Linoleic acid benefit and side effects
March 22 2017

Linoleic acid is an unsaturated omega-6 fatty acid with an 18-carbon chain and two cis double bonds; the first double bond is located at the sixth carbon from the omega end. Compare this to linolenic acid.

The consumption of omega-3 (n3) and omega-6 (n6) essential fatty acids in Western diets has changed during the 20th century. The availability of linoleic acid (LA) increased from 2.8% to 7% of energy, whereas the availability of α-linolenic acid (ALA) increased from 0.39% to 0.72% of energy. Data show substantial declines in dietary availability (percentage of energy) of n−6 arachidonic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Predicted net effects of these dietary changes included declines in tissue n--3 highly unsaturated fatty acid status. The apparent increased consumption of LA, which was primarily from soybean oil, has likely decreased tissue concentrations of EPA and DHA during the 20th century.

Supplementation
We are constantly being told to take and eat foods with omega 3's, etc. I have been taking a well known omega 3-6-9 complex that contains alpha linoleic acid 200mg and 50 mg linoleic acid from flax oil, and 125mg of linoleic acid from borage oil. However, I just read an article in Hammer Nutrition Endurance newsletter dealing with good and bad effects of cholesterol. This article cites some research detailing negative effects of linoleic acid- linking oxidizing of blood cholesterol with cardiovascular disease, and linoleic acid as a cause. Also, risks of stroke, inflammatory bowel disease, cancer tumors etc. as being linked to excess linoleic fatty acid intake. What thoughts & info do you have on this? Are the above amounts excessive? Would it be better to stick to fish oil and stay away from flax and borage?
    A. Linoleic acid is an omega-6 fatty acid and most Americans consume too much of this fatty acid compared to omega-3 fatty acids. Hence, I don't see the need to take additional amounts through supplements.

Postepy Dermatology Alergol. 2013. Supplementation with long chain polyunsaturated fatty acids in treatment of atopic dermatitis in children. Some recent studies indicate that unsaturated fatty acids, components of cellular membranes and precursors of immunomodulators, play a significant role in the pathogenesis of some symptoms of atopic dermatitis. Since they cannot be synthesized by the human body, they must be provided with nutrition as the so called exogenous fatty acids: linoleic (a precursor of arachidonic acid) and α-linolenic acid (a precursor of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)). Their deficiency facilitates the development of some disorders, e.g. of the cardiovascular system or of the nervous system, or becomes the cause of intensification of ailments in their course e.g. pruritus and dryness in atopic dermatitis.

Anim Science J. 2015. Dietary conjugated linoleic acids increase intramuscular fat deposition and decrease subcutaneous fat deposition in Yellow Breed Simmental cattle.