Vitex can work but you need to take about 400mg x2 daily... I don't believe there is any definative study that shows wheither or not this is truley a preventative against prolactin gyno, but I do know body builders who have been prone to gyno and while stacking bromo and vitex together have managed to keep it under control.. I myself have never been prone to gyno, but I do take vitex while on tren..just to be safe..a lb of prevention is better than an ounce of pain any day.
One thing to consider here, is the administration of arimidex...You may try around .5mg to 1mg ED to try and prevent high levels of estrogen in your body that may cause prolactin gyno.. Simply put, if you keep estrogen low enough, there won't be enough to cause gyno.