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The best probiotic depends on the individual and their health goals. Other important factors include the strain of bacteria, how much bacteria the supplement contains, and whether it contains prebiotics.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Medical News Today chooses probiotics based on the following criteria:

  • Colony forming units (CFU): We include products with a high CFU stated clearly on the product.
  • Bacteria strains: We have chosen probiotics with different strains, including options with a blend of multiple bacteria strains.
  • Safety: We include products that clearly state ideal use, including recommended dosage, when to take them, storage suggestions, and any contraindications.
  • Effectiveness: We select brands that outline possible timelines for seeing health benefits.
  • Reputation: We only choose products from vetted brands that do not make unsubstantiated health claims or promises.
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Please note that the writer of this article has not tried these products. All information presented is purely research-based and correct at the time of publication.

Medical News Today follows a strict product selection and vetting process. Learn more here.

Best overall: Ritual Synbiotic+

  • Price: $54
  • Quantity: 30 capsules (30 day supply)
  • Daily dose: 1 capsule
  • CFU: 11 billion
  • Bacteria strains: Lactobacillus rhamnosus, Bifidobacterium animalis

Ritual Synbiotic+ contains prebiotic, probiotic, and postbiotic bacteria.

Learn about prebiotics vs. probiotics here.

Ritual claims that results from human clinical trials showed this product supported the growth of beneficial bacteria in the gut. It may help provide relief from bloating, gas, and diarrhea.

It contains Lactobacillus rhamnosus and Bifidobacterium animalis in a delayed-release capsule. Capsules come in a moisture-controlled container that does not need to be refrigerated.

The manufacturer tests Synbiotic+ for identity and strength. A third-party lab certifies it is free from contaminants.

This probiotic is suitable for vegans and free from major allergens such as gluten.

Ritual recommends taking one capsule daily in the morning or evening without food. People may feel the effects after two to four weeks.

Read our review of Ritual vitamins here.

Best for probiotic for women: Wisp Daily Probiotics

  • Price: $30
  • Quantity: 180 tablets (90 day supply)
  • Daily dose: 2 tablets
  • CFU: 200 billion
  • Bacteria strains: Lactobillus acidophilus

Wisp recommends this probiotic to support vaginal health and help manage chronic yeast infections such as bacterial vaginosis (BV) or chronic UTIs

It is suitable for use when taking antibiotics or for vaginal infections.

Learn about more of the best probiotics for women here.

The bacteria strain is Lactobacillus acidophilus. The tablets contain gelatin, making them unsuitable for vegetarians or vegans.

Wisp recommends taking one tablet twice daily and states that people should notice effects within six weeks.

Read our review of Wisp telehealth here.

Best probiotic for men: Garden of Life Raw Probiotics Men

  • Price: $39.99
  • Quantity: 90 capsules (30 day supply)
  • Daily dose: 3 capsules
  • CFU: 85 billion
  • Bacteria strains: Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus acidophilus, Bifidobacterium bifidum, Bifidobacterium lactis, and more.

Garden of Life claims this product may suit men’s health needs by supporting the gut, prostate, and heart.

Alongside 31 bacteria strains, the product contains a wide range of vitamins, minerals, and a dairy-digesting enzyme blend.

As a raw food, this product is not cooked or treated. This product is suitable for vegetarians and free from gluten, soy, binders, fillers, carriers, and GMOs.

The recommended dose is three capsules daily, each taken at separate times with or without food.

Best allergen-free probiotic: Care/of

  • Price: $11
  • Quantity: 30 capsules (30 day supply)
  • Daily dose: 1 capsule
  • CFU: 8 billion
  • Bacteria strains: Bifidobacterium lactis, Lactobacillus rhamnosus, Lactobacillus acidophilus

Care/of claims that this probiotic may support gastrointestinal function and the immune system.

This probiotic contains the bacteria strains B. lactis, L. rhamnosus, and L. acidophilus.

It is suitable for vegans and does not contain fillers or GMOs. It is also free from:

Care/of recommends taking one capsule daily with a meal.

Care/of provides personalized supplement recommendations after customers complete an online quiz. Probiotics are available via monthly subscription.

Read our review of Care/of here.

Best vegan probiotic: MegaFood MegaFlora

  • Price: $26.99
  • Quantity: 30 capsules (30 day supply)
  • Daily dose: 1 capsule
  • CFU: 20 billion
  • Bacteria strains: Bifidobacterium lactis, Lactobacillus acidophilus, Bifidobacterium longum, Lactobacillus plantarum, Bifidobacterium bifidum, Lactobacillus rhamnosus, and more.

