Even if some of the bacteria in a probiotic managed to survive and propagate in the intestine, there would likely be far too few of them to dramatically alter the overall composition of one's internal ecosystem. Whereas the human gut contains tens of trillions of bacteria, there are only between 100 million and a few hundred billion bacteria in a typical serving of yogurt or a microbe-filled pill. Last year a team of scientists at the University of Copenhagen published a review of seven randomized, placebo-controlled trials (the most scientifically rigorous types of studies researchers know how to conduct) investigating whether probiotic supplements—including biscuits, milk-based drinks and capsules—change the diversity of bacteria in fecal samples. Only one study—of 34 healthy volunteers—found a statistically significant change, and there was no indication that it provided a clinical benefit. “A probiotic is still just a drop in a bucket,” says Shira Doron, an infectious disease expert at Tufts Medical Center. “The gut always has orders of magnitude more microbes.”
Today, most of the Japanese population begins the day with a warm bowl of miso soup, believed to stimulate the digestive system and energize the body. Made from fermented soybeans, rice or barley, adding a tablespoon of miso to some hot water makes an excellent, quick, probiotic-rich soup. The fermentation process can take anywhere from a few days to a couple of years to complete, and the end result is a red, white or dark brown paste with a buttery texture.
Although probiotics have been around since the early 1900s, they have recently gained popularity due to their ability to treat a wide range of ailments. Research also suggests that probiotics can help you lose weight and maintain a healthy body-mass index, according to a meta-analysis that reviewed 20 studies that was published in May 2016 in the International Journal of Food Sciences and Nutrition.
How can something as small as a microscopic organism be so important for health? The reason is that there is not just one microbe, nor a handful; there are approximately 1 trillion microbes per gram of feces. Microbes within you are found on your mucous membranes, spanning from your mouth to your anus, from your nasal passages to your lungs, in your urinary tract, and even on your eyes. In fact, in your digestive tract alone, it is calculated that for every cell of yours that is human, there are an equal number of bacterial cells.
Kefir: This could be the most ideal probiotic dairy product because it contains both bacteria and yeast working together to provide the numerous health benefits. In a recent eight-week study, people with diabetes were given kefir milk containing Lactobacillus casei, Lactobacillus acidophilus, and bifidobacteria vs. conventional fermented milk. The hemoglobin A1C levels were significantly lower in the group consuming the kefir.
Method of delivery: "The probiotic needs to be able to survive the acidic environment of the stomach and reach the intestine," explains Dr. Nazareth. This can be optimized through the way you take the probiotic and what's included in the formula. "Some delivery systems to consider are time-released tablet/caplet, capsules with an enteric coating and/or microcapsules, and ones that contain prebiotics and the optimal combination of probiotics," says Lori Chang, a registered dietitian with Kaiser Permanente in West Los Angeles.
Although some probiotics have shown promise in research studies, strong scientific evidence to support specific uses of probiotics for most health conditions is lacking. The U.S. Food and Drug Administration (FDA) has not approved any probiotics for preventing or treating any health problem. Some experts have cautioned that the rapid growth in marketing and use of probiotics may have outpaced scientific research for many of their proposed uses and benefits.

Taking a probiotic every day is a good way to help prevent getting sick and having to go on antibiotics in the first place. Preventative measures, of course, are preferred. Another that is believed to help is upping your vitamin D intake when your immune system needs a boost. Diet is also huge in terms of preventing sickness. Studies show that you can change your microbiome within hours of adjusting your diet. If you’re not into sauerkraut, even just cutting back on sugar and eating more whole foods can make a difference.

More and more evidence shows that the gut microbiota may play an important role in the development of obesity, obesity-associated inflammation and insulin resistance. Obesity and Type 2 diabetes are associated with changes in gut microbiota. Several studies describe differences between the microbiota of lean individuals and those who are obese. The potential for using probiotics in weight management and obesity and diabetes prevention is exciting.
The side effects of antibiotic use are often not trivial. Many people experience discomfort and a change in bowel habits, but some experience more severe infections, such as opportunistic colonization of the gut with bacteria such as Clostridium difficile (C.diff), which affected half a million Americans in 2015 and was directly responsible for at least 15,000 deaths.
The first major finding was that many people were essentially resistant to any effect from probiotics and their gut microbiome did not change after taking them.  Of 19 people in the study taking probiotics consisting of 11 of the most commonly found strains, only 8 had any notable colonization of their gut with the bacteria in the probiotics, with 3 people considered to have significant colonization and 5 people with "mild" colonization.

Keep in mind that when supplements contain a specific number of organisms, this number may not be what is actually within each capsule at the time of purchase. Probiotics are living organisms and can die out easily. Especially if that supplement sits on your drugstore or warehouse shelf for months or longer, the number of organisms you get may be far less than what the bottle claims. Hardier strains have a longer shelf life. Capsule strength decays faster if the probiotic has been sitting around at elevated temperatures during transport to the store. Companies actually have to produce probiotics with a much higher CFU (colony-forming units; see below) count in each capsule in order to guarantee the label potency by the expiration date.

