Probiotics have received a lot of attention recently.
These living organisms have been credited with providing all kinds of health benefits related to gut function and beyond ().
If you're looking to use them to boost your own health, it's important to make sure you take the right probiotic supplements to get the results you're after.
This article takes a detailed look at the effects of probiotics and provides recommendations for supplements that address specific health issues.
Your gut contains bacteria acquired at birth and onward in a process called colonization.
Many of these bacteria are considered beneficial or "friendly." Their functions include converting fiber into short-chain fatty acids, synthesizing certain vitamins and supporting your immune system ().
Taking probiotics may help boost the numbers of these healthy bacteria.
The formal definition of probiotics is, "live microorganisms which when administered in adequate amounts confer a health beneﬁt on the host" ().
Basically, probiotics are microorganisms that provide beneficial effects when you consume them in the right amounts.
Probiotics can be consumed in supplement form or in fermented foods like sauerkraut, kefir and yogurt.
They should not be confused with prebiotics, which are types of fiber that serve as a food source for the bacteria living in your colon ().
Summary: Probiotics are health-promoting bacteria found in supplement form and some foods. Taking probiotics can help increase the number of beneficial bacteria that reside in your gut.
Your gut microbiome, or gut flora, consists of a wide variety of bacteria.
Its exact composition is unique to you.
Your colon contains billions of bacteria with types from over 500 different species ().
Probiotics that have been found to provide health benefits include various strains of Bifidobacterium, Lactobacillus and Saccharomyces. Many probiotic supplements contain a combination of different strains in the same supplement.
Research has shown that some strains seem to be more effective than others for treating certain conditions.
Therefore, you're more likely to get good results by taking probiotics that have been shown to achieve specific effects, such as controlling diarrhea.
In addition, it's important to consume probiotics in sufficient amounts.
Probiotics are typically measured in colony-forming units (CFU). Generally, higher doses have been found to produce the best results in most studies ().
However, some probiotics may be effective at dosages of 1–2 billion CFU per day, while others may require at least 20 billion CFU to achieve the desired effects.
Taking extremely high doses hasn't been found to cause harm. One study gave participants up to 1.8 trillion CFU per day. However, it's expensive and doesn't appear to provide any additional benefits ().
Importantly, scientists still don't know everything about probiotics. Although research has rapidly expanded within the past several years, there is much left to explore.
Summary: Different types of probiotic bacteria may provide health benefits. Taking a sufficient amount of the right probiotic is important for achieving the desired effects.
Constipation is characterized by bowel movements that are hard, difficult to pass and infrequent. Everyone experiences constipation once in a while, but in some people it becomes a chronic problem.
Chronic constipation is most common among the elderly and adults who are bedridden, although it can also occur in children.
In addition, some people with irritable bowel syndrome (IBS) experience persistent constipation as their main symptom. This is known as constipation-predominant IBS.
Conventional treatments include laxatives and stool softeners. However, in recent years, dietary changes and probiotic supplements have become increasingly popular alternative approaches ().
A number of studies have shown that supplementing with certain probiotic strains can reduce constipation in both adults and children (, , , , , ).
In a study comparing probiotics and prebiotics in children with IBS, B. lactis was shown to provide significant constipation relief.
The probiotics group also experienced less belching, abdominal fullness and bloating after meals than the prebiotics group ().
Other probiotics that may improve constipation include B. longum, S. cerevisiae and a combination of L. acidophilus, L. reuteri, L. plantarum, L. rhamnosus and B. animalis (, , ).
Recommended Probiotics for Constipation
Summary: Several probiotic strains have been shown to provide relief from constipation in children and adults when taken alone or together.
Diarrhea is defined as loose-to-liquid bowel movements that occur more frequently than normal.
It is typically short-lived, but can become chronic in some people.
Probiotics have been found to reduce stool frequency in the infection-related diarrhea that occurs with food poisoning and gastroenteritis, commonly known as "stomach flu" ().
A large review of 34 studies found that probiotics reduced the risk of diarrhea from various causes by 34%.
Effective strains included Lactobacillus rhamnosus GG, Lactobacillus acidophilus and Lactobacillus bulgaricus ().
