How much fiber is enough?

 
We all know that fiber from our diet (e.g., vegetables, fruit, whole grains, beans, and nuts) lowers cholesterol, reduces the risk of stroke and type 2 diabetes, and helps with weight loss. Dietary fiber also lowers the risk of colorectal cancer. However, with the adoption of a westernized lifestyle, the dietary habits of the past have changed dramatically. First, the amount of dietary fiber consumed daily has decreased, and second, the number of eating episodes per day have increased. 

Paleolithic humans subsisted on a wide variety of foraged plants, seeds, nuts, and lean meats from wild animals; this diet is estimated to have included an intake of more than 100 grams of fiber per day. Only within the last 10,000 years, human society has started to rely on a limited number of crops, domesticated animals, and their byproducts. 

Of all modern human populations, Australian aborigines come closest to the diet of the ancestral hunter-gatherers, with a daily dietary fiber intake of 80 to 130 grams. A similar level of dietary fiber intake has been reported for rural Uganda, where Burkitt and Trowell first developed the hypothesis for a protective role of fiber against colorectal cancer.  

 Despite the knowledge of what constitutes a high fiber diet, epidemiological studies on the effects of fiber in western societies have typically considered an intake of 25-30 grams of fiber a day as “a high fiber diet”. Thus, the current recommendation for women is a daily intake of 21-25 grams a fiber, and for men – 30 to 38 grams of fiber. Whereas this categorization is justified since the average fiber intake in western countries is only 15-16 grams a day, it is misleading with respect to the levels of fiber intake that might protect against colorectal cancer and other diseases.
 
Actionable
Add more fiber to your diet. The change in fiber intake should be slow and accompanied by drinking more water. 

And yes, apples do have fiber; however, only one apple a day will not do the trick: a medium size apple has approximately four grams of fiber. Here is a table with the fiber contents in our foods.