The macronutrient composition of food supply in China has altered dramatically in the past 70 years. Fat (oil) has increased more than 4.2-times while the carbohydrate content has declined by 34%. Vegetable oils are the major component of the fat intake and since these oils are rich in linoleic acid, there has been a significant rise in the consumption of this fatty acid (as much as a 4-fold rise). Linoleic acid has essential functions in the body in skin and as a precursor of prostaglandins and related compounds. The current intakes of linoleic acid are well in excess of the minimum requirements. In this review, the effects of a food supply rich in linoleic acid on pain in arthritis and headache, non-alcoholic fatty liver and neural function are explored, with emphasis on lipid mediators derived from linoleic acid and other long chain polyunsaturated fatty acids. The current world food systems have created an imbalance of dietary linoleic acid in relation to n-3 polyunsaturated fatty acids, and an imbalance in the lipid mediators derived from these polyunsaturated fatty acids which may be contributing to sub-optimal health status.