Flax and Linseed - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 237

Table 11.3 Classification of linseed varieties according to the content of fatty acids

Oleic
acid

Linoleic
acid

Linolenic
acid

Palmitic
acid

Stearic
acid ω 9 ω 6 ω 3

Low content LA, traditional con-
tent ALA

4.9 1.8 16.6 17.6 59.1

High content LA, low content
ALA

5.7 1.4 13.3 73.3 6.3

Medium content LA, medium
content ALA

5.3 1.6 15.5 41.2 36.4

Comment: LA linoleic acid (omega 6), ALA linolenic acid (omega-3)

cholesterol were assessed in 36 comparisons from these studies having 1,548
participants, while LDL cholesterol level in blood was observed in 35 comparisons
from 27 studies with 1,471 participants. Flaxseed was found to reduce total cho-
lesterol by 0.10 mmol l 1 . A significant

reduction in total and LDL cholesterol levels was observed when using whole
flaxseeds (

l 1 and LDL cholesterol by 0.08 mmol

l 1 , respectively) and lignans (

0.21 and 0.16 mmol 0.28 and

l 1 , respectively), but not with flax oil. Cholesterol decrease was
more significant in women (especially those at postmenopausal stage) and individ-
uals with high initial concentration of cholesterol. No significant changes were
observed in HDL (high-density lipoprotein) cholesterol and triglycerides.
Flaxseed (Table 11.3 ) contains on average 36-41 % of fat of which approxi-
mately 70 % are polyunsaturated fatty acids (PUFA) and more than half of them is
created by alpha-linolenic acid (ALA, C18, n-3/omega-3/fatty acid) with 50-62 %
from linseed oil. Linoleic acid [LA, C18, n-6 (omega-6)] represents approximately
17 % of all fatty acids. This characteristic corresponds to the linseed varieties with
traditional fatty acid composition of alpha-linolenic acid content [ 26 ]. Flaxseed
with high content (approximately 73 %) of linoleic acid (LA, omega-6) is sepa-
rately categorized from those with very low content of alpha-linolenic acid (ALA,
omega-3) (Table 11.3 ). There is also a completely new type with medium content of
both fatty acids (LA and ALA) as shown in Table 11.3 .

0.16 mmol

Taxonomy and Domestication

The exact geographic origin of flax or linseed ( L. usitatissimum ) is unknown
[ 27 ]. Among the eight independent centers of origin of the world's most important
cultivated plants [ 28 ], Linum species were reported to have probably originated in
four: the Central Asiatic, the Near Eastern, the Mediterranean, and the Abyssinian
Center. Gill [ 29 ] and Rakousky et al. [ 30 ] have also discussed these four probable
centers of flax origin. Alternatively, other researchers believe that Egypt could be a
center of origin [ 31 ] as well as an area east of the Mediterranean toward India
because a diverse form of flax is found in the area [ 31 , 32 ].