Effects of increasing dietary arachidonic acid on changes in plasma/serum phospholipid fatty acid concentration. Mice were fed background diets that mimicked the composition of a Western diet with increasing levels (% change, based on energy) of arachidonic acid. The data (mole %) is presented as mean ± SD. Means with the same superscript within the same row (i.e., individual fatty acid) are not statistically different at (p < 0.05). Groups of bars within each fatty acid without superscripts indicate no significant differences were observed among groups. Abbreviations: AA, arachidonic acid.