Prebiotics and Fiber: Supplemental Treasures or Marketing Ploys?

Hi, this is Lindsey Parsons, your host of The Perfect Stool: Understanding and Healing the Gut Microbiome. And today I'm going to be talking about prebiotics and fiber and whether and in what situations you should supplement with them. But first, if you haven't yet, I've been putting this content into newsletter articles with links and additional information, so be sure to pop by HighDesertHealthCoaching.com and subscribe if you want to get those. Also, I have a Facebook group called Gut Healing, which is linked in the show notes, so you're welcome to join and ask your gut health questions there. Now on to today's topic. Because their names are so similar and because they're often combined into one supplement, people often confuse the terms probiotics and prebiotics. And you've probably heard a lot from me about probiotics so far because I'm a big fan, but today we're going to be talking about prebiotics. So the term prebiotic can be used officially as a food ingredient if you can scientifically demonstrate that it resists gastric acidity, meaning your stomach acid doesn't break it down, resist hydrolysis by mammalian enzymes. And hydrolysis is any chemical reaction in which a molecule of water ruptures one or more chemical bonds, also known as we can digest it, and absorption in the upper gastrointestinal tract. It's fermented by the intestinal microflora, and it selectively stimulates the growth and/or activity of intestinal bacteria potentially associated with health and well-being. So in other words, we can't digest it and good bacteria can. That's what a prebiotic is. So the most widely accepted prebiotic supplements are the fermentable oligosaccharides inulin, FOS or fructooligosaccharides or fructans, GOS galactooligosaccharides, and XOS or xylooligosaccharides, and lactulose. And besides being found in supplements, these beneficial substances are handily located in something we could all stand to eat more of: fruits and vegetables, in particular legumes, as well as in whole grains, nuts, and seeds. So the more of these foods you're eating, in particular fruits and vegetables, and the greater variety of them, the more and different types of prebiotics you are getting. And each prebiotic feeds a particular bacteria. So some bacteria eat some prebiotics and other bacteria eat other prebiotics, which is why variety is so important. So some examples of particularly good food sources of prebiotics are onions, leeks, radishes, carrots, coconut meat and coconut flour, flax and chia seeds, tomatoes, bananas, garlic, chicory root, dandelion greens, Jerusalem artichoke, jicama, asparagus, and yams. And if you hadn't heard of some of those or have never eaten some of those, that's my challenge to you is go out and eat one of those this week. So both prebiotics and probiotics nurture the good bacteria required by the digestive tract for proper health, beginning in your mouth. And while probiotics are live, active bacterial cultures capable of multiplying in numbers, prebiotics serve as the food source for that bacteria, but they don't grow or reproduce. So as such, they're considered functional foods because they provide numerous health benefits and they aid in the prevention and treatment of various health conditions and diseases. In particular, prebiotics have been shown to have many positive effects, including increasing the health of the intestinal mucous membrane, which improves digestion and gut health in general, decreasing blood sugar and insulin levels, and consequently the risk of obesity and weight gain, decreasing inflammation lowering cholesterol and the risk for cardiovascular disease, lowering the stress response, helping with hormonal balance, and modulating the immune system and helping manage autoimmune systems. In particular, prebiotic foods can result in significant changes in the composition of the gut microbiome that can help improve immunity, which is shown by improvements in biomarkers and activities of the immune system, including reduced levels of certain cancer-promoting enzymes and bacterial metabolites in the gut. Meaning the byproducts of bacterial digestion. And other benefits of prebiotics include preventing traveler's diarrhea and aiding in the digestion of lactose in those who are lactose intolerant, in particular with the prebiotic GOS. And I'm linking to that in the show notes because I can tell you I was excited to hear that there was a prebiotic that helped with lactose intolerance since I am lactose intolerant. So now that we've talked about some of the benefits of prebiotics, let's get to some of the potential concerns, especially if we're talking about supplementing with prebiotics as opposed to just getting them from food. So first, because you're giving your gut bacteria a sudden pure form of food, you'll likely have some bloating from the gases that the bacteria produce after eating it until the bacteria balance out in your intestines and more of the bacteria that consume the gas made by the other bacteria grow to accommodate it. So start slow and build up either with a supplement or with a new prebiotic food you don't normally consume. So if you think about like when you have the occasional chili with beans or, or meal with beans, if you're not a regular bean eater and you have gas, it's because your system isn't adjusted to the regular consumption. But if you eat them regularly, then your system will adjust. And then in his great book, Healthy Gut, Healthy You, Dr. Michael Ruscio summarizes the research on prebiotics for various gut conditions. So if you have a particular gut condition— this isn't for everybody, but particular people with these conditions— this is what the evidence says. So for irritable bowel syndrome, or IBS, and SIBO, small intestine bacterial