Can you destroy the fiber in smoothies?
For those who are busy, impatient or don’t like to read, the short answer is yes.
For the 1% left who are kind of nerdy like me, hear me out.
I am a fan of green smoothies in the morning. They are quick to make, portable, and make me feel like I’m putting our food processor to good use. Although most of my smoothies aren’t particularly appetizing, you can find lots of recipes online and make yours very tasty.
There are many powerful blenders on the market that will essentially liquefy anything from frozen fruits to kale. However, have you ever wondered if and how high-speed blending alters the foods you eat and your digestive process?
I will provide more evidence-based insight to these questions in the future newsletters. As a start, let’s talk about how super-fine blending affects the fibers in your green smoothies.
Fibers Help Me “Go”, Right?
Yes and No.
Not all fibers are the same in terms of their properties and health benefits. Here is a quick and dirty synopsis:
- If the fiber is poorly fermented, or not degraded by gut bacteria, then it will have an effect on bowel movements. Some have a laxative effect (eg. Wheat bran). Some can improve both diarrhea AND constipation (eg. Psyllium).
- If the fiber is soluble and readily fermented (eg. inulin, wheat dextrin, oatmeal), it will feed the bacteria in the gut. These fibers are “prebiotics”. All prebiotics are fibers, but not all fiber is prebiotic.
- If the fiber is soluble and sticky, or gel forming, it helps control blood sugar and cholesterol. The prime example is oatmeal. There is a scientific yet simple way to test your fiber supplement. You can read about it here.
- Fiber may have one or more of the above-mentioned properties.
What Does Blending Do To Fibers?
Blending can alter a fiber’s solubility and antioxidant activities, but we don’t know much about it yet. What we do know is that high-speed blending cuts the fibers into really fine particles. So if you are using green smoothies to help you “go”, you maybe out of luck.
Size Does Matter!
Certain fibers can improve constipation because they mechanically stimulate the gut and keep more water in the stool. However, studies show that as the fiber particles get smaller, their ability to retain water drastically decreases. Interestingly, small smooth particles also lose the ability to mechanically stimulate the gut.
I don’t know who came up with this crazy idea, but in the 80s and 90s, researchers had volunteers swallow a bunch of small (<2mm in diameter) plastic balls to compare its laxative effect to wheat bran. And guess what they found? The plastic balls and the COARSE wheat bran made the stools bulkier, softer and leave the gut sooner, while the FINE wheat bran pretty much did nothing. So they concluded that… size matters!
What To Do
There is no reason to stop drinking green smoothies. However, if constipation or overly loose stool is a concern, there is a way to make your smoothie work for you.
How about using a cheap blender and simply make your smoothie less smooth?
About the Author
Dr. Lily Semrow is a Board Certified Chiropractic Neurologist who focuses on Neuro-Structural Correction. She has a B.S. in Nutrition and a doctorate in Chiropractic. She has a passion for serving families, and helping people who could not get better through traditional and alternative means.