microbiome, probiotics, weight loss

What 25 Studies Say About Probiotics for Health + Weight Loss: Series on Probiotics

Your body is full of bacteria-both good and bad, that have a strong impact on how you feel and what your digestive system does with your food.  Specifically, probiotics are live bacteria (as well as some yeasts) that mostly reside in your digestive system.  These little buggers have a hand in your digestion, moods, immunity, wellness, and even your weight.

real food, weight loss, healthy diet, weight loss

The connection between the gut microbiome and health has been well established with evidence-based research and longer term clinical studies. Probiotics are in the news for many different reasons, like:

Despite all this research and positive press about using probiotics to help reduce symptoms-even get to the root cause of a persistent health issue, many people are leery of trying.

What Are Probiotics?

Have you been told that probiotics will help you?  Just like anti-biotics are effective treatments for specific diseases and illnesses, each larger group of pro-biotics and their smaller groups called strains have clinically proven purposes for health, disease prevention, and even weight loss:

  • There’s a specific strain of beneficial bacteria, or probiotics, that help prevent cavities and reduce plaque!
  • There’s a combination of probiotics that reduce anxiety and depression!
  • There’s a balanced ratio of larger strains of probiotics that determine your weight.
  • There’s a group of bad, or pathogenic, bacteria that make you crave carbohydrates and sugar. (It’s not all in your mind! Read this post.)

The Good, the Bad, and the Ugly

Figure 1: Microbial community composition at different body locations in a healthy human.The relative abundances of the six dominant bacterial phyla in each of the different body sites: the external auditory canal (nine subjects), the hair on the head (nine subjects), the mouth (ten subjects), the oesophagus (four subjects), the gastrointestinal tract (nine subjects), the vagina (eight subjects), the penis (12 subjects), the skin (nine subjects) and the nostril (nine subjects). Data taken from Refs 93, 94, 95, 96, 97.

Just like the beneficial bacteria outnumber each person’s DNA 10:1, surely that points to not every bacteria performing the same function since they are alive in every different part of our body! Check out the chart from Nature Reviews detailing the major groups of bacteria found on these body parts.

Did you know that there have been numerous published studies proving that probiotics are an effective treatment for antibiotic associated diarrhea? Specifically, the strains “LactobacillusSaccharomyces, and a mixture of probiotics were all beneficial in reducing the risk of developing CDAD” [source] and [source].

Genetics and Major Probiotic Groups

Image result for major strains of probiotics visualProbiotic classification starts with the largest group called the Genus, which is then categorized into Species, which then have specific, single Strains. Therefore, each of these main Genus groups has the same core genes:

  1. Bacillus
  2. Bifidobacterium
  3. Lactobacillus
  4. Saccharomyces
  5. Streptococcus [10]

Short cut question: Is there a main group of probiotic strains that are always effective or important for overall health?  Dr. Mercola says, yes to 3 strains of Lactobacillus and 2 of Bifidobacterium:

“There’s a handful of probiotic strains that I believe belong in any good probiotic supplement. I consider them foundational probiotic bacterial strains because of their far-reaching potential benefits for most people.”

Why Probiotics for Health + Weight Loss

Pushing past the known information on efficacy and quality of probiotics, let’s apply specific probiotic strains to purpose.  Dr. David Williams states, “My interpretation of the research to date has convinced me that it’s not the total number of bacteria in a product that is most important; it’s the number of different strains of bacteria it includes” [9].

His thoughts on why groupings of probiotic strains are important:

“Because the different strains of probiotic bacteria have slightly different functions and are concentrated in various places along the digestive tract, probiotic supplements that contain multiple strains tend to be more effective overall than products containing an extremely high concentration of just one or two strains. This is because many strains work synergistically to influence our health. The whole literally is greater than the sum of its parts.”


Regardless of diet, beneficial bacteria called probiotics combat a whole host of environmental- even psychological and biological, factors that assault your body on a daily basis.  Per Dr. Mercola, the following things all negatively influence the balance of beneficial and pathogenic bacteria in the body:

  • processed flour and sugar foods,
  • chlorinated and added fluoride in water,
  • common over the counter medications and antibiotic use,
  • herbicides,
  • stress and sleep disturbances,
  • pollution

Guaranteed that there are things on that list that are out of your control but still negatively impacting your health. Fortunately, probiotic foods and supplements can help repair and restore some of these damaging influences!

If you have a specific health condition that causes you discomfort and interrupts your daily life often enough that you have to pay attention to lifestyle activities or foods, then I suggest you consider including strain specific probiotics in order to improve your quality of life. You’ll see some weight loss results, too, because weight gain is usually a symptom of the real cause.

How do you know your underlying root cause? Read this post and subscribe for the free Root Cause Symptoms Tracker + Starter Food List.

Here’s a simple breakdown of some of the main purposes of probiotics within the body:


Within the digestive system, beneficial bacteria break down the fiber from foods into usable energy.  A healthy system will also create, absorb, and efficiently utilize nutrients from our foods.  When your body is functioning well, it won’t need to consume excessive calories each day!

