine, 13 Feb. 2008. Web. 15 June 2016.
- Hulston, Carl J., Amelia A. Churnside, and Michelle C. Venables. "Probiotic Supplementation Prevents High-fat, Overfeeding-induced Insulin Resistance in Human Subjects." British Journal of Nutrition Br J Nutr 113.04 (2015): 596-602. Web. 15 June 2016.
- Lecovin, Geoff. "You Might Want To Start Considering Your Gut, If You Want To Lose It." DrGeoffLecovin.com. Northwest Integrative Medicine, 24 Feb. 2016. Web. 15 June 2016.
- Mach, Núria, and Dolors Fuster-Botella. "Endurance Exercise and Gut Microbiota: A Review." Endurance Exercise and Gut Microbiota: A Review. ScienceDirect, 10 May 2016. Web. 15 June 2016.
- Global Market Insights Inc. "Probiotics Market Size to Exceed USD 64 Billion by 2023: Global Market Insights Inc." Prnewswire.com. PR Newswire, 10 May 2016. Web. 15 June 2016.
- Underwood, Anne. "Have You Had Your Probiotics Today?" Prevention.com. Rodale Inc., 18 Dec. 2012. Web. 15 June 2016.