Probiotics 101: What to Look for in a Probiotic Supplement

Probiotic supplement jars viewed from above.

Liz DeSousa for Byrdie

While the idea of live bacteria and yeast living inside your body may not sound the least bit appealing, they are actually good for you and a crucial part of digestion. Probiotics are actually the “good” bacteria your body needs to help digest food, destroy disease-causing cells and produce vitamins, per the National Institutes of Health. In recent years, probiotic supplements have become increasingly popular, as they offer a method of infusing these healthy, live microorganisms into your system.  

Meet the Expert

  • Niket Sonpal, MD, is a New York City-based internist and gastroenterologist, and faculty member at the Touro College of Medicine.
  • Lauren Minchen, MPH, RDN, CDN, is a nutrition consultant for Freshbit, an AI-driven visual diet diary app.

What Are Probiotics?

Probiotics are the live bacteria found in many fermented drinks or foods such as kombucha or yogurt, explains Sonpal. The most common is from the Bifidobacterium and Lactobacillus groups. Consuming them in plentiful amounts provides many health benefits, like balancing the bad and good bacterial species found in the gut. 

“Probiotics are good bacteria because they help keep the gut healthy,” he explains. “People choose to take probiotic supplements to make sure they are keeping up the population of good bacteria and because they have to compete with the 1,000 other bacteria species in your gut.” 

How Do They Work?

Minchen explains that healthy bacteria populate the gut lining (and other body areas, like skin) to protect it from harmful bacteria and viruses, keep tissue intact and strong, and boost the absorption of nutrients from food. 

“Without probiotics, the integrity of our gut lining can become compromised, allowing harmful bacteria and viruses to take root. Harmful bacteria and viruses can induce inflammatory conditions in our gut and lead to more systemic inflammation later. The ultimate result may be a greater risk of disease, poor digestion, nutrient deficiencies, and chronic infections,” she says. 

The Benefits of Probiotic Supplements

  • Improved Gut Function: The main job of probiotics is to fight bad bacteria and viruses in the gut that can lead to gut dysfunction and disease. “They help digest and utilize nutrients in food while promoting smooth digestion by helping to maintain the gut lining and barrier,” Minchen says. These protective effects ultimately lead to a more efficient digestive system, including less/no gas or bloating, reduced diarrhea, regular bowel movements, and general digestive comfort with meals and snacks.
  • Healthier Skin: Probiotics also have aesthetic benefits, per Minchen. They include reduced eczema and dermatitis. “Infants and toddlers who supplement with probiotics may experience fewer incidences of eczema rashes, while probiotics may help reduce the inflammatory response to cow's milk that often leads to eczema and dermatitis,” she adds. “Our skin is also naturally covered in good bacteria, and any imbalance or disruption of good bacteria on the skin can lead to eczema, rashes, acne, and rosacea. Supplementing with probiotics or eating them in fermented foods may help reduce occurrences of these skin conditions.”
  • Improved Immunity: Probiotics boost immune cells throughout the body, including immunoglobulin-A cells, T-lymphocytes, and natural killer cells, says Minchen. “These powerful immune cells fight disease and infection. Probiotics, when sufficiently populated throughout the body, help prevent harmful bacteria from taking root in our digestive tract, on our skin, and in our tissues, reducing the risk of infection,” she explains. 
  • Boost Mental Health: Several studies, including this one published in 2017 in Annals of General Psychology, have shown that Bifidobacterium and Lactobacillus probiotic strains can reduce anxiety, depression, OCD, and autism, boosting mood and memory. “While more research is needed to confirm these correlations, the research so far is promising in linking a healthy bacterial balance with mental health,” Minchen says. 
  • Promote Heart Health: Research has found that certain strains of probiotics may help reduce total and LDL cholesterol by breaking bile down in the gut (bile contains cholesterol).

Who Should Take a Probiotic Supplement?

While probiotic supplement research is still underway, research shows that probiotic supplements show promise in treating or preventing many following conditions, including high blood pressure, lactose intolerance, constipation, yeast infections, irritable bowel syndrome, type 2 diabetes, colitis, and colon cancer, Sonpal maintains. And they have been found safe and effective for all ages. 

However, Minchen suggests talking with a dietitian to discuss the best strains and dosage for you, depending on your health goals, medications, and health history. “A dietitian can help identify strains that will specifically target the conditions you want to manage,” she points out. 

How to Add Probiotics to Your Diet

  • Take It In Supplement Form: Minchen maintains that an easy way to add probiotics to your diet is to take daily supplements. “Probiotic supplements vary in strains and number of bacteria, depending on their target condition,” she explains. 
  • Eat Fermented Foods: “Eating fermented foods can help increase intake of natural bacteria,” Minchen states. These foods include fermented veggies (e.g., sauerkraut, kimchi), kefir (fermented cow's or goat milk), and kombucha (a fermented green or black tea). “Fermented foods largely contain bifidobacterium and lactobacillus strains of bacteria, which benefit IBS, immunity, cholesterol, and mental health,” she explains. 
  • Boost Your Fiber Intake: Adding fibrous foods can help feed and grow probiotics in number and variety. “Fiber serves as a prebiotic for probiotics, which means it provides the fuel for probiotics to increase,” Minchen says. “Aiming for about 25 grams of fiber from veggies, fruits, whole grains, root vegetables, and legumes is a great way to also naturally boost the number and variety of probiotics in your gut.”

Potential Side Effects

Sonpal explains that there are some potential side effects or health risks to taking probiotics. “One theoretical risk of probiotics is someone could get sick from them if they have a weakened immune system,” he reveals. 

Another worry about probiotics is the FDA does not monitor the manufacture of probiotics because they are considered dietary supplements, not drugs. “Therefore, it is not clear if high-quality probiotics can be bought at health food stores or pharmacies,” he says.  Another possibility is that low-quality products may not even contain probiotic bacteria that are listed on the label. 

Some people experience loose stool or gas during the first few days of taking probiotic supplements, “but this goes away after a few days; take probiotics once you finish your meal to help reduce this side effect,” he suggests. Minchen adds that this is more common when wrong dosages or strains are taken. “These symptoms can be due to the presence of too much yeast in the gut or another imbalance of bacteria that reacts with the probiotic,” she explains. “Starting with a gentle dose and speaking with a dietitian to identify the best strains for you can be helpful here.” 

Also, some probiotic strains may contain soy, cow's milk, or egg, which may trigger an allergic reaction for those who are allergic to these foods. “Checking labels on probiotic supplements is essential for avoiding these allergens,” Minchen states.

Probiotics may also produce biogenic amines, including histamine, tyramine, tryptamine, and phenylethylamine. “These amines can lead to increased excitement of the nervous system, increased or decreased blood flow, and headaches/migraines for those who are sensitive to them,” says Minchen. These reactions occur most often when eating probiotic foods, as opposed to taking a supplement. 

The Takeaway 

Although more research needs to be done, probiotics are generally beneficial for boosting gut health, immunity, heart health, mental health, and skin health. And they have very few drawbacks. However, speaking with a dietitian and/or a doctor to identify the best strains and dosages for you is important to maximize the benefits of probiotics and avoid possible side effects, Minchen states. “Also, achieving healthy probiotic intake through the foods and supplements that contain the right strains for you may be best for variety and sustainability.”

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