If you want physical and emotional well-being, you need to get the right guys living in your gut! It turns out your gut bacteria (microbiota) plays a vital role in your health. In this article, we will explore the health benefits of probiotics – your friendly gut bacteria.
Table of Contents
- What are probiotics?
- Health benefits
- 1) Diarrhea Prevention and Treatment
- 2) Irritable Bowel Syndrome (IBS)
- 3) Cardiovascular Health
- 4) Immune System Support
- 5) Gut-Brain-Mood
- What are CFUs?
- Does cooking or freezing affect probiotics?
- Adding probiotics to your diet
- What are prebiotics?
- Are there any cons?
- Take home message
What are probiotics?
Probiotics are the health-promoting microbes, sometimes labeled the “good” bacteria. Specifically, probiotics are live microorganisms that provide health benefits when consumed in an adequate amount (1). The most common probiotics are Lactobacillus and Bifidobacterium, which are bacteria, and Saccharomyces boulardii, a kind of yeast.
You can get probiotics from fermented foods and dietary supplements. Common food sources include yogurt, kefir, cheese, kombucha, tempeh, kimchi, miso, and sauerkraut.
When we consume probiotics, they travel to the gut and attach to the intestine’s inner lining. They reside primarily in the lower intestine, but they don’t stay long. Think of them as friendly house guests that stay for a few days to a week (2, 3). Because they are temporary guests, we need to consume them regularly.
A healthy gut with a diverse microbiome can improve cardiovascular health, improve mood, strengthen the immune system, and decrease the duration of something we all dread, diarrhea.
These friendly bacteria are essential because they improve gastrointestinal (GI) health and help balance the gut microbiome (the community of microorganisms, such as bacteria and viruses, that live in your body). This may not sound like a big deal, but it is!
Probiotics have different effects depending on the type of probiotics, the amount consumed, the delivery method (e.g., food, supplement), how often they are consumed, and the individual’s health. Keep in mind that one probiotic or combination of probiotics may help in some cases and not in others.
1) Diarrhea Prevention and Treatment
Diarrhea is one of the most researched topics on probiotics. There are many causes of diarrhea, and it typically resolves on its own within four days (4). Most people would love to shorten that. Probiotics to the rescue! Research shows probiotics can shorten the duration. Saccharomyces boulardii has the strongest support in adults, but Lactobacillus containing probiotics can also prevent and treat diarrhea (5).
In children with rotaviral diarrhea, probiotics have been shown to decrease the length of diarrhea by 1-3 days (6, 7). Numerous studies have found participants taking antibiotics along with probiotics (dietary supplements or fermented milk) reduced the risk of antibiotic-associated diarrhea.
Products containing Lactobacillus rhamnosus GG and Saccharomyces boulardii seem to be the most effective strains (8, 9, 10). When probiotics are taken with antibiotics, they should be started as soon as possible.
2) Irritable Bowel Syndrome (IBS)
IBS is one of the most common functional GI disorders worldwide. It is a group of symptoms that can include abdominal pain, gas, bloating, and unusual bowel movements (constipation, diarrhea, or both). Research now shows an imbalance in the gut bacteria can play a role (11). Several recent studies have shown improved symptoms, especially abdominal pain (12).
One study found that a mixture of strains of Lactobacillus acidophilus compared to a placebo taken over 8-weeks significantly reduced the severity of symptoms (13). There is also evidence that taking bifidobacteria (B infantis 35624) can reduce bloating, abdominal pain, and bowel movement difficulty within one week (14).
Activia yogurt, which contains Bifidobacterium lactis DN-173 010, has been shown to improve regularity, reduce stomach pain, and decrease bloating in people with IBS. The researchers found that at least two servings per day were necessary to see results (15).
We suggest probiotics, taken as a group, to improve global symptoms as well as bloating and flatulence in IBS patients (16).The American College of Gastroenterology
IBS should not be confused with IBD (Inflammatory Bowel Disease). IBD is a very complex inflammatory autoimmune disease that includes ulcerative colitis and Crohn’s Disease. Although there is research examining the effects of probiotics on IBD, the research is not conclusive. There is some support for commercially available products, VSL#3, which contains Lactobacilli, Bifidobacteria, and Streptococcus species (17).
3) Cardiovascular Health
Studies show an association between intestinal microbiota and cardiovascular disease (18). Both hypertension (high blood pressure) and elevated cholesterol are risk factors for cardiovascular disease (CVD). Several studies have found beneficial effects of probiotics on both these conditions. However, evidence for cholesterol support is stronger.
