evidence: Herbal remedies and traditional medicines are used by millions of people around the world. Chamomile can make us feel soothed and relaxed, while ginger can boost digestion and echinacea is thought to support the immune system. Medicinal herbs, leaves and roots are used to prevent and treat common ailments from colds and anxiety to nausea and skin ailments. [...] Today, plants are helping to cure some of the world's deadliest diseases. According to the World Health Organisation, globally the most common causes of death are heart disease, stroke, chronic obstructive pulmonary disease, respiratory infections and Alzheimer diseases and other dementias. Diarrhoeal diseases, cancer and diabetes are also big killers. There are treatments that were originally derived from nature available for almost all of them. [...] Childhood leukaemia is treated with drugs derived from the Madagascar periwinkle, Catharanthus roseus, a decorative herb native to the island of Madagascar. The Indigenous People of the island traditionally use the plant to treat diabetes. When western researchers were investigating its chemical properties in the 1950s, they realised that extracts from the plant contained chemicals with anti-cancer properties.