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What probiotics are, the health benefits that have real evidence behind them, who should avoid them, and how to choose a supplement or food.
By Editorial Team · Updated · 2 min read
This article is awaiting review by a qualified medical professional.
Quick answer
Probiotics are live microorganisms, usually bacteria or yeast, that can benefit health when taken in adequate amounts. The best-supported benefits are reducing antibiotic-associated diarrhea, shortening some infectious diarrhea, and easing symptoms in some people with irritable bowel syndrome. Effects depend on the specific strain, and they are not suitable for everyone.
Probiotics are live microorganisms that, when taken in adequate amounts, can benefit your health. They are found in some foods and are sold as supplements. The most common types belong to the groups Lactobacillus and Bifidobacterium, and the yeast Saccharomyces boulardii.
Research shows that probiotics work best for specific problems, and that each strain behaves differently. The benefits with the strongest evidence are:
Claims that probiotics boost immunity, help weight loss or improve general wellbeing in healthy people are not well proven.
Foods called prebiotics feed the good bacteria already in your gut. They include oats, bananas, onions, garlic, leeks, asparagus and legumes.
Most people have no problems. Mild effects can include gas, bloating and loose stools during the first few days.
Probiotics can occasionally cause serious infections in:
Supplements are not regulated like medicines in many countries, so the strains and amounts on the label may not match what is inside.
Speak to a doctor before starting probiotics if you are immunocompromised, seriously ill or pregnant, or if you are giving them to a baby. See a doctor if you have persistent diarrhea, blood in your stool, unexplained weight loss or severe abdominal pain, rather than treating it yourself with supplements.
The best evidence is for preventing antibiotic-associated diarrhea, shortening acute infectious diarrhea (especially in children) and easing symptoms in some people with irritable bowel syndrome. Benefits are strain-specific, and there is little proof that healthy people gain much from taking them.
For most healthy people they are safe, and side effects are usually mild gas or bloating. They can cause serious infections in people with weakened immune systems, people who are critically ill, and premature babies, so ask a doctor first if that applies to you.
Yogurt with live cultures, kefir, sauerkraut and kimchi can add beneficial microbes to your diet, but the strains and amounts are not standardised. Supplements contain defined strains and doses, but quality varies between products.
Follow the product label, because it depends on the strain and formulation. If you are taking antibiotics, take the probiotic a couple of hours apart from the antibiotic dose.
This article is for educational purposes only and does not replace advice from a doctor or other qualified health professional. See our medical disclaimer.
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