Polyunsaturated Fat

Omega-3 | Omega-6 | O-6/O-3 Balance | Arachidonic Acid

Polyunsaturated Fats

  • Liquid at room temperature
  • Two or more pairs of double bonds
    • Lack four or more hydrogen atoms
    • Unpaired electrons at the double bonds make polyunsaturated fats highly reactive
  • Largely found in safflower, sesame, corn, cottonseed, and soybean oils
  • Also found in meats, milk, eggs in form of Arachidonic Acid
  • Large intake may
    • increase the risk for some types of cancer (Enig 1978)
    • linked to decrease in mortality (Hu 2005)
  • Linolenic Acid (Omega-3 Fatty Acids) and Linoleic acid (Omega-6 Fatty Acids)
    • Considered essential, since our body cannot make these fatty acids
  • Stability

Omega-3 fatty acids

  • Classification
    • Type of Polyunsaturated fatty acid
    • Triple unsaturated with three double bonds
    • Omega number indicates position of first double bond
  • Forms
    • Produced by plants
      • ALA (alpha-linolenic acid) or Linolenic acid
    • Animal forms
      • DFA (docosahexaenoic acid)
      • EPA (eicosapentaenoic acid)
    • Animals convert ALA to DFA and EFA
      • process only produces very small amounts of both
      • our ability to utilize ALA diminishes with age
  • Benefits
    • Maintains cardiovascular health
      • reduce triglyceride levels
    • May be important in preventing many health problems including heart disease, rheumatoid arthritis, and cancer
    • Maintains mental clarity
    • Anti-inflammatory properties
      • maintaining proper balance in prostaglandin production
      • may help arthritis and lupus
      • helps lubricate joints
    • Metabolizing important sulphur-containing amino acids
  • Omega-3 sources
    • Fish and fish oils
      • Salmon, mackerel, lake trout, herring, sardines, white (albacore) tuna, cod, halibut, mahi-mahi, catfish, flounder, tilapia, bluefish, whitefish
        • Particularly wild caught
      • Up to 12 oz (340 g) of fatty fish (low mercury) per week recommended
      • Oily fish may contain harmful chemicals, such as dioxins and PCBs
        • UK Food Standards Agency recommendation (FSA 2004)
          • men eat no more than four portions of oily fish per week
          • women and children no more than two portions
      • Krill oil
      • See Omega-3 content in Seafood
    • Walnuts, soybeans, beans, winter squash, avocados
    • Seeds
      • Flaxseed, kiwi seed, perilla seed, sacha inchi seed, and chia seeds
    • Oils
    • Small concentrations in green leafy vegetables (kale, collard greens) and certain algae
    • Foods fortified with DHA from algae
      • fish gets their DHA from algae
    • Grass-fed animals
      • Grass-fed animals provide more omega-3 fats, whereas, grain-fed animals provide more omega-6 fats
    • Organic or flax eggs (Artemis 1992)
      • organic eggs from free range hens allowed to feed on insects and green plants
      • eggs from hens feed flax
    • Supplements
      • Consider taking fish oil or flaxseed oil if diet is insufficient in Omega-3
        • No mercury, dioxin, and PCBs often found in fish
        • Patients with congestive heart failure or chronic recurrent angina should not be urged to consume fish oil or more fish (Leaf 2006)
  • Recommended / Minimum Intake
    • 7 to 11 grams of omega-3 fatty acids each week
    • Minimum 250-500 mg omega-3 fatty acids daily

Omega-6 fatty acids

  • Linoleic acid
    • Family of unsaturated fatty acids
    • Double unsaturated with two double bonds
    • Omega number indicates position of first double bond
  • Too much Omega-6 promotes inflammation
    • Metabolites of omega-6 are more inflammatory (esp. arachidonic acid) than those of omega-3
    • Increases risk of coronary heart disease and other chronic illnesses
    • may counter anti-inflammatory effects of omega-3 fatty acids
      • must be accompanied by adequate Omega-3 to provide protective effects
  • Possible increase risk for cancer
    • May increase the likelihood of development of breast cancer in postmenopausal women (Sonestedt 2008).
  • Sources
    • Plant based
    • Animal based (Arachidonic Acid)
      • meats, eggs, milk
      • Grain feed animals contain more omega-6 fats and less omega-3 fats than grass feed animals
      • Standard store bought eggs contain higher ratio of Omega-6 to Omega-3 fats
      • Farm raised fish contain more Omega-6 fatty acids compared to wild caught fish

Omega-6 & Omega-3 Fatty Acid Balance

  • Ratio of Omega-6 to Omega-3 in diet (Simopoulos 2012)
    • Recommended ratio is 2:1 to 4:1 for overall diet
    • Average Western Diet is 15:1-16.7:1
    • Early man's diet was approximately 1:1
  • Average modern diet contain too much Omega-6 and too little Omega-3
    • Partly due to modern farming and food production practices
    • Omega-6 to Omega-3 ratios in oils:
      • Flaxseed Oil (1:3)
      • Canola Oil (2:1)
      • Olive Oil (13:1)
      • Corn Oil (46:1)
  • Regulates cardiac pro inflammatory pathways
    • A study using pigs suggests the potential cardiovascular benefit of Omega-3 fatty acid is achieved only when Omega-6 fatty acid is reduced concomitantly rather than fed with a high Omega-6 fatty acid diet (Ghosh 2007).
  • Mental Health

Arachidonic Acid

  • Arachidonic Acid is Omega-6, polyunsaturated fat
  • Regulator of localized muscle inflammation and is necessary for the repair and growth of skeletal muscle tissue via conversion to active components such as prostaglandin PGF2alpha.
  • Found in animal food including meats, organ meats, and eggs.
  • Arachidonic Acid can be produced by the body from linoleic acid, an essential fatty acid.
  • Other studies show that dietary linoleic acid intake does not appear to result in increased Arachidonic Acid in adipose tissue (Baylin 2004)
  • Some mammals, such as cats, lack the ability to produce significant amounts of arachidonic acid, making it an essential part of their diet.
  • Arachidonic acid in adipose had been correlated with incidence of myocardial infarctions (Baylin 2004)
    • This relationship does not appear to be related to dietary intake of omega-6 fatty acids including linoleic acid.


Baylin A, Campos H (2004). Arachidonic acid in adipose tissue is associated with nonfatal acute myocardial infarction in the central valley of Costa Rica. J Nutr. 134(11),3095-9.

Colin A, Reggers J, Castronovo V, Ansseau M (2003). Lipids, depression and suicide. Encephale. 29(1), 49-58.

Ghosh S, Novak EM, Innis SM (2007). Cardiac proinflammatory pathways are altered with different dietary n-6 linoleic to n-3 alpha-linolenic acid ratios in normal, fat-fed pigs. Am J Physiol Heart Circ Physiol. 293(5), H2919-27

Simopoulos AP (2002). The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother. 56(8),365-79.

Sonestedt E, Ericson U, Gullberg B, Skog K, Olsson H, Wirfält E (2008). Do both heterocyclic amines and omega-6 polyunsaturated fatty acids contribute to the incidence of breast cancer in postmenopausal women of the Malmö diet and cancer cohort?. The International Journal of Cancer (UICC International Union Against Cancer) 123 (7), 1637–1643.

Trappe TA, Fluckey JD, White F, Lambert CP, Evans WJ (2001). Skeletal muscle PGF(2)(alpha) and PGE(2) in response to eccentric resistance exercise: influence of ibuprofen acetaminophen. The Journal of Clinical Endocrinology and Metabolism 86 (10): 5067–70.

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