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tisdag 7 mars 2023

Pitkäketjuisten essentiellien rasvahappojen osuudet nykyajan dieeteissä

Pohdittavaa! Onko nykyajan suositukset  evoluutionäkökohdasta käsin aivan parhainta mahdollista tieteellistä tietoa ihmisen perustavista  ravitsemuksellisista tarpeista?  Yleensä perustetaan suositukset  ihmisten käyttämään yleiseen  ravintoon nykyaikana eikä  ihmisen evolutionaaliseen  ravitsemukseen esim  satoja vuosia sitten. tosin  tietämys on vain possulkevaa tietoa. Silloin EI OLLUT nykyaan prosessoituja ja modifioituja ja jalostettuja ym tuotteita  ainakaan, vaikka sodan, kadon, ruton ja genosidisten piirteiden  ravinnonsaantiin vaikuttamat asiat lienevät  kaikkina aikoina samanlaisen alkeellisia. 
 
doi: 10.1016/j.plefa.2006.05.010. Epub 2006 Jul 28.

Long-chain polyunsaturated fatty acids in maternal and infant nutrition

Affiliations
Abstract

Homo sapiens has evolved on a diet rich in alpha-linolenic acid  C18:3 n3 (short  omega3)  and long chain polyunsaturated fatty acids (LCP). We have, however, gradually changed our diet from about 10,000 years ago and accelerated this change from about 100 to 200 years ago. The many dietary changes, including lower intake of omega3-fatty acids, are related to 'typically Western' diseases. After a brief introduction in essential fatty acids (EFA), LCP and their functions, this contribution discusses our present low status of notably LCP omega3 in the context of our rapidly changing diet within an evolutionary short time frame. It then focuses on the consequences in pregnancy, lactation and neonatal nutrition, as illustrated by some recent data from our group. We discuss the concept of a 'relative' EFA/LCP deficiency in the fetus as the outcome of high transplacental glucose flux. This flux may in the fetus augment de novo synthesis of fatty acids, which not only dilutes transplacentally transported EFA/LCP, but also causes competition of de novo synthesized oleic acid ( C18:1n9) with linoleic acid for delta-6 desaturation. Such conditions were encountered by us in mothers with high body mass indices, diabetes mellitus and preeclampsia. The unifying factor might be compromised glucose homeostasis. In search of the milk arachidonic acid (AA, C20:4n6) and docosahexaenoic acid (DHA, C22:6n3) contents of our African ancestors, we investigated women in Tanzania with high intakes of freshwater fish as only animal lipid source. These women had milk AA and DHA contents that were well above present recommendations for infant formulae. Both studies stimulate rethinking of 'optimal homeostasis'. Subtle signs of dysbalanced maternal glucose homeostasis may be important and observations from current Western societies may not provide us with an adequate basis for dietary recommendations.  

Essentiellit rasvahapot AA, EPA ja DHA solukalvoissa.

 AA, C20:4 omega6 (Eicosatetraeenihappo eli  arakidonihappo  C20:4 omega 6 linjasta on lähtöaine eikosanoideille. Linolihappo (LA)   kasvikunnasta johtaa tähän arakidonihappoon kehoentsyymien avulla.
EPA, C20:5 (eicosapentaeenihappo)   omega 3 linjasta.  Alfa-linoleenihappo (ALA) kasvikunnasta johtaa tähän EPA:5  rasvahappoon. 
DHA, C22:6 omega 3 linjasta. Docosahexaeenihappoa muodustuu  jatkossa ihmiskehon entsyymeilä .  
 omega 6 linjasta. Myös  kalarasvoista saa näitä pitkiä rasvahappoja valmiina EPA ja DHA muotoa.

Tiedetään, että ihmisen kaikki  solut, joissa  vain on membraaneja, keräävät membraanin lipidirakenteeseen arakidonihappoa (C20:4), koska  se on lähtöaine  solun monissa funktioissa ja varsinkin kudosten korjaantumisissa ja immuunivasteessa.  Entä sitten  paralleelin  omega3-linjan  rasvahappojen merkitys? Niitäkin solumembraanin  fosfolipidit(PL) keräävät rakenteeseensa ja tämä rasvahappojen valinta  fosfolipidirakenteeseen on  solu- ja kudosspesifistä. Koska nämä kolme pitkää tärkeää essentielliä rakennetta ovat hieman erilaisia ja  koska niiden  kertymiseen vaikuttaa dieetin antamat  essentiellit  linjaa muodostavat  alkumuodot kuten linolihapon (C18:2  omega 6)  ja alfalinoleenihapon (C18:3 omega 3)  saanti, niin mitä tiedeään membraaniaanirakennevaikutuksesta?
 
. 2021;62:100106.
doi: 10.1016/j.jlr.2021.100106. Epub 2021 Aug 13.

EPA and DHA containing phospholipids have contrasting effects on membrane structure

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Free PMC article
Abstract

Omega-3 FAs EPA and DHA influence membrane fluidity, lipid rafts, and signal transduction. A clinical trial, Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial, demonstrated that high-dose EPA (4 g/d icosapent ethyl) reduced composite cardiovascular events in statin-treated high-risk patients. EPA benefits correlated with on-treatment levels, but similar trials using DHA-containing formulations did not show event reduction. We hypothesized that differences in clinical efficacy of various omega-3 FA preparations could result from differential effects on membrane structure. To test this, we used small-angle X-ray diffraction to compare 1-palmitoyl-2-eicosapentaenoyl-sn-glycero-3-phosphocholine (PL-EPA), 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (PL-DHA), and 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PL-AA) in membranes with and without 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol. Electron density profiles (electrons/Å3 vs. Å) were used to determine membrane structure, including membrane width (d-space). PL-EPA and PL-DHA had similar membrane structures without POPC and/or cholesterol but had contrasting effects in the presence of POPC and cholesterol. PL-EPA increased membrane hydrocarbon core electron density over an area of ±0-10 Å from the center, indicating an extended orientation. PL-DHA increased electron density in the phospholipid head group region, concomitant with disordering in the hydrocarbon core and a similar d-space (58 Å). Adding equimolar amounts of PL-EPA and PL-DHA produced changes that were attenuated compared with their separate effects. PL-AA increased electron density centered ±12 Å from the membrane center. The contrasting effects of PL-EPA, PL-DHA, and PL-AA on membrane structure may contribute to differences observed in the biological activities and clinical actions of various omega-3 FAs.

Keywords: X-ray diffraction; arachidonic acid; docosahexaenoic acid; eicosapentaenoic acid; membrane structure; omega-3 FAs.