MegaFood claims that this probiotic can help support digestive and immune health.

This product is made from a proprietary blend of 14 strains of bacteria, including:

  • Bifidobacterium lactis
  • Lactobacillus acidophilus
  • Lactobacillus case
  • Lactobacillus plantarum
  • Lactobacillus rhamnosus
  • Lactobacillus salivarius
  • Lactobacillus brevis
  • Lactobacillus bulgaricus
  • Lactobacillus gasser
  • Lactococcus lactis
  • Bifidobacterium longum
  • Bifidobacterium bifidum
  • Bifidobacterium infants
  • Streptococcus thermophilus.

MegaFood MegaFlora is also available in 60 and 90 capsule size bottles, reducing the price per capsule from $0.73 to $0.63 and $0.53, respectively. A subscription option is available.

This probiotic is suitable for vegans and free from gluten, dairy, soy, and GMOs.

MegaFood recommends taking one capsule a day with a meal and a beverage. This product requires refrigeration.

Best probiotic for gut health: Life Extension Florassist GI

  • Price: $24.75
  • Quantity: 30 capsules (30 day supply)
  • Daily dose: 1 capsule
  • CFU: 15 billion
  • Bacteria strains: Lactobacillus plantarum, Lactobacillus breve, Bifidobacterium longum, Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus rhamnosus, Bifidobacterium animalis

Life Extension claims this probiotic may support gastrointestinal health by targeting unwanted bacteria in the GI tract and supporting optimal nutritional absorption.

It has a dual encapsulation system, which Life Extension claims enables the beneficial bacteria to survive stomach acid, delivering them to the colon.

The proprietary probiotic blend consists of 7 bacteria strain, including Lactobacillus plantarum, Lactobacillus breve, Bifidobacterium longum, Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus rhamnosus, and Bifidobacterium animalis.

The product is vegetarian, gluten-free, and does not contain any GMOs.

Best probiotic for weight loss: Thorne FloraMend Prime Probiotic

  • Price: $49
  • Quantity: 30 capsules (30 day supply)
  • Daily dose: 1 capsule
  • CFU: 5 billion
  • Bacteria strains: Lactobacillus gasseri, Bifidobacterium longum, and Bifidobacterium bifidum

Thorne claims that this probiotic may support weight and body mass index (BMI) management.

The manufacturer states the ingredients have been clinically studied for their effect on weight management. The study found that participants regularly taking the probiotics experienced a 5% average reduction in visceral and subcutaneous body fat.

However, research into the relationship between probiotic supplementation and weight loss is limited and ongoing.

Learn more about the best probiotics for weight loss here.

Thorne also claims the proprietary blend of Lactobacillus gasseri, Bifidobacterium longum, and Bifidobacterium bifidum may support gut and immune health.

The probiotics are free from gluten, dairy, and soy. They come in a delayed-release capsule that is resistant to stomach acid and moisture.

Thorne recommends taking one capsule daily with a meal. This probiotic does not require refrigeration.

Best probiotic for skin: HUM Skin Squad Pre+Probiotic

  • Price: $40
  • Quantity: 60 capsules (30 day supply)
  • Daily dose: 2 capsules
  • CFU: 40 billion
  • Bacteria strains: Bifidobacterium lactis, Lactobacillus rhamnosus, Lactobacillus acidophilus, Bacillus coagulans, and more.

Hum claims that this probiotic may support skin and gut health. It may help with the management of non-cystic acne by reducing breakouts.

Alongside konjac root extract, it contains a proprietary blend of the following bacteria strains:

  • Lactobacillus rhamnosus
  • Bacillus subtilis
  • Lactobacillus acidophilus
  • Bacillus coagulans
  • Lactobacillus paracasei
  • Bifidobacterium lactis
  • Lactobacillus salivarius

It is vegan, third-party tested and certified by the Clean Label project. It is free from most major allergens, including wheat, gluten, soy, milk, egg, fish, shellfish, and peanuts. It does not contain artificial colors, flavors, or preservatives.

Hum recommends taking two capsules a day with or without food. It does not require refrigeration, but Hum recommends refrigerating after opening to preserve the CFU count for longer.

