The use of henna, as documented in the Ebers Papyrus (one of the oldest know medical records dating to c. 1550 BCE) is consistent with what we know about henna today.
Henna plants produce the highest levels of lawsone (dye content) in hot climates with iron-bearing soils. Henna plants have differing levels of lawsone in different climates and with different soil conditions. This means that even in optimal growing climates, the henna leaf harvests will be affected by climatic changes as well as changes in soil composition.
Henna has been used for its health benefits, beautification, and to track women’s fertility over millennia. With regular use, henna hair coloring can improve scalp and hair health. With anti-inflammatory and anti-fungal properties, henna is effective against ringworm and other fungal scalp issues.
“Since artisanal herbal hair color is made from pure plant pigments that are affected by climate and soil conditions, my hair color formulations are regularly reviewed and adjusted to produce more consistent color results year over year.” - Jaiya