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What Is the Recommended Daily Amount of Prebiotics?

Posted by Brad Dennis, Ph.D. on

What Is the Recommended Daily Amount of Prebiotics?

As an expert in prebiotics, I often get asked how much prebiotic fiber should one be getting into my diet each day?  That’s the question on a lot of minds, as the concept of prebiotics and their importance to our diet and our health is still in its early days.

The short answer is that right now, there is no broad scientific consensus on a recommended daily serving amount. I’d expect that to change within the next five years as research and studies continue. That said, I would like to share with you what we’ve learned from our historical research and recommendations on dietary fiber as a whole as well as research on various specific prebiotic fibers such as inulin and oligosaccharides.  I will also share what I’ve discovered through my own personal experimentation with prebiotics.

I want to start by noting that though the term prebiotic, itself, is fairly new, humans have had prebiotics in their diet since prehistoric times. Based on the examination of human coprolites (yep, fossilized human poop!), we know that our ancient ancestors were eating foods high in prebiotic fibers; estimates are that they were probably getting close to 135 grams of prebiotic fiber in their daily diets. Even our Neanderthal cousins have been found to have had plenty of fibrous vegetables, berries, and nuts in their diet.

Scientists have been studying prebiotics (though we weren’t calling them that) and their effect on our overall health for decades. In the mid-1990s, the USDA surveyed how much inulin and oligofructose was in the average American’s diet, finding that on average, the mean intake of these two prebiotic fibers was less than 3.5 grams a day for American adults over the age of 19.

From 135 grams per day to less than 3.5? Talk about a significant decrease in our daily consumption of prebiotic fiber! It’s no wonder so many of us suffer from poor gut health.

The research into the benefits of prebiotics has only increased as we’ve become more informed about the importance of our gut to our overall health and well-being. Studies on prebiotics have examined the potential beneficial effects of prebiotics on gut-specific diseases such as Crohn’s and IBS, and how prebiotics may help inflammation related problems like IBD. Prebiotics also aid the body’s ability to absorb minerals like magnesium and calcium.

Dietary Fiber Recommendation

The US Government’s Dietary Guidelines for 2015-2020 state that most Americans aren’t getting enough dietary fiber in their daily diet. And while exactly how much fiber we need can vary slightly, depending on which authority’s data you’re looking at, they are all within the range of 25-40 grams per day. In general, women should be getting 25 grams of fiber per day, and men should be getting 38 grams per day. Best estimates are that most of us are only getting about 15 grams per day—and much of that isn’t from sources that are prebiotic-specific. This difference, about 15 grams on average, is called “The Fiber Gap”. While there’s not been a recent survey, there’s nothing to indicate that our prebiotic consumption has significantly increased since the 1990s, which means most Americans are likely still averaging less than 4 grams of prebiotic fiber a day.

Personal Prebiotic Experiments

When I first got into prebiotics I was very motivated by the Paleo movement. I had been a believer in the premise of the Paleo diet (which is essentially that our food technology has evolved faster than our bodies) since my brother first introduced me to NeanderThin nearly 15 years ago. So after I had started to see some positive effect with my very first prebiotic prototype I began to wonder how much fiber and prebiotics our paleo-ancestors were getting each day. There are several numbers on this, one I’ve already shared, and they generally range from 77 grams to that 135 gram number I mentioned earlier. So I started to experiment. My daily prebiotic dosing was already a heaping tablespoon, which was about 15 grams. I had started with this amount by working backward from the FDA’s recommendations for dietary fiber, The Fiber Gap,  and I was seeing a difference at this level of supplementation. I began to increase my dosage. My first attempt was to take it all the way up to 100g. That didn’t work very well. I found myself bloated, constipated, gassy, and all around unwell. As it turns out these are the symptoms of having too much fiber too quickly. I ceased supplementation until I was well again and tried another time.This time by half. Same results. After several months of experimentation, I eventually developed a safe-for-me protocol for increasing my prebiotic fiber intake. Starting at the fiber levels I was already accustomed to I would increment by a level tablespoon and wait three days. I happened across this number experimentally, but I’ve since found support for the number as three days is about what it takes for your gut to shift as a result of dietary changes. If at the end of three days I was still having symptoms, I would reduce the amount of the increase by half and try again. If at the end three days everything was smooth and easy, sailing, I increased by a level tablespoon again. I repeated this process until I was tolerating six heaping tablespoons of my Oligo30™ prototype. This was about 95 grams a day I had split into two doses, one in the morning, one at night. The 95 grams added to my regular diet put me in the Paleo ranges of prebiotic fiber intake. This level for me was life-changing. All the positive effects I was feeling before, the reduced hunger, reduced anxiety, easier stools, seemed to be magnified ten-fold. I was passing about two easy stools a day, my anxiety problems vanished, my joint swelling disappeared, and I lost weight. It was incredible. I’ve since tried more and have tried less, but for me, 6 heaping tablespoons a day is my magic number. I make sure to take two tablespoons of prebiotics before bed to take advantage of their sleep promoting effects.

Prebiotic Fiber Recommendation

Where does that leave a prebiotic recommendation for you? Before I answer that, let me state clearly that my Ph.D. is in Software Engineering, and I am not a medical professional and anything I suggest should not be construed as medical advice.  That being said, if we aren’t even managing to get enough dietary fiber in our diet, we certainly aren’t getting enough prebiotic fiber. I believe that if you’re eating a diverse diet of fibrous whole, minimally processed vegetables and fruits every day you probably have nothing to worry about. If not, check this article out on some foods you can easily add to your lifestyle to make it richer in prebiotics. It’s always preferred to provide the nutrients your body needs through whole, minimally processed, clean foods, but when you can’t we need supplementation. This is why I formulated my Great Gut Prebiotic Fiber powder to ensure that every person is able to get the amount of prebiotics they need to live a great life and feel normal again. The formula is enough prebiotic fiber to just about close the Fiber Gap as well as increase your daily prebiotic intake by 200-300%. While that’s not the 135 grams our ancestors were getting or the 95 grams a day that I take, that should be enough to make a difference for you.  Ultimately, I would start with the FDA’s recommendations for fiber, making as much of that as possible prebiotic, and then personally experiment to find the optimal amount for you and your microbiome.


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