overgrowth, the best evidence suggests that prebiotics should be avoided and a low prebiotic diet like the low FODMAP diet should be adopted. And if you're not familiar with low FODMAPs, it stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Say that 10 times fast. And it's a huge list of foods including many fruits and vegetables, whole grains, dairy products, and more that you have to avoid. Keep in mind, this is a temporary diet and an elimination and reintroduction process, not a permanent diet until you've resolved your SIBO or dysbiosis or IBS. I've done the low FODMAP diet on 2 different occasions, and let me tell you, it is very limiting because it excludes 2 very common food ingredients, onion and garlic, including their powders. So imagine trying to go to a restaurant and not eating FODMAPs. It's like, I'll have a plain lettuce salad with steak with salt and pepper and oil and vinegar dressing. So anyway, low FODMAPs is temporary. And, and you know, when I, when I was on the low FODMAPs diet, I had a funny thing happen to me, and I'd be dying to know if anybody else has ever had this experience. But when I'm excluding FODMAPs, after a couple of days, everyone's breath starts to smell like garlic to me, to the point where I can't even kiss my husband because it's just like putrid, which he's not pleased with, of course. So it's interesting how much, you know, our bacteria and die-off— number one, when you take away its food— and how much that die-off can influence our senses. So if you do try low FODMAP, keep in mind it's more about managing symptoms rather than solving the problem, because if you just go back on those foods, the bacteria will regrow. So typically you're going to need to take antimicrobials or other supplements to bring a dysbiotic or overgrown gut into balance. Okay, back to the research on prebiotics. So for IBD or irritable bowel disease, which describes the disorders that involve chronic inflammation of your digestive tract like Crohn's disease and ulcerative colitis, and that show up physically on a colonoscopy, the best evidence suggests that you should avoid supplemental prebiotics as some trials have shown harm from using those supplements. And while you're in a flared state, you should also adopt a low prebiotic state like the low FODMAP diet or the specific carbohydrate diet. And if you thought that low FODMAP was limiting, boy, you should look at LCD, because that eliminates all sources of grains and pseudo-grains like quinoa, even the white ones which you can eat on low FODMAPs, all but the long fermented dairy. It eliminates processed meats, most processed sugar, artificial sweeteners, sugar alcohols, and all processed foods. Suffice it to say, I never went on that diet. In terms of weight loss and gain, while a systematic review of 26 clinical trials concluded that prebiotics are effective in lowering blood sugar, many studies show prebiotic supplements have little or no effect on weight loss, although they may prevent weight gain. So that one's not terribly, uh, solid. Finally, for celiac disease, there's no studies available, but indirect evidence suggests that avoiding prebiotics may be advisable, especially in those who don't fully respond to a gluten-free diet. Now on to another related topic. While I'm talking about prebiotics, I should also mention synbiotics, which are combination products of probiotics and larger amounts of prebiotics than the nominal amounts typically added to a lot of probiotics. So one review that was published in 2014 concluded that the use of synbiotics may promote an increase in the number of Bifidobacteria, glycemic control, which is blood sugar control, reduction of blood cholesterol, balancing the intestinal flora, which of course aids in reducing constipation and, and diarrhea, improves intestinal permeability, and stimulates the immune system. So I will link to that study in the show notes as it does have some particular recommendations on dosages of certain prebiotics and probiotics in order to see the benefits. And then a related topic, of course, is fiber supplements. So while all prebiotics are dietary fibers, not all dietary fibers are prebiotics. But first, let's talk a little bit about what fiber actually is and why it's important. So fiber is the part of the plant-based foods—fruits, vegetables, nuts, seeds, legumes, etc.—that give the food its structure. And there's many, many types of fiber, but we've basically separated fiber into two major types. For simplicity's sake, which is soluble fiber, which dissolves in water and gastrointestinal fluids when it enters the stomach and intestines, and then it's transformed into a gel-like substance, and it helps to positively slow absorption of nutrients during digestion. And then there's insoluble fiber, which passes through the body and becomes a bulking agent to take up and help eliminate the byproducts of metabolic processes, like bacteria that need to be cleared, excess estrogen, and excess waste. By the way, I don't know if you knew this, but 60% of our stool is actually dead bacteria. So both soluble and insoluble fiber play an important role in digestion and the health of microbiome. And while the soluble fiber does feed the bacteria in the gut, the insoluble fiber ensures that nothing harmful lingers too long and creates a state of putrefaction or dysbiosis. So they're both really important. So you can find soluble fiber in supplements like Metamucil, or its simplest form without additives is psyllium husk, which is one of my favorites. Citrucel, which is another form of fiber called methylcellulose, and then supplements like Fibercon, Fiberlax, Equilactin, and Mitrolon, which are all another type of fiber called polycarbophil. And you can also find insoluble fiber in foods like beans, barley, corn, rice bran, whole