Best probiotic for mental health: Hers Mood Mental Health Probiotic

  • Price: $24
  • Quantity: 30 capsules (30 day supply)
  • Daily dose: 1 capsule
  • CFU: 1 billion
  • Bacteria strains: Bacillus Subtilis

Hers claims that this supplement may help support digestive and emotional health.

The ingredients of this probiotic include 1 billion CFU of Bacillus Subtilis, ashwagandha, and spinach leaf extract. It also contains vitamins D3, B6, and B12.

This product is vegetarian, gluten-free, and contains no GMOs. It does contain coconut, making it unsuitable for people with tree nut allergies.

Hers recommends taking one capsule each morning before eating. It does not require refrigeration.

Hers is a telehealth company that focuses on women’s health.

Read our review of Hers here.

Best subscription probiotic: Persona Daily Probiotic

  • Price: $14
  • Quantity: 28 capsules (28 day supply)
  • Daily dose: 1 capsule
  • CFU: 3 billion
  • Bacteria strains: Lactobacillus acidophilus, Bifidobacterium bifidum, Lactobacillus salivarius, Lactobacillus bulgaricus

Persona claims this probiotic may relieve occasional digestive problems, irregularity, and bloating.

It contains a proprietary blend of Lactobacillus acidophilus, Bifidobacterium bifidum, Lactobacillus salivarius, and Lactobacillus bulgaricus.

Persona is a vitamin and supplement subscription brand that provides personalized recommendations and products.

Read our review of Persona here.

This product contains gelatin and milk, making it unsuitable for vegetarians and vegans. It is packaged in a facility that handles wheat, soy, lactose, corn, egg, fish, shellfish, tree nuts, peanuts, and gluten, making it unsuitable for people with these allergies.

Persona recommends taking capsules with food and water.

Best affordable probiotic: Nurish Multi-strain Probiotics

  • Price: $13.33
  • Quantity: 30 capsules (30 day supply)
  • Daily dose: 1 capsule
  • CFU: 8 billion
  • Bacteria strains: Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus gasseri, Lactobacillus rhamnosus, and more.

Nurish claims this product may help combat negative impact of environmental factors such as chronic stress, poor nutrition, or illness.

It contains over 8 billion CFU from 12 bacteria strains, including Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus gasseri, Lactobacillus rhamnosus, and Lactobacillus acidophilus.

This product is vegetarian. It does not contain any dairy or artificial colors and flavors. It is processed in a facility that handles dairy, shellfish, and wheat.

Nurish recommends taking one capsule daily with food and water. It may take two weeks for the effects to be noticeable. These probiotics do not require refrigeration.

With a subscription, the price per 30-day supply reduces from $13.33 to $12.

Best probiotic when taking with antibiotics: Culturelle Ultimate Balance for Antibiotics

  • Price: $27.99
  • Quantity: 30 capsules (30 day supply)
  • Daily dose: 1 capsule
  • CFU: 20 billion
  • Bacteria strains: Lactobacillus rhamnosus.

Culturelle claims that these probiotics may help reduce side effects when taking a course of antibiotics, specifically digestive issues such as diarrhea, gas, and bloating.

This probiotic contains 20 billion CFUs of Lactobacillus rhamnosus.

Learn about the side effects of antibiotics here.

The capsules are vegetarian and free from tree nuts, peanuts, dairy, and egg. They do not require refrigeration.

Culturelle recommends taking one capsule daily for ten days after completing a course of antibiotics. They do not require refrigeration.

Learn about what to eat while taking antibiotics here.

The following table compares the probiotics in this article on key points:

PriceProduct size
(Daily supply)
Daily dosePrice per doseCFU count
Ritual Synbiotic+$5430 capsules
(30 days)
1 capsule$1.8011 billion
Wisp Daily Probiotics$30180 tablets
(90 days)
2 tablets$0.33200 billion
Garden of Life Raw Probiotics Men$39.9990 capsules
(30 days)
3 capsules$1.3085 billion
Care/of$1130 capsules
(30 days)
1 capsule$0.368 billion
MegaFood MegaFlora$26.9930 capsules
(30 days)
1 capsule$0.7320 billion
Life Extension Florassist GI$24.7530 capsules
(30 days)
1 capsule$0.8314 billion
Thorne FloraMend Prime Probiotic$4930 capsules
(30 days)
1 capsule$1.635 billion
HUM Skin Squad Pre+Probiotic$4060 capsules
(30 days)
2 capsules$1.3340 billion
Hers Mood Mental Health Probiotic$2430 capsules
(30 days)
1 capsule$0.801 billion
Persona Daily Probiotic$1428 capsules
(28 days)
1 capsule$0.503 billion
Nurish Multi-strain Probiotics$13.3330 capsules
(30 days)
1 capsule$0.448 billion
Culturelle Ultimate Balance for Antibiotics$27.9930 capsules
(30 days)
1 capsule$0.9320 billion

Probiotics are harmless microorganisms that may support the presence of healthy bacteria in the body.

