Chia as a source of Antioxidants
and Fiber
Antioxidants
Analysis of chia seed press cake left following removal
of the oil has been shown to possess strong antioxidant
activity (Taga et al., 1984). These antioxidants make
chia a very stable source of ω-3 fatty acids, and
explains why the Aztecs were able to store chia seed and
flour for extended periods of time without becoming
rancid.
The most important antioxidants in chia are chlorogenic
acid and caffeic acid, but it also contains myricetin,
quercetin and kaempferol flavonols. These compounds are
both primary and synergistic antioxidants, and
contribute to the strong antioxidant activity of chia (Taga
et al., 1984; Castro-Martinez et al., 1986).
Caffeic acid and chlorogenic acid, have been shown to
exhibit strong free radical and superoxide scavenging
activity, and to inhibit lipid peroxidation. These
antioxidant properties are significantly stronger than
those of ferulic acid as well as common antioxidants
such as vitamin C (ascorbic acid) and vitamin E (α-tocopherol)
(Kweon et al., 2001). Research also has shown that
quercetin is a powerful antioxidant which can prevent
oxidation of lipids, proteins, and DNA, and that its
antioxidant properties are significantly more effective
than other flavonols (Makris and Rossiter, 2001).
Epidemiological studies indicate that consumption of
high levels of flavonol-rich foods and beverages may
protect against CHD (Hertog et al., 1993, 1995; Hertog
and Hollman,1996; Cook and Samaman, 1996; Knekt et al.,
1996), stroke (Keli et al., 1996), lung cancer (Knekt et
al., 1997), and stomach cancer (Garcia Closas et al.,
1999). In particular flavonoids such as quercetin have
been reported to inhibit platelet adhesion to collagen
and collagen-induced platelet aggregates, and could
explain the relationship between these antioxidants and
a decreased risk of cardiovascular disease (Pignatelli
et al., 2000; Hirovonen et al., 2001).
Lipid oxidation in foods is a problem, particularly with
polyunsaturated ω-6 and ω-3 fatty acids. If not
controlled oxidation produces not only off-flavors in
food (typically a fishy flavor), but also promotes aging
and the degenerative diseases of aging such as cancer,
cardiovascular diseases, cataracts, immune system
decline, and brain dysfunction (Okuyama et al., 1997).
In foods containing antioxidants, oxidation and loss of
palatability due to generation of off-flavors is slowed.
Synthetic as well as natural antioxidants can be added
to foods, however recent trends have been away from
synthetic products because of the suspicion that these
compounds may promote carcinogenicity (White and Xing,
1997).
Chia, when used as an ω-3 source, does not require the
use of artificial antioxidants such as vitamins.
Antioxidant vitamins have been shown to nullify the
protector effects of cardiovascular drugs. As examples
vitamin E, vitamin C, and β-carotene reduce the increase
in high density lipoprotein (HDL) cholesterol levels the
drug simvastatin (a cardiovascular protection compound)
can achieve (Brown et al., 2001).
Dietary Fiber
Dietary fiber has been found to improve the management
of diabetes mellitus, and aids in the prevention of
coronary artery disease and a number of chronic
disorders. For these reasons a variety of organizations
(including the Institute of Medicine - www.iom.edu)
recommend consumption of dietary fiber to be
approximately 25 grams per day, with a range of 20-35
grams being desirable, with the fiber coming from both
soluble and insoluble sources.
The benefits of consuming a high-carbohydrate,
high-fiber, low-fat diet on blood glucose levels has
been demonstrated (Odea et al.,1989). Soluble fiber
increases intestinal transit time, delays gastric
emptying and slows the rate of glucose absorption,
thereby reducing cholesterol absorption (Anderson et
al., 1984; Marlett et al., 1994). These actions lower
postprandial blood glucose, and decrease both total and
LDL-cholesterol concentrations. According to the
American Association of Cereal Chemists (2001) “One of
the means of directly measuring an immediate
physiological effect of dietary fiber and high fiber
foods is the attenuation of glucose level in the blood
for several hours after ingestion of the food”.
Comparing the fiber content of chia with traditional
cereals, chia seed has more fiber per 100 grams of an
edible portion than does barley, wheat, oats, corn, and
rice.
Cereal fibers of medium-to-large particle size appear to
have little effect on small intestine absorption
(Jenkins et al., 1994). Chia seed contains about 5%
soluble fiber which appears as clear mucilage when it is
placed in water. This remains tightly bound to the seed
and has a very large molecular weight, averaging 1.5 x
106 Dalton (Lin and Daniel, 1994). The high viscosity of
chia mucilage renders it more likely to produce desired
metabolic effects than lower viscosity dietary fibers
such as guar or beta-glucan (Wood et al., 1989). Hence
chia is useful as a dietary fiber, and because of this
may possess application in the food industry (Whistler,
1982; Weber et al., 1991; Lin and Daniel, 1994).
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