wheat, vegetables, and apple and pear skins. Other supplemental fibers you may wanna consider include SunFiber, which is made from the guar plant and is actually a low FODMAP fiber. Glucomannan, acacia, pectin, and inulin. In foods, you'll find some of these same and other fibers as well, including cellulose, which is found in legumes, nuts, and bran; inulin, found in bananas, garlic, onions, asparagus, wheat, barley, and rye; pectin, found in apples, strawberries, citrus fruits, carrots, and potatoes, and in smaller amounts in legumes and nuts; beta glucans, found in oats, barley, shiitake mushrooms, and reishi mushrooms; and lignin, found in whole grain foods, legumes, green beans, cauliflower, zucchini, avocado, unripe bananas, and nuts and seeds. So you've probably heard that we all need more fiber, and you've likely heard of the recommended daily allowance of fiber, which is 30 to 38 grams a day for men, 25 grams a day for women between 18 and 50, and 21 grams a day if a woman is 51 and older, or just in general 14 grams of fiber for every 1,000 calories in your diet. But it's important to remember that while fiber can help some people, and probably most people, feel better, especially if you're currently eating a standard American diet that's high in fat and high in sugar and high in simple carbohydrates and low in vegetables, it will definitely help you out, but it can make other people feel worse, especially those with inflammatory bowel disease during a flare. But for anyone who is considering supplementing with fiber, it's a great first step in trying to solve some lower-level bowel issues like constipation, but be sure to do it with a full glass of water or other liquids. And another component of our diets that functions like fiber is called resistant starch. And it's called resistant because it feeds your healthy gut bacteria and it resists digestion by us. So it's naturally found in foods like green bananas and their flour, banana skins, cooked and then cooled potatoes, rice and pasta, beans and legumes, raw potato starch, high maize flour, and oats. So I like to think of resistant starch as free food because of the amazing thing that by cooking and cooling and then optionally reheating to no more than 130 degrees Fahrenheit, foods like potatoes and rice, you can save yourself many calories but eat the same foods. And so what happens is that these starches that you would normally digest convert into resistant starches, so we don't absorb the calories, and then they promote feelings of fullness on top, so you end up eating less. So there's one study that showed that men who had a meal with resistant starch in it versus a placebo ate 90 fewer calories. So one great trick that I learned is that if you buy organic bananas and you use them in smoothies, you can leave the skin on and you'll also get a nice serving of resistant starch. It'll fill you up a lot more without adding calories. And then also I'll tend to make my rice ahead of time and reheat it throughout the week as I eat it, which helps with the resistant starch. But it's also primarily because no one else in my house will eat my whole grain rice, so I have to make it for myself while they're eating white rice every night. We're big rice eaters in our family. So in terms of the research on the benefits of fiber, Michael Ruscio also sums it up in his great book, Healthy Gut, Healthy You. So in terms of digestive tract cancers, the overall impact of supplemental fiber, including resistant starch, on colorectal cancer appears minimal. Most of the data shows no positive impact. For irritable bowel disease, randomized controlled trials have shown fiber to be helpful, but again, when IBD is in remission. So low fiber diets are best for those who are— have active disease or flaring disease. For IBS, fiber has been shown to help IBS symptoms including stool frequency and consistency and quality of life. However, high fiber intake can be problematic for some IBS patients. So you may recall from past shows that something like 80% of IBS is believed to be caused by small intestine bacterial overgrowth. So as you can imagine, if If your small intestine bacteria is overgrown, adding more fuel to the fire wouldn't be ideal. As a result, low fiber diets like low FODMAPs have also been shown to be helpful in IBS, at least until the SIBO is cleared, if that's your underlying cause. And in general, fiber has the most benefit for those with IBS-C or constipation, although I have to say that I have tended more towards the IBS-D and found that supplementing with psyllium husk gave me much better stool quality as it absorbed some of the excess water in my colon. For celiac disease, there's no quality data available regarding the impact of fiber. For type 2 diabetes, high-level science shows supplemental fiber can help lower fasting blood glucose by about 35 points, which is pretty significant, and hemoglobin A1c by about 1%, again also significant. If you take a 6.6 A1c and, and drop it to a 5.6, you've gone from pre-diabetic to healthy. Yeah, so that's with the A1c in patients with type 2 diabetes. But if you already have really healthy blood sugar, the supplemental fiber will have less of an effect. For heart health, supplemental fiber may cause a small decrease in blood pressure and cholesterol levels, but there doesn't appear to be a super clear benefit for heart disease from fiber supplementation. For obesity and weight loss, there was a review paper that showed the average weight loss from fiber supplementation was around 4.2 pounds. So it's not huge, but it's something. The viscous fibers, the gel-forming type, might be best for weight loss, but they can also cause digestive side effects. So overall, it's not a super big weight loss method, but it may help. And now I wanted to talk about a study from 2018 related to