α-Linolenic acid is an organic compound found in many common
vegetable oilsVegetable fats and oils are lipid materials derived from plants. Physically, oils are liquid at room temperature, and fats are solid. Chemically, both fats and oils are composed of triglycerides, as contrasted with waxes which lack glycerin in their structure...
.
SystematicallyThe IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry . Ideally, every organic compound should have a name from which an unambiguous structural formula can be drawn. There is...
, it is named
all-
cis-9,12,15-octadecatrienoic acid. In physiological literature, it is given the name 18:3 (
n−3).
α-Linolenic acid is a
carboxylic acidCarboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -COH, usually written -COOH or -CO2H. Carboxylic acids are Brønsted-Lowry acids — they are proton donors. Salts and anions of carboxylic acids are called...
with an 18-carbon chain and three
cisCis may have the following meanings:* "Cis-" as a prefix of Latin origin, meaning "on the same side [as]" or "on this side [of]", with several derived usages:** In chemistry, cis- refers to cis-trans isomerism...
double bonds. The first double bond is located at the third carbon from the
n end. Thus, α-linolenic acid is a
polyunsaturatedPolyunsaturated fatty acids are those that contain more than one double bond.- Methylene-Interrupted Polyenes :These fatty acids have 2 or more cis double bonds that are separated from each other by a single methylene group...
n−3n−3 fatty acids are a family of unsaturated fatty acids that have in common a final carbon–carbon double bond in the n−3 position; that is, the third bond from the methyl end of the fatty acid.Important nutritionally essential n−3 fatty acids are: α-linolenic acid , eicosapentaenoic acid...
(omega-3) fatty acid.
α-Linolenic acid is an organic compound found in many common
vegetable oilsVegetable fats and oils are lipid materials derived from plants. Physically, oils are liquid at room temperature, and fats are solid. Chemically, both fats and oils are composed of triglycerides, as contrasted with waxes which lack glycerin in their structure...
.
SystematicallyThe IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry . Ideally, every organic compound should have a name from which an unambiguous structural formula can be drawn. There is...
, it is named
all-
cis-9,12,15-octadecatrienoic acid. In physiological literature, it is given the name 18:3 (
n−3).
α-Linolenic acid is a
carboxylic acidCarboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -COH, usually written -COOH or -CO2H. Carboxylic acids are Brønsted-Lowry acids — they are proton donors. Salts and anions of carboxylic acids are called...
with an 18-carbon chain and three
cisCis may have the following meanings:* "Cis-" as a prefix of Latin origin, meaning "on the same side [as]" or "on this side [of]", with several derived usages:** In chemistry, cis- refers to cis-trans isomerism...
double bonds. The first double bond is located at the third carbon from the
n end. Thus, α-linolenic acid is a
polyunsaturatedPolyunsaturated fatty acids are those that contain more than one double bond.- Methylene-Interrupted Polyenes :These fatty acids have 2 or more cis double bonds that are separated from each other by a single methylene group...
n−3n−3 fatty acids are a family of unsaturated fatty acids that have in common a final carbon–carbon double bond in the n−3 position; that is, the third bond from the methyl end of the fatty acid.Important nutritionally essential n−3 fatty acids are: α-linolenic acid , eicosapentaenoic acid...
(omega-3) fatty acid. It is an isomer of γ-linolenic acid, a polyunsaturated
n−6n−6 fatty acids are a family of unsaturated fatty acids that have in common a final carbon–carbon double bond in the n−6 position, that is, the sixth bond from the end of the fatty acid.The biological effects of the n−6 fatty acids are largely mediated by their conversion to n-6 eicosanoids that...
(omega-6) fatty acid.
Dietary sources
Seed oils are the richest sources of α-linolenic acid, notably those of
rapeseedRapeseed , also known as rape, oilseed rape, rapa, rapaseed and canola, is a bright yellow flowering member of the family Brassicaceae...
