• Sarah Greenfield, RD

Personalize Your Microbiome: How to Choose the Right Probiotics for You

Probiotics are no longer news in the realm of wellness discoveries, they are everywhere. From protein powders to energy bars, and even some granola is spiked with billions of these microscopic organisms! You may have been heard more terms like prebiotics and postbiotics– it’s true, that’s a thing. I often get asked about what probiotics are best. Do they really live up to the hype? What are they actually doing in the body? This article will give you the low-down on probiotics, prebiotics, and postbiotics and how you can learn more about which ones are right for your body.

Probiotics 101

The word “bacteria” might make your cringe or trigger a Purell bender, bringing to mind the filthiest subway stations in The Lower East Side and strangers who cough without covering their mouths. The truth of the matter is, your body is home to trillions of bacteria– microorganisms that are absolutely essential to your health and daily function. Probiotics themselves are live bacteria that keep your gut and other “self-cleaning” bodily systems in check and create metabolites that promote health.

These bacteria are friends, not foes. They hang out along your GI tract and are most concentrated in your large intestines where they really work their magic. When food is digested, it is exposed to enzymes in the mouth which begin the process of breakdown, then stomach acid, which kills off harmful pathogens, and only then they are exposed to the bacteria in the gut..These bacteria help digest food properly, aiding in the absorption of vital nutrients, while kicking out harmful pathogens and fostering the production of vitamins, neurotransmitters, hormones and fatty acids that make your skin glow and your immune functions kick ass. These are guests you definitely want invited to your gut party.

When things go wrong

Having healthy gut flora and healthy digestion makes our lives easier, more comfortable, and prevents a plethora of diseases, but keeping the gut healthy can prove to be challenging. We have a lot working against the health of our gut. The standard American diet which is high in inflammatory oils, sugar, and gluten, can create inflammation in the gut, making our intestines more permeable. Permeability means there is more space between the cells of intestinal wall for undesirable compounds to get into our bloodstream. When these compounds enter the bloodstream, our immune system goes crazy. This is when we start to see things like eczema, food sensitivities, and a variety of autoimmune diseases. Inflammation is the last thing you want in your gut.

Stress is another huge cause of digestive imbalance and gut issues. When we experience stress, our bodies have a physiological reaction, a hormonal response. Cortisol is released in response to stress and when we are constantly stressed out, cortisol is constantly being released. Cortisol can up-regulate inflammation in the gut, which we’ve just learned is a recipe for immune system disaster. Also, when we have high levels of cortisol, this can also increase histamines in our body. When we have high levels of histamines, our allergies will be at an all time high. Our gut houses the DAO enzyme which breaks down histamines, but if our gut or body is out of balance, this enzyme will not work as efficiently.

The increased use of antibiotics can disrupt the natural environment of our gut. Antibiotics are the antithesis of probiotics. In antibiotics’ plight to destroy all evil, our healthy organisms become casualties, leaving our guts vulnerable to other issues, digestive, and otherwise. When healthy bacteria are obliterated in the honorable efforts of antibiotics, any harmful bacteria that has been living in harmony in the gut, now has all the space in world to multiply, quickly. This is often referred to as dysbiosis. This can bring on a slew of digestive issues like constipation, diarrhea and bloating.

Keeping up with the Microorganisms

Now here comes the tricky part. In order to have more friends than strangers and hostiles in your gut party, you have to consider maintaining them. Probiotic supplements along with a diet of good variety will help to diversify your gut like previously mentioned, which is important because we all need variety to keep things interesting, right? However, probiotics can only help this while you are taking them, they cannot colonize your gut. That’s where prebiotics come in.

Prebiotics are the food that your probiotic needs to eat to continue flourishing. Just how bad bacteria– the kind that causes illness and flu-like symptoms– feed on processed sugars and alcohol, probiotic bacteria has gotta eat, too! Eating a fiber-rich diet is one way to feed these important gut guests. Specifically, garlic, onions, dandelion greens, slightly-green bananas, sunchokes, and dark, leafy greens are great sources of prebiotic goodness.

But wait, there’s more. You may have encountered a supplement that has prebiotics, probiotics, and postbiotics! Postbiotics are the metabolites our probiotics make, like short-chain fatty acids and vitamins. These are showing up more and more in the retail world, and it’s a super efficient way to prioritize the health of your gut. It’s like a new toy on Christmas day, batteries included. Ok, so maybe it’s not that exciting, but your gut will thank you for the bugs and the food to fuel them, all in one easy pill to swallow.