fiber that seems to have gone virtually unnoticed in the functional health world because I never hear anyone talking about it, but it didn't escape my notice. So researchers at the University of Toledo found a link between refined dietary fiber, gut bacteria, and liver cancer, at least in mice. So this study challenges the conventional wisdom that dietary fiber is good no matter how you get it. So you may see in a lot of processed foods that chicory root is used as a source of inulin to add fiber to foods. And in this study, they gave the mice this chicory root inulin and they developed liver cancer. And the ones that developed liver cancer had altered and elevated gut bacteria or dysbiosis. And what was interesting was the researchers also gave inulin to mice that were treated with broad spectrum antibiotics to deplete their gut bacteria, and those ones didn't develop liver cancer. So it was clearly the impact of the fiber on the bacteria that was at the root of the cancer. So given this was just on mice, it was just one study, probably the biggest takeaway is that fortifying processed foods with refined soluble fiber may not be safe or advisable for people with SIBO or dysbiosis whose abnormal fermentation of the fiber could potentially increase their susceptibility to liver cancer. But of course, it's just one study and it's on mice, so you have to take that all with a grain of salt. So I will link to that study in the show notes. On the other hand, there are also studies supporting the positive effects of fiber, in particular in kidney disease. So there was a 12-week single-blind study published in 2014 in the Journal of Renal Nutrition that found that supplemental inulin was beneficial, in particular with increasing stool frequency. And while many people with chronic kidney disease don't get enough fiber because many fiber sources are too high in potassium and phosphorus, if you have kidney disease and wanna get more fiber, do, do it carefully with your doctor's advice and support. And I will link to that one as well. And speaking of stool frequency, in case you weren't sure, ideal stool frequency is around 1 to 2 bowel movements a day. So it is important to keep the GI tract moving, which fiber does. And this can also help prevent diverticulosis, or those pockets that develop inside the colon, which can become diverticulitis when they become inflamed or infected, which is a very painful condition that can lead to bowel surgery. So do keep that bowel moving regularly. That's very important. So to sum it all up, what am I doing with all this information if I'm just an average person? So my general approach to fiber and prebiotics has been to get it from my diet rather than to supplements. So I'm always trying to eat tons of fruits and vegetables. Although I will say that prior to solving all my bowel issues, I did have success with a tablespoon of psyllium husk in my smoothies, and I now put it in my keto bread. And Jason Harolek, a naturopath, probiotic researcher, and esteemed university lecturer, recommends aiming for 40 different whole plant foods a week. So next time you're shopping, try and pick one new fruit or vegetable you've never tried and incorporate it into your diet. And then maybe add another one the following week. And just because you like the broccoli and you've finally gotten the kids to eat it, don't just buy broccoli every week. Like, switch it up, get something different, try new recipes. And so I'm actually going to include a few of my favorite vegetable recipes to the show notes to inspire you, and also my favorite salad recipe. It's not really a recipe per se, just all the stuff I put in my salad. And I hope that'll inspire you to get a bunch of different fruits and vegetables. I posted on my Facebook page the 40 that I managed to eat like a week ago, and no one responded with their 40. So I'd love to hear somebody else's 40 fruits and veg if you actually managed to hit it. So that's your challenge. Come to my Facebook page and share your fruits and veg. And if you're someone with IBD and you're flaring, do switch to a low, low fiber diet. But once your flare's over, slowly increase your fiber again to protect yourself from future flares. And if you're considering investing in a prebiotic or a symbiotic supplement, look for research to support its effectiveness, but don't be like the folks I've seen some Facebook groups who are selectively supplementing with certain prebiotics in hopes of increasing very specific individual gut bacteria, because we really just don't know enough about individual gut bacteria to be targeting them, or whether there are other bacteria that can take over if those ones are extinct or low. So just think more about how well your gut is functioning overall. So that's all I've got on prebiotics and fiber. And if you're struggling with your gut health or want to reverse your autoimmune disease naturally, I do free 1-hour breakthrough sessions to talk about what's going on and hear about how health coaching could help. I also offer individual single appointments. My call— phone functional health and nutrition reviews or consultations just to throw all my knowledge at you. If you've already been, you know, looking at a bunch of stuff and you wanna see if I have any other ideas to help you. Sometimes people start that way and then we decide on a, on an appropriate coaching package after that. So I include links in the show notes from there. And if you do listen in Apple Podcasts and haven't yet rated the show, please throw a 5-star rating at me or even write out an actual rating. I'd really appreciate it. Hope you're all staying safe and well and wearing masks if you're out in public and indoor spaces to protect everyone around you and slow the spread of the coronavirus. And here's wishing you all the perfect stool.