The high amount of LA in westernised diets contributes to chronic pain

Proposed mechanisms linking high intake of linoleic acid to chronic pain. (a) Dietary LA can be endogenously converted to pro-nociceptive mediators (e.g. 9-HODE). A small fraction of dietary LA is converted to n-6 AA, the precursor to pro- and anti-nociceptive mediators. High intakes of dietary LA competitively inhibit hepatic conversion of n-3 ALA into EPA and DHA. (b) In circulation, LA and HODE are predominantly esterified in cholesteryl esters, triacylglycerol, and phospholipid components of lipoproteins. LA and HODE in circulating LDL are delivered to peripheral tissues via LDL receptors and scavenger receptors. (c) High intakes of LA produce tissue-specific increases in LA and AA and reduction in EPA and DHA content of cellular membranes. (d) High intake of dietary LA increases the production of pro-nociceptive mediators (e.g. 9-HODE and PGE2) and reduces the production of anti-nociceptive lipid autacoids (e.g. EpDPEs and EpETEs). (e) These alterations in nociceptive lipid mediators modulate receptors (e.g. TRPV1, E-prostanoid) creating a biochemical susceptibility to develop chronic pain. LA: linoleic acid; ALA: α-linolenic acid; AA: arachidonic acid; EPA: eicosapentaenoic acid; DHA: docosahexaenoic acid; CE: cholesteryl ester; PL: phospholipid; HODE: hydroxyoctadecadienoic acid; EpDPE: Epoxy-docosapentaenoic acid GPCR, G-protein coupled receptor; TRPV1: transient receptor potential vanilloid, type 1.
http://www.ncbi.nlm.nih.gov/pubmed/27030719

The issue of W3 vs W6 PUFA in the signalling of pain

One must keep in mind that if some fat is reduced in low fat products it is replaced by 

- other fats, id est mainly PUFA of the W6 series 

- carbs mainly simple carbohydrates
It is not simply an issue from the agro industry but also a question of palatability. If you buy a low fat yogurt you will be tempted to sweet it. if you buy a full fat dairy the taste of fat will enough reward your brain.

The high amount of LA in westernised diets contributed to chronic pain