By April Segal, PharmD, APh, BCPS, Remedy Pharmacy Owner
What ‘Prebiotics’ actually ARE-- and whether or not we need them-- remains a huge topic of debate! The definition has gone through some twists and turns over the years, and while certain key points remain constant, a lot more may go into ‘prebiotic’ action than initially speculated. Let’s discuss!
How to Approach Prebiotics
You may be familiar with the phrase that prebiotics are ‘food for your microbiome’. The term ‘prebiotic’ was coined about 20 years ago, when researchers G R Gibson and M B Roberfroid discovered that certain plant carbohydrates (i.e. inulin) helped spur the growth of the gut-bacteria strain Bifidobacterium (1). Since then, their findings have served as a guideline for what could constitute a ‘true’ prebiotic.
Specifically, a prebiotic would need to:
1) Remain resistant to digestive acids and enzymes.This is to ensure they reach the colon relatively intact. Once there, they must
2) Only stimulate the activity of specific ‘beneficial’ bacteria strains-- Lactobacillus and Bifidobacterium, almost exclusively.
As research on gut ecology grows, we see how such strict parameters which were initially placed on this definition can detract from a holistic understanding of gut health. By only giving one or two specific strains our attention (or even labeling strains as ‘good or bad’ at all!), we run the risk of losing out on the benefits that arise from supporting true microbiome diversity.
In their proposal for a new prebiotic definition, researchers Dr. Laure Bindels et. al argue that diversity is better for supporting ecosystems in general, including the gut (2, 13). Nothing in an ecosystem happens in isolation-- similarly, research is discovering that it is highly unlikely for a prebiotic to show the strict selectivity that Roberfroid and Gibson originally stressed (2).
In 2008, the 6th Meeting of the International Scientific Association of Probiotics and Prebiotics (ISAPP) defined “dietary prebiotics” as “a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health”.
The foundational step would, then, be to embrace all types of regular diet prebiotic fiber as staples for a healthy microbiome (there are certain caveats-- more on these in a bit). Although not all fibers offer prebiotic effects (1), they all play important functional roles in holistically supporting microbiome health.
The effects of prebiotics on human health are mediated by fermentation, which is the process of gut flora breaking down prebiotic fiber. Fermentation is KEY, as it creates byproducts that help locally and pass into the bloodstream and benefit your other organs (3). The structure of prebiotics and the bacterial composition of the gut determines what the fermentation products will be, and thus what the effects on your health are.
The fermentation products we are concerned with are called short-chain fatty acids (SCFAs), including lactic acid, butyric acid, and propionic acid. These products can have multiple effects on the body. As an example, propionate affects T helper 2 cells in the airways and macrophages, as well as dendritic cells in the bone marrow (16). SCHAs also lower intestinal pH (1), making it an undesirable environment for pathogens. A lower pH also improves nutrient absorption and boosts intestinal lining integrity (3, 8)-- all super important for host immunity!! Since SCFAs can diffuse to blood circulation through enterocytes, prebiotics have the ability to affect not only the gastrointestinal tract but also distant site organs.
Great! So you ask - what is the best way to get these prebiotic fibers? Do we need to take prebiotic supplements or can we get enough from diet alone?
Prebiotics from Diet
All prebiotics are classified as fiber, which is the indigestible portion of plants, but all fibers are not prebiotics. Dietary fiber can be split into two categories: soluble fiber, which is fermented by gut bacteria, and insoluble fiber, which is not fermentable and acts as roughage. Although prebiotics fit the chemical definition of soluble fiber, not all fibers are prebiotics because they are not all metabolized by beneficial gut microbes.
All plants contain prebiotics in small amounts, although certain foods such as onions, garlic, bananas, chicory root, and Jerusalem artichoke contain higher concentrations. Different foods contain different types of prebiotics. For instance, oats and barley have high amounts of beta-glucans, fruit and berries contain pectins, seeds contain gums, onions and Jerusalem artichokes are rich in inulin and oligofructose, and bananas and legumes contain resistant starch.
