Rehmannia root extract concentrates compounds from the Rehmannia glutinosa root. Traditional Chinese medicine uses the root, and this extract offers a convenient way to get a steady amount of active constituents.
Many people take it to support a healthy response to stress and to help regulate immune activity. It also serves as a tonic to nourish the body after illness or during fatigue.
The extract comes in capsules or liquid, with doses depending on the concentration ratio. Keep in mind that rehmannia can lower blood sugar, so monitor glucose if you have diabetes or use blood-sugar medication. It may also thin the blood slightly; be cautious if you take anticoagulants or plan surgery. Due to limited safety data, avoid it during pregnancy and breastfeeding.