More importantly, studies have confirmed that “A microbiome of greater microbial content and diversity is likely a healthier microbiome” (source).

While lean people generally have more Bacteroidetes and less Firmicutes bacteria, obesity is directly linked with higher Firmicutes in the digestive system.  There’s great news: “the microbial profile in the gut is malleable; each of us can alter our own microbiome” (source).

Beneficial Bacteria In the Body

If specific groups of beneficial bacteria have a significant impact on health and body weight, what and where are these probiotics located and how do we get more of the good for short and long term benefits?

Image result for gut microbiome image

According to Health Line, the two most consumed and clinically studied probiotics are Bifidobacteria, which is found in the intestines, and Lactobacillus, which populates the mouth, small intestine, and vagina.  Both of these break down lactose, the sugar found in dairy, and also inhibit pathogenic bacteria.

Bifidobacteria and its smaller strains have been shown to boost the immune system whereas the smaller strains of Lactobacillus probiotics focus more on digestive issues.

Life Extension, which has an excellent line of quality probiotic supplements, states that “Bifidobacteria are used as a probiotic to improve intestinal flora balance, inhibit harmful bacteria, promote good digestion, boost immune function, and increase resistance to infection.”  Bifidobacteria decreases inflammation in the digestive system, specifically with inflammatory bowel issues!

However, here’s the caveat: not every probiotic supplement, strain, or combination is going to work the same way in every person.  There’s billions of beneficial bacteria! While pharma companies can patent a specific strain or combination, the variable becomes how your body responds to it.

Individuality Rules in the Gut

Each person’s gut microbiome, or ecology, or “healthy functional core” (NCBI study) is unique to your:

  • genetics,
  • changing environment,
  • past and present food choices,
  • and even method of birthRelated image

Case in point: if you are someone who suffers with an inflammatory bowel issue, supplementing with a Bifidobacteria may or may not help once your condition is established.  Researchers have found that once colitis is present and causing harm in the digestive system, this supplement may still upset the condition because the chain linked immune response system is already ineffective.

Another theory about immune responses to probiotics is being studied in relation to fiber intake, which for many people with IBS symptoms is problematic.  A known cancer researcher, Robert Sandler, “says fiber might protect some people but not others against colon cancer because we all have different bacteria in us that react differently to fiber.”  Citing that “bacteria fight each other for space in our bellies,” they haven’t been able to confirm what upsets the balance of bacteria in unhealthy bodies; “It could be diet that leads to some bacteria growing faster than others” (Mark Derewicz).

Most discomfort from probiotics is often just a result of the process of altering the gut microbiome or an ineffective pairing of strains.  For instance, a friend had major bloating and gas after taking a 2 strain specific digestion probiotic; the strains were effective in targeting toxins via digesting protein matter but did not include a strain of probiotics or enzymes to help flush and remove it!

Overall, the immune response to the probiotic is generally dependent on 4 factors:

  1. the ability of the LAB (lactic acid bacteria) strain to influence the person’s immune system
  2. dose dependent
  3. medium of intake (supplement and coating, fermented food, cultured dairy)
  4. state of the probiotic

Why Probiotics are Needed in the Gut

How do you know how your body will respond to a strain or combination of probiotics?  Is it worth the money and time to purchase a probiotic supplement to improve your health and reach your weight loss goals?

Yes, and no.

Beneficial bacteria are living micro-organisms.  If you are after a quick fix, then you will likely not see visible results as quickly as you may be expecting.  Weight goes on pretty quickly, but off? Not so much LOL.

There are a plethora of changes that will catapult your success- it will just take time to notice.  Researchers have found that it takes an average of 3 months to heal and bring about positive changes within the gut. And that’s not taking into account an individual’s baseline health, nutritional deficiencies, or genetics.

Dr. Will Cole, a leading functional medicine expert, wrote a great post in response to this question called, Here’s How Long It Actually Takes To Heal Your Gut:

“The gut-healing time of people who don’t have autoimmune conditions, food sensitivities, or other inflammatory health issues varies, but studies suggest that it’s somewhere between two and 12 weeks.

Another study from Harvard, published in the medical journal Nature, found significant changes in the makeup of the gut bacteria occurring just three days after a dietary change! This demonstrates the amazing power of the foods we eat, but in reality, most people interested in healing their gut have other health issues that make healing more complex and a lot slower.

If you have one or more of these health issues, gut healing will definitely be a journey: chronic inflammation, Lyme disease, chronic viral infections, blood sugar issues, adrenal fatigue, SIBO, an autoimmune condition, histamine intolerance, candida overgrowth, or leaky gut syndrome.”

Probiotics are powerful for the healing process and for sustaining a healthy gut & weight.  In the next post in the series, we will explore what causes “leaks” in your health and how probiotics will help you achieve health and weight loss.

The final post in the series will give you a list of probiotics according to purpose as a guide for your health and weight with the help of probiotics.

What has been your experience with probiotics?

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The 4 Step Solution for a Healthy Gut + Weight Loss: Series on Probiotics