Let’s circle back to prebiotic foods, because everyone’s gut is different and requires different solutions and fuel sources. If you happen to have a bad reaction to these foods, or find that supplements with prebiotics don’t make you feel great, testing for bacterial overgrowth is something you might want to consider. A simple breath test or stool test can help determine the issue, or rule out this notion all together. Only one way to find out!

Stool Test Take-aways

Stool testing has been a game-changer in my practice. It’s one of the only ways to get direct insight into what types of bacteria you have in your gut, and can help explain mysterious gut imbalances, even when you think you’re doing everything right!

Although your stool is only a fragment of the story from ingestion to, ehem, excretion, it’s a big part of getting to know and understand your own microbiome and what probiotics would best support your specific needs. It’s also the best (and fastest!) way to begin the healing process. To get to know your stool, I suggest these two tests:

GI Effects– 16-s sequencing, measuring 24 different commensal bacteria in your large intestine. It measures inflammation, protein, and fat breakdown as well as parasites, yikes!

GI Map: PCR test that looks at opportunistic bacteria and commensal. This test also looks at H. Pylori– a bacteria that can live in your gut for years, leading to ulcers, stomach pain, and irregularity.

Shopping for the Right Probiotic For You

Once you’ve completed a stool test, you may be an expert on your own microbiome and know exactly which bacteria is best. If you haven’t taken that deep dive into your digestive understanding, you can try different strains based on your symptoms and see what works. Before you go out and buy several brands and start blind testing, here are some symptoms paired with the strain best suited for the job:

Diarrhea. It plagues us all at some point, and not just when you eat less-than-fresh seafood. L. Casei sp. Paracasei or L. Plantarum are excellent choices. L, Reuteri also helps with diarrhea, as well as the nasty aforementioned bacteria, H. Pylori. It’s also the best choice for kids and babies. It’s readily available in fermented dairy products like kefir, and it’s also in GoodBelly (look for the options with low sugar), and BioGaia Protectis, which is the top choice for babies.

Bloating is a discomfort that many, if not most people deal with on a regular basis. But you don’t have to! Saccharomyces Boulrdii is a a great strain for bloating, and highly recommended for those with SIBO. (Most other strains are cultured with FOS, which can exacerbate bloating and SIBO!) This particular strain is also effective for H. Pylori and parasites. Klaire Labs is a superb product for this strain. I also like Florastor.

Constipation can be infuriating at times, especially when you feel you’re doing everything to alleviate it, i.e. drinking water, eating fiber. Sometimes, the answer is in the bacteria. I. Casei Shirota and L. Reuteri are effective to help get things moving. I recommend Yakult (it’s dairy-based, for those who can swing it), and BioGaia Protectis.

Healthy skin starts with digestion! For issues that manifest themselves in eczema, breakouts, or dry, irritated skin, try L. Rhamnosus GG, or a high quality blend of probiotics in general like Klaire Labs Ther-biotic. They support the skin through regulation of the expression of matrix Meralloprotinase-1, which are enzymes that the body uses to turn over new skin cells. Yes, that means aging, too! Klaire Labs is great for this as well. I also recommend Culturelle Probiotic Advantage, and HUM Nutrition Skin Heroes, which I formulated!

Weight control is an enormous spectrum, but proper digestion is key to passing waste so that it doesn’t get stored as fat, and absorbing nutrients that keep your organs healthy and functioning. B. Animalis ssp. Lactis 420 (B420) is known to aid in reduction of body weight, fat mass, and waist circumference. FloraVantage Control is an excellent product.

Now, you don’t want to single out strains to “quick fix” one problem area. Probiotics come in blends for a reason; getting a variety of billions of organisms is the most beneficial way to consume probiotics to encourage the population of good bacteria to the party in your gut. Diversify, diversify, diversify! They work best together, and personalizing your probiotic cocktail with these guidelines will eventually fine tune your digestion. Just remember to be patient, listen to your gut, and most importantly, take a gander at your stool to see what it’s telling you.

If you are interested in learning more about your poop, we offer stool testing with our 3 month program so you can get to the root cause of your digestive imbalances. We then begin a plan to correct and improve your digestive health! You’ve got nothing to lose (except stool) and lots of great bacteria to gain.


Sarah Greenfield RD, CSSD


16550 Riverside Drive


Studio City CA 91602 



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