Prebiotics can also be added to foods such as yogurts, cereals, bread, biscuits, and drinks. To check if a product contains prebiotics look at the ingredient list for:
These can also be sold in supplement form. In order to receive the health benefit of prebiotics, you need to aim to obtain 2.5-10 grams of prebiotics per day (18). The International Scientific Association of Probiotics and Prebiotics recommends getting at least 5 grams of prebiotics per day. This is equal to approximately 2 tablespoons of chicory root, ¾ cup of Jerusalem artichoke, 3 garlic cloves or 1/4 pound of asparagus.
Do you eat these foods regularly? If not, your microbiome may be suffering. It can be hard to get the adequate amount of prebiotics through your diet unless you are intentionally selecting food known for their prebiotic content. Many people end up supplementing with prebiotics or otherwise using a synbiotic product (a supplement that contains both a prebiotic and a probiotic) to ensure they get enough prebiotic to support their microbiome.
Products that combine prebiotics + probiotics are called ‘synbiotics’. Their goal is to maximize the efficacy of the product’s bacteria strains. A few others that we stock at Remedy include:
Probiotic-10 + Inulin by Now - Supplemental inulin is derived from artichoke, asparagus, and chicory root (15). More common sources of dietary inulin include onions, garlic, leeks, yams, and bananas (15). Inulin is the first prebiotic shown to greatly spur the activity of Bifidobacterium and Lactobacillus (1).
Saccharomyces Boulardii plus MOS - Mannose oligosaccharide (MOS) is a well-studied prebiotic shown to alter the gut microbiome. Studies on obese mice have shown the presence of MOS correlates with improved levels of butyrate, lower body weight, and decreased inflammation (10).
All-Flora Probiotic - Includes a prebiotic blend of fermented aloe and carminative herbs to promote digestive regularity, like organic peppermint, coriander, cardamom, and artichoke. This formula is derived from whole foods for easier absorption. This one is a fan favorite for Remedy patients that run on the more constipated side.
Probiomed Infant - A synergistic combination of seven diverse, well-researched Lactobacillus and Bifidobacterium probiotic bacteria strains, Human Milk Oligosaccharides and NutraFlora® prebiotic fiber which is a Fruto-Oligosaccharide.
The Caveat: Side Effects
Intestinal enzymes cannot break down oligosaccharides and polysaccharides. They are transported to the colon to be fermented by the gut microbiota. Due to this, diarrhea, bloating, cramping, and flatulence can sometimes be experienced when starting a prebiotic. The prebiotics chain length is an influential parameter for the development of their side effects. Interestingly, prebiotics with shorter chain lengths may have more side effects. People with chronic issues such as IBS may be sensitive to prebiotic fibers. The workaround would be to stick to certain fruits and vegetables specifically suited to a low FODMAP diet, like bananas, eggplant, cabbage, kiwi and oats, to name a few (6). Certain probiotic formulas like our Ther-Biotic® Synbiotic this one are clinically designed to suit folks on low-FODMAP diets. It features Sunfiber, a patent prebiotic derived from partially hydrolyzed guar gum (PHGG), which ferments at a slower rate than typical prebiotic fibers (9). This makes it an excellent formula for people who cannot otherwise tolerate common prebiotics because of issues like gas.
Besides chain length, the prebiotic dose can also have an effect. Aim for a daily dose of 2.5–10 g prebiotics, which is what is required to exert their beneficial functions. Most products of prebiotics in the market have doses of 1.5–5 g per portion.
The foods we eat interact with our microbiome to exert broad, synergistic actions that result in overall host health. Ensuring that you are consuming 2.5-10 grams of prebiotics daily either from foods or supplemental prebiotics promotes a healthy microbiome and overall health. If you are unsure whether your diet is feeding your gut flora, or would like a recommendation on a probiotic formula to fit your body’s specific needs, drop by our store or book a complimentary herbalist consultation to speak to one of our clinicians! Shop our online collection of prebiotics and probiotics here!
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