Antibiotic use is another common cause of diarrhea. When antibiotic therapy kills harmful bacteria that cause infection, beneficial bacteria are destroyed as well. The shift in bacterial balance can lead to inflammation and diarrhea.
Studies in children and adults have shown that taking probiotics can help decrease the diarrhea that may happen as a result of antibiotic therapy (, ).
A large review of 82 controlled studies found that taking probiotic supplements reduced the risk of developing antibiotic-associated diarrhea by 42%. However, the most effective probiotic strains weren't discussed ().
Although some people with IBS struggle with constipation, others experience frequent episodes of diarrhea, which is known as diarrhea-predominant IBS.
Research suggests that certain probiotics seem to be especially effective for diarrhea-predominant IBS, including B. coagulans, S. boulardii and a combination of several Lactobacillus and Bifidobacterium strains (, , , ).
However, one study did not find any significant improvement in diarrhea among IBS patients who were treated with S. boulardii ().
Recommended Probiotics for Diarrhea
Summary: Probiotic therapy has been shown help reduce the severity and frequency of diarrhea related to infection, antibiotic use and IBS, among other causes.
Sometimes the main symptoms of IBS aren't related to stool consistency or frequency. Instead, some people experience bloating, gas, nausea and lower abdominal pain on a regular basis.
A review of 19 studies found that while some people reported improvement in IBS symptoms while taking probiotics, results varied between individuals. Researchers couldn't determine which probiotics were most effective ().
In addition, because the symptoms of IBS are so diverse, sometimes one symptom improves while others do not.
For instance, one study of people with constipation-predominant IBS found that although S. cerevisiae improved constipation, it didn't have much of an effect on abdominal pain or discomfort ().
In another study, participants with diarrhea-predominant IBS were given a supplement known as VSL#3, which contains Lactobacillus, Bifidobacterium and Streptococcus strains.
Bowel movement frequency and consistency didn't improve, but bloating did ().
Another study found significant reductions in pain and bloating during treatment with VSL#3. Researchers believe the probiotics led to an increase in melatonin, a hormone involved in digestive function (, ).
Recommended Probiotics for IBS
Summary: Certain probiotics have been shown to help relieve bloating, abdominal pain and other symptoms of irritable bowel syndrome. However, taking probiotic supplements may not improve all symptoms.
There is growing evidence that the balance of bacteria in your gut can profoundly affect body weight ().
Some studies suggest that taking probiotic supplements may be helpful for achieving weight loss and a healthier body composition.
Animal and human studies have found that certain bacterial strains may decrease the amount of fat and calories your gut absorbs, promote a healthy balance of gut bacteria and reduce weight and belly fat (, , , , , ).
According to a 2014 analysis of several studies, probiotics that seem to be effective for fat loss include Lactobacillus gasseri, Lactobacillus rhamnosus and the combination of Lactobacillus rhamnosus and Bifidobacterium lactis ().
In one study, obese men who took L. gasseri for 12 weeks experienced significant reductions in body weight and body fat, including up to an 8.5% decrease in belly fat. By contrast, the placebo group had very little change in body weight or body fat ().
In another study, obese women who took L. rhamnosus for three weeks lost twice as much weight as those who received a placebo.
What's more, they continued losing weight during the maintenance phase of the study, whereas the placebo group gained weight ().
Taking probiotic supplements may also help limit weight gain during times of high calorie intake.
In a four-week study, lean young men ate 1,000 excess calories per day. Those who took the probiotic formulation VSL#3 gained less weight than the control group ().
However, because results from some studies haven't been impressive, researchers feel there isn't enough evidence at this time to draw firm conclusions about the benefits of probiotics for weight loss ().
Recommended Probiotics for Weight Loss
Summary: Results from several studies suggest that certain probiotics may promote fat loss in obese subjects. However, further research is needed.
There is a strong connection between gut and brain health.
A review of 38 studies on animals and humans found that various probiotics helped improve symptoms of anxiety, depression, autism, obsessive-compulsive disorder and poor memory ().
The strains most commonly used in these studies were Bifidobacterium longum, Bifidobacterium breve, Bifidobacterium infantis, Lactobacillus helveticus and Lactobacillus rhamnosus.
Probiotics appear to be effective for both generalized anxiety and anxiety related to specific causes (, , ).
