I’m a big fan of supplements. They help people meet their daily required values of important nutrients that are otherwise difficult to get from food alone. However when it comes to fiber, you’re much better off trying to get it from whole fruits and vegetables than from a supplement. For a while now, we’ve known that fiber seems to help lower cholesterol, control appetite and weight, and prevent heart disease, but we didn’t really know why. It seems like the primary reason anyone recommended fiber was to help prevent constipation and keep you regular. Since that seemed to be the primary goal, a swell of fiber supplements appeared to meet this need.
As we learned more and more about the trillions of helpful bacteria that compose your microbiome, we discovered the biggest benefit of fiber was that it kept helpful bacteria happy and healthy, so that they in turn could do the same for you.
We’re now realizing that a lack of fiber causes important bacteria species to either die off completely or start feeding on their host (you) in order to survive. Both of these scenarios cause all kinds of dysfunction such as rampant inflammation, autoimmune diseases, mental and mood disorders, cancers, and obesity. The greater the variety of bacteria in a person’s microbiome, the healthier and more balanced it is. That leads us to the problem with fiber supplements.
Too limited a food source
We may be learning a lot about the microbiome, but the biggest thing we’ve discovered is that we barely understand it at all. There are over 1000 different species of bacteria and they all have unique dietary needs. This means that some respond to certain fiber sources and not others, and many bacteria only eat the metabolites released from other bacteria species. There are many varieties we can’t even study outside of the body because we don’t know what other bacteria need to be present in order for them to survive.
This is why the biggest recommendation to maintain a healthy microbiome is to eat a wide variety of plants. Since we’re in the infancy of understanding the microbiome, the best advice is to take a shotgun approach and consume a little bit of everything. Fiber supplements are basically the exact opposite. They take out every other type of fiber and nutrient that might also be beneficial and leave you with one or two types of fiber. One study looked at a common side effect of a low-fiber diet to see if common fiber types found in supplements and processed foods offered any protection.
Poking holes in your intenstines
Your microbiome is considered the first line of defense of your immune system. Every time you eat something, you take in foreign bacteria and viruses. One way your microbiome prevents these invaders from crossing over from your intestines into your bloodstream is by feeding the intestinal cells short-chained fatty acids so they can create a thick mucosal barrier.
Without the necessary fiber, these bacteria not only don’t feed the intestinal cells, but they actually feed on those same cells in order to survive. This puts serious holes in your defensive wall and leaves you more open to infection and inflammation as invading organisms spread throughout your body.
One mouse study found that feeding mice a mixed diet with plenty of natural plant sources created a strong mucosal barrier that protected them from infection when they were fed a pathogen bacteria that can cause irritation, inflammation, diarrhea and more. They then tested what would happen if this dietary fiber was then removed or if the fiber was replaced with a common fiber supplement. In both cases, it only took a matter of days for their “good” bacteria to start devouring their intestinal lining. When they are then given the pathogen, it quickly spread through their bodies and caused widespread inflammation and illness.
Mix it up
If you are taking a fiber supplement, feel free to continue. It isn’t causing harm and it can feed many of the species in your microbiome, but it is not enough on it’s own. To truly receive the benefits of fiber, you need to consume a wide variety of plants. This will not only provide your microbiome with the nutrients we know it needs, but it will also provide it with the ones we haven’t figured out yet. You can check out my article on the microbiome for some suggestions.