The human body contains millions of live bacteria. Many exist in the gut. Gut bacteria make up a person’s “microbiome.”

The microbiome is unique to each individual, and studies show it may be determined before birth. Research suggests that the microbiome changes throughout a person’s life based on their diet, lifestyle, and exposure to different environmental influences.

Probiotics can help populate the gut with good bacteria. This is a key part of a person’s immune system. Gut bacteria have many functions in the body and affect things such as weight, mood, and inflammation.

In recent years, there has been a lot of interest in how probiotics can support health and reduce a person’s risk and symptoms of certain conditions.

Some people take probiotics to maintain everyday health. When using a probiotic for a specific health concern, people should speak to a healthcare professional about the best strategy. Clinical trials show that different probiotics and dosages are effective for different conditions and situations.

Probiotic manufacturers measure amounts of bacteria in colony-forming units (CFUs). Supplements can vary, but most have a CFU in the billions. Foods with added probiotics often contain lower numbers of bacteria. Generally, people take higher-CFU products for specific conditions and lower-CFU products for general health maintenance.

Some research suggests that probiotics can help keep the gut healthy and may help relieve the symptoms of some health conditions.

A 2018 review states that the “strongest evidence in favor of probiotics lies in the prevention or treatment” of five conditions:

Some other potential uses and benefits of probiotics include:

Probiotics for gut health

Probiotics may support a person’s gut health and relieve gastrointestinal issues.

Damage to the gut’s lining may lead to intestinal permeability, or “leaky gut.” This can allow molecules to enter the bloodstream and cause inflammation or immune reactions.

Antibiotics can kill both bad and good bacteria. Sometimes, this can cause a person to experience symptoms of diarrhea when taking them. Taking probiotics alongside antibiotics may help repopulate a person’s gut with beneficial bacteria and ease symptoms of diarrhea.

In particular, the probiotic yeast Saccharomyces boulardii has been effective in preventing and treating diarrhea that occurs when taking antibiotics or following infection. The yeast may also effectively treat irritable bowel syndrome and inflammatory bowel disease, but more research is needed to confirm this.

Probiotics for constipation

A review of studies indicates that probiotics may reduce gut transit time — the time it takes for food to pass as a bowel movement — by 12.4 hours and increase total bowel movements by 1.3 per week.

The Bifidobacterium lactis strain seems most efficient in improving gut transit time, stool frequency, and consistency, and in reducing flatulence.

However, the researchers advise caution when interpreting the results, as there may be bias in some of the studies included.

Probiotics for weight loss

The bacteria in a person’s gut may connect with their weight. A small 2019 study found that people following a low calorie diet for 15 weeks experienced changes in their gut bacteria. They also had a reduction in bacteria associated with atherosclerosis, which occurs when the arteries become clogged with plaque.

The links between weight and gut bacteria could indicate that probiotics may support weight loss.

Some experts suggest that supplementation with synbiotics — a combination of prebiotics and probiotics — , using strains such as Lactobacillus gasseri, may lead to weight reduction. Adding certain fibers may increase these effects.

A 2019 review looking at obesity and probiotics concluded that mixtures of probiotic strains may be more effective in treating obesity than single strains. In particular, Bifidobacterium may be effective for reducing body mass index (BMI).

One 2018 review concluded that probiotics may result in a reduction of weight and fat percentage. However, there have not been enough high quality studies to confirm that probiotics have this effect.

Most research into this has used Lactobacillus and Bifidobacterium strains. However, there are still unanswered questions about specific strains, duration of treatment, and appropriate dosages.

Probiotics for mental health

Research into the effects of probiotics on mental health is limited, but early studies suggest there may be a connection between gut microbiota and the central nervous system. This is referred to as the gut-brain axis.

Researchers have used Bifidobacterium and Lactobacillus to treat the symptoms of anxiety, depression, and obsessive-compulsive disorder.

