He still advocates PPS 10 years on so perhaps worth a gamble. My understanding is that the evidence behind this product stems from studies on the animal derived category not the current soy category. Cheaper options are 25g or so of carbs post-workout, plain old vitamin C, magnesium, ashwaganda and rhodiola. I routinely take these on a ketogenic diet (given the absence of carbs ‘may’ negatively impact on cortisol post-workout). I do take PPS but will likely not renew it due to expense. However, upshot is that unless you are actively monitoring cortisol through testing it is impossible to state whether any of these have any efficacy.