Research shows dietary supplements and fermented milk products can reduce blood pressure (BP). A meta-analysis (a study combining and analyzing data from multiple studies) found BP-lowering effects were most significant when participants consumed multiple species, took products for at least eight weeks, or consumed at least 1011 CFUs (100 billion) per day (19).
Several clinical trials suggest that probiotics help lower cholesterol levels. Products containing lactobacillus, including fermented milk products, have the most support. One study compared probiotic yogurt containing Lactobacillus acidophilus and Bifidobacterium lactis with an ordinary yogurt. The participants replaced milk with yogurt (~10 oz per day). The researchers found a significant reduction in total cholesterol in the participants eating the probiotic yogurt.
A meta-analysis found that participants who were given probiotics for 3 to 12 weeks reduced total cholesterol by 7.8 mg/dL and LDL cholesterol by 7.3 mg/dL. Several of the studies in this analysis used Lactobacillus acidophilus or a mixture of Lactobacillus acidophilus and Bifidobacterium lactis, and Lactobacillus plantarum (20).
4) Immune System Support
Probiotics, our friendly house guests, protect us from invaders. They do a great job of keeping our gut secure. But if an unwanted guest arrives, probiotics make the environment very unpleasant, so our unwanted guests move along. Probiotics help regulate tight junctions.
Tight junctions function as a physical intestinal barrier and regulate the movement of substances across the intestine. The integrity of the gut barrier is important because it helps to defend against pathogens getting into the bloodstream. Probiotics Lactobacillus rhamnosus and Lactobacillus plantarum appear to strengthen the tight junctions, which leads to improved barrier function (21).
Once probiotics like lactobacilli attach to the intestine and colonize, they make it harder for pathogens to attach. Additionally, probiotics compete with pathogens for nutrients and alter the environment (e.g., lower pH), making it difficult for pathogens to survive. Not only are they competing, but probiotics also alter pathogen-derived toxins (22).
Additionally, probiotics support the activity of our immune cells. They positively alter immune fighting cells, and they stimulate the production of antibodies. Interestingly, they appear to know how to modify the immune system depending on the person’s needs. In people with hypersensitive immune systems, probiotics seem to decrease immune function. In healthy people, they appear to stimulate the immune system (23).
DanActive, a probiotic drink that contains the Lactobacillus casei DN 114-001 strain, has been shown to support the immune system. Each bottle contains 10 billion live and active probiotics (24). The probiotics stay in the digestive tract, where a large percentage of our immune cells are found. Two servings of DanActive per day was found to decrease the frequency and length of the common cold and the flu (15).
It is well known today that our gut and brain communicate with each other. This is called the gut-brain axis. To be more specific, the microbiota-gut-brain axis. There is back-and-forth communication between the gut and brain through the immune system, endocrine system, and nervous system, especially through the vagus nerve (25).
Microbes in the gut appear to initiate biochemical signals in the brain that affect emotional state. It turns out that probiotics can make neurochemicals that are just like the ones humans make, such as serotonin, dopamine, and gamma-amino-butyric acid (GABA) (25). These signaling chemicals can influence behaviors, such as anxiety. Bifidobacterium breve, Bifidobacterim longum, and Lactobacillus gasseri have all been associated with reduced anxiety and depression (26, 27).
Probiotics may also alter mood by producing short-chain fatty acids (SCFA, e.g., butyrate). SCFAs are important in microbiota-gut-brain communication, and they appear to affect emotions. Research has shown lower SCFA concentrations in people with depression, and butyrate seems to have an antidepressant-like effect (28).
What are CFUs?
It is helpful to understand how probiotics are measured so you can compare products. Probiotics are measured by the number of viable cells or colony-forming units (CFUs). In other words, the CFU is the number of bacteria in probiotics that can divide and form colonies. If you read a product label, you might see 1 x 109 or 1 billion CFUs or 1 x 1010 or 10 billion CFUs (29). The packaging on Lifeway Kefir, for example, states the product contains 25-30 billion CFU per 8 ounces.
The table below will give you a general idea of the CFUs in fermented food.
|Cultured Yogurt||10,000 – 1,000,000,000 CFU/gram|
|Kombucha (fermented tea)||1,000,000 – 10,000,000 CFU/mL|
|Fermented Vegetables (sauerkraut, kimchi, olives, pickles)||1,000 – 100,000,000 CFU/gram|
|Fermented Milk (kefir, cultured buttermilk)||100,000 – 1,000,000,000 CFU/gram|
|Cheese (highest levels in Tilsit cheese aged 2–4 months)||less than 1,000 – 1,000,000,000 CFU/gram|
|Miso, Fish Sauce, Tempeh||100 – 10,000,000 CFU/gram|
There is not a set recommendation for daily probiotic intake, and studies have shown a wide range. 1-10 billion CFUs is commonly recommended for healthy people. The dose can increase quite a bit for specific health conditions. Keep in mind that most of the research showing health benefits have been conducted using fermented dairy products (e.g., yogurt) and dietary supplements.