One study found that when throat cancer patients took probiotics for two weeks prior to surgery, they had lower levels of stress hormones in their blood and their anxiety decreased by 48% ().
In other studies, probiotics have been shown to improve overall mood and reduce sadness in healthy individuals and people with chronic fatigue syndrome (, , ).
Taking probiotic supplements also appears to help people struggling with depression, including those with major depressive disorder (, ).
In an eight-week study of patients with major depression, those who took L. acidophilus, L. casei and B. bifidum had a significant decrease in depression.
What's more, they experienced reductions in insulin levels and inflammatory markers ().
Recommended Probiotics for Brain Health
Summary: Brain and gut health are strongly connected. Taking certain probiotics may promote better mental health by reducing anxiety, sadness, depression and other symptoms.
Taking probiotics may help reduce the risk of heart disease.
Several studies have found that certain bacteria in yogurt or probiotic supplements may lead to favorable changes in heart health markers.
These include a decrease in "bad" LDL cholesterol and an increase in "good" HDL cholesterol (, , , , ).
Specific bacterial strains that seem to be effective at lowering cholesterol levels include Lactobacillus acidophilus, Bifidobacterium longum and Lactobacillus reuteri.
An analysis of 14 studies found that probiotics led to an average reduction in LDL cholesterol, a slight increase in HDL and a decrease in triglycerides ().
There are probably several processes responsible for these effects on LDL cholesterol, including changes in fat metabolism and decreased absorption of cholesterol in the gut ().
Probiotics may also help lower blood pressure.
One review of nine controlled studies found a modest reduction in blood pressure among those who took probiotics. However, only treatment longer than eight weeks at doses higher than 10 billion CFU per day had significant effects ().
Recommended Probiotics for Heart Health
Summary: Taking certain probiotic supplements may help lower LDL cholesterol, raise HDL cholesterol and decrease blood pressure.
Studies suggest that taking probiotic supplements may shift the balance of gut bacteria in a way that increases your body's defenses against allergies, infections and cancer ().
Of particular note are the strains Lactobacillus GG, Lactobacillus crispatus, Lactobacillus gasseri, Bifidobacterium bifidum and Bifidobacterium longum.
These types of bacteria appear to reduce the risk of respiratory illness and eczema in children, as well as urinary tract infections in adult women (, , ).
In addition, probiotics have been shown to reduce inflammation, a known risk factor for many diseases.
In one study, older adults consumed a blend of Lactobacillus gasseri, Bifidobacterium bifidum and Bifidobacterium longum or a placebo for three weeks each.
After taking probiotic supplements, their inflammatory markers decreased, anti-inflammatory markers increased and gut bacteria balances became more like the type seen in young, healthy people ().
Certain probiotics may also help prevent gingivitis, or gum infection.
A 14-day study looked at adults who refrained from brushing and flossing while being treated with Lactobacillus brevis or a placebo.
Gingivitis progressed more rapidly in the placebo group, suggesting the probiotics helped protect against infection ().
Recommended Probiotics for Immune Health
Summary: Taking probiotics may help strengthen your immune system and help reduce the risk of infection and illness.
In addition to targeting specific diseases and conditions, you can also take probiotics to promote overall health.
A recent study in healthy adults showed that taking Bifidobacterium bifidum for four weeks helped boost production of beneficial short-chain fatty acids ().
There's also some evidence suggesting that probiotics may promote better aging by reducing inflammation that typically occurs as you grow older (, ).
Of course, it's important to make sure you're consuming a healthy diet and practicing other health-promoting behaviors as well. Otherwise, you can't expect probiotics to provide much benefit.
In addition, although probiotics are safe for most people, they may cause harm in people who are extremely ill or have compromised immune systems, including those with HIV or AIDS ().
Recommended Probiotics for General Health
Summary: Probiotics may help support wellness in healthy people. However, taking probiotic supplements may be dangerous for people who are very ill or have compromised immune systems.
Having a healthy gut microbiome is extremely important.
Although research is still emerging, probiotics appear to provide beneficial effects for a number of different conditions and may also support better general health.
Taking the right type of probiotics may help you target specific health issues and improve your overall health and quality of life.