Ginger
Against nausea it is the best studied thing in your kitchen. Beyond that, more is claimed than measured.
How to use it
Fresh and grated through food, as tea, or pressed through a juice. For nausea, as tea or as a piece to chew.
The best version
Fresh root with smooth, tight skin. Dried powder is a different product with a different taste and less of the volatile oil.
How to prepare it
Young root does not need peeling, and scraping with a spoon beats peeling with a knife. Grate it fine, because in chunks it gives up almost nothing.
What it does
For nausea and vomiting in pregnancy, ginger has been set against other treatments across 33 randomised trials. Against placebo it came out at a relative risk of 1.68 for improvement, and nausea fell by 1.21 points on a ten-point scale.
Watch out
The reviewers call this evidence low quality themselves, and on vomiting alone ginger did no better than placebo. It helps the sick feeling, not the being sick.