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Probiotics are live microorganisms that can be consumed through fermented foods or supplements (1).

More and more studies show that the balance or imbalance of bacteria in your digestive system is linked to overall health and disease.

Probiotics promote a healthy balance of gut bacteria and have been linked to a wide range of health benefits.

These include benefits for weight loss, digestive health, immune function and more (2, 3).

This is an overview of the key health benefits linked to probiotics.

1. Probiotics Help Balance The Friendly Bacteria in Your Digestive System

Probiotics include “good” bacteria. These are live microorganisms that can provide health benefits when consumed (1).

These benefits are thought to result from the ability of probiotics to restore the natural balance of gut bacteria (4).

An imbalance means there are too many bad bacteria and not enough good bacteria. It can happen due to illness, medication such as antibiotics, poor diet and more.

Consequences can include digestive issues, allergies, mental health problems, obesity and more (5).

Probiotics are usually found in fermented foods or taken as supplements. What’s more, they appear to be safe for most people.

Bottom Line:

Probiotics are live microorganisms. When taken in sufficient amounts, they can help restore the natural balance of gut bacteria. As a result, health benefits may follow.

2. Probiotics Can Help Prevent and Treat Diarrhea

Probiotics are widely known for their ability to prevent diarrhea or reduce its severity.

Diarrhea is a common side effect of taking antibiotics. It occurs because antibiotics can negatively affect the balance of good and bad bacteria in the gut (6).

Several studies suggest probiotic use is associated with a reduced risk of antibiotic-associated diarrhea (7).

In one study, researchers found that taking probiotics reduced C. difficile infection (CDAD) by 60% (8).

Probiotics can also help with other forms of diarrhea not associated with antibiotics.

A large review of 35 studies found certain strains of probiotics can reduce the duration of diarrhea by an average of 25 hours (9).

Probiotics also reduced the risk of travelers’ diarrhea (10).

Effectiveness varies, depending on the type and dose of the probiotic taken (11).

Strains such as Lactobacillus rhamnosus, Lactobacillus casei and the yeast Saccharomyces boulardii are most commonly associated with a reduced risk of diarrhea (7, 10).

Bottom Line:

Probiotics can reduce the risk and severity of diarrhea from a number of different causes.

3. Probiotic Supplements Improve Some Mental Health Conditions

An increasing number of studies link gut health to mood and mental health (12).

Both animal and human studies find that probiotic supplements can improve some mental health disorders (13).

A review of 13 human studies found supplementing with Bifidobacterium and Lactobacillus strains for 1–2 months can improve anxiety, depression, autism, obsessive-compulsive disorder (OCD) and memory (13).

One study followed 70 chemical workers for 6 weeks. Those who consumed 100 grams of probiotic yogurt per day or took a daily probiotic capsule experienced benefits for general health, depression, anxiety and stress (14).

Benefits were also seen in a study of 40 patients with depression.

Taking probiotic supplements for 8 weeks decreased depression levels and reduced levels of C-reactive protein (a marker of inflammation) and hormones such as insulin, compared to people who did not take a probiotic (15).

Bottom Line:

Research shows taking probiotics may help improve symptoms of mental health disorders such as depression, anxiety, stress and memory, among others.

4. Certain Probiotic Strains Can Help Keep Your Heart Healthy

Probiotics may help keep your heart healthy by lowering LDL (“bad”) cholesterol and blood pressure.

Certain lactic acid-producing bacteria may reduce cholesterol by breaking down bile in the gut (16).

Bile, a naturally occurring fluid mostly made of cholesterol, helps digestion.

By breaking down bile, probiotics can prevent it from being reabsorbed in the gut, where it can enter the blood as cholesterol (17).

Bottom Line:

Probiotics may help protect the heart by reducing “bad” LDL cholesterol levels and modestly lowering blood pressure.

5. Probiotics May Reduce the Severity of Certain Allergies and Eczema

Older research suggests certain probiotic strains may reduce the severity of eczema in children and infants (18).

However, compared with no probiotic, currently available probiotic strains probably make little or no difference in improving eczema (19).

The link between probiotics and reduced eczema severity is still weak, and more research needs to be done (20, 21).

Bottom Line:

Probiotics may reduce the risk and severity of certain allergies, such as eczema in infants. However, more research is needed.

6. Probiotics Can Help Reduce Symptoms of Certain Digestive Disorders

Over one million people in the US suffer from inflammatory bowel disease, including ulcerative colitis and Crohn’s disease (22).

Certain types of probiotics from the Bifidobacterium and Lactobacillus strains have improved symptoms in people with mild ulcerative colitis (23).

However, probiotics appear to have little effect on symptoms of Crohn’s disease (24).

Nevertheless, probiotics may have benefits for other bowel disorders. Early research suggests they may help with symptoms of irritable bowel syndrome (IBS) (25).

Bottom Line:

Probiotics may help reduce the symptoms of bowel disorders like ulcerative colitis, IBS and necrotizing enterocolitis.

Older research suggests that taking probiotics reduced the likelihood and duration of respiratory infections. However, the quality of the evidence was low (26).

The probiotic Lactobacillus crispatus has also been shown to reduce the risk of urinary tract infections (UTIs) in women by 50% (27).

Ultimately, more research is needed to find out about the link between probiotics and immunity.

Bottom Line:

Probiotics may help boost your immune system and protect against infections.

8. Probiotics May Help You Lose Weight and Belly Fat

Probiotics may help with weight loss through a number of different mechanisms (28).

For example, some probiotics prevent the absorption of dietary fat in the intestine.

The fat is then excreted through feces rather than stored in the body (29).

In a study, synbiotic supplementation increased the abundance of gut bacteria associated with positive health effects, especially Bifidobacterium and Lactobacillus. It also appeared to increase the gut microbiota richness and increased the abundance of potentially beneficial microbial species (30).

More studies are needed to clarify the link between probiotics and weight (31).

Bottom Line:

Certain probiotics may help you lose weight and belly fat. However, other strains have been linked to weight gain.

The Best Way to Benefit From Probiotics

You can get probiotics from a variety of foods or supplements.

If you want to buy a probiotic supplement, then there is an excellent selection on Amazon with thousands of customer reviews.

Live probiotic cultures are often found in fermented dairy products such as yogurts and milk drinks. Fermented foods like pickled vegetables, tempeh, miso, kefir, kimchi, sauerkraut and soy products may also contain some lactic acid bacteria.

You can also take probiotics as tablets, capsules and powders that contain the bacteria in dried form.

However, be aware that some probiotics can be destroyed by stomach acid before they even reach the gut — meaning that you get none of the intended benefits.

If you want to experience any of the health benefits discussed above, it’s important that you consume adequate amounts.

Most of the studies showing benefits used dosages of 1 billion to 100 billion live organisms or colony-forming units (CFU) per day.

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