Fish oil
Fish oils, including Omega-3 fatty acids, are dietary "oils high in unsaturated fats extracted from the bodies of fish or fish parts, especially the livers. Those from the liver are usually high in vitamin A. The oils are used as dietary supplements, in soaps and detergents, as protective coatings, and as a base for other food products such as vegetable shortenings."[1]
Biochemistry
Polyunsaturated fatty acids (PUFAs) metabolic pathways in humans.[2]
Dietary fatty acids can be divided into saturated fatty acids and unsaturated fatty acids.[2] Unsaturated fatty acids can be further divided into monounsaturated and polyunsaturated fatty acids (PUFAs).
PUFAs are divided into two groups: omega-3 fatty acids and omega-6 fatty acids. Whereas omega-3 fatty acid have health benefits due to several mechanisms; omega-6 fatty acids are precursors to arachidonic acid (AA) which leads to thrombaxanes which promote platelet aggregation and vasoconstriction.
Two PUFAs, alpha-linolenic acid (ALA) and linoleic acid (LA) are called essential fatty acids because human function requires them, yet humans cannot synthesize then in vivo.[2] ALA is a omega-3 fatty acid while AL is a omega-6 fatty acid. In North America, LA comprises 89% of the total PUFAs consumed, while ALA comprises 9%.[2] LA is in many commonly used oils, including safflower, sunflower, soy, and corn oil. ALA is in leafy green vegetables and in canola and soybean oil.
Dietary fish oils are converted to eicosapentaenoic acid (EPA) which is further converted to docosahexaenoic acid (DHA). Both EPA and HHA are omega-3 fatty acids.
Benefit to human health
The benefit of fish oil is controversial with conflicting conclusions reached by a negative meta-analysis[3][4] of randomized controlled trials by the international Cochrane Collaboration and a partially positive systematic review[2] by the Agency for Healthcare Research and Quality.
Since these two reviews, a randomized controlled trial reported a reduction on coronary events in Japanese hypercholesterolemic patients.[5]
Subsequent randomized controlled trials have also had conflicting results finding both benefit[5] and harm[6]. Fish oil may benefit people with chronic heart failure.[7]
References
- ↑ Anonymous (2024), Fish oil (English). Medical Subject Headings. U.S. National Library of Medicine.
- ↑ 2.0 2.1 2.2 2.3 2.4 Wang C, Harris WS, Chung M, Lichtenstein AH, Balk EM, Kupelnick B, Jordan HS, Lau J (2006). "n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review". Am. J. Clin. Nutr. 84 (1): 5-17. PMID 16825676. [e] http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=hstat1a.chapter.38290
- ↑ Hooper L, Thompson RL, Harrison RA, Summerbell CD, Ness AR, Moore HJ, Worthington HV, Durrington PN, Higgins JP, Capps NE, Riemersma RA, Ebrahim SB, Davey Smith G (2006). "Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review". BMJ 332 (7544): 752-60. DOI:10.1136/bmj.38755.366331.2F. PMID 16565093. Research Blogging.
- ↑ Hooper L, Thompson RL, Harrison RA, et al (2004). "Omega 3 fatty acids for prevention and treatment of cardiovascular disease". Cochrane Database Syst Rev (4): CD003177. DOI:10.1002/14651858.CD003177.pub2. PMID 15495044. Research Blogging.
- ↑ 5.0 5.1 Yokoyama M, Origasa H, Matsuzaki M, et al (2007). "Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label, blinded endpoint analysis". Lancet 369 (9567): 1090-8. DOI:10.1016/S0140-6736(07)60527-3. PMID 17398308. Research Blogging.
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<ref>tag; name "pmid17398308" defined multiple times with different content - ↑ Raitt MH, Connor WE, Morris C, et al (2005). "Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial". JAMA 293 (23): 2884–91. DOI:10.1001/jama.293.23.2884. PMID 15956633. Research Blogging.
- ↑ Gissi-Hf Investigators (August 2008). "Effect of n-3 polyunsaturated fatty acids in patients with chronic heart failure (the GISSI-HF trial): a randomised, double-blind, placebo-controlled trial". Lancet. DOI:10.1016/S0140-6736(08)61239-8. PMID 18757090. Research Blogging.