Agriculture Reference
In-Depth Information
Fatty acid composition of nut and seed oil
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Alpha-linolenic- acid (ALA, 18:3, omega-3)
Linoleic acid (LA, 18:2, omega-6)
Oleic acid (18:1, omega-9)
Stearidonic acid (SDA, 18:4, omega-3)
Gamma-linolenic acid (GLA, 18:3, omega-6)
Saturated fatty acids
Fig. 16.3.
Fatty acid composition of nut and seed oils.
Note
: Fatty acid spectrum of hemp is for the Finola variety.
Source
: Leson and Associates, 2005.
more omega-6 than omega-3 fatty acids, yet
nutritional scientists recommend maintaining a
ratio of between 2:1 and 4:1; that is, a much
higher
relative
omega-3 consumption.
Many clinical studies implicate this imbal-
ance as a key factor in the rising rate of inflam-
matory disorders and have demonstrated the
benefits of a balanced dietary omega-3/
omega-6 intake. Such benefits include a
reduced risk of atherosclerosis, sudden cardiac
death and some forms of cancer, alleviation of
the symptoms of rheumatoid arthritis, mood
improvement in bipolar disorders and opti-
mized development in infants. It is this proven
need to increase relative omega-3 intake that
ultimately drives public attention and growing
demand for plant- and animal-based sources of
omega-3 fatty acids.
As Fig. 16.3 shows, most common cook-
ing oils contain significant amounts of linoleic
acid, the basic omega-6 fatty acid, but little if
any omega-3s. The reason is not malignance
or ignorance on the part of food companies,
rather convenience. As a triple-unsaturated
fatty acid, the main plant-derived omega-3
fatty acid, ALA (alpha-linolenic acid), oxidizes,
or turns rancid, rapidly, something neither pro-
ducers nor consumers like. A high ALA con-
tent also limits the versatility of food oil, as it
cannot be used for frying. To improve the sta-
bility of cooking oils, industry has, over the last
decades, moved to the use of oils with lower
omega-3 content. This was done through plant
breeding or hydrogenation (hardening) of the
omega-3 present, for example, in soybean oil.
That process is still the main source of trans
fatty acids in our diet, increasingly a suspect
contributor to cardiovascular disease.
Figure 16.4 visualizes the metabolic path-
ways for the omega-3 and omega-6 families.
Part of the EFAs are converted to longer and
more unsaturated fatty acids and ultimately to
eicosanoids, a series of potent hormone-like
substances, such as the well-known prostaglan-
dins, which control the process of inflamma-
tion, fever and pain, reduce blood pressure and
