Which Source of Fiber is Best?

Recently, I read and commented on an interesting post by @HealthHabits in which he is conducting a within person trial to determine the effects of various diet & training regimens on insulin levels.  The diets he is examining include Vegetarian, Mediterranean, Standard American (aka Junk food) and Paleo to name a few.

I suggested that he also compare the difference between diets comprised of foods that are more processed that are higher in fiber and those that have similar fiber levels but are less processed food sources, essentially to control for the possible effects of fiber content.

In other words, I would like to see how the level of processing of foods in a given diet, while controlling for calories and fiber content will be associated with insulin levels.

Little did I know that he would call my bluff and ask me to write an introductory article for the Hive explaining my thoughts on how food processing might affect the healthy blood-sugar lowering effects of dietary fiber.

So, here we go….

As it stands, the governing health bodies in North America promote a high fiber diet essentially irrespective of processing level.  They promote whole grain foods that are still quite highly processed compared to the fiber containing less processed foods.  There is also an increase in the use of fiber supplements as this could actually help a diet normally low in fiber become adequate for fiber as per current government recommendations.

I am curious to see if it matters whether an individuals’ fiber amount comes from more processed or less processed food items and what effect this difference in processing/refinement might have on an individuals’ insulin levels.

The obvious hypothesis is that the more processed diet will increase insulin levels much more than the less processed one, independent of the fiber content.  If this happens, then we will have more evidence, albeit judged “anecdotal” by the governing bodies I’m sure, that it is critical to eat as few processed foods as possible.

This (further) evidence could be used to suggest to governing health bodies that recommending a number of food servings AND distinguishing between how processed a food is would be a better strategy to encourage health and weight control in a population.  It is very likely this lack of distinguishing between more and less processing, while recommending target number of servings of food items is one of the contributing factors that has lead the Western world into its current obesity epidemic.  Maybe this would motivate an independent funded impartial lab to conduct a larger scale trial comparing these diets or even using them as possible treatment arms in an RCT.

The purpose of my suggestion was to control for the high fiber content and test the effect of a processed high fiber diet vs. that which is much less processed.  For example, this could be a government promoted “healthy diet” including some processed foods with higher levels of fiber in them.  Some examples include All Bran buds and original, Fiber 1 original, high fiber breads &/or pastas, fiber supplements, as well as any other food items that one might consider high fiber, but are still relatively highly processed.  Whereas, foods that contain significant fibers but are much less processed include whole fruits, non-starchy & starchy vegetables, Quinoa, Wild Rice, nuts, seeds, legumes, beans, etc…

What do you think???

  • Does it matter where you get your fiber?
  • Is natural better than processed?

[box type=”note”]Doug at Health Habits has promised to run my experiment in the very near future. We will link to that experiment here at the Hive as well. [/box]

If anyone wants to discuss this further, you can comment here or reach me at my website or on Twitter.


- Registered Dietitian trained in Montreal, QC, currently working in Psychiatry and Obesity management in the Golden Horseshoe area of Ontario, Canada. - Research Scientist currently pursuing my PhD in Human Nutritional Biochemistry at McGill University in Montreal, QC. - Husband to my Beautiful, Sexy and Incredibly smart wife, Nicole. - Lover of life, who demands to improve daily and also expects that of others!

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