Dietary Fibre - ILSI Argentina

18 Concise Monograph Series
FOOD SOURCES
The major food sources of dietary fibre and indigestible
carbohydrates are plant foods such as cereal grains,
legumes, vegetables, fruits and seeds, as shown in
Table 6. The term whole grain is frequently used in
connection with cereals and has recently been redefined
by the AACC. In terms of consumption, the major cereal
grains are wheat, rice, maize, oats and rye. Minor ones
are barley, triticale, millet and sorghum. Buckwheat, wild
rice, amaranth and quinoa are not classified as grains
botanically, but are associated with them in a dietary
context because of their similar composition. The whole
grain consists of a protective hull, beneath which are the
bran layer, the protein-rich aleurone layer, the endosperm
of which 50-75% is starch, and the germ (Figure 2).
Whole grains have a high content of dietary fibre, including
resistant starch and non-digestible oligosaccharides, but are
also rich in nutrients and potentially beneficial phytochemicals
(including phenolic compounds, phytoestrogens
and plant sterols). Most of these are located in the aleurone
and germ fractions of the grain.
TABLE 6
Natural sources of various components of dietary fibre
Fibre component
Cellulose
Hemicellulose
Lignin
ß-glucans
Pectins
Gums
Inulin and
oligofructoses/fructooligosaccharides
Oligosaccharides
Resistant starches See Box 3
(types RS1 and
RS2)
Main food source
Vegetables, woody plants, cereal brans
Cereal grains
Cereal brans, rice and legume hulls,
woody plants
Grains (oats, barley, rye, wheat)
Fruits, vegetables, legumes, sugar beet,
potato
Legumes, seaweed, micro-organisms
(guar, locust bean, carrageenan, xanthan,
gum arabic)
Chicory, Jerusalem artichoke, onions
Human milk, grain legumes
FIGURE 2
Structure of a whole grain
Endosperm
Germ
Bran
Source: Slavin J. Whole grains and human health. Nutrition
Research Reviews 2004;17:99-110. Reprinted with permission