Every once in a while, I see a paper that makes me chuckle. This was one (thanks, Tod!). This study set out to see what amazing benefits they could get by increasing the fiber in a group of normal American eaters who were eating about 28g of whole grains daily prior to the study.
In two 6 week intervention arms, the study groups ate a low-fiber diet with 0g per day of whole grains, and then the same diet, but with 168g of whole grains. Result: Nothing here to see.
|(From paper linked above. RG - Refined Grain. WG - Whole Grain|
The increased WG intake during the WG arm of the study was accompanied by an increase in plasma alkylresorcinols, which are present in rye, wheat, and barley, and broadly fulfill the criteria to act as biomarkers of intake of WG rye and WG wheat.
All this showed is that the 'human lab rats' ate wheat, rye, and barley. And, the study leaders admit that nearly all of the whole grain intake was from wheat:
In most studies, including the current study, wheat was either the sole or main contributor to WG intake during the intervention. Wheat is high in insoluble and low in soluble fiber, unlike oats, corn, and barley, and it has been suggested that soluble fiber improves glucose metabolism and lowers TC, LDL cholesterol, and BP to a greater degree than insoluble fiber.
Also of surprise to the study leaders--there were no substantial changes in the gut microbiome, particularly the increase in bifidobacteria they were expecting to see, as they explain:
Surprisingly, there were no effects of the WG intervention on the composition of gut microbiota. Previous interventions using WG maize or barley and brown rice reported increased numbers of fecal bifidobacteria... It could be speculated that processing involved in the manufacturing of the WG foods used in the current study may have resulted in a lower content of indigestible, fermentable carbohydrates than the intact grain and therefore a lack of effect on bacterial populations.
Gee...ya think? Let's look closer at these 168g of 'whole grains.' First, how much actual fiber did 168g of whole grains supply?
28 grams per day.
Great, not even the recommended daily allowance set forth by our caring government overlords.
Here's where this massive amount of fiber was from:
That, my friends, is as healthy as one can hope to be on the SAD. These people weren't eating "whole grains" they were eating food labeled "High in Fiber!" and "A great source of whole grains!"
Remember those days?
And all this to get a measly 28 grams of most non-fermentable fiber...that did nothing for them.
Take-home message: Most "fiber-added" foods and wheat products labelled "whole grain" do absolutely nothing healthy for you. You want fiber, you need to look past the food label and get it from places like beans, oatmeal, green bananas, cold/raw potatoes, fruit and various veggies...not pasta, bread, and cereal.
Hope you got a chuckle, too.