(
canolaCanola is one of two cultivars of rapeseed or Brassica campestris . Their seeds are used to produce edible oil that is fit for human consumption because it has lower levels of erucic acid than traditional rapeseed oils and to produce livestock feed because it has reduced levels of the toxin...
), soybeans, walnuts, flaxseed (
Linseed oilLinseed oil, also known as "flax seed oil" is a clear to yellowish oil obtained from the dried ripe seeds of the flax plant . The oil is obtained by cold pressing, sometimes followed by solvent extraction....
),
perillaPerilla oil is obtained from the seeds of perennial herbs of the genus Perilla, usually Perilla frutescens. The seeds contain 35 to 45 percent oil which is obtained by pressing. Perilla oil is used along with synthetic resins in the production of varnishes...
, chia, and
hempHemp is the name of the soft, durable fiber that is cultivated from plants of the Cannabis genus, cultivated only for industrial use....
. α-Linolenic acid is also obtained from the
thylakoid membranesA thylakoid is a membrane-bound compartment inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. The word "thylakoid" is derived from the Greek thylakos, meaning "sac". Thylakoids consists of a thylakoid membrane surrounding a thylakoid lumen...
of the green leaves of broadleaf plants (the membranes responsible for photosynthesis). Greens, therefore, and animals that eat greens, are often a good source of α-linolenic acid.
| Common name |
Alternate name |
Linnaean name |
% ALA† |
ref. |
| Chia |
chia sage |
Salvia hispanica |
64% |
|
KiwifruitThe kiwifruit, often shortened to kiwi, is the edible berry of a cultivar group of the woody vine Actinidia deliciosa and hybrids between this and other species in the genus Actinidia...
seeds |
Chinese gooseberry |
Actinidia chinensis |
62% |
|
PerillaPerilla is a genus of annual herb that is a member of the mint family, Lamiaceae. In mild climates the plant reseeds itself. There are both green-leafed and purple-leafed varieties which are generally recognized as separate species by botanists. The leaves resemble stinging nettle leaves, being...
|
shiso |
Perilla frutescens |
58% |
|
FlaxFlax is a member of the genus Linum in the family Linaceae. It is native to the region extending from the eastern Mediterranean to India and was probably first domesticated in the Fertile Crescent. This is called as Agasi/Akshi in Kannada, Jawas/Javas or Alashi in Marathi...
|
linseed |
Linum usitatissimum |
55% |
|
| Lingonberry |
cowberry |
Vaccinium vitis-idaea |
49% |
|
PurslanePortulaca is the type genus of the purslane family Portulacaceae, comprising about 40-100 species found in the tropics and warm temperate regions. It is also sometimes known as Rose Moss or more commonly Moss Roses....
|
portulaca |
Portulaca oleracea |
35% |
|
| Sea Buckthorn |
seaberry |
Hippophae rhamnoides L. |
32% |
|
HempHemp is the name of the soft, durable fiber that is cultivated from plants of the Cannabis genus, cultivated only for industrial use....
|
cannabis |
Cannabis sativa |
20% |
|
RapeseedRapeseed , also known as rape, oilseed rape, rapa, rapaseed and canola, is a bright yellow flowering member of the family Brassicaceae...
|
canola |
Brassica napus |
10% |
|
| Soybean |
soya |
Glycine max |
8% |
|
| |
†average val |
Role in nutrition and health
α-Linolenic acid, an
n−3 fatty acid, is a member of the group of essential fatty acids, so called because they cannot be produced within the body and must be acquired through diet. Most seeds and seed oils are much richer in an
n−6 fatty acid,
linoleic acidLinoleic acid is an unsaturated omega-6 fatty acid. It is a colorless liquid. In physiological literature, it is called 18:2. Chemically, linoleic acid is a carboxylic acid with an 18-carbon chain and two cis double bonds; the first double bond is located at the sixth carbon from the omega...
. Linoleic acid is also an essential fat, but it, and the other
n−6 fats, compete with
n−3s for positions in cell membranes and have very different effects on human health.
