As devastating as it is for human health, few I have come across truly understand the difference between a whole grain or refined carbohydrate. The typical answer include white sugars and flours. The real answer is far more expansive.
The whole grain contains the germ (the bulk of the protective nutrients), endosperm (the calories) and the bran (the fiber). To extend shelf life and increase palatability to the oblivious American public, the germ and bran is lopped off and we’re left with the endosperm–the calories minus some 90% of the phytonutrients that where present in the whole grain. The result is a devastating calorie rich/phytonutrient poor staple consumed by the vast majority of Americans. So “enriched wheat flour,” “sugar” and “high fructose corn syrup” all fall into this category.
In comes the fiber story. There is no doubt that fiber, both soluble (able to be digested by the bacteria in our guts to beneficial compounds) and insoluble (“roughage”-not digestible at all) are good for our gut. This study just expands on this, finding that fiber’s benefits extend to lowering pretty much every other cause of death.
But do not fall into the opposite end of the processed grains spectrum. Many products like fiber supplements and many of the big name breakfast cereals (Quaker, Post, Kellogg’s, etc…) contain only the bran. This leaves out the heavy phytonutrient content of the germ that is also devoid in the refined carbs like enriched wheat flour.
I have no doubt that the benefits of whole grains and dietary fiber are derived not merely from the fiber content, but rather the entire blend of the grain, nut, fruit, vegetable or bean. Remember this next time you read an ingredient label. “Fiber” does NOT appear on the ingredient label of a whole grain.
http://archinte.ama-assn.org/cgi/content/abstract/171/12/1061