90 THE CHINA STUDYDietary fiber is exclusively found in plant-based foods. This mate-
rial, which gives rigidity to the cell walls of plants, comes in thousands
of different chemical variations. It is mostly made of highly complex
carbohydrate molecules. We digest very little or no fiber. Nonetheless,
fiber, having few or no calories itself, helps dilute the caloric density of
our diets, creates a sense of fullness and helps to shut down appetite,
among other things. In doing so, it satisfies our hunger and minimizes
the overconsumption of calories.
Average fiber intake (Chart 4.lO) is about three times higher in China
than in the U.S. 40 These differences are exceptional, especially consider-
ing the fact that many county averages were even much higher.
But according to some "experts" in the U.s., there is a dark side to
dietary fiber. They contend that if fiber intake is too high our bodies
are not able to absorb as much iron and related minerals, which are
essential for health. The fiber may bind with these nutrients and carry
them through our system before we are able to digest them. They say
that the maximum level of fiber intake should be around thirty to thirty-
five grams per day, which is only about the average intake of the rural
Chinese.
We studied this iron/fiber issue very carefully in the China Study. As
it turns out, fiber is not the enemy of iron absorption as so many experts
claim it to be. We measured how much iron the Chinese were consum-
ing and how much was in their bodies. Iron was measured in six differ-
ent ways (four blood biomarkers and two estimates of iron intake) and
CHART 4.10: AVERAGE INTAKES OF DIETARY FIBER, GM/DAY40302010o
China United States