(See Essential fatty acid interactionsThe actions of the ω-3 and ω-6 essential fatty acids are best characterized by their interactions; they cannot be understood separately.Arachidonic acid is a 20-carbon ω-6 essential fatty acid...
.)
Eicosapentaenoic acidEicosapentaenoic acid is an omega-3 fatty acid. In physiological literature, it is given the name 20:5. It also has the trivial name timnodonic acid...
(EPA; 20:5,
n−3) and
docosahexaenoic acidDocosahexaenoic acid is an omega-3 fatty acid. In chemical structure, DHA is a carboxylic acid with a 22-carbon chain and six cis double bonds; the first double bond is located at the third carbon from the omega end...
(DHA; 22:6,
n−3) play a vital role in many metabolic processes. Although these two fatty acids are readily available from fish, these marine-derived fatty acids can also be synthesized by humans from α-linolenic acid. Humans, however, can obtain α-linolenic acid only through their diets, because the absence of the required 12- and 15-desaturase enzymes makes de novo synthesis from
stearic acidStearic acid or 18:0 is a saturated fatty acid. It is a waxy solid, and its chemical formula is C
18H
36O
2, or CH
316COOH. Its name comes from the Greek word stéar , which means tallow...
impossible. Furthermore, conversion of dietary α-linolenic acid into EPA is limited. Because the efficacy of
n−3 long-chain polyunsaturated fatty acid (LC-PUFA) synthesis decreases down the cascade of α-linolenic acid conversion, DHA synthesis from α-linolenic acid is even more restricted than that of EPA.
It is generally assumed that linoleic acid (LA; 18:2,
n−6) reduces EPA synthesis because of the competition between α-linolenic acid and LA for common desaturation and elongation enzymes.
Studies have found evidence that α-linolenic acid is related to a lower risk of cardiovascular disease.
However, the mechanism is still unclear: The body converts α-linolenic acid into the longer chain fatty acids EPA and DHA, and it is unknown whether the protective effect against
cardiac arrhythmiaCardiac arrhythmia is a term for any of a large and heterogeneous group of conditions in which there is abnormal electrical activity in the heart. The heart beat may be too fast or too slow, and may be regular or irregular....
is exerted by α-linolenic acid itself, or by these
metabolicMetabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter,...
products.
A large 2006 study found no association between total α-linolenic acid intake and overall risk of prostate cancer.
Research has also suggested a major neuroprotective effect of α-linolenic acid in
in-vivoIn vivo refers to experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
models of both global
ischemiaIn medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue...
and KA-induced
epilepsyEpilepsy is a common chronic neurological disorder characterized by recurrent unprovoked seizures...
.
Hydrogenation
In order for manufacturers to achieve desirable traits such as texture, spreadability and mouth feel, as well as to increase shelf life of products, unsaturated vegetable oils are often hydrogenated. Hydrogenation involves reacting the oils with hydrogen gas under pressure and high heat with the aid of a catalyst such as platinum orkel. Fully hydrogenated fatty acids become saturated fatty acids, although as fats they are not suitable for using in food as they are as hard as wax due to the chain lengths of the original unsaturated fatty acids in the vegetable oils. Instead oils are often only partially hydrogenated.
When partially
hydrogenatedHydrogenation is the chemical reaction that results from the addition of hydrogen . The process is usually employed to reduce or saturate organic compounds. The process typically constitutes the addition of pairs of hydrogen atoms to a molecule. Catalysts are required for the reaction to be...
, all unsaturated fatty acids form trans fats.
SoybeanThe soybean or soya bean is a species of legume native to East Asia. The plant is classed as an oilseed rather than a pulse. It is an annual plant that has been used in China for 5,000 years to primarily add nitrogen into the soil as part of crop rotation...
s are the largest source of
edible oilsVegetable fats and oils are lipid materials derived from plants. Physically, oils are liquid at room temperature, and fats are solid. Chemically, both fats and oils are composed of triglycerides, as contrasted with waxes which lack glycerin in their structure...
in the U.S., and 40% of soy oil production is partially hydrogenated. The low
oxidative stabilityRancidification is the chemical decomposition of fats, oils and other lipids. There are three basic types of rancidity. Hydrolytic rancidity occurs when water splits fatty acid chains away from the glycerol backbone in glycerides. Oxidative rancidity occurs when the double bonds of an unsaturated...
of α-linolenic acid is one reason for producers deciding to partially hydrogenate
soybean oilIn processing soybeans for oil extraction and subsequent soy flour production, selection of high quality, sound, clean, dehulled yellow soybeans is very important. Soybeans having a dark colored seed coat, or even beans with a dark hilum will inadvertently leave dark specks in the flour, and are...
