Since many "alternative" or complementary products are considered as a more gentle form of medicine, people choose to use them. The German Institute for Quality and Efficiency in Health Care has now analysed the recent studies on several products and released the results along with a guide for consumers. For instance, St John's wort (hypericum) could help to ease mild depression, but it does not help with severe depression. It also probably cannot help with the symptoms of premenstrual syndrome (PMS). However, calcium and vitamin B6 (pyridoxine) might help relieve premenstrual syndrome. On the other hand, evening primrose oil has not been proven to help. Conflicting research results in recent years have caused confusion and controversy about St. John's wort, According to the Institute. It concluded this is partly because the effects vary from product to product, and the effect depends as well as on how severe depression is.