Food Fiber: Beyond Just Adding Bulk…It’s Prebiotic! by Cynthia Briscoe
I remember my first macrobiotic cooking class with Aveline Kushi. We drove from Kansas City to Chicago in our Hornet station wagon purchased for $150. Talk about trust in the Universe! The brakes gave out during rush hour traffic upon entering Chicago. Miraculously, we made it to the hotel ballroom where Aveline Kushi lightly floated behind butane-fueled cook stoves preparing a delicate blanched salad. I recall her words of wisdom as she blanched the whole stems of parsley. She advised us to include the stems because, “They are like little toothbrushes in the intestines.” The image her words invoked stuck with me, especially whenever I mince parsley!
This was in the ‘80’s (post Wonder Bread generation), when fiber was recommended to moisten the stool, cleanse the intestinal villi and add bulk in order to move the stool along, thereby preventing constipation and avoiding diverticulitis. The gamut of IBD (Irritable Bowel Disease), such as Crohn’s, ulcerative colitis, gluten intolerance and other subsequent related inflammatory diseases were not yet common medical diagnoses.
Oh, life gets more and more complex! It seems that generationally, diseases progressively compound to mirror our ever-increasingly refined dietary practices. Also, subsequent generations inherit the health conditions arising from the previous generation’s dietary patterns, both at the dinner table and through their genomes.
Here’s the good news, though. Aveline Kushi’s words still ring true, as does the wisdom within a macrobiotic diet centered on whole grains, vegetables and legumes. Current science reveals much more than little fibrous toothbrushes scrubbing the lining of our intestines. While fiber was previously thought of as indigestible to humans, turns out to be an essential food for literally hundreds of commensal bacteria (helpful microbes) in our colon with outstanding implications to our health. Perhaps it is the microbes that are wielding teensy tiny little toothbrushes.
Fiber is found exclusively in whole plant-based foods. You will not find a speck of fiber in flesh foods or dairy foods. Fiber provides a source of energy that plants can utilize, but fiber is virtually unaffected by the digestive enzymes of humans. Fiber travels all the way through the digestive tract intact until it reaches the colon. Most of the excess water and nutrients have already been extracted along the way. At the end of the line, we have colonies of specialized bacteria waiting for the “goodie wagon” to arrive so that they can have dinner. These bacteria thrive on fiber and are able to digest the complex carbohydrate locked within fiber and turn it a myriad of chemical substances and short chain fatty acids.
One of the most notable of these by-products of microbial fiber digestion is butyrate. Butyrate repairs the gut mucosal lining so that toxic waste and pathogens do not leak through the intestinal wall and enter the blood stream. It keeps our heart healthy by removing plaque from our arteries. Butyrate acts as an epigenetic switch that serves a healthy immune system by stimulating the production of regulatory T-cells in the gut. By keeping these friendly microbes fed with plant fiber, we can avoid the cascade of autoimmune diseases such as atherosclerosis, rheumatoid arthritis, IBD, and diabetes to name just a few.
An interesting experiment conducted by Tim Spector, Professor of epidemiology at King’s College in London illustrates the significance of fiber. He collaborated with his 23-year-old son who was working on his dissertation toward a college degree in genetics. His son ate only a fast food diet consisting of burgers, fries and Coke for ten consecutive days. As a special “treat” he could also break the burger monotony by sometimes substituting chicken nuggets in place of the burger. He was also allowed extra “nutrition” in the evening in the form of beer and chips.
His microbial gut profile was carefully monitored and recorded through 3 different labs to ensure that the results were accurate. The lab results showed that in 10 days, he had lost over 1200 microbial species, a 40% reduction in microbial diversity. Spector stated that this experiment had changed he and his son’s perspective on why junk food is bad for us. Previously, they had thought that junk food is bad for you because of the sugar and high fat content. After the experiment, they concluded that the 10-day diet, lacking dietary fiber had literally starved off these helpful bacteria that need fiber to survive.
So next time you are craving French fries, a burger or a soda, think of your colon friends and have mercy upon them. Cook up a yummy dinner with whole grain, veggies and beans. And when you are mincing parsley, remember Aveline Kushi’s wise words and think twice before tossing those stems into the compost.