Probiotics have also been researched for how they support the immune system. Studies suggest that probiotics can improve how the immune system functions such as by decreasing upper respiratory tract infections in adults and reducing the need for antibiotics. Studies in children show that a regular diet including probiotics reduces colds and flu-like symptoms and improves attendance in preschool and day care settings. 

Lebwohl says IBS isn’t just about intestinal distress. For many IBS sufferers, it’s about the way our brain receives messages about pain. He describes the human colon as “almost reptilian” in the way that it contracts and relaxes throughout the day, but says these contractions are usually happening way below our threshold of consciousness, so we don’t even notice. In people with IBS, the neurotransmitters in our gut (yes, we have them in there too) may be sending severe distress signals to the brain about benign contractions happening in digestive tract.
To factor strain-specific benefits into our efficacy score, we referenced the information in these guides. Products were rewarded for containing strains on these lists. Additionally, measured levels of each strain were compared to what is thought to be effective based on these guides, and scores were scaled accordingly. In cases where products did not list strain-specific amounts, or their listed strains were not included in these guides, total measured CFUs were compared to a general effectiveness threshold of 1 billion CFUs cited by research published in the American Journal of Clinical Nutrition11.
That doesn't mean that all probiotics, or probiotic-containing foods are created equal. So what should you look for? "There is a lot of 'noise' in this space as more and more 'food products' are coming out with Probiotics," Dr. Shekhar K. Challa, a gastroenterologist and the author of Probiotics For Dummies tells The Huffington Post. "Unfortunately it is impossible to quantitate the CFU's of probiotics in most food products."
There have been multiple additional studies which link stress to changes in gut bacteria, so there does appear to be some sort of link. But Lebwohl says it’s not enough to recommend widespread use in clinical practice. He referred to these as “hypothesis-generating studies,” which should lead to concrete clinical trials in which the probiotics are tested against a placebo. “These are important studies,” he says. “But it’s premature to call them practice-changing studies.”
However, it is not just digestive woes that probiotics can help address. A clinical case series followed 300 patients who took a probiotic mixture of L. acidophilus and L. Bulgaricus. They documented that 80% of acne patients had some degree of clinical improvement, particularly effective in inflammatory acne. Later, an Italian study involving 40 patients found L. Acidophilus and B. Bifidum supplementation produced better clinical outcomes in acne as well as better tolerance and compliance with antibiotics [2].
I’m 65 years of age. I have been taking acid reflux medication daily for at least 15 years and recently my doctor said my kidneys were declining. I’ve read that acid reflux medications taken over a long period of time, can cause kidney damage. By taking a probiotic, will it help reduce stomach acid, where I may be able to stop taking my acid reflux medication altogether?
In the past, probiotics have been proposed as part of a weight loss diet. However, a 2015 meta-analysis looked at available randomized, controlled trials investigating this effect and determined that the studies did not seem to support this hypothesis, as body weight and BMI were not consistently reduced. The researchers did point out the need for better designed trials, because they were not convinced the results were based on well-designed science.
There are four significant takeaways from this study: (1) murine gut mucosal probiotic colonization is only mildly enhanced by antibiotics, (2) Human gut mucosal probiotic colonization is significantly enhanced by antibiotics, (3) After taking antibiotics, probiotics delay gut microbiome and transcriptome reconstitution in mice and humans, (4) Autologous fecal microbiome transplant (aFMT) restores mucosal microbiome and gut transcriptome reconstitution. 
Whether a brand of probiotics works really depends on its quality and your body's own gut. Everyone has a different set of gut flora so try several to see what works for you. Using a brand of at least 40 billion CFU is best. There seems to be some debate as to whether one should use refrigerated or unrefrigerated probiotics. I went with the side that claims unrefrigerated are sturdier and less prone to die off.

Quality matters for any supplement, and that goes triple for probiotics. Many commercial brands lack the technology to identify specific strains and how much of that strain each dose contains. That could mean you get an ineffective or potentially harmful dose. It's a great sign if the company is using strains that have been used specifically in clinical trials at a dose similar to or the same as that used in the study. This is one of the only ways to guarantee a probiotic's clinical effectiveness.


A popular dish in Japan consisting of fermented soybeans, natto contains the extremely powerful probiotic bacillus subtilis, which has been proven to bolster your immune system, support cardiovascular health and enhance digestion of vitamin K2. Natto can also contain vitamin B12, which is usually lacking in vegan diets. It’s also one of the highest plant-based proteins.
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