Alpha-linolenic acid

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α-Linolenic acid
Other names Linolenic acid; α-Linolenic acid; cis,cis,cis-9,12,15-Octadecatrienoic acid; (Z,Z,Z)-9,12,15-Octadecatrienoic acid; Industrene 120
Identifiers
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Properties
C18H30O2
Molar mass 278.43 g//mol
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Alpha-linolenic acid (ALA) is a polyunsaturated omega-3 fatty acid. It is a component of many common vegetable oils and is important to human nutrition.

Chemistry

ALA's molecular formula is C18H30O2 and molar mass 278.43 g/mol. In physiological literature, it is given the name 18:3(n-3). Its systematic chemical name is all-cis-9,12,15-octadecatrienoic acid.[1] Chemically, ALA is a carboxylic acid with an 18-carbon chain and three cis double bonds; the first double bond is located at the third carbon from the omega end. It is an isomer of γ-linolenic acid, an omega-6 fatty acid. Reduction of alpha-linolenic acid gives linolenyl alcohol.


Dietary sources

Flax is a rich source of alpha linolenic acid (ALA)

Seed oils are the richest sources of alpha linolenic acid, notably those of rapeseed (canola), soybeans, walnuts, flaxseed (Linseed), perilla, chia and hemp. Alpha linolenic acid is also obtained from the thylakoid membranes of the green leaves of broadleaf plants (the membranes responsible for photosynthesis).[2] Greens, therefore, and animals that eat greens, are often a good source of ALA.

Common name Alternate name Linnaean name % ALA ref.
Chia chia sage Salvia hispanica 64% [3]
Kiwi Chinese gooseberry Actinidia chinensis 62% [3]
Perilla shiso Perilla frutescens 58% [3]
Flax linseed Linum usitatissimum 55% [3]
Lingonberry cowberry Vaccinium vitis-idaea 49% [3]
Purslane portulaca Portulaca oleracea 35% [3]
Sea Buckthorn seaberry Hippophae rhamnoides L. 32% [4]
Hemp cannabis Cannabis sativa 20% [3]
Rapeseed canola Brassica napus 10% [1]
Soybean soya Glycine max 8% [1]
  average val

Role in nutrition and health

Alpha-linolenic acid is a member of the group of essential fatty acids called omega-3 fatty acids, so called because they are an essential dietary requirement for all mammals. Most seeds and seed oils are much richer in the omega-6 fat linoleic acid. Linoleic acid is also an essential fat, but it, and the other omega-6 fats, compete with omega-3s for positions in cell membranes and have very different effects on human health. (See Essential fatty acid interactions.)

Studies have found evidence that ALA is related to a lower risk of cardiovascular disease.[5][6] However, the mechanism is still unclear: The body converts ALA into the longer chain fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and it is unknown whether the protective effect against cardiac arrhythmia is exerted by ALA itself, or by these metabolic products. Some studies have linked ALA with rapidly progressing prostate cancer[7] and macular degeneration,[8] increasing the risk 70% over control subjects (over those that did not receive ALA). Research has also suggested a major neuroprotective effect of ALA in in-vivo models of both global ischemia and KA-induced epilepsy.[9]

Linolenic acid and trans fats

When partially hydrogenated, all unsaturated fatty acids form trans fats. Soybeans are the largest source of edible oils in the U.S., and 40% of soy oil production is partially hydrogenated.[10][11] The low oxidative stability of ALA is one reason that soybean oil undergoes partial hydrogenation. Regulations forcing the listing or banning of trans fats have spurred the development of low-linolenic soybeans. These yield a more stable oil requiring hydrogenation less often, and therefore providing trans-free alternatives into many applications such as frying oil.[12] Several consortia are bringing low-linolenic soy to market. DuPont's effort involves silencing the FAD2 gene that codes for Δ6-desaturase, giving soy oil very low levels of both α-linolenic and linoleic acids. [13]

Other uses—drying oils

See main article: drying oil

ALA is the most abundant unsaturated component of several drying oils (e.g. perilla, walnut and linseed oils.)

See also

References

  1. 1.0 1.1 1.2 Beare-Rogers (2001). "IUPAC Lexicon of Lipid Nutrition" (pdf). Unknown parameter |accessyear= ignored (|access-date= suggested) (help); Unknown parameter |accessmonthday= ignored (help)
  2. Chapman, David J.; De-Felice, John and Barber, James (1983). "Growth Temperature Effects on Thylakoid Membrane Lipid and Protein Content of Pea Chloroplasts 1". Plant Physiol. 72(1): 225–228. Retrieved 2007-01-15. Unknown parameter |month= ignored (help)
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Seed Oil Fatty Acids - SOFA Database Retrieval
  4. Li, Thomas S. C. (1999). "Sea buckthorn: New crop opportunity". Perspectives on new crops and new uses. Alexandria, VA: ASHS Press. pp. 335–337. Retrieved 2006-10-28.
  5. Penny M. Kris-Etherton, William S. Harris, [and] Lawrence J. Appel, for the Nutrition Committee (2002). "Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and Cardiovascular Disease" (pdf). Circulation. 106 (21): 2747–2757. doi:10.1161/01.CIR.0000038493.65177.94. Retrieved 2006-07-25. PMID 12438303
  6. William E. Connor (2000). "Importance of n-3 fatty acids in health and disease" (pdf). American Journal of Clinical Nutrition. 71 (1 Suppl.): 171S–5S. Retrieved 2006-07-25. PMID 10617967
  7. Brouwer IA, Katan MB, Zock PL (2004). "Dietary alpha-linolenic acid is associated with reduced risk of fatal coronary heart disease, but increased prostate cancer risk: a meta-analysis". Journal of Nutrition. 134 (4): 919–22. Retrieved 2006-11-13. PMID 15051847
  8. Eunyoung Cho, Shirley Hung, Walter C Willett, Donna Spiegelman, Eric B Rimm, Johanna M Seddon, Graham A Colditz and Susan E Hankinson (2001). "Prospective study of dietary fat and the risk of age-related macular degeneration". American Journal of Clinical Nutrition. 73 (2): 209–218. Retrieved 2006-11-13. PMID 11157315
  9. Inger Lauritzen, Nicolas Blondeau, Catherine Heurteaux, Catherine Widmann, Georges Romey and Michel Lazdunski (2000). "Polyunsaturated fatty acids are potent neuroprotectors". The EMBO Journal. 19 (8): 1784–1793. Retrieved 2005-10-06. PMID 10775263
  10. Fitzgerald, Anne and Brasher, Philip. "Ban on trans fat could benefit Iowa". Truth About Trade and Technology. Retrieved January 3. Unknown parameter |accessyear= ignored (|access-date= suggested) (help); Check date values in: |accessdate= (help)
  11. Kinney, Tony. "Metabolism in Plants to Produce Healthier Food Oils (slide #2)" (PDF). Retrieved 2007-01-11.
  12. Monsanto. "ADM To Process Monsanto's VISTIVE™ Low Linolenic Soybeans At Indiana Facility". Retrieved 2007-01-06.
  13. Kinney, Tony. "Metabolism in Plants to Produce Healthier Food Oils" (PDF). Retrieved 2007-01-11.

External links

da:Alfalinolensyre de:Linolensäure lv:Linolēnskābe nl:Alfa-linoleenzuur sv:Alfa-linolensyra


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