Inside your body bacterial and other microbial cells live in close contact with your own cells, and in healthy conditions the thing that separates them from you is a layer of mucus. Between that layer of mucus and the inside of you is a layer of skin-like cells one-cell thick. One thing you have to understand about your gastrointestinal (GI) tract is that although it resides within you, it is really connected to the outside world, from your lips to your anus, and the things that protect you from the outside world are the mucus; the skin-like layer of cells with immune, nervous, and endocrine cells below it; and the beneficial microbes. At least 70 percent of your immune system is in your GI tract! This is why taking probiotics benefits the immune system greatly.
Known as the most clinically proven effective probiotic strain, Lactobacillus rhamnosus GG (otherwise known as “LGG”) has been clinically proven to maintain healthy numbers of bacteria and yeast for optimal digestive health. This powerful probiotic is also paired with some of the best probiotic strains for feminine health, making it an ideal choice for any woman that is looking for complete care from her probiotic.
Probiotics may seem new to the food and supplement industry, but they have been with us from our first breath. During a delivery through the birth canal, a newborn picks up the bacteria Bacteroides, Bifidobacterium, Lactobacillus, and Escherichia coli from his/her mother. These good bacteria are not transmitted when a Cesarean section is performed and have been shown to be the reason why some infants born by C-section have allergies, less than optimal immune systems, and lower levels of gut microflora.

The beneficial microbes, including probiotics, live with other microbes that are either benign, pathogenic (disease-causing), or opportunistic, meaning that they normally play nicely but can get out of control if given the opportunity. Actually, any microbe can cause you problems if it ends up in a place other than where it is supposed to be. Such a scenario can happen with intestinal permeability, commonly called leaky gut. Leaky gut happens when the layer of skin-like cells in your GI tract develops gaps in between the cells, allowing food particles, toxins, microbes, and other hazards to enter your bloodstream, if not stopped by the immune system. Since mucus, the thin layer of cells, and your immune system are your only defenses against the outside world within your digestive tract, it is very beneficial to you to have helpful microbes protecting you from potentially pathogenic microbes. These beneficial microbes can produce acids or antimicrobial products called bacteriocins, which hinder or kill pathogens. They can also stand in solidarity to prevent pathogens from taking up residence, or displace them if they do.
Animals, including humans, have microbes inside them that benefit them in multiple ways. These microbes are in a loose sense like probiotics, but the definition of probiotics was established to designate those microbes that have been isolated, studied, tested in a laboratory dish and/or clinically in animals and/ or humans, and proven to have beneficial properties. In many cases their genetic fingerprints were sequenced for identification purposes and also to check for potentially harmful genetic components. The official term “probiotics” established specific criteria for scientific studies and probiotic supplements, foods, and drinks.
Microbes are tiny organisms (bacteria, viruses, parasites, or fungi) -- so tiny that millions can fit into the eye of a needle -- that are so powerful that an imbalance in the body is related to numerous diseases. These microorganisms can be found in almost every part of the human body, living on the skin, in the nose, and in the gut. There are trillions of these microorganisms in our bodies. They outnumber human cells by 10 to one, but due to their small size, they only make up 1%-3% of a body's total mass.
The two main species you want to look for are: Lactobacillus and Bifidobacterium. Within these two species, there are a lot of different strains. The strains we chose for our probiotic—Lactobacillus acidophilus, Lactobacillus plantarum, and Bifidobacterium longum—have been shown to help modulate the immune system, help with autoimmunity conditions (which affect most of my patients), and counter infections in the gut.
Sick of fighting off cold after cold? The Align Daily Immune Support Probiotic Supplement is a great way to give your immune system a boost while protecting your gut bacteria. Align is one of the most popular probiotic brands out there and is trusted by both doctors and nutritionists. The Daily Immune Support has Bifidobacterium lactis BB-12, a probiotic strain thought to be most beneficial to your immune health. It’s a lactic acid bacteria that can also help to fight lactose intolerance. This probiotic contains five billion CFUs (generally, most adults should take at least one billion CFUs in a probiotic) and is meant to be taken once a day.
We found the most evidence linking strains to antibiotic recovery, immune health, and IBS/IBD relief. We made checklists of the most researched strains that treat those issues (10 strains known to boost general health, six for immune health, seven for antibiotic recovery, and seven for IBS/IBD relief) and dug into ingredient lists to find the supplements containing the highest number of effective strains for each use case.
"Probiotics applied topically sit on the skin's surface and prevent the skin cells from seeing the bad bacteria and parasites that can cause this immune system response," confirms Engelman. "This is known as 'bacterial interference,' as probiotics protect the skin and interfere with the ability of bad bugs like bacteria and parasites to provoke an immune reaction.
Although people often think of bacteria and other microorganisms as harmful “germs,” many microorganisms help our bodies function properly. For example, bacteria that are normally present in our intestines help digest food, destroy disease-causing microorganisms, and produce vitamins. Large numbers of microorganisms live on and in our bodies. Many of the microorganisms in probiotic products are the same as or similar to microorganisms that naturally live in our bodies.
What exactly do probiotics do? They are believed to protect us in two ways. The first is the role that they play in our digestive tract. We know that our digestive tract needs a healthy balance between the good and bad bacteria, so what gets in the way of this? It looks like our lifestyle is both the problem and the solution. Poor food choices, emotional stress, lack of sleep, antibiotic overuse, other drugs, and environmental influences can all shift the balance in favor of the bad bacteria.