Does cooking or freezing affect probiotics?
Heat kills cultures. Bacteria used in making yogurt, for example, will be killed at temperatures above 130°F (54.4ºC) (31). Yogurt-covered raisins that go through heat treatment don’t have active bacteria. Surprisingly freezing does not kill the live microbes.
There are products hitting the market that provide Lactobacillus casei and Lactobacillus rhamnosus. According to the National Yogurt Association, freezing seems to put the cultures to sleep and they defrost inside the body (32, 33).
Adding probiotics to your diet
Remember, probiotics are temporary guests. We, therefore, need to consume them regularly to continue reaping the health benefits. We can do this with food sources and dietary supplements. Health professionals may use dietary supplements to prescribe a higher dosage level and tailor the type of probiotic to the patient’s health condition (e.g., IBS).
For general health, food sources should be sufficient, and they provide other essential nutrients (e.g., protein, calcium). Several commercially available products have been used in clinical trials (34, 35).
As stated earlier, there is no recommended daily dose of probiotics. However, research suggests 1-10 billion CFUs. This CFU level can be met with an 8-ounce glass of kefir or 1-2 cups of yogurt with live and active cultures. Not all products list the CFUs on the food label. You might simply focus on adding a serving of probiotic-rich food every day.
To help consumers identify yogurts with live and active cultures, the National Yogurt Association has implemented the Live & Active Cultures (LAC) seal.
This voluntary seal is found on the product containers. Yogurt products with this seal must contain at least 100 million cultures per gram of yogurt when manufactured. Frozen yogurt products that contain at least 10 million cultures per gram at the time of manufacture may also use the LAC seal.
Additionally, yogurt must be fermented to use the LAC seal (32, 33). Not all manufacturers will use the LAC seal. This doesn’t necessarily mean they don’t contain live and active cultures. If you don’t see the seal, look for products that say they contain live and active cultures on the packaging.
What are prebiotics?
Prebiotics support the growth of probiotics and support our well-being! They are non-digestible food components we get from eating fiber-rich plants. Chicory root, Jerusalem artichokes, barley, bananas, onions, garlic, leeks, asparagus, artichokes, beans, rye bran or grain, wheat bran, and even chocolate are sources of prebiotics.
Because prebiotics are not digested, they become nutrition for probiotics. And, prebiotics work synergistically with probiotics to support health. This is why many probiotic products add prebiotics. For example, a product might contain the probiotic Lactobacillus acidophilus and the prebiotic fructooligosaccharides (FOS). The combination of a pre- and probiotic is called a synbiotic (36, 37).
You could also create a synbiotic meal or snack by combining pre- and probiotic food sources. Here are a few examples:
- Yogurt topped with bananas
- Miso soup and edamame
- Whole-grain crackers with gouda cheese
- Asparagus and yogurt dipping sauce
There are not any specific daily intake recommendations. However, it has been suggested that 4-10 grams of prebiotics are beneficial. The following each provide approximately 6 grams of prebiotics:
- Raw Jerusalem artichoke (19 grams)
- Raw garlic (34 grams)
- Raw leek (51 grams)
- Raw onion (70 grams)
- Cooked onion (120 grams)
- Whole-cooked wheat flour (125 grams)
- Raw banana (600 grams)
An increase in prebiotics can increase bloating and bowel movements. It helps to increase the amount gradually.
Are there any cons?
Probiotics appear to be extremely safe. The most common side effects are gas and bloating. However, caution is advised in those who are immunocompromised (e.g., cancer patients receiving chemotherapy), have indwelling medical devices, previous bowel surgery, severe acute pancreatitis, and are critically ill. It is always best to seek medical advice before making any dietary changes.
Take home message
Probiotics have been studied extensively. There is compelling evidence that probiotics restore balance to the intestinal flora leading to many beneficial effects. They strengthen the immune system, have antimicrobial effects helping us fight off pathogens, reduce the duration of diarrhea, strengthen the gut barrier, reduce the risk of cardiovascular disease, and help reduce stress, anxiety, and depression.
It is essential to consume an adequate amount of probiotics regularly if you want to reap these benefits. Simply adding 1-2 cups of yogurt each day will put you on the path to getting the right guys living in your gut!