Fiber
Written By Kelly Dodds
Dietary fibers are types of carbohydrates found in plants that we are unable to break down in our digestive tract to be used for energy. Humans lack the enzymes to break apart the chemical bonds that form fiber polysaccharides. Even though we do not utilize fiber directly, the latest research shows that consuming fiber is essential for our health. Some benefits of eating fiber include removing excess cholesterol from our body to maintain healthy lipid levels, increasing satiety to promote fat loss, reducing spikes in blood glucose and insulin, and eating foods that are high in fiber are usually nutrient-dense– meaning they are a good source of vitamins, minerals, antioxidants, and other beneficial phytonutrients. Most importantly, fiber is necessary to feed trillions of colonies of microbes living in our gut microbiome. Feeding our gut microbes a wide variety of fibers has many health benefits, and not feeding them enough fiber can be detrimental to us. Unfortunately, only about 5% of Americans meet their daily recommended amount of fiber daily. This is thought to contribute to the obesity and chronic disease epidemics happening in this country. Our “Western diet” consists of lots of processed, shelf-stable foods; meaning, fiber is extracted from foods during processing, which contributes to our lack of fiber intake.
We are estimated to have ~100 trillion microbes living in our gut– mostly bacteria, but also fungus, viruses, and other protozoa. These colonies of microbes create an ecosystem in our digestive tract that can be symbiotic (beneficial) to us, but sometimes overgrowths or loss of diversity can lead to dysbiosis or infection (pathology). Microbes compete for territory in the gut, they can also have complementary or competing food sources, and their byproducts can harm or benefit neighboring microbial colonies or the host (us). Think about a forest that has millions of different plants and animals coexisting in a balanced ecosystem, but a parasite or fire kills a large area of trees that were a food source or habitat for other species of plants and animals. There would then be a ripple effect leading to further loss of diversity in the forest. Invasive, fast-growing plants could grow where the ecosystem died off, preventing the return of the trees, which would evolve into a different ecosystem. In the gut, antibiotics, food choices, sleep patterns, hormonal changes, stress, and exposure to new microbes all change the ecosystem. Since the lifespan of a microbe is not long (hours to days), the microbiome is constantly evolving.
Some bacteria have been identified as “good” or “bad,” though, 99% of microbes are harmless and beneficial while less than 1% are considered pathogenic. However, sometimes an overgrowth of harmless bacteria leads to unfavorable conditions. Diversity of different types of microbes in the gut has been linked to better health. Similar to diversifying an investment portfolio, the more diversity in types of investments across many sectors, the lower the overall risk. Likewise, diversity in microbiome colonies keeps microbes in check, so that one can’t gain more resources and territory that can lead to harmful conditions in our body. This is why it is important to eat a wide variety of foods that contain different kinds of fibers to diversify our gut microbial colonies. When we eat a variety of foods, especially perishable foods (unprocessed foods like fruits, vegetables, whole grains, legumes (beans/peas), dairy, eggs, meats), we introduce a variety of microbes to our digestive tract that eat those specific food sources. By continuing to regularly eat those varieties of foods, we feed many different strains of microbes so that they can create a balanced ecosystem in the microbiome; and it will allow the “good” microbes to thrive while protecting us from the “bad” microbes that won't have room to take up territory in our gut.
Regularly eating foods that are high in fiber is especially important because many “good” bacteria eat fiber and produce byproducts called short-chain fatty acids (SCFAs). These SCFAs have many benefits for us– including immune, brain, cardiovascular, mitochondrial, and intestinal health. Microbes also produce byproducts such as neurotransmitters that regulate mood, energy, and hunger through the vagus nerve and gut-brain axis. Microbiome research has found correlations between certain microbes and depression, anxiety, cognitive ability, dementia, and many other neurological/behavioral disorders. Additionally, there are several other signaling molecules and vitamins that microbes produce in our gut that have a huge impact on our physiology. Numerous studies have linked the gut microbiome with many chronic diseases, autoimmune diseases, allergies, and a shortened lifespan, which is what makes this new field of study so important to know about… and why eating fiber to feed our microbiome is very important for our health.
Fiber supplementation is not as beneficial as getting a wide variety of fiber (and additional nutrients) from foods. Just as different fruits, vegetables, whole grains, and legumes all look and taste different, they are composed of different types of fiber and phytonutrients. As mentioned above, variety is best. Fiber supplements are usually a single type of extracted fiber, lacking variety and additional phytonutrients we would get from eating the whole food. However, for people who are on special diets or are unable to meet the necessary daily fiber requirements (30-40g), psyllium husk fiber is the best supplemental fiber to use. Studies have shown that a dose of 10g of psyllium husk fiber can lower cholesterol in 3 weeks in patients who had high cholesterol and were lacking sufficient fiber in their diet. It’s important to get plenty of water when taking psyllium husk fiber– a 10g dose should be taken with at least a 250ml (8 ounce) serving of water.
The Protocol:
Aim to get at least 30 grams of fiber daily
Eat a minimum of 4-5 cups of fruits, vegetables, and legumes daily (these are high-fiber, nutrient-dense foods that are great for you and your microbiome). Smoothies count, but juices do not.
Bonus: eat a serving of fermented food on most days to boost your microbiome diversity. Yogurt*, kefir, kombucha, kimchi, sauerkraut, miso, or any other food with “live cultures*.” *Switch up different brands to get different strains of active cultures.