Ginger has a very long history of use in various forms of traditional/alternative medicine. It has been used to help digestion, reduce nausea and help fight the flu and common cold, to name a few. It has anti-inflammatory properties and helps to ease muscle and joint discomfort.
Ginger may also relieve nausea and vomiting after surgery, and in cancer patients undergoing chemotherapy.
It may be the most effective in higher doses for relieving pregnancy-related nausea, such as morning sickness.
According to a review of 12 studies that included a total of 1,278 pregnant women, 1.1-1.5 grams of ginger can significantly reduce symptoms of nausea. However, ginger had no significant effect on vomiting episodes in this study. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3995184/).
Ginger has a gentle stabilizing effect on blood sugar levels and inflammatory markers. High doses of ginger (2 grams of ginger powder per day) used in a 2015 study of 41 participants with type 2 diabetes, lowered fasting blood sugar by 12%. It also dramatically improved HbA1c (a marker for long-term blood sugar levels), leading to a 10% reduction over a period of 12 weeks.
There was also a 28% reduction in the ApoB/ApoA-I ratio, and a 23% reduction in markers for oxidized lipoproteins. These are both major risk factors for heart disease. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4277626/)
In a controlled trial of 247 people with osteoarthritis of the knee, those who took ginger extract had less pain and required less pain medication. (https://www.ncbi.nlm.nih.gov/pubmed/11710709) (https://www.ncbi.nlm.nih.gov/pubmed/20418184)