You have the right idea in trying to learn as much as possible about these products. But your research will need to extend beyond pharmacy journals to journals on nutrition and biochemistry. The Internet is a huge source of information, but remember that whatever information you gather from that source should be looked at carefully for reliability. The other important direction for your research is in health behaviour. If we consider why people are searching for alternative or complementary treatments to their regular medical treatments, then we can better understand how to deal with them, and maintain their confidence.
People often feel that the medical system is too impersonal.
They may feel that the various health professionals they deal with do not take enough time to completely understand their health problems. As well, health professionals often do not take a holistic approach, considering the patient's environment and social aspects which may contribute to the causes and the solutions to his or her illness. Alternative practitioners generally do take this holistic view, and can be very successful in the outcomes, possibly more as a result of their patient-centred approach than from the actual treatments prescribed. You can also take this patient-centred approach, inquiring into the reasons why people are seeking these remedies, and showing empathy for their situations and concerns. Then provide information that you feel confident about, even if it is simply to tell them that the product has little evidence of effectiveness.