Blood is viewed as the mother of qi. It is the dense substance that is developed out of the essences derived from food. Together with influences from the lung and kidney the heart distributes this blood throughout the body. The function of the blood is to nourish the body (esp. the eyes, hair, muscles, tendons/ligaments, and skin. In addition the blood houses the mind.
You need to tonify blood if: anemic, pale lips, pale tongue, scanty menstrual flow, dry eyes, muscle spasms, fatigue, disturbed vision, memory problems, dream disturbed sleep,etc.
Other blood issues in TCM include Blood Stasis, Heat in the Blood.
Foods that Tonify Blood are:
Beef, Liver, green leafy veggies, "green food" mixes, chlorophyll, beets, carrots, seaweed, shitake, yam, apricot, cherry, berries, dates, brown rice, oat, quinoa, legumes, goat milk, salmon and soy.
Herbs: dang gui, goji berries, he shou wu
Foods to avoid: coffee, cold and raw foods
