Agriculture Reference
In-Depth Information
Figure 2.19. Fiber content of selected common foods. (Data from Agricultural Research Ser-
vice Nutrient Data Laboratory USDA National Nutrient Database for Standard Reference,
Release 17, http: // www.nal.usda.gov / fnic / foodcomp / Data / SR17 / reports / sr17page.htm.)
the grain white, for example, rice or wheat flour. Removal of this layer or layers
removes much of the fiber and many vitamins and minerals.
Eating whole fresh food that has undergone a minimum of processing results in the
intake of the maximum amount of fiber and the eater receives the maximum benefit
from it. As seen in Figure 2.19, barley has the highest fiber content of the common
grains, while passion fruit and almonds in the fruit and nut food groups have high
fiber. Although brown rice has a lower fiber content, it is still important because its
fiber is highly soluble. It should be noted that the outer layers of rice are high in vita-
mins that are lost when they are removed.
2.8
VITAMINS
Vitamins are essential components or molecules required by the body in milligram (mg,
10 23 g) or microgram (mg, 10 26 g) amounts on a daily basis to carry out essential func-
tions. Table 2.7 lists the vitamins, their scientific and common names, and the general
concentration levels in foods. In some cases as with ascorbic acid (vitamin C) and the B
vitamins, they may be relatively simple molecules. In other cases such as vitamin B 12
they may be complex structures as shown in Table 2.8. Vitamins can be divided into
water soluble (Table 2.8) and fat soluble (Table 2.9). This is an important distinction
in that water-soluble vitamins are readily excreted from the body and not stored,
with the exception of B 12 , while fat-soluble vitamins are stored in fat and the liver.
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