Ph D Fitness Overview Ph D CLA is one of the highest quality conjugated linoleic acid supplements on the market. In the past decade, the potential beneficial effects of Conjugated Linoleic Acid (CLA) on human health have been widely investigated. Several studies have demonstrated that CLA can positively affect body mass & has a beneficial effect on lean muscle mass. Ph D CLA contains the highest concentration of the two active CLA isomers, c 9, t 11 & t 10, c 12, that have been identified as being effective.