Studies into using probiotics to treat mental illness are ongoing and showing promise.

Probiotics for females and males

The effects of probiotics may be different in females and males.

Emerging research indicates that probiotics could improve gut-brain wellness and help address issues such as Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD), IBS, and depression. These conditions affect males and females differently, highlighting the importance of gender-specific research into probiotics.

In an older 2014 study, researchers gave females and males with obesity Lactobacillus rhamnosus. The results suggested that females lost weight and fat during the trial and maintained the loss after study completion. The males in the study, however, did not.

A study in people with Salmonella infection suggested that the effects of taking Lactobacillus plantarum varied according to sex. Although the study authors saw little evidence that this probiotic may treat Salmonella, they noted how males and females experienced the symptoms and clearance of the infection differently.

Scientists need to conduct more studies to establish whether probiotic therapy should differ depending on a person’s sex.

Some probiotic supplements also contain prebiotics, which are compounds that the probiotics can feed on. If a formula contains both probiotics and prebiotics, it is called a “synbiotic.”

Some formulas may also contain prebiotics. Including prebiotics can be beneficial, as they provide substances for probiotics to digest. This process can produce short-chain fatty acids, which can help maintain the health of a person’s colon and immune system.

Some research indicates that for prebiotics to be effective, they must withstand food processing and reach the colon undigested. Some of the most common types of prebiotics in supplements and foods are called oligosaccharides.

Some people’s bodies can be sensitive to prebiotics, so taking too much of them can cause flatulence or diarrhea. Such people can obtain the health benefits of prebiotics by instead including plenty of fiber and resistant starch in their diets and eating foods such as garlic, onions, bananas, and oats.

Learn more about the relationship between prebiotics and probiotics here.

People can take probiotics in supplement form or in the form of foods and beverages such as yogurt and drinks with live cultures added.

Learn about the best food sources of probiotics here.

Fermented foods naturally contain beneficial bacteria. Examples of fermented foods include:

Learn more about fermented foods here.

The following are common questions and answers about probiotics:

What is the best probiotic?

The best probiotic is one which meets a person’s unique health needs. Every individual biome is different. Look for probiotics with a high CFU count, multiple or specific bacteria strains, and clear usage recommendations.

Ritual Synbiotic+ is suitable for most people and health goals. However, a person should consult a doctor for guidance on probiotics.

What probiotic do gastroenterologists recommend?

The American Gastroenterological Association (AGA) does not recommend using probiotics as a primary treatment for most digestive conditions.

The AGA only recommends using probiotics in the following cases:

  • preventing Clostridioides difficile
  • when taking antibiotics
  • necrotizing enterocolitis in preterm or low birth weight infants
  • managing pouchitis, a complication of irritable bowel disease.

For conditions such as Crohn’s disease, ulcerative colitis, IBS, and acute infectious gastroenteritis, probiotics are only recommended in the context of a clinical trial.

A person should speak to their gastroenterologist for specific probiotic guidance and recommendations based on their health conditions and goals.

Which probiotics actually work?

The effectiveness of probiotics depends on a person’s unique gut microbiome, lifestyle factors, and the CFU and strains of bacteria in the supplement.

People may need to take probiotics consistently for at least two weeks to notice any benefits.

Are some probiotic strains better than others?

Many probiotics contain mixtures of two or more individual strains of bacteria or yeasts.

Products often contain Lactobacillus or Bifidobacterium species, although many other species exist. According to some research, different strains of the same species of probiotics can act in different ways.

The best probiotic strain depends on the health goals a person has.

In recent years, the extensive research into probiotics and the microbiome leaves no doubt that these novel products can benefit some aspects of human health.

Specifically, science has identified areas of use for diarrhea, respiratory conditions, and some infant illnesses and conditions. Probiotics may also help with weight management, gut issues and constipation, and mental health.

People can do their own research into which specific strains might work for their particular condition. A healthcare professional can help with this.

They can choose probiotics according to their CFU, the strains included, and whether or not the product also contains prebiotics. It can be more cost effective to choose a product with a lower CFU for general health maintenance.

Those taking probiotics for the first time might want to monitor any effects and build up their dosage slowly, especially if the product contains prebiotics, which can cause excess gas.

People who have an immune condition or severe illness should speak to their doctor before taking probiotics, as they may not be suitable. Also, people with allergies or intolerances should be sure to read product labels carefully to avoid triggering a reaction.