.
Regulations forcing the listing or banning of trans fats have spurred the development of low-α-linolenic acid soybeans. These yield a more stable oil requiring hydrogenation less often, and therefore providing trans-free alternatives into many applications such as frying oil.
Several consortia are bringing low-α-linolenic acid soy to market.
DuPontE. I. du Pont de Nemours and Company , commonly referred to as DuPont or Du Pont, is an American chemical company that was founded in July 1802 as a gunpowder mill by Eleuthère Irénée du Pont. DuPont is currently the world's second largest chemical company in terms of market capitalization and...
's effort involves
silencingGene silencing is a general term describing epigenetic processes of gene regulation. The term gene silencing is generally used to describe the "switching off" of a gene by a mechanism other than genetic modification...
the FAD2 gene that codes for
Δ6-desaturaseA Desaturase is an enzyme which removes two hydrogen atoms from an organic compound, creating a carbon/carbon double bond. Desaturases are classified as...
, giving a soy oil with very low levels of both α-linolenic acid and LA. Monsanto Company has introduced to the market
VistiveVistive is a brand name for Monsanto Company's line of soybean seed that was introduced in 2005. Currently the only Vistive seed on the market is a low-linolenic soybean that reduces or eliminates trans-fatty acids...
their brand of low α-linolenic acid soybeans.
Cardiovascular
Dietary α-linolenic acid has been assessed for its role in cardiovascular health. Clinical benefits have been seen in some but not all studies. Still, a review in 2005 concluded "The weight of the evidence favors recommendations for modest dietary consumption of α-linolenic acid (2 to 3 g per day) for the primary and secondary prevention of
coronary heart diseaseCoronary artery disease is the end result of the accumulation of atheromatous plaques within the walls of the coronary arteries that supply the myocardium with oxygen and nutrients...
."
Drying oils
α-Linolenic acid is the most abundant unsaturated component of several
drying oilA drying oil is an oil that hardens to a tough, solid film after a period of exposure to air. The term "drying" is actually a misnomer - the oil does not harden through the evaporation of water or other solvents, but through a chemical reaction in which the components crosslink by the action of...
s (e.g.
perillaPerilla oil is obtained from the seeds of perennial herbs of the genus Perilla, usually Perilla frutescens. The seeds contain 35 to 45 percent oil which is obtained by pressing. Perilla oil is used along with synthetic resins in the production of varnishes...
,
walnutWalnuts are plants in the family Juglandaceae. They are deciduous trees, 10–40 meters tall , with pinnate leaves 200–900 millimetres long , with 5–25 leaflets; the shoots have chambered pith, a character shared with the wingnuts but not the hickories in the same family.The 21 species...
and
linseed oilLinseed oil, also known as "flax seed oil" is a clear to yellowish oil obtained from the dried ripe seeds of the flax plant . The oil is obtained by cold pressing, sometimes followed by solvent extraction....
s.)
See also
- Essential fatty acid
Essential fatty acids, or EFAs, are fatty acids that cannot be constructed within an organism from other components by any known chemical pathways, and therefore must be obtained from the diet. The term refers to fatty acids involved in biological processes, and not those which may just play a...
- List of n−3 fatty acids
- Essential nutrient
An essential nutrient is a nutrient required for normal body functioning that either cannot be synthesized by the body at all, or cannot be synthesized in amounts adequate for good health , and thus must be obtained from a dietary source. Some